@subheading gnutls_certificate_get_trust_list
@anchor{gnutls_certificate_get_trust_list}
@deftypefun {void} {gnutls_certificate_get_trust_list} (gnutls_certificate_credentials_t @var{res}, gnutls_x509_trust_list_t * @var{tlist})
@var{res}: is a @code{gnutls_certificate_credentials_t}  type.

@var{tlist}: Location where to store the trust list.

Obtains the list of trusted certificates stored in  @code{res} and writes a
pointer to it to the location  @code{tlist} . The pointer will point to memory
internal to  @code{res} , and must not be deinitialized. It will be automatically
deallocated when the  @code{res} structure is deinitialized.

@strong{Since:} 3.4.0
@end deftypefun

@subheading gnutls_certificate_set_trust_list
@anchor{gnutls_certificate_set_trust_list}
@deftypefun {void} {gnutls_certificate_set_trust_list} (gnutls_certificate_credentials_t @var{res}, gnutls_x509_trust_list_t @var{tlist}, unsigned @var{flags})
@var{res}: is a @code{gnutls_certificate_credentials_t}  type.

@var{tlist}: is a @code{gnutls_x509_trust_list_t}  type

@var{flags}: must be zero

This function sets a trust list in the gnutls_certificate_credentials_t type.

Note that the  @code{tlist} will become part of the credentials
structure and must not be deallocated. It will be automatically deallocated
when the  @code{res} structure is deinitialized.

@strong{Since:} 3.2.2
@end deftypefun

@subheading gnutls_certificate_verification_profile_get_id
@anchor{gnutls_certificate_verification_profile_get_id}
@deftypefun {gnutls_certificate_verification_profiles_t} {gnutls_certificate_verification_profile_get_id} (const char * @var{name})
@var{name}: is a profile name

Convert a string to a @code{gnutls_certificate_verification_profiles_t}  value.  The names are
compared in a case insensitive way.

@strong{Returns:} a @code{gnutls_certificate_verification_profiles_t}  id of the specified profile,
or @code{GNUTLS_PROFILE_UNKNOWN}  on failure.
@end deftypefun

@subheading gnutls_certificate_verification_profile_get_name
@anchor{gnutls_certificate_verification_profile_get_name}
@deftypefun {const char *} {gnutls_certificate_verification_profile_get_name} (gnutls_certificate_verification_profiles_t @var{id})
@var{id}: is a profile ID

Convert a @code{gnutls_certificate_verification_profiles_t}  value to a string.

@strong{Returns:} a string that contains the name of the specified profile or @code{NULL} .
@end deftypefun

@subheading gnutls_pkcs8_info
@anchor{gnutls_pkcs8_info}
@deftypefun {int} {gnutls_pkcs8_info} (const gnutls_datum_t * @var{data}, gnutls_x509_crt_fmt_t @var{format}, unsigned int * @var{schema}, unsigned int * @var{cipher}, void * @var{salt}, unsigned int * @var{salt_size}, unsigned int * @var{iter_count}, char ** @var{oid})
@var{data}: Holds the PKCS @code{8}  data

@var{format}: the format of the PKCS @code{8}  data

@var{schema}: indicate the schema as one of @code{gnutls_pkcs_encrypt_flags_t} 

@var{cipher}: the cipher used as @code{gnutls_cipher_algorithm_t} 

@var{salt}: PBKDF2 salt (if non-NULL then  @code{salt_size} initially holds its size)

@var{salt_size}: PBKDF2 salt size

@var{iter_count}: PBKDF2 iteration count

@var{oid}: if non-NULL it will contain an allocated null-terminated variable with the OID

This function will provide information on the algorithms used
in a particular PKCS @code{8}  structure. If the structure algorithms
are unknown the code @code{GNUTLS_E_UNKNOWN_CIPHER_TYPE}  will be returned,
and only  @code{oid} , will be set. That is,  @code{oid} will be set on encrypted PKCS @code{8} 
structures whether supported or not. It must be deinitialized using @code{gnutls_free()} .
The other variables are only set on supported structures.

@strong{Returns:} @code{GNUTLS_E_INVALID_REQUEST}  if the provided structure isn't an encrypted key,
@code{GNUTLS_E_UNKNOWN_CIPHER_TYPE}  if the structure's encryption isn't supported, or
another negative error code in case of a failure. Zero on success.

@strong{Since:} 3.4.0
@end deftypefun

@subheading gnutls_pkcs_schema_get_name
@anchor{gnutls_pkcs_schema_get_name}
@deftypefun {const char *} {gnutls_pkcs_schema_get_name} (unsigned int @var{schema})
@var{schema}: Holds the PKCS @code{12}  or PBES2 schema (@code{gnutls_pkcs_encrypt_flags_t} )

This function will return a human readable description of the
PKCS12 or PBES2 schema.

@strong{Returns:} a constraint string or @code{NULL}  on error.

@strong{Since:} 3.4.0
@end deftypefun

@subheading gnutls_pkcs_schema_get_oid
@anchor{gnutls_pkcs_schema_get_oid}
@deftypefun {const char *} {gnutls_pkcs_schema_get_oid} (unsigned int @var{schema})
@var{schema}: Holds the PKCS @code{12}  or PBES2 schema (@code{gnutls_pkcs_encrypt_flags_t} )

This function will return the object identifier of the
PKCS12 or PBES2 schema.

@strong{Returns:} a constraint string or @code{NULL}  on error.

@strong{Since:} 3.4.0
@end deftypefun

@subheading gnutls_session_set_verify_output_function
@anchor{gnutls_session_set_verify_output_function}
@deftypefun {void} {gnutls_session_set_verify_output_function} (gnutls_session_t @var{session}, gnutls_verify_output_function * @var{func})
@var{session}: is a @code{gnutls_x509_trust_list_t}  type.

@var{func}: is the callback function

This function sets a callback to be called when the peer's certificate
chain has to be verified and full path to the trusted root has to be
printed.

The callback's function prototype is defined in `x509.h':
int (*callback)(
gnutls_x509_crt_t cert,
gnutls_x509_crt_t issuer,
gnutls_x509_crl_t crl,
unsigned int verification_output);

If the callback function is provided then gnutls will call it, in the
certificate verification procedure.
To verify the certificate chain and print its path uptp the trusted root,
functions such as @code{gnutls_certificate_verify_peers()} ,
@code{gnutls_x509_trust_list_verify_crt()} , and @code{gnutls_x509_trust_list_verify_crt2()} 
can be used. The callback is set in @code{_gnutls_verify_crt_status()}  and
@code{_gnutls_pkcs11_verify_crt_status()} .

@strong{Since:} 3.7.0
@end deftypefun

@subheading gnutls_subject_alt_names_deinit
@anchor{gnutls_subject_alt_names_deinit}
@deftypefun {void} {gnutls_subject_alt_names_deinit} (gnutls_subject_alt_names_t @var{sans})
@var{sans}: The alternative names

This function will deinitialize an alternative names structure.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_subject_alt_names_get
@anchor{gnutls_subject_alt_names_get}
@deftypefun {int} {gnutls_subject_alt_names_get} (gnutls_subject_alt_names_t @var{sans}, unsigned int @var{seq}, unsigned int * @var{san_type}, gnutls_datum_t * @var{san}, gnutls_datum_t * @var{othername_oid})
@var{sans}: The alternative names

@var{seq}: The index of the name to get

@var{san_type}: Will hold the type of the name (of @code{gnutls_subject_alt_names_t} )

@var{san}: The alternative name data (should be treated as constant)

@var{othername_oid}: The object identifier if  @code{san_type} is @code{GNUTLS_SAN_OTHERNAME}  (should be treated as constant)

This function will return a specific alternative name as stored in
the  @code{sans} type. The returned values should be treated as constant
and valid for the lifetime of  @code{sans} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the index is out of bounds, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_subject_alt_names_init
@anchor{gnutls_subject_alt_names_init}
@deftypefun {int} {gnutls_subject_alt_names_init} (gnutls_subject_alt_names_t * @var{sans})
@var{sans}: The alternative names

This function will initialize an alternative names structure.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_subject_alt_names_set
@anchor{gnutls_subject_alt_names_set}
@deftypefun {int} {gnutls_subject_alt_names_set} (gnutls_subject_alt_names_t @var{sans}, unsigned int @var{san_type}, const gnutls_datum_t * @var{san}, const char * @var{othername_oid})
@var{sans}: The alternative names

@var{san_type}: The type of the name (of @code{gnutls_subject_alt_names_t} )

@var{san}: The alternative name data

@var{othername_oid}: The object identifier if  @code{san_type} is @code{GNUTLS_SAN_OTHERNAME} 

This function will store the specified alternative name in
the  @code{sans} .

Since version 3.5.7 the @code{GNUTLS_SAN_RFC822NAME} , @code{GNUTLS_SAN_DNSNAME} , and
@code{GNUTLS_SAN_OTHERNAME_XMPP}  are converted to ACE format when necessary.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0), otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_aia_deinit
@anchor{gnutls_x509_aia_deinit}
@deftypefun {void} {gnutls_x509_aia_deinit} (gnutls_x509_aia_t @var{aia})
@var{aia}: The authority info access

This function will deinitialize an authority info access type.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_aia_get
@anchor{gnutls_x509_aia_get}
@deftypefun {int} {gnutls_x509_aia_get} (gnutls_x509_aia_t @var{aia}, unsigned int @var{seq}, gnutls_datum_t * @var{oid}, unsigned * @var{san_type}, gnutls_datum_t * @var{san})
@var{aia}: The authority info access

@var{seq}: specifies the sequence number of the access descriptor (0 for the first one, 1 for the second etc.)

@var{oid}: the type of available data; to be treated as constant.

@var{san_type}: Will hold the type of the name of @code{gnutls_subject_alt_names_t}  (may be null).

@var{san}: the access location name; to be treated as constant (may be null).

This function reads from the Authority Information Access type.

The  @code{seq} input parameter is used to indicate which member of the
sequence the caller is interested in.  The first member is 0, the
second member 1 and so on.  When the  @code{seq} value is out of bounds,
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.

Typically  @code{oid} is @code{GNUTLS_OID_AD_CAISSUERS}  or @code{GNUTLS_OID_AD_OCSP} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_aia_init
@anchor{gnutls_x509_aia_init}
@deftypefun {int} {gnutls_x509_aia_init} (gnutls_x509_aia_t * @var{aia})
@var{aia}: The authority info access

This function will initialize an authority info access type.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_aia_set
@anchor{gnutls_x509_aia_set}
@deftypefun {int} {gnutls_x509_aia_set} (gnutls_x509_aia_t @var{aia}, const char * @var{oid}, unsigned @var{san_type}, const gnutls_datum_t * @var{san})
@var{aia}: The authority info access

@var{oid}: the type of data.

@var{san_type}: The type of the name (of @code{gnutls_subject_alt_names_t} )

@var{san}: The alternative name data

This function will store the specified alternative name in
the  @code{aia} type. 

Typically the value for  @code{oid} should be @code{GNUTLS_OID_AD_OCSP} , or
@code{GNUTLS_OID_AD_CAISSUERS} .

Since version 3.5.7 the @code{GNUTLS_SAN_RFC822NAME} , and @code{GNUTLS_SAN_DNSNAME} ,
are converted to ACE format when necessary.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0), otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_aki_deinit
@anchor{gnutls_x509_aki_deinit}
@deftypefun {void} {gnutls_x509_aki_deinit} (gnutls_x509_aki_t @var{aki})
@var{aki}: The authority key identifier type

This function will deinitialize an authority key identifier.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_aki_get_cert_issuer
@anchor{gnutls_x509_aki_get_cert_issuer}
@deftypefun {int} {gnutls_x509_aki_get_cert_issuer} (gnutls_x509_aki_t @var{aki}, unsigned int @var{seq}, unsigned int * @var{san_type}, gnutls_datum_t * @var{san}, gnutls_datum_t * @var{othername_oid}, gnutls_datum_t * @var{serial})
@var{aki}: The authority key ID

@var{seq}: The index of the name to get

@var{san_type}: Will hold the type of the name (of @code{gnutls_subject_alt_names_t} )

@var{san}: The alternative name data

@var{othername_oid}: The object identifier if  @code{san_type} is @code{GNUTLS_SAN_OTHERNAME} 

@var{serial}: The authorityCertSerialNumber number

This function will return a specific authorityCertIssuer name as stored in
the  @code{aki} type, as well as the authorityCertSerialNumber. All the returned
values should be treated as constant, and may be set to @code{NULL}  when are not required.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the index is out of bounds, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_aki_get_id
@anchor{gnutls_x509_aki_get_id}
@deftypefun {int} {gnutls_x509_aki_get_id} (gnutls_x509_aki_t @var{aki}, gnutls_datum_t * @var{id})
@var{aki}: The authority key ID

@var{id}: Will hold the identifier

This function will return the key identifier as stored in
the  @code{aki} type. The identifier should be treated as constant.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the index is out of bounds, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_aki_init
@anchor{gnutls_x509_aki_init}
@deftypefun {int} {gnutls_x509_aki_init} (gnutls_x509_aki_t * @var{aki})
@var{aki}: The authority key ID type

This function will initialize an authority key ID.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_aki_set_cert_issuer
@anchor{gnutls_x509_aki_set_cert_issuer}
@deftypefun {int} {gnutls_x509_aki_set_cert_issuer} (gnutls_x509_aki_t @var{aki}, unsigned int @var{san_type}, const gnutls_datum_t * @var{san}, const char * @var{othername_oid}, const gnutls_datum_t * @var{serial})
@var{aki}: The authority key ID

@var{san_type}: the type of the name (of @code{gnutls_subject_alt_names_t} ), may be null

@var{san}: The alternative name data

@var{othername_oid}: The object identifier if  @code{san_type} is @code{GNUTLS_SAN_OTHERNAME} 

@var{serial}: The authorityCertSerialNumber number (may be null)

This function will set the authorityCertIssuer name and the authorityCertSerialNumber 
to be stored in the  @code{aki} type. When storing multiple names, the serial
should be set on the first call, and subsequent calls should use a @code{NULL}  serial.

Since version 3.5.7 the @code{GNUTLS_SAN_RFC822NAME} , @code{GNUTLS_SAN_DNSNAME} , and
@code{GNUTLS_SAN_OTHERNAME_XMPP}  are converted to ACE format when necessary.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_aki_set_id
@anchor{gnutls_x509_aki_set_id}
@deftypefun {int} {gnutls_x509_aki_set_id} (gnutls_x509_aki_t @var{aki}, const gnutls_datum_t * @var{id})
@var{aki}: The authority key ID

@var{id}: the key identifier

This function will set the keyIdentifier to be stored in the  @code{aki} type.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_cidr_to_rfc5280
@anchor{gnutls_x509_cidr_to_rfc5280}
@deftypefun {int} {gnutls_x509_cidr_to_rfc5280} (const char * @var{cidr}, gnutls_datum_t * @var{cidr_rfc5280})
@var{cidr}: CIDR in RFC4632 format (IP/prefix), null-terminated

@var{cidr_rfc5280}: CIDR range converted to RFC5280 format

This function will convert text CIDR range with prefix (such as '10.0.0.0/8')
to RFC5280 (IP address in network byte order followed by its network mask).
Works for both IPv4 and IPv6.

The resulting object is directly usable for IP name constraints usage,
for example in functions @code{gnutls_x509_name_constraints_add_permitted} 
or @code{gnutls_x509_name_constraints_add_excluded} .

The data in datum needs to be deallocated using @code{gnutls_free()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.5.4
@end deftypefun

@subheading gnutls_x509_crl_check_issuer
@anchor{gnutls_x509_crl_check_issuer}
@deftypefun {unsigned} {gnutls_x509_crl_check_issuer} (gnutls_x509_crl_t @var{crl}, gnutls_x509_crt_t @var{issuer})
@var{crl}: is the CRL to be checked

@var{issuer}: is the certificate of a possible issuer

This function will check if the given CRL was issued by the given
issuer certificate.

@strong{Returns:} true (1) if the given CRL was issued by the given issuer,
and false (0) if not.
@end deftypefun

@subheading gnutls_x509_crl_deinit
@anchor{gnutls_x509_crl_deinit}
@deftypefun {void} {gnutls_x509_crl_deinit} (gnutls_x509_crl_t @var{crl})
@var{crl}: The data to be deinitialized

This function will deinitialize a CRL structure.
@end deftypefun

@subheading gnutls_x509_crl_dist_points_deinit
@anchor{gnutls_x509_crl_dist_points_deinit}
@deftypefun {void} {gnutls_x509_crl_dist_points_deinit} (gnutls_x509_crl_dist_points_t @var{cdp})
@var{cdp}: The CRL distribution points

This function will deinitialize a CRL distribution points type.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_crl_dist_points_get
@anchor{gnutls_x509_crl_dist_points_get}
@deftypefun {int} {gnutls_x509_crl_dist_points_get} (gnutls_x509_crl_dist_points_t @var{cdp}, unsigned int @var{seq}, unsigned int * @var{type}, gnutls_datum_t * @var{san}, unsigned int * @var{reasons})
@var{cdp}: The CRL distribution points

@var{seq}: specifies the sequence number of the distribution point (0 for the first one, 1 for the second etc.)

@var{type}: The name type of the corresponding name (gnutls_x509_subject_alt_name_t)

@var{san}: The distribution point names (to be treated as constant)

@var{reasons}: Revocation reasons. An ORed sequence of flags from @code{gnutls_x509_crl_reason_flags_t} .

This function retrieves the individual CRL distribution points (2.5.29.31),
contained in provided type. 

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the index is out of bounds, otherwise a negative error value.
@end deftypefun

@subheading gnutls_x509_crl_dist_points_init
@anchor{gnutls_x509_crl_dist_points_init}
@deftypefun {int} {gnutls_x509_crl_dist_points_init} (gnutls_x509_crl_dist_points_t * @var{cdp})
@var{cdp}: The CRL distribution points

This function will initialize a CRL distribution points type.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_crl_dist_points_set
@anchor{gnutls_x509_crl_dist_points_set}
@deftypefun {int} {gnutls_x509_crl_dist_points_set} (gnutls_x509_crl_dist_points_t @var{cdp}, gnutls_x509_subject_alt_name_t @var{type}, const gnutls_datum_t * @var{san}, unsigned int @var{reasons})
@var{cdp}: The CRL distribution points

@var{type}: The type of the name (of @code{gnutls_subject_alt_names_t} )

@var{san}: The point name data

@var{reasons}: Revocation reasons. An ORed sequence of flags from @code{gnutls_x509_crl_reason_flags_t} .

This function will store the specified CRL distribution point value
the  @code{cdp} type.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0), otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_crl_export
@anchor{gnutls_x509_crl_export}
@deftypefun {int} {gnutls_x509_crl_export} (gnutls_x509_crl_t @var{crl}, gnutls_x509_crt_fmt_t @var{format}, void * @var{output_data}, size_t * @var{output_data_size})
@var{crl}: Holds the revocation list

@var{format}: the format of output params. One of PEM or DER.

@var{output_data}: will contain a private key PEM or DER encoded

@var{output_data_size}: holds the size of output_data (and will
be replaced by the actual size of parameters)

This function will export the revocation list to DER or PEM format.

If the buffer provided is not long enough to hold the output, then
@code{GNUTLS_E_SHORT_MEMORY_BUFFER}  will be returned.

If the structure is PEM encoded, it will have a header
of "BEGIN X509 CRL".

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_export2
@anchor{gnutls_x509_crl_export2}
@deftypefun {int} {gnutls_x509_crl_export2} (gnutls_x509_crl_t @var{crl}, gnutls_x509_crt_fmt_t @var{format}, gnutls_datum_t * @var{out})
@var{crl}: Holds the revocation list

@var{format}: the format of output params. One of PEM or DER.

@var{out}: will contain a private key PEM or DER encoded

This function will export the revocation list to DER or PEM format.

The output buffer is allocated using @code{gnutls_malloc()} .

If the structure is PEM encoded, it will have a header
of "BEGIN X509 CRL".

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

Since 3.1.3
@end deftypefun

@subheading gnutls_x509_crl_get_authority_key_gn_serial
@anchor{gnutls_x509_crl_get_authority_key_gn_serial}
@deftypefun {int} {gnutls_x509_crl_get_authority_key_gn_serial} (gnutls_x509_crl_t @var{crl}, unsigned int @var{seq}, void * @var{alt}, size_t * @var{alt_size}, unsigned int * @var{alt_type}, void * @var{serial}, size_t * @var{serial_size}, unsigned int * @var{critical})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{seq}: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

@var{alt}: is the place where the alternative name will be copied to

@var{alt_size}: holds the size of alt.

@var{alt_type}: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).

@var{serial}: buffer to store the serial number (may be null)

@var{serial_size}: Holds the size of the serial field (may be null)

@var{critical}: will be non-zero if the extension is marked as critical (may be null)

This function will return the X.509 authority key
identifier when stored as a general name (authorityCertIssuer) 
and serial number.

Because more than one general names might be stored
 @code{seq} can be used as a counter to request them all until 
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.

@strong{Returns:} Returns 0 on success, or an error code.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_crl_get_authority_key_id
@anchor{gnutls_x509_crl_get_authority_key_id}
@deftypefun {int} {gnutls_x509_crl_get_authority_key_id} (gnutls_x509_crl_t @var{crl}, void * @var{id}, size_t * @var{id_size}, unsigned int * @var{critical})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{id}: The place where the identifier will be copied

@var{id_size}: Holds the size of the result field.

@var{critical}: will be non-zero if the extension is marked as critical
(may be null)

This function will return the CRL authority's key identifier.  This
is obtained by the X.509 Authority Key identifier extension field
(2.5.29.35).  Note that this function 
only returns the keyIdentifier field of the extension and
@code{GNUTLS_E_X509_UNSUPPORTED_EXTENSION} , if the extension contains
the name and serial number of the certificate. In that case
@code{gnutls_x509_crl_get_authority_key_gn_serial()}  may be used.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code in case of an error.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crl_get_crt_count
@anchor{gnutls_x509_crl_get_crt_count}
@deftypefun {int} {gnutls_x509_crl_get_crt_count} (gnutls_x509_crl_t @var{crl})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

This function will return the number of revoked certificates in the
given CRL.

@strong{Returns:} number of certificates, a negative error code on failure.
@end deftypefun

@subheading gnutls_x509_crl_get_crt_serial
@anchor{gnutls_x509_crl_get_crt_serial}
@deftypefun {int} {gnutls_x509_crl_get_crt_serial} (gnutls_x509_crl_t @var{crl}, unsigned @var{indx}, unsigned char * @var{serial}, size_t * @var{serial_size}, time_t * @var{t})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{indx}: the index of the certificate to extract (starting from 0)

@var{serial}: where the serial number will be copied

@var{serial_size}: initially holds the size of serial

@var{t}: if non null, will hold the time this certificate was revoked

This function will retrieve the serial number of the specified, by
the index, revoked certificate.

Note that this function will have performance issues in large sequences
of revoked certificates. In that case use @code{gnutls_x509_crl_iter_crt_serial()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_get_dn_oid
@anchor{gnutls_x509_crl_get_dn_oid}
@deftypefun {int} {gnutls_x509_crl_get_dn_oid} (gnutls_x509_crl_t @var{crl}, unsigned @var{indx}, void * @var{oid}, size_t * @var{sizeof_oid})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{indx}: Specifies which DN OID to send. Use (0) to get the first one.

@var{oid}: a pointer to store the OID (may be null)

@var{sizeof_oid}: initially holds the size of 'oid'

This function will extract the requested OID of the name of the CRL
issuer, specified by the given index.

If oid is null then only the size will be filled.

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is
not long enough, and in that case the sizeof_oid will be updated
with the required size.  On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crl_get_extension_data
@anchor{gnutls_x509_crl_get_extension_data}
@deftypefun {int} {gnutls_x509_crl_get_extension_data} (gnutls_x509_crl_t @var{crl}, unsigned @var{indx}, void * @var{data}, size_t * @var{sizeof_data})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{indx}: Specifies which extension OID to send. Use (0) to get the first one.

@var{data}: a pointer to a structure to hold the data (may be null)

@var{sizeof_data}: initially holds the size of  @code{oid} 

This function will return the requested extension data in the CRL.
The extension data will be stored as a string in the provided
buffer.

Use @code{gnutls_x509_crl_get_extension_info()}  to extract the OID and
critical flag.  Use @code{gnutls_x509_crl_get_extension_info()}  instead,
if you want to get data indexed by the extension OID rather than
sequence.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crl_get_extension_data2
@anchor{gnutls_x509_crl_get_extension_data2}
@deftypefun {int} {gnutls_x509_crl_get_extension_data2} (gnutls_x509_crl_t @var{crl}, unsigned @var{indx}, gnutls_datum_t * @var{data})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{indx}: Specifies which extension OID to read. Use (0) to get the first one.

@var{data}: will contain the extension DER-encoded data

This function will return the requested by the index extension data in the
certificate revocation list.  The extension data will be allocated using
@code{gnutls_malloc()} .

Use @code{gnutls_x509_crt_get_extension_info()}  to extract the OID.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.
@end deftypefun

@subheading gnutls_x509_crl_get_extension_info
@anchor{gnutls_x509_crl_get_extension_info}
@deftypefun {int} {gnutls_x509_crl_get_extension_info} (gnutls_x509_crl_t @var{crl}, unsigned @var{indx}, void * @var{oid}, size_t * @var{sizeof_oid}, unsigned int * @var{critical})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{indx}: Specifies which extension OID to send, use (0) to get the first one.

@var{oid}: a pointer to store the OID

@var{sizeof_oid}: initially holds the maximum size of  @code{oid} , on return
holds actual size of  @code{oid} .

@var{critical}: output variable with critical flag, may be NULL.

This function will return the requested extension OID in the CRL,
and the critical flag for it.  The extension OID will be stored as
a string in the provided buffer.  Use
@code{gnutls_x509_crl_get_extension_data()}  to extract the data.

If the buffer provided is not long enough to hold the output, then
* @code{sizeof_oid} is updated and @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  will be
returned.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crl_get_extension_oid
@anchor{gnutls_x509_crl_get_extension_oid}
@deftypefun {int} {gnutls_x509_crl_get_extension_oid} (gnutls_x509_crl_t @var{crl}, unsigned @var{indx}, void * @var{oid}, size_t * @var{sizeof_oid})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{indx}: Specifies which extension OID to send, use (0) to get the first one.

@var{oid}: a pointer to store the OID (may be null)

@var{sizeof_oid}: initially holds the size of  @code{oid} 

This function will return the requested extension OID in the CRL.
The extension OID will be stored as a string in the provided
buffer.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crl_get_issuer_dn
@anchor{gnutls_x509_crl_get_issuer_dn}
@deftypefun {int} {gnutls_x509_crl_get_issuer_dn} (gnutls_x509_crl_t @var{crl}, char * @var{buf}, size_t * @var{sizeof_buf})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{buf}: a pointer to a structure to hold the peer's name (may be null)

@var{sizeof_buf}: initially holds the size of  @code{buf} 

This function will copy the name of the CRL issuer in the provided
buffer. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

If buf is @code{NULL}  then only the size will be filled.

This function does not output a fully RFC4514 compliant string, if
that is required see @code{gnutls_x509_crl_get_issuer_dn3()} .

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is
not long enough, and in that case the sizeof_buf will be updated
with the required size, and 0 on success.
@end deftypefun

@subheading gnutls_x509_crl_get_issuer_dn2
@anchor{gnutls_x509_crl_get_issuer_dn2}
@deftypefun {int} {gnutls_x509_crl_get_issuer_dn2} (gnutls_x509_crl_t @var{crl}, gnutls_datum_t * @var{dn})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{dn}: a pointer to a structure to hold the name; must be freed using @code{gnutls_free()} 

This function will allocate buffer and copy the name of the CRL issuer.
The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

This function does not output a fully RFC4514 compliant string, if
that is required see @code{gnutls_x509_crl_get_issuer_dn3()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.1.10
@end deftypefun

@subheading gnutls_x509_crl_get_issuer_dn3
@anchor{gnutls_x509_crl_get_issuer_dn3}
@deftypefun {int} {gnutls_x509_crl_get_issuer_dn3} (gnutls_x509_crl_t @var{crl}, gnutls_datum_t * @var{dn}, unsigned @var{flags})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{dn}: a pointer to a structure to hold the name; must be freed using @code{gnutls_free()} 

@var{flags}: zero or @code{GNUTLS_X509_DN_FLAG_COMPAT} 

This function will allocate buffer and copy the name of the CRL issuer.
The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

When the flag @code{GNUTLS_X509_DN_FLAG_COMPAT}  is specified, the output
format will match the format output by previous to 3.5.6 versions of GnuTLS
which was not not fully RFC4514-compliant.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.5.7
@end deftypefun

@subheading gnutls_x509_crl_get_issuer_dn_by_oid
@anchor{gnutls_x509_crl_get_issuer_dn_by_oid}
@deftypefun {int} {gnutls_x509_crl_get_issuer_dn_by_oid} (gnutls_x509_crl_t @var{crl}, const char * @var{oid}, unsigned @var{indx}, unsigned int @var{raw_flag}, void * @var{buf}, size_t * @var{sizeof_buf})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{oid}: holds an Object Identified in null terminated string

@var{indx}: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.

@var{raw_flag}: If non-zero returns the raw DER data of the DN part.

@var{buf}: a pointer to a structure to hold the peer's name (may be null)

@var{sizeof_buf}: initially holds the size of  @code{buf} 

This function will extract the part of the name of the CRL issuer
specified by the given OID. The output will be encoded as described
in RFC4514. The output string will be ASCII or UTF-8 encoded,
depending on the certificate data.

Some helper macros with popular OIDs can be found in gnutls/x509.h
If raw flag is (0), this function will only return known OIDs as
text. Other OIDs will be DER encoded, as described in RFC4514 -- in
hex format with a '#' prefix.  You can check about known OIDs
using @code{gnutls_x509_dn_oid_known()} .

If buf is null then only the size will be filled.

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is
not long enough, and in that case the sizeof_buf will be updated
with the required size, and 0 on success.
@end deftypefun

@subheading gnutls_x509_crl_get_next_update
@anchor{gnutls_x509_crl_get_next_update}
@deftypefun {time_t} {gnutls_x509_crl_get_next_update} (gnutls_x509_crl_t @var{crl})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

This function will return the time the next CRL will be issued.
This field is optional in a CRL so it might be normal to get an
error instead.

@strong{Returns:} when the next CRL will be issued, or (time_t)-1 on error.
@end deftypefun

@subheading gnutls_x509_crl_get_number
@anchor{gnutls_x509_crl_get_number}
@deftypefun {int} {gnutls_x509_crl_get_number} (gnutls_x509_crl_t @var{crl}, void * @var{ret}, size_t * @var{ret_size}, unsigned int * @var{critical})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{ret}: The place where the number will be copied

@var{ret_size}: Holds the size of the result field.

@var{critical}: will be non-zero if the extension is marked as critical
(may be null)

This function will return the CRL number extension.  This is
obtained by the CRL Number extension field (2.5.29.20).

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code in case of an error.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crl_get_raw_issuer_dn
@anchor{gnutls_x509_crl_get_raw_issuer_dn}
@deftypefun {int} {gnutls_x509_crl_get_raw_issuer_dn} (gnutls_x509_crl_t @var{crl}, gnutls_datum_t * @var{dn})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{dn}: will hold the starting point of the DN

This function will return a pointer to the DER encoded DN structure
and the length.

@strong{Returns:} a negative error code on error, and (0) on success.

@strong{Since:} 2.12.0
@end deftypefun

@subheading gnutls_x509_crl_get_signature
@anchor{gnutls_x509_crl_get_signature}
@deftypefun {int} {gnutls_x509_crl_get_signature} (gnutls_x509_crl_t @var{crl}, char * @var{sig}, size_t * @var{sizeof_sig})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{sig}: a pointer where the signature part will be copied (may be null).

@var{sizeof_sig}: initially holds the size of  @code{sig} 

This function will extract the signature field of a CRL.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value. 
@end deftypefun

@subheading gnutls_x509_crl_get_signature_algorithm
@anchor{gnutls_x509_crl_get_signature_algorithm}
@deftypefun {int} {gnutls_x509_crl_get_signature_algorithm} (gnutls_x509_crl_t @var{crl})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

This function will return a value of the @code{gnutls_sign_algorithm_t} 
enumeration that is the signature algorithm.

Since 3.6.0 this function never returns a negative error code.
Error cases and unknown/unsupported signature algorithms are
mapped to @code{GNUTLS_SIGN_UNKNOWN} .

@strong{Returns:} a @code{gnutls_sign_algorithm_t}  value
@end deftypefun

@subheading gnutls_x509_crl_get_signature_oid
@anchor{gnutls_x509_crl_get_signature_oid}
@deftypefun {int} {gnutls_x509_crl_get_signature_oid} (gnutls_x509_crl_t @var{crl}, char * @var{oid}, size_t * @var{oid_size})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{oid}: a pointer to a buffer to hold the OID (may be null)

@var{oid_size}: initially holds the size of  @code{oid} 

This function will return the OID of the signature algorithm
that has been used to sign this CRL. This is function
is useful in the case @code{gnutls_x509_crl_get_signature_algorithm()} 
returned @code{GNUTLS_SIGN_UNKNOWN} .

@strong{Returns:} zero or a negative error code on error.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_crl_get_this_update
@anchor{gnutls_x509_crl_get_this_update}
@deftypefun {time_t} {gnutls_x509_crl_get_this_update} (gnutls_x509_crl_t @var{crl})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

This function will return the time this CRL was issued.

@strong{Returns:} when the CRL was issued, or (time_t)-1 on error.
@end deftypefun

@subheading gnutls_x509_crl_get_version
@anchor{gnutls_x509_crl_get_version}
@deftypefun {int} {gnutls_x509_crl_get_version} (gnutls_x509_crl_t @var{crl})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

This function will return the version of the specified CRL.

@strong{Returns:} The version number, or a negative error code on error.
@end deftypefun

@subheading gnutls_x509_crl_import
@anchor{gnutls_x509_crl_import}
@deftypefun {int} {gnutls_x509_crl_import} (gnutls_x509_crl_t @var{crl}, const gnutls_datum_t * @var{data}, gnutls_x509_crt_fmt_t @var{format})
@var{crl}: The data to store the parsed CRL.

@var{data}: The DER or PEM encoded CRL.

@var{format}: One of DER or PEM

This function will convert the given DER or PEM encoded CRL
to the native @code{gnutls_x509_crl_t}  format. The output will be stored in 'crl'.

If the CRL is PEM encoded it should have a header of "X509 CRL".

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_init
@anchor{gnutls_x509_crl_init}
@deftypefun {int} {gnutls_x509_crl_init} (gnutls_x509_crl_t * @var{crl})
@var{crl}: A pointer to the type to be initialized

This function will initialize a CRL structure. CRL stands for
Certificate Revocation List. A revocation list usually contains
lists of certificate serial numbers that have been revoked by an
Authority. The revocation lists are always signed with the
authority's private key.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_iter_crt_serial
@anchor{gnutls_x509_crl_iter_crt_serial}
@deftypefun {int} {gnutls_x509_crl_iter_crt_serial} (gnutls_x509_crl_t @var{crl}, gnutls_x509_crl_iter_t * @var{iter}, unsigned char * @var{serial}, size_t * @var{serial_size}, time_t * @var{t})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{iter}: A pointer to an iterator (initially the iterator should be @code{NULL} )

@var{serial}: where the serial number will be copied

@var{serial_size}: initially holds the size of serial

@var{t}: if non null, will hold the time this certificate was revoked

This function performs the same as @code{gnutls_x509_crl_get_crt_serial()} ,
but reads sequentially and keeps state in the iterator 
between calls. That allows it to provide better performance in sequences 
with many elements (50000+).

When past the last element is accessed @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
is returned and the iterator is reset.

After use, the iterator must be deinitialized using @code{gnutls_x509_crl_iter_deinit()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_iter_deinit
@anchor{gnutls_x509_crl_iter_deinit}
@deftypefun {void} {gnutls_x509_crl_iter_deinit} (gnutls_x509_crl_iter_t @var{iter})
@var{iter}: The iterator to be deinitialized

This function will deinitialize an iterator type.
@end deftypefun

@subheading gnutls_x509_crl_list_import
@anchor{gnutls_x509_crl_list_import}
@deftypefun {int} {gnutls_x509_crl_list_import} (gnutls_x509_crl_t * @var{crls}, unsigned int * @var{crl_max}, const gnutls_datum_t * @var{data}, gnutls_x509_crt_fmt_t @var{format}, unsigned int @var{flags})
@var{crls}: Indicates where the parsed CRLs will be copied to. Must not be initialized.

@var{crl_max}: Initially must hold the maximum number of crls. It will be updated with the number of crls available.

@var{data}: The PEM encoded CRLs

@var{format}: One of DER or PEM.

@var{flags}: must be (0) or an OR'd sequence of gnutls_certificate_import_flags.

This function will convert the given PEM encoded CRL list
to the native gnutls_x509_crl_t format. The output will be stored
in  @code{crls} .  They will be automatically initialized.

If the Certificate is PEM encoded it should have a header of "X509 CRL".

@strong{Returns:} the number of certificates read or a negative error value.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_crl_list_import2
@anchor{gnutls_x509_crl_list_import2}
@deftypefun {int} {gnutls_x509_crl_list_import2} (gnutls_x509_crl_t ** @var{crls}, unsigned int * @var{size}, const gnutls_datum_t * @var{data}, gnutls_x509_crt_fmt_t @var{format}, unsigned int @var{flags})
@var{crls}: Will contain the parsed crl list.

@var{size}: It will contain the size of the list.

@var{data}: The PEM encoded CRL.

@var{format}: One of DER or PEM.

@var{flags}: must be (0) or an OR'd sequence of gnutls_certificate_import_flags.

This function will convert the given PEM encoded CRL list
to the native gnutls_x509_crl_t format. The output will be stored
in  @code{crls} .  They will be automatically initialized.

If the Certificate is PEM encoded it should have a header of "X509
CRL".

@strong{Returns:} the number of certificates read or a negative error value.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_crl_print
@anchor{gnutls_x509_crl_print}
@deftypefun {int} {gnutls_x509_crl_print} (gnutls_x509_crl_t @var{crl}, gnutls_certificate_print_formats_t @var{format}, gnutls_datum_t * @var{out})
@var{crl}: The data to be printed

@var{format}: Indicate the format to use

@var{out}: Newly allocated datum with null terminated string.

This function will pretty print a X.509 certificate revocation
list, suitable for display to a human.

The output  @code{out} needs to be deallocated using @code{gnutls_free()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_set_authority_key_id
@anchor{gnutls_x509_crl_set_authority_key_id}
@deftypefun {int} {gnutls_x509_crl_set_authority_key_id} (gnutls_x509_crl_t @var{crl}, const void * @var{id}, size_t @var{id_size})
@var{crl}: a CRL of type @code{gnutls_x509_crl_t} 

@var{id}: The key ID

@var{id_size}: Holds the size of the serial field.

This function will set the CRL's authority key ID extension.  Only
the keyIdentifier field can be set with this function. This may
be used by an authority that holds multiple private keys, to distinguish
the used key.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crl_set_crt
@anchor{gnutls_x509_crl_set_crt}
@deftypefun {int} {gnutls_x509_crl_set_crt} (gnutls_x509_crl_t @var{crl}, gnutls_x509_crt_t @var{crt}, time_t @var{revocation_time})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{crt}: a certificate of type @code{gnutls_x509_crt_t}  with the revoked certificate

@var{revocation_time}: The time this certificate was revoked

This function will set a revoked certificate's serial number to the CRL.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_set_crt_serial
@anchor{gnutls_x509_crl_set_crt_serial}
@deftypefun {int} {gnutls_x509_crl_set_crt_serial} (gnutls_x509_crl_t @var{crl}, const void * @var{serial}, size_t @var{serial_size}, time_t @var{revocation_time})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{serial}: The revoked certificate's serial number

@var{serial_size}: Holds the size of the serial field.

@var{revocation_time}: The time this certificate was revoked

This function will set a revoked certificate's serial number to the CRL.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_set_next_update
@anchor{gnutls_x509_crl_set_next_update}
@deftypefun {int} {gnutls_x509_crl_set_next_update} (gnutls_x509_crl_t @var{crl}, time_t @var{exp_time})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{exp_time}: The actual time

This function will set the time this CRL will be updated.
This is an optional value to be set on a CRL and this call
can be omitted when generating a CRL.

Prior to GnuTLS 3.5.7, setting a nextUpdate field was required
in order to generate a CRL.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_set_number
@anchor{gnutls_x509_crl_set_number}
@deftypefun {int} {gnutls_x509_crl_set_number} (gnutls_x509_crl_t @var{crl}, const void * @var{nr}, size_t @var{nr_size})
@var{crl}: a CRL of type @code{gnutls_x509_crl_t} 

@var{nr}: The CRL number

@var{nr_size}: Holds the size of the nr field.

This function will set the CRL's number extension. This
is to be used as a unique and monotonic number assigned to
the CRL by the authority.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crl_set_this_update
@anchor{gnutls_x509_crl_set_this_update}
@deftypefun {int} {gnutls_x509_crl_set_this_update} (gnutls_x509_crl_t @var{crl}, time_t @var{act_time})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{act_time}: The actual time

This function will set the time this CRL was issued.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_set_version
@anchor{gnutls_x509_crl_set_version}
@deftypefun {int} {gnutls_x509_crl_set_version} (gnutls_x509_crl_t @var{crl}, unsigned int @var{version})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{version}: holds the version number. For CRLv1 crls must be 1.

This function will set the version of the CRL. This
must be one for CRL version 1, and so on. The CRLs generated
by gnutls should have a version number of 2.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_sign
@anchor{gnutls_x509_crl_sign}
@deftypefun {int} {gnutls_x509_crl_sign} (gnutls_x509_crl_t @var{crl}, gnutls_x509_crt_t @var{issuer}, gnutls_x509_privkey_t @var{issuer_key})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{issuer}: is the certificate of the certificate issuer

@var{issuer_key}: holds the issuer's private key

This function is the same a @code{gnutls_x509_crl_sign2()}  with no flags,
and an appropriate hash algorithm. The hash algorithm used may
vary between versions of GnuTLS, and it is tied to the security
level of the issuer's public key.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_sign2
@anchor{gnutls_x509_crl_sign2}
@deftypefun {int} {gnutls_x509_crl_sign2} (gnutls_x509_crl_t @var{crl}, gnutls_x509_crt_t @var{issuer}, gnutls_x509_privkey_t @var{issuer_key}, gnutls_digest_algorithm_t @var{dig}, unsigned int @var{flags})
@var{crl}: should contain a gnutls_x509_crl_t type

@var{issuer}: is the certificate of the certificate issuer

@var{issuer_key}: holds the issuer's private key

@var{dig}: The message digest to use. GNUTLS_DIG_SHA256 is the safe choice unless you know what you're doing.

@var{flags}: must be 0

This function will sign the CRL with the issuer's private key, and
will copy the issuer's information into the CRL.

This must be the last step in a certificate CRL since all
the previously set parameters are now signed.

A known limitation of this function is, that a newly-signed CRL will not
be fully functional (e.g., for signature verification), until it
is exported an re-imported.

After GnuTLS 3.6.1 the value of  @code{dig} may be @code{GNUTLS_DIG_UNKNOWN} ,
and in that case, a suitable but reasonable for the key algorithm will be selected.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crl_verify
@anchor{gnutls_x509_crl_verify}
@deftypefun {int} {gnutls_x509_crl_verify} (gnutls_x509_crl_t @var{crl}, const gnutls_x509_crt_t * @var{trusted_cas}, unsigned @var{tcas_size}, unsigned int @var{flags}, unsigned int * @var{verify})
@var{crl}: is the crl to be verified

@var{trusted_cas}: is a certificate list that is considered to be trusted one

@var{tcas_size}: holds the number of CA certificates in CA_list

@var{flags}: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

@var{verify}: will hold the crl verification output.

This function will try to verify the given crl and return its verification status.
See @code{gnutls_x509_crt_list_verify()}  for a detailed description of
return values. Note that since GnuTLS 3.1.4 this function includes
the time checks.

Note that value in  @code{verify} is set only when the return value of this 
function is success (i.e, failure to trust a CRL a certificate does not imply 
a negative return value).

Before GnuTLS 3.5.7 this function would return zero or a positive
number on success.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0), otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_deinit
@anchor{gnutls_x509_crq_deinit}
@deftypefun {void} {gnutls_x509_crq_deinit} (gnutls_x509_crq_t @var{crq})
@var{crq}: the type to be deinitialized

This function will deinitialize a PKCS@code{10}  certificate request
structure.
@end deftypefun

@subheading gnutls_x509_crq_export
@anchor{gnutls_x509_crq_export}
@deftypefun {int} {gnutls_x509_crq_export} (gnutls_x509_crq_t @var{crq}, gnutls_x509_crt_fmt_t @var{format}, void * @var{output_data}, size_t * @var{output_data_size})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{format}: the format of output params. One of PEM or DER.

@var{output_data}: will contain a certificate request PEM or DER encoded

@var{output_data_size}: holds the size of output_data (and will be
replaced by the actual size of parameters)

This function will export the certificate request to a PEM or DER
encoded PKCS10 structure.

If the buffer provided is not long enough to hold the output, then
@code{GNUTLS_E_SHORT_MEMORY_BUFFER}  will be returned and
* @code{output_data_size} will be updated.

If the structure is PEM encoded, it will have a header of "BEGIN
NEW CERTIFICATE REQUEST".

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_export2
@anchor{gnutls_x509_crq_export2}
@deftypefun {int} {gnutls_x509_crq_export2} (gnutls_x509_crq_t @var{crq}, gnutls_x509_crt_fmt_t @var{format}, gnutls_datum_t * @var{out})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{format}: the format of output params. One of PEM or DER.

@var{out}: will contain a certificate request PEM or DER encoded

This function will export the certificate request to a PEM or DER
encoded PKCS10 structure.

The output buffer is allocated using @code{gnutls_malloc()} .

If the structure is PEM encoded, it will have a header of "BEGIN
NEW CERTIFICATE REQUEST".

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

Since 3.1.3
@end deftypefun

@subheading gnutls_x509_crq_get_attribute_by_oid
@anchor{gnutls_x509_crq_get_attribute_by_oid}
@deftypefun {int} {gnutls_x509_crq_get_attribute_by_oid} (gnutls_x509_crq_t @var{crq}, const char * @var{oid}, unsigned @var{indx}, void * @var{buf}, size_t * @var{buf_size})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{oid}: holds an Object Identifier in null-terminated string

@var{indx}: In case multiple same OIDs exist in the attribute list, this
specifies which to get, use (0) to get the first one

@var{buf}: a pointer to a structure to hold the attribute data (may be @code{NULL} )

@var{buf_size}: initially holds the size of  @code{buf} 

This function will return the attribute in the certificate request
specified by the given Object ID.  The attribute will be DER
encoded.

Attributes in a certificate request is an optional set of data
appended to the request. Their interpretation depends on the CA policy.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_get_attribute_data
@anchor{gnutls_x509_crq_get_attribute_data}
@deftypefun {int} {gnutls_x509_crq_get_attribute_data} (gnutls_x509_crq_t @var{crq}, unsigned @var{indx}, void * @var{data}, size_t * @var{sizeof_data})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{indx}: Specifies which attribute number to get. Use (0) to get the first one.

@var{data}: a pointer to a structure to hold the data (may be null)

@var{sizeof_data}: initially holds the size of  @code{oid} 

This function will return the requested attribute data in the
certificate request.  The attribute data will be stored as a string in the
provided buffer.

Use @code{gnutls_x509_crq_get_attribute_info()}  to extract the OID.
Use @code{gnutls_x509_crq_get_attribute_by_oid()}  instead,
if you want to get data indexed by the attribute OID rather than
sequence.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_attribute_info
@anchor{gnutls_x509_crq_get_attribute_info}
@deftypefun {int} {gnutls_x509_crq_get_attribute_info} (gnutls_x509_crq_t @var{crq}, unsigned @var{indx}, void * @var{oid}, size_t * @var{sizeof_oid})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{indx}: Specifies which attribute number to get. Use (0) to get the first one.

@var{oid}: a pointer to a structure to hold the OID

@var{sizeof_oid}: initially holds the maximum size of  @code{oid} , on return
holds actual size of  @code{oid} .

This function will return the requested attribute OID in the
certificate, and the critical flag for it.  The attribute OID will
be stored as a string in the provided buffer.  Use
@code{gnutls_x509_crq_get_attribute_data()}  to extract the data.

If the buffer provided is not long enough to hold the output, then
* @code{sizeof_oid} is updated and @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  will be
returned.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_basic_constraints
@anchor{gnutls_x509_crq_get_basic_constraints}
@deftypefun {int} {gnutls_x509_crq_get_basic_constraints} (gnutls_x509_crq_t @var{crq}, unsigned int * @var{critical}, unsigned int * @var{ca}, int * @var{pathlen})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{critical}: will be non-zero if the extension is marked as critical

@var{ca}: pointer to output integer indicating CA status, may be NULL,
value is 1 if the certificate CA flag is set, 0 otherwise.

@var{pathlen}: pointer to output integer indicating path length (may be
NULL), non-negative error codes indicate a present pathLenConstraint
field and the actual value, -1 indicate that the field is absent.

This function will read the certificate's basic constraints, and
return the certificates CA status.  It reads the basicConstraints
X.509 extension (2.5.29.19).

@strong{Returns:} If the certificate is a CA a positive value will be
returned, or (0) if the certificate does not have CA flag set.
A negative error code may be returned in case of errors.  If the
certificate does not contain the basicConstraints extension
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  will be returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_challenge_password
@anchor{gnutls_x509_crq_get_challenge_password}
@deftypefun {int} {gnutls_x509_crq_get_challenge_password} (gnutls_x509_crq_t @var{crq}, char * @var{pass}, size_t * @var{pass_size})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{pass}: will hold a (0)-terminated password string

@var{pass_size}: Initially holds the size of  @code{pass} .

This function will return the challenge password in the request.
The challenge password is intended to be used for requesting a
revocation of the certificate.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_get_dn
@anchor{gnutls_x509_crq_get_dn}
@deftypefun {int} {gnutls_x509_crq_get_dn} (gnutls_x509_crq_t @var{crq}, char * @var{buf}, size_t * @var{buf_size})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{buf}: a pointer to a structure to hold the name (may be @code{NULL} )

@var{buf_size}: initially holds the size of  @code{buf} 

This function will copy the name of the Certificate request subject
to the provided buffer.  The name will be in the form
"C=xxxx,O=yyyy,CN=zzzz" as described in RFC 2253. The output string
 @code{buf} will be ASCII or UTF-8 encoded, depending on the certificate
data.

This function does not output a fully RFC4514 compliant string, if
that is required see @code{gnutls_x509_crq_get_dn3()} .

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is not
long enough, and in that case the * @code{buf_size} will be updated with
the required size.  On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crq_get_dn2
@anchor{gnutls_x509_crq_get_dn2}
@deftypefun {int} {gnutls_x509_crq_get_dn2} (gnutls_x509_crq_t @var{crq}, gnutls_datum_t * @var{dn})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{dn}: a pointer to a structure to hold the name; must be freed using @code{gnutls_free()} 

This function will allocate buffer and copy the name of the Certificate 
request. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

This function does not output a fully RFC4514 compliant string, if
that is required see @code{gnutls_x509_crq_get_dn3()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value. and a negative error code on error.

@strong{Since:} 3.1.10
@end deftypefun

@subheading gnutls_x509_crq_get_dn3
@anchor{gnutls_x509_crq_get_dn3}
@deftypefun {int} {gnutls_x509_crq_get_dn3} (gnutls_x509_crq_t @var{crq}, gnutls_datum_t * @var{dn}, unsigned @var{flags})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{dn}: a pointer to a structure to hold the name; must be freed using @code{gnutls_free()} 

@var{flags}: zero or @code{GNUTLS_X509_DN_FLAG_COMPAT} 

This function will allocate buffer and copy the name of the Certificate 
request. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

When the flag @code{GNUTLS_X509_DN_FLAG_COMPAT}  is specified, the output
format will match the format output by previous to 3.5.6 versions of GnuTLS
which was not not fully RFC4514-compliant.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value. and a negative error code on error.

@strong{Since:} 3.5.7
@end deftypefun

@subheading gnutls_x509_crq_get_dn_by_oid
@anchor{gnutls_x509_crq_get_dn_by_oid}
@deftypefun {int} {gnutls_x509_crq_get_dn_by_oid} (gnutls_x509_crq_t @var{crq}, const char * @var{oid}, unsigned @var{indx}, unsigned int @var{raw_flag}, void * @var{buf}, size_t * @var{buf_size})
@var{crq}: should contain a gnutls_x509_crq_t type

@var{oid}: holds an Object Identifier in a null terminated string

@var{indx}: In case multiple same OIDs exist in the RDN, this specifies
which to get. Use (0) to get the first one.

@var{raw_flag}: If non-zero returns the raw DER data of the DN part.

@var{buf}: a pointer to a structure to hold the name (may be @code{NULL} )

@var{buf_size}: initially holds the size of  @code{buf} 

This function will extract the part of the name of the Certificate
request subject, specified by the given OID. The output will be
encoded as described in RFC2253. The output string will be ASCII
or UTF-8 encoded, depending on the certificate data.

Some helper macros with popular OIDs can be found in gnutls/x509.h
If raw flag is (0), this function will only return known OIDs as
text. Other OIDs will be DER encoded, as described in RFC2253 --
in hex format with a '\#' prefix.  You can check about known OIDs
using @code{gnutls_x509_dn_oid_known()} .

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is
not long enough, and in that case the * @code{buf_size} will be
updated with the required size.  On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crq_get_dn_oid
@anchor{gnutls_x509_crq_get_dn_oid}
@deftypefun {int} {gnutls_x509_crq_get_dn_oid} (gnutls_x509_crq_t @var{crq}, unsigned @var{indx}, void * @var{oid}, size_t * @var{sizeof_oid})
@var{crq}: should contain a gnutls_x509_crq_t type

@var{indx}: Specifies which DN OID to get. Use (0) to get the first one.

@var{oid}: a pointer to a structure to hold the name (may be @code{NULL} )

@var{sizeof_oid}: initially holds the size of  @code{oid} 

This function will extract the requested OID of the name of the
certificate request subject, specified by the given index.

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is
not long enough, and in that case the * @code{sizeof_oid} will be
updated with the required size.  On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crq_get_extension_by_oid
@anchor{gnutls_x509_crq_get_extension_by_oid}
@deftypefun {int} {gnutls_x509_crq_get_extension_by_oid} (gnutls_x509_crq_t @var{crq}, const char * @var{oid}, unsigned @var{indx}, void * @var{buf}, size_t * @var{buf_size}, unsigned int * @var{critical})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{oid}: holds an Object Identifier in a null terminated string

@var{indx}: In case multiple same OIDs exist in the extensions, this
specifies which to get. Use (0) to get the first one.

@var{buf}: a pointer to a structure to hold the name (may be null)

@var{buf_size}: initially holds the size of  @code{buf} 

@var{critical}: will be non-zero if the extension is marked as critical

This function will return the extension specified by the OID in
the certificate.  The extensions will be returned as binary data
DER encoded, in the provided buffer.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code in case of an error.  If the certificate does not
contain the specified extension
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  will be returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_extension_by_oid2
@anchor{gnutls_x509_crq_get_extension_by_oid2}
@deftypefun {int} {gnutls_x509_crq_get_extension_by_oid2} (gnutls_x509_crq_t @var{crq}, const char * @var{oid}, unsigned @var{indx}, gnutls_datum_t * @var{output}, unsigned int * @var{critical})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{oid}: holds an Object Identifier in a null terminated string

@var{indx}: In case multiple same OIDs exist in the extensions, this
specifies which to get. Use (0) to get the first one.

@var{output}: will hold the allocated extension data

@var{critical}: will be non-zero if the extension is marked as critical

This function will return the extension specified by the OID in
the certificate.  The extensions will be returned as binary data
DER encoded, in the provided buffer.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code in case of an error.  If the certificate does not
contain the specified extension
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  will be returned.

@strong{Since:} 3.3.8
@end deftypefun

@subheading gnutls_x509_crq_get_extension_data
@anchor{gnutls_x509_crq_get_extension_data}
@deftypefun {int} {gnutls_x509_crq_get_extension_data} (gnutls_x509_crq_t @var{crq}, unsigned @var{indx}, void * @var{data}, size_t * @var{sizeof_data})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{indx}: Specifies which extension number to get. Use (0) to get the first one.

@var{data}: a pointer to a structure to hold the data (may be null)

@var{sizeof_data}: initially holds the size of  @code{oid} 

This function will return the requested extension data in the
certificate.  The extension data will be stored as a string in the
provided buffer.

Use @code{gnutls_x509_crq_get_extension_info()}  to extract the OID and
critical flag.  Use @code{gnutls_x509_crq_get_extension_by_oid()}  instead,
if you want to get data indexed by the extension OID rather than
sequence.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_extension_data2
@anchor{gnutls_x509_crq_get_extension_data2}
@deftypefun {int} {gnutls_x509_crq_get_extension_data2} (gnutls_x509_crq_t @var{crq}, unsigned @var{indx}, gnutls_datum_t * @var{data})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{indx}: Specifies which extension OID to read. Use (0) to get the first one.

@var{data}: will contain the extension DER-encoded data

This function will return the requested extension data in the
certificate request.  The extension data will be allocated using
@code{gnutls_malloc()} .

Use @code{gnutls_x509_crq_get_extension_info()}  to extract the OID.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_crq_get_extension_info
@anchor{gnutls_x509_crq_get_extension_info}
@deftypefun {int} {gnutls_x509_crq_get_extension_info} (gnutls_x509_crq_t @var{crq}, unsigned @var{indx}, void * @var{oid}, size_t * @var{sizeof_oid}, unsigned int * @var{critical})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{indx}: Specifies which extension number to get. Use (0) to get the first one.

@var{oid}: a pointer to store the OID

@var{sizeof_oid}: initially holds the maximum size of  @code{oid} , on return
holds actual size of  @code{oid} .

@var{critical}: output variable with critical flag, may be NULL.

This function will return the requested extension OID in the
certificate, and the critical flag for it.  The extension OID will
be stored as a string in the provided buffer.  Use
@code{gnutls_x509_crq_get_extension_data()}  to extract the data.

If the buffer provided is not long enough to hold the output, then
* @code{sizeof_oid} is updated and @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  will be
returned.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_key_id
@anchor{gnutls_x509_crq_get_key_id}
@deftypefun {int} {gnutls_x509_crq_get_key_id} (gnutls_x509_crq_t @var{crq}, unsigned int @var{flags}, unsigned char * @var{output_data}, size_t * @var{output_data_size})
@var{crq}: a certificate of type @code{gnutls_x509_crq_t} 

@var{flags}: should be one of the flags from @code{gnutls_keyid_flags_t} 

@var{output_data}: will contain the key ID

@var{output_data_size}: holds the size of output_data (and will be
replaced by the actual size of parameters)

This function will return a unique ID that depends on the public key
parameters.  This ID can be used in checking whether a certificate
corresponds to the given private key.

If the buffer provided is not long enough to hold the output, then
* @code{output_data_size} is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
be returned.  The output will normally be a SHA-1 hash output,
which is 20 bytes.

@strong{Returns:} In case of failure a negative error code will be
returned, and 0 on success.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_key_purpose_oid
@anchor{gnutls_x509_crq_get_key_purpose_oid}
@deftypefun {int} {gnutls_x509_crq_get_key_purpose_oid} (gnutls_x509_crq_t @var{crq}, unsigned @var{indx}, void * @var{oid}, size_t * @var{sizeof_oid}, unsigned int * @var{critical})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{indx}: This specifies which OID to return, use (0) to get the first one

@var{oid}: a pointer to store the OID (may be @code{NULL} )

@var{sizeof_oid}: initially holds the size of  @code{oid} 

@var{critical}: output variable with critical flag, may be @code{NULL} .

This function will extract the key purpose OIDs of the Certificate
specified by the given index.  These are stored in the Extended Key
Usage extension (2.5.29.37).  See the GNUTLS_KP_* definitions for
human readable names.

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is
not long enough, and in that case the * @code{sizeof_oid} will be
updated with the required size.  On success 0 is returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_key_rsa_raw
@anchor{gnutls_x509_crq_get_key_rsa_raw}
@deftypefun {int} {gnutls_x509_crq_get_key_rsa_raw} (gnutls_x509_crq_t @var{crq}, gnutls_datum_t * @var{m}, gnutls_datum_t * @var{e})
@var{crq}: Holds the certificate

@var{m}: will hold the modulus

@var{e}: will hold the public exponent

This function will export the RSA public key's parameters found in
the given structure.  The new parameters will be allocated using
@code{gnutls_malloc()}  and will be stored in the appropriate datum.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_key_usage
@anchor{gnutls_x509_crq_get_key_usage}
@deftypefun {int} {gnutls_x509_crq_get_key_usage} (gnutls_x509_crq_t @var{crq}, unsigned int * @var{key_usage}, unsigned int * @var{critical})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{key_usage}: where the key usage bits will be stored

@var{critical}: will be non-zero if the extension is marked as critical

This function will return certificate's key usage, by reading the
keyUsage X.509 extension (2.5.29.15).  The key usage value will
ORed values of the: @code{GNUTLS_KEY_DIGITAL_SIGNATURE} ,
@code{GNUTLS_KEY_NON_REPUDIATION} , @code{GNUTLS_KEY_KEY_ENCIPHERMENT} ,
@code{GNUTLS_KEY_DATA_ENCIPHERMENT} , @code{GNUTLS_KEY_KEY_AGREEMENT} ,
@code{GNUTLS_KEY_KEY_CERT_SIGN} , @code{GNUTLS_KEY_CRL_SIGN} ,
@code{GNUTLS_KEY_ENCIPHER_ONLY} , @code{GNUTLS_KEY_DECIPHER_ONLY} .

@strong{Returns:} the certificate key usage, or a negative error code in case of
parsing error.  If the certificate does not contain the keyUsage
extension @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  will be
returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_pk_algorithm
@anchor{gnutls_x509_crq_get_pk_algorithm}
@deftypefun {int} {gnutls_x509_crq_get_pk_algorithm} (gnutls_x509_crq_t @var{crq}, unsigned int * @var{bits})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{bits}: if bits is non-@code{NULL}  it will hold the size of the parameters' in bits

This function will return the public key algorithm of a PKCS@code{10} 
certificate request.

If bits is non-@code{NULL} , it should have enough size to hold the
parameters size in bits.  For RSA the bits returned is the modulus.
For DSA the bits returned are of the public exponent.

@strong{Returns:} a member of the @code{gnutls_pk_algorithm_t}  enumeration on
success, or a negative error code on error.
@end deftypefun

@subheading gnutls_x509_crq_get_pk_oid
@anchor{gnutls_x509_crq_get_pk_oid}
@deftypefun {int} {gnutls_x509_crq_get_pk_oid} (gnutls_x509_crq_t @var{crq}, char * @var{oid}, size_t * @var{oid_size})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{oid}: a pointer to a buffer to hold the OID (may be null)

@var{oid_size}: initially holds the size of  @code{oid} 

This function will return the OID of the public key algorithm
on that certificate request. This function
is useful in the case @code{gnutls_x509_crq_get_pk_algorithm()} 
returned @code{GNUTLS_PK_UNKNOWN} .

@strong{Returns:} zero or a negative error code on error.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_crq_get_private_key_usage_period
@anchor{gnutls_x509_crq_get_private_key_usage_period}
@deftypefun {int} {gnutls_x509_crq_get_private_key_usage_period} (gnutls_x509_crq_t @var{crq}, time_t * @var{activation}, time_t * @var{expiration}, unsigned int * @var{critical})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{activation}: The activation time

@var{expiration}: The expiration time

@var{critical}: the extension status

This function will return the expiration and activation
times of the private key of the certificate.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.
@end deftypefun

@subheading gnutls_x509_crq_get_signature_algorithm
@anchor{gnutls_x509_crq_get_signature_algorithm}
@deftypefun {int} {gnutls_x509_crq_get_signature_algorithm} (gnutls_x509_crq_t @var{crq})
@var{crq}: should contain a @code{gnutls_x509_cr_t}  type

This function will return a value of the @code{gnutls_sign_algorithm_t} 
enumeration that is the signature algorithm that has been used to
sign this certificate request.

Since 3.6.0 this function never returns a negative error code.
Error cases and unknown/unsupported signature algorithms are
mapped to @code{GNUTLS_SIGN_UNKNOWN} .

@strong{Returns:} a @code{gnutls_sign_algorithm_t}  value

@strong{Since:} 3.4.0
@end deftypefun

@subheading gnutls_x509_crq_get_signature_oid
@anchor{gnutls_x509_crq_get_signature_oid}
@deftypefun {int} {gnutls_x509_crq_get_signature_oid} (gnutls_x509_crq_t @var{crq}, char * @var{oid}, size_t * @var{oid_size})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{oid}: a pointer to a buffer to hold the OID (may be null)

@var{oid_size}: initially holds the size of  @code{oid} 

This function will return the OID of the signature algorithm
that has been used to sign this certificate request. This function
is useful in the case @code{gnutls_x509_crq_get_signature_algorithm()} 
returned @code{GNUTLS_SIGN_UNKNOWN} .

@strong{Returns:} zero or a negative error code on error.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_crq_get_spki
@anchor{gnutls_x509_crq_get_spki}
@deftypefun {int} {gnutls_x509_crq_get_spki} (gnutls_x509_crq_t @var{crq}, gnutls_x509_spki_t @var{spki}, unsigned int @var{flags})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{spki}: a SubjectPublicKeyInfo structure of type @code{gnutls_x509_spki_t} 

@var{flags}: must be zero

This function will return the public key information of a PKCS@code{10} 
certificate request. The provided  @code{spki} must be initialized.

@strong{Returns:} Zero on success, or a negative error code on error.
@end deftypefun

@subheading gnutls_x509_crq_get_subject_alt_name
@anchor{gnutls_x509_crq_get_subject_alt_name}
@deftypefun {int} {gnutls_x509_crq_get_subject_alt_name} (gnutls_x509_crq_t @var{crq}, unsigned int @var{seq}, void * @var{ret}, size_t * @var{ret_size}, unsigned int * @var{ret_type}, unsigned int * @var{critical})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{seq}: specifies the sequence number of the alt name, 0 for the
first one, 1 for the second etc.

@var{ret}: is the place where the alternative name will be copied to

@var{ret_size}: holds the size of ret.

@var{ret_type}: holds the @code{gnutls_x509_subject_alt_name_t}  name type

@var{critical}: will be non-zero if the extension is marked as critical
(may be null)

This function will return the alternative names, contained in the
given certificate.  It is the same as
@code{gnutls_x509_crq_get_subject_alt_name()}  except for the fact that it
will return the type of the alternative name in  @code{ret_type} even if
the function fails for some reason (i.e.  the buffer provided is
not enough).

@strong{Returns:} the alternative subject name type on success, one of the
enumerated @code{gnutls_x509_subject_alt_name_t} .  It will return
@code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if  @code{ret_size} is not large enough to
hold the value.  In that case  @code{ret_size} will be updated with the
required size.  If the certificate request does not have an
Alternative name with the specified sequence number then
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_subject_alt_othername_oid
@anchor{gnutls_x509_crq_get_subject_alt_othername_oid}
@deftypefun {int} {gnutls_x509_crq_get_subject_alt_othername_oid} (gnutls_x509_crq_t @var{crq}, unsigned int @var{seq}, void * @var{ret}, size_t * @var{ret_size})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{seq}: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

@var{ret}: is the place where the otherName OID will be copied to

@var{ret_size}: holds the size of ret.

This function will extract the type OID of an otherName Subject
Alternative Name, contained in the given certificate, and return
the type as an enumerated element.

This function is only useful if
@code{gnutls_x509_crq_get_subject_alt_name()}  returned
@code{GNUTLS_SAN_OTHERNAME} .

@strong{Returns:} the alternative subject name type on success, one of the
enumerated gnutls_x509_subject_alt_name_t.  For supported OIDs,
it will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types,
e.g. @code{GNUTLS_SAN_OTHERNAME_XMPP} , and @code{GNUTLS_SAN_OTHERNAME}  for
unknown OIDs.  It will return @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if
 @code{ret_size} is not large enough to hold the value.  In that case
 @code{ret_size} will be updated with the required size.  If the
certificate does not have an Alternative name with the specified
sequence number and with the otherName type then
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_get_tlsfeatures
@anchor{gnutls_x509_crq_get_tlsfeatures}
@deftypefun {int} {gnutls_x509_crq_get_tlsfeatures} (gnutls_x509_crq_t @var{crq}, gnutls_x509_tlsfeatures_t @var{features}, unsigned int @var{flags}, unsigned int * @var{critical})
@var{crq}: An X.509 certificate request

@var{features}: If the function succeeds, the
features will be stored in this variable.

@var{flags}: zero or @code{GNUTLS_EXT_FLAG_APPEND} 

@var{critical}: the extension status

This function will get the X.509 TLS features
extension structure from the certificate request.
The returned structure needs to be freed using
@code{gnutls_x509_tlsfeatures_deinit()} .

When the  @code{flags} is set to @code{GNUTLS_EXT_FLAG_APPEND} ,
then if the  @code{features} structure is empty this function will behave
identically as if the flag was not set. Otherwise if there are elements 
in the  @code{features} structure then they will be merged with.

Note that  @code{features} must be initialized prior to calling this function.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error value.

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_crq_get_version
@anchor{gnutls_x509_crq_get_version}
@deftypefun {int} {gnutls_x509_crq_get_version} (gnutls_x509_crq_t @var{crq})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

This function will return the version of the specified Certificate
request.

@strong{Returns:} version of certificate request, or a negative error code on
error.
@end deftypefun

@subheading gnutls_x509_crq_import
@anchor{gnutls_x509_crq_import}
@deftypefun {int} {gnutls_x509_crq_import} (gnutls_x509_crq_t @var{crq}, const gnutls_datum_t * @var{data}, gnutls_x509_crt_fmt_t @var{format})
@var{crq}: The data to store the parsed certificate request.

@var{data}: The DER or PEM encoded certificate.

@var{format}: One of DER or PEM

This function will convert the given DER or PEM encoded certificate
request to a @code{gnutls_x509_crq_t}  type.  The output will be
stored in  @code{crq} .

If the Certificate is PEM encoded it should have a header of "NEW
CERTIFICATE REQUEST".

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_init
@anchor{gnutls_x509_crq_init}
@deftypefun {int} {gnutls_x509_crq_init} (gnutls_x509_crq_t * @var{crq})
@var{crq}: A pointer to the type to be initialized

This function will initialize a PKCS@code{10}  certificate request
structure.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_print
@anchor{gnutls_x509_crq_print}
@deftypefun {int} {gnutls_x509_crq_print} (gnutls_x509_crq_t @var{crq}, gnutls_certificate_print_formats_t @var{format}, gnutls_datum_t * @var{out})
@var{crq}: The data to be printed

@var{format}: Indicate the format to use

@var{out}: Newly allocated datum with null terminated string.

This function will pretty print a certificate request, suitable for
display to a human.

The output  @code{out} needs to be deallocated using @code{gnutls_free()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_set_attribute_by_oid
@anchor{gnutls_x509_crq_set_attribute_by_oid}
@deftypefun {int} {gnutls_x509_crq_set_attribute_by_oid} (gnutls_x509_crq_t @var{crq}, const char * @var{oid}, void * @var{buf}, size_t @var{buf_size})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{oid}: holds an Object Identifier in a null-terminated string

@var{buf}: a pointer to a structure that holds the attribute data

@var{buf_size}: holds the size of  @code{buf} 

This function will set the attribute in the certificate request
specified by the given Object ID. The provided attribute must be be DER
encoded.

Attributes in a certificate request is an optional set of data
appended to the request. Their interpretation depends on the CA policy.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_set_basic_constraints
@anchor{gnutls_x509_crq_set_basic_constraints}
@deftypefun {int} {gnutls_x509_crq_set_basic_constraints} (gnutls_x509_crq_t @var{crq}, unsigned int @var{ca}, int @var{pathLenConstraint})
@var{crq}: a certificate request of type @code{gnutls_x509_crq_t} 

@var{ca}: true(1) or false(0) depending on the Certificate authority status.

@var{pathLenConstraint}: non-negative error codes indicate maximum length of path,
and negative error codes indicate that the pathLenConstraints field should
not be present.

This function will set the basicConstraints certificate extension.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_set_challenge_password
@anchor{gnutls_x509_crq_set_challenge_password}
@deftypefun {int} {gnutls_x509_crq_set_challenge_password} (gnutls_x509_crq_t @var{crq}, const char * @var{pass})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{pass}: holds a (0)-terminated password

This function will set a challenge password to be used when
revoking the request.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_set_dn
@anchor{gnutls_x509_crq_set_dn}
@deftypefun {int} {gnutls_x509_crq_set_dn} (gnutls_x509_crq_t @var{crq}, const char * @var{dn}, const char ** @var{err})
@var{crq}: a certificate of type @code{gnutls_x509_crq_t} 

@var{dn}: a comma separated DN string (RFC4514)

@var{err}: indicates the error position (if any)

This function will set the DN on the provided certificate.
The input string should be plain ASCII or UTF-8 encoded. On
DN parsing error @code{GNUTLS_E_PARSING_ERROR}  is returned.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_set_dn_by_oid
@anchor{gnutls_x509_crq_set_dn_by_oid}
@deftypefun {int} {gnutls_x509_crq_set_dn_by_oid} (gnutls_x509_crq_t @var{crq}, const char * @var{oid}, unsigned int @var{raw_flag}, const void * @var{data}, unsigned int @var{sizeof_data})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{oid}: holds an Object Identifier in a (0)-terminated string

@var{raw_flag}: must be 0, or 1 if the data are DER encoded

@var{data}: a pointer to the input data

@var{sizeof_data}: holds the size of  @code{data} 

This function will set the part of the name of the Certificate
request subject, specified by the given OID.  The input string
should be ASCII or UTF-8 encoded.

Some helper macros with popular OIDs can be found in gnutls/x509.h
With this function you can only set the known OIDs.  You can test
for known OIDs using @code{gnutls_x509_dn_oid_known()} .  For OIDs that are
not known (by gnutls) you should properly DER encode your data, and
call this function with raw_flag set.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_set_extension_by_oid
@anchor{gnutls_x509_crq_set_extension_by_oid}
@deftypefun {int} {gnutls_x509_crq_set_extension_by_oid} (gnutls_x509_crq_t @var{crq}, const char * @var{oid}, const void * @var{buf}, size_t @var{sizeof_buf}, unsigned int @var{critical})
@var{crq}: a certificate of type @code{gnutls_x509_crq_t} 

@var{oid}: holds an Object Identifier in null terminated string

@var{buf}: a pointer to a DER encoded data

@var{sizeof_buf}: holds the size of  @code{buf} 

@var{critical}: should be non-zero if the extension is to be marked as critical

This function will set an the extension, by the specified OID, in
the certificate request.  The extension data should be binary data DER
encoded.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_set_key
@anchor{gnutls_x509_crq_set_key}
@deftypefun {int} {gnutls_x509_crq_set_key} (gnutls_x509_crq_t @var{crq}, gnutls_x509_privkey_t @var{key})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{key}: holds a private key

This function will set the public parameters from the given private
key to the request.  

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_set_key_purpose_oid
@anchor{gnutls_x509_crq_set_key_purpose_oid}
@deftypefun {int} {gnutls_x509_crq_set_key_purpose_oid} (gnutls_x509_crq_t @var{crq}, const void * @var{oid}, unsigned int @var{critical})
@var{crq}: a certificate of type @code{gnutls_x509_crq_t} 

@var{oid}: a pointer to a null-terminated string that holds the OID

@var{critical}: Whether this extension will be critical or not

This function will set the key purpose OIDs of the Certificate.
These are stored in the Extended Key Usage extension (2.5.29.37)
See the GNUTLS_KP_* definitions for human readable names.

Subsequent calls to this function will append OIDs to the OID list.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_set_key_rsa_raw
@anchor{gnutls_x509_crq_set_key_rsa_raw}
@deftypefun {int} {gnutls_x509_crq_set_key_rsa_raw} (gnutls_x509_crq_t @var{crq}, const gnutls_datum_t * @var{m}, const gnutls_datum_t * @var{e})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{m}: holds the modulus

@var{e}: holds the public exponent

This function will set the public parameters from the given private
key to the request. Only RSA keys are currently supported.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.6.0
@end deftypefun

@subheading gnutls_x509_crq_set_key_usage
@anchor{gnutls_x509_crq_set_key_usage}
@deftypefun {int} {gnutls_x509_crq_set_key_usage} (gnutls_x509_crq_t @var{crq}, unsigned int @var{usage})
@var{crq}: a certificate request of type @code{gnutls_x509_crq_t} 

@var{usage}: an ORed sequence of the GNUTLS_KEY_* elements.

This function will set the keyUsage certificate extension.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_set_private_key_usage_period
@anchor{gnutls_x509_crq_set_private_key_usage_period}
@deftypefun {int} {gnutls_x509_crq_set_private_key_usage_period} (gnutls_x509_crq_t @var{crq}, time_t @var{activation}, time_t @var{expiration})
@var{crq}: a certificate of type @code{gnutls_x509_crq_t} 

@var{activation}: The activation time

@var{expiration}: The expiration time

This function will set the private key usage period extension (2.5.29.16).

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_set_spki
@anchor{gnutls_x509_crq_set_spki}
@deftypefun {int} {gnutls_x509_crq_set_spki} (gnutls_x509_crq_t @var{crq}, const gnutls_x509_spki_t @var{spki}, unsigned int @var{flags})
@var{crq}: a certificate request of type @code{gnutls_x509_crq_t} 

@var{spki}: a SubjectPublicKeyInfo structure of type @code{gnutls_x509_spki_t} 

@var{flags}: must be zero

This function will set the certificate request's subject public key
information explicitly. This is intended to be used in the cases
where a single public key (e.g., RSA) can be used for multiple
signature algorithms (RSA PKCS1-1.5, and RSA-PSS).

To export the public key (i.e., the SubjectPublicKeyInfo part), check
@code{gnutls_pubkey_import_x509()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.6.0
@end deftypefun

@subheading gnutls_x509_crq_set_subject_alt_name
@anchor{gnutls_x509_crq_set_subject_alt_name}
@deftypefun {int} {gnutls_x509_crq_set_subject_alt_name} (gnutls_x509_crq_t @var{crq}, gnutls_x509_subject_alt_name_t @var{nt}, const void * @var{data}, unsigned int @var{data_size}, unsigned int @var{flags})
@var{crq}: a certificate request of type @code{gnutls_x509_crq_t} 

@var{nt}: is one of the @code{gnutls_x509_subject_alt_name_t}  enumerations

@var{data}: The data to be set

@var{data_size}: The size of data to be set

@var{flags}: @code{GNUTLS_FSAN_SET}  to clear previous data or
@code{GNUTLS_FSAN_APPEND}  to append.

This function will set the subject alternative name certificate
extension.  It can set the following types:

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crq_set_subject_alt_othername
@anchor{gnutls_x509_crq_set_subject_alt_othername}
@deftypefun {int} {gnutls_x509_crq_set_subject_alt_othername} (gnutls_x509_crq_t @var{crq}, const char * @var{oid}, const void * @var{data}, unsigned int @var{data_size}, unsigned int @var{flags})
@var{crq}: a certificate request of type @code{gnutls_x509_crq_t} 

@var{oid}: is the othername OID

@var{data}: The data to be set

@var{data_size}: The size of data to be set

@var{flags}: @code{GNUTLS_FSAN_SET}  to clear previous data or
@code{GNUTLS_FSAN_APPEND}  to append.

This function will set the subject alternative name certificate
extension.  It can set the following types:

The values set must be binary values and must be properly DER encoded.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_crq_set_tlsfeatures
@anchor{gnutls_x509_crq_set_tlsfeatures}
@deftypefun {int} {gnutls_x509_crq_set_tlsfeatures} (gnutls_x509_crq_t @var{crq}, gnutls_x509_tlsfeatures_t @var{features})
@var{crq}: An X.509 certificate request

@var{features}: If the function succeeds, the
features will be added to the certificate
request.

This function will set the certificate request's
X.509 TLS extension from the given structure.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error value.

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_crq_set_version
@anchor{gnutls_x509_crq_set_version}
@deftypefun {int} {gnutls_x509_crq_set_version} (gnutls_x509_crq_t @var{crq}, unsigned int @var{version})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{version}: holds the version number, for v1 Requests must be 1

This function will set the version of the certificate request.  For
version 1 requests this must be one.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_sign
@anchor{gnutls_x509_crq_sign}
@deftypefun {int} {gnutls_x509_crq_sign} (gnutls_x509_crq_t @var{crq}, gnutls_x509_privkey_t @var{key})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{key}: holds a private key

This function is the same a @code{gnutls_x509_crq_sign2()}  with no flags,
and an appropriate hash algorithm. The hash algorithm used may
vary between versions of GnuTLS, and it is tied to the security
level of the issuer's public key.

A known limitation of this function is, that a newly-signed request will not
be fully functional (e.g., for signature verification), until it
is exported an re-imported.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crq_sign2
@anchor{gnutls_x509_crq_sign2}
@deftypefun {int} {gnutls_x509_crq_sign2} (gnutls_x509_crq_t @var{crq}, gnutls_x509_privkey_t @var{key}, gnutls_digest_algorithm_t @var{dig}, unsigned int @var{flags})
@var{crq}: should contain a @code{gnutls_x509_crq_t}  type

@var{key}: holds a private key

@var{dig}: The message digest to use, i.e., @code{GNUTLS_DIG_SHA256} 

@var{flags}: must be 0

This function will sign the certificate request with a private key.
This must be the same key as the one used in
@code{gnutls_x509_crt_set_key()}  since a certificate request is self
signed.

This must be the last step in a certificate request generation
since all the previously set parameters are now signed.

A known limitation of this function is, that a newly-signed request will not
be fully functional (e.g., for signature verification), until it
is exported an re-imported.

After GnuTLS 3.6.1 the value of  @code{dig} may be @code{GNUTLS_DIG_UNKNOWN} ,
and in that case, a suitable but reasonable for the key algorithm will be selected.

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  on success, otherwise a negative error code.
@code{GNUTLS_E_ASN1_VALUE_NOT_FOUND}  is returned if you didn't set all
information in the certificate request (e.g., the version using
@code{gnutls_x509_crq_set_version()} ).
@end deftypefun

@subheading gnutls_x509_crq_verify
@anchor{gnutls_x509_crq_verify}
@deftypefun {int} {gnutls_x509_crq_verify} (gnutls_x509_crq_t @var{crq}, unsigned int @var{flags})
@var{crq}: is the crq to be verified

@var{flags}: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

This function will verify self signature in the certificate
request and return its status.

@strong{Returns:} In case of a verification failure @code{GNUTLS_E_PK_SIG_VERIFY_FAILED}  
is returned, and zero or positive code on success.

Since 2.12.0
@end deftypefun

@subheading gnutls_x509_crt_check_email
@anchor{gnutls_x509_crt_check_email}
@deftypefun {unsigned} {gnutls_x509_crt_check_email} (gnutls_x509_crt_t @var{cert}, const char * @var{email}, unsigned int @var{flags})
@var{cert}: should contain an gnutls_x509_crt_t type

@var{email}: A null terminated string that contains an email address (RFC822)

@var{flags}: should be zero

This function will check if the given certificate's subject matches
the given email address.

@strong{Returns:} non-zero for a successful match, and zero on failure.
@end deftypefun

@subheading gnutls_x509_crt_check_hostname
@anchor{gnutls_x509_crt_check_hostname}
@deftypefun {unsigned} {gnutls_x509_crt_check_hostname} (gnutls_x509_crt_t @var{cert}, const char * @var{hostname})
@var{cert}: should contain an gnutls_x509_crt_t type

@var{hostname}: A null terminated string that contains a DNS name

This function will check if the given certificate's subject matches
the given hostname.  This is a basic implementation of the matching
described in RFC6125, and takes into account wildcards,
and the DNSName/IPAddress subject alternative name PKIX extension.

For details see also @code{gnutls_x509_crt_check_hostname2()} .

@strong{Returns:} non-zero for a successful match, and zero on failure.
@end deftypefun

@subheading gnutls_x509_crt_check_hostname2
@anchor{gnutls_x509_crt_check_hostname2}
@deftypefun {unsigned} {gnutls_x509_crt_check_hostname2} (gnutls_x509_crt_t @var{cert}, const char * @var{hostname}, unsigned int @var{flags})
@var{cert}: should contain an gnutls_x509_crt_t type

@var{hostname}: A null terminated string that contains a DNS name

@var{flags}: gnutls_certificate_verify_flags

This function will check if the given certificate's subject matches
the given hostname.  This is a basic implementation of the matching
described in RFC6125, and takes into account wildcards,
and the DNSName/IPAddress subject alternative name PKIX extension.

IPv4 addresses are accepted by this function in the dotted-decimal
format (e.g, ddd.ddd.ddd.ddd), and IPv6 addresses in the hexadecimal
x:x:x:x:x:x:x:x format. For them the IPAddress subject alternative
name extension is consulted. Previous versions to 3.6.0 of GnuTLS
in case of a non-match would consult (in a non-standard extension)
the DNSname and CN fields. This is no longer the case.

When the flag @code{GNUTLS_VERIFY_DO_NOT_ALLOW_WILDCARDS}  is specified no
wildcards are considered. Otherwise they are only considered if the
domain name consists of three components or more, and the wildcard
starts at the leftmost position.
When the flag @code{GNUTLS_VERIFY_DO_NOT_ALLOW_IP_MATCHES}  is specified,
the input will be treated as a DNS name, and matching of textual IP addresses
against the IPAddress part of the alternative name will not be allowed.

The function @code{gnutls_x509_crt_check_ip()}  is available for matching
IP addresses.

@strong{Returns:} non-zero for a successful match, and zero on failure.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_crt_check_ip
@anchor{gnutls_x509_crt_check_ip}
@deftypefun {unsigned} {gnutls_x509_crt_check_ip} (gnutls_x509_crt_t @var{cert}, const unsigned char * @var{ip}, unsigned int @var{ip_size}, unsigned int @var{flags})
@var{cert}: should contain an gnutls_x509_crt_t type

@var{ip}: A pointer to the raw IP address

@var{ip_size}: the number of bytes in ip (4 or 16)

@var{flags}: should be zero

This function will check if the IP allowed IP addresses in 
the certificate's subject alternative name match the provided
IP address.

@strong{Returns:} non-zero for a successful match, and zero on failure.
@end deftypefun

@subheading gnutls_x509_crt_check_issuer
@anchor{gnutls_x509_crt_check_issuer}
@deftypefun {unsigned} {gnutls_x509_crt_check_issuer} (gnutls_x509_crt_t @var{cert}, gnutls_x509_crt_t @var{issuer})
@var{cert}: is the certificate to be checked

@var{issuer}: is the certificate of a possible issuer

This function will check if the given certificate was issued by the
given issuer. It checks the DN fields and the authority
key identifier and subject key identifier fields match.

If the same certificate is provided at the  @code{cert} and  @code{issuer} fields,
it will check whether the certificate is self-signed.

@strong{Returns:} It will return true (1) if the given certificate is issued
by the given issuer, and false (0) if not.  
@end deftypefun

@subheading gnutls_x509_crt_check_key_purpose
@anchor{gnutls_x509_crt_check_key_purpose}
@deftypefun {unsigned} {gnutls_x509_crt_check_key_purpose} (gnutls_x509_crt_t @var{cert}, const char * @var{purpose}, unsigned @var{flags})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{purpose}: a key purpose OID (e.g., @code{GNUTLS_KP_CODE_SIGNING} )

@var{flags}: zero or @code{GNUTLS_KP_FLAG_DISALLOW_ANY} 

This function will check whether the given certificate matches
the provided key purpose. If  @code{flags} contains @code{GNUTLS_KP_FLAG_ALLOW_ANY}  then
it a certificate marked for any purpose will not match.

@strong{Returns:} zero if the key purpose doesn't match, and non-zero otherwise.

@strong{Since:} 3.5.6
@end deftypefun

@subheading gnutls_x509_crt_check_revocation
@anchor{gnutls_x509_crt_check_revocation}
@deftypefun {int} {gnutls_x509_crt_check_revocation} (gnutls_x509_crt_t @var{cert}, const gnutls_x509_crl_t * @var{crl_list}, unsigned @var{crl_list_length})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{crl_list}: should contain a list of gnutls_x509_crl_t types

@var{crl_list_length}: the length of the crl_list

This function will check if the given certificate is
revoked.  It is assumed that the CRLs have been verified before.

@strong{Returns:} 0 if the certificate is NOT revoked, and 1 if it is.  A
negative error code is returned on error.
@end deftypefun

@subheading gnutls_x509_crt_cpy_crl_dist_points
@anchor{gnutls_x509_crt_cpy_crl_dist_points}
@deftypefun {int} {gnutls_x509_crt_cpy_crl_dist_points} (gnutls_x509_crt_t @var{dst}, gnutls_x509_crt_t @var{src})
@var{dst}: a certificate of type @code{gnutls_x509_crt_t} 

@var{src}: the certificate where the dist points will be copied from

This function will copy the CRL distribution points certificate
extension, from the source to the destination certificate.
This may be useful to copy from a CA certificate to issued ones.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_deinit
@anchor{gnutls_x509_crt_deinit}
@deftypefun {void} {gnutls_x509_crt_deinit} (gnutls_x509_crt_t @var{cert})
@var{cert}: The data to be deinitialized

This function will deinitialize a certificate structure.
@end deftypefun

@subheading gnutls_x509_crt_equals
@anchor{gnutls_x509_crt_equals}
@deftypefun {unsigned} {gnutls_x509_crt_equals} (gnutls_x509_crt_t @var{cert1}, gnutls_x509_crt_t @var{cert2})
@var{cert1}: The first certificate

@var{cert2}: The second certificate

This function will compare two X.509 certificate structures.

@strong{Returns:} On equality non-zero is returned, otherwise zero.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_crt_equals2
@anchor{gnutls_x509_crt_equals2}
@deftypefun {unsigned} {gnutls_x509_crt_equals2} (gnutls_x509_crt_t @var{cert1}, const gnutls_datum_t * @var{der})
@var{cert1}: The first certificate

@var{der}: A DER encoded certificate

This function will compare an X.509 certificate structures, with DER
encoded certificate data.

@strong{Returns:} On equality non-zero is returned, otherwise zero.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_crt_export
@anchor{gnutls_x509_crt_export}
@deftypefun {int} {gnutls_x509_crt_export} (gnutls_x509_crt_t @var{cert}, gnutls_x509_crt_fmt_t @var{format}, void * @var{output_data}, size_t * @var{output_data_size})
@var{cert}: Holds the certificate

@var{format}: the format of output params. One of PEM or DER.

@var{output_data}: will contain a certificate PEM or DER encoded

@var{output_data_size}: holds the size of output_data (and will be
replaced by the actual size of parameters)

This function will export the certificate to DER or PEM format.

If the buffer provided is not long enough to hold the output, then
*output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
be returned.

If the structure is PEM encoded, it will have a header
of "BEGIN CERTIFICATE".

@strong{Returns:} In case of failure a negative error code will be
returned, and 0 on success.
@end deftypefun

@subheading gnutls_x509_crt_export2
@anchor{gnutls_x509_crt_export2}
@deftypefun {int} {gnutls_x509_crt_export2} (gnutls_x509_crt_t @var{cert}, gnutls_x509_crt_fmt_t @var{format}, gnutls_datum_t * @var{out})
@var{cert}: Holds the certificate

@var{format}: the format of output params. One of PEM or DER.

@var{out}: will contain a certificate PEM or DER encoded

This function will export the certificate to DER or PEM format.
The output buffer is allocated using @code{gnutls_malloc()} .

If the structure is PEM encoded, it will have a header
of "BEGIN CERTIFICATE".

@strong{Returns:} In case of failure a negative error code will be
returned, and 0 on success.

@strong{Since:} 3.1.3
@end deftypefun

@subheading gnutls_x509_crt_get_activation_time
@anchor{gnutls_x509_crt_get_activation_time}
@deftypefun {time_t} {gnutls_x509_crt_get_activation_time} (gnutls_x509_crt_t @var{cert})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

This function will return the time this Certificate was or will be
activated.

@strong{Returns:} activation time, or (time_t)-1 on error.
@end deftypefun

@subheading gnutls_x509_crt_get_authority_info_access
@anchor{gnutls_x509_crt_get_authority_info_access}
@deftypefun {int} {gnutls_x509_crt_get_authority_info_access} (gnutls_x509_crt_t @var{crt}, unsigned int @var{seq}, int @var{what}, gnutls_datum_t * @var{data}, unsigned int * @var{critical})
@var{crt}: Holds the certificate

@var{seq}: specifies the sequence number of the access descriptor (0 for the first one, 1 for the second etc.)

@var{what}: what data to get, a @code{gnutls_info_access_what_t}  type.

@var{data}: output data to be freed with @code{gnutls_free()} .

@var{critical}: pointer to output integer that is set to non-zero if the extension is marked as critical (may be @code{NULL} )

Note that a simpler API to access the authority info data is provided
by @code{gnutls_x509_aia_get()}  and @code{gnutls_x509_ext_import_aia()} .

This function extracts the Authority Information Access (AIA)
extension, see RFC 5280 section 4.2.2.1 for more information.  The
AIA extension holds a sequence of AccessDescription (AD) data.

The  @code{seq} input parameter is used to indicate which member of the
sequence the caller is interested in.  The first member is 0, the
second member 1 and so on.  When the  @code{seq} value is out of bounds,
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.

The type of data returned in  @code{data} is specified via  @code{what} which
should be @code{gnutls_info_access_what_t}  values.

If  @code{what} is @code{GNUTLS_IA_ACCESSMETHOD_OID}  then  @code{data} will hold the
accessMethod OID (e.g., "1.3.6.1.5.5.7.48.1").

If  @code{what} is @code{GNUTLS_IA_ACCESSLOCATION_GENERALNAME_TYPE} ,  @code{data} will
hold the accessLocation GeneralName type (e.g.,
"uniformResourceIdentifier").

If  @code{what} is @code{GNUTLS_IA_URI} ,  @code{data} will hold the accessLocation URI
data.  Requesting this  @code{what} value leads to an error if the
accessLocation is not of the "uniformResourceIdentifier" type.

If  @code{what} is @code{GNUTLS_IA_OCSP_URI} ,  @code{data} will hold the OCSP URI.
Requesting this  @code{what} value leads to an error if the accessMethod
is not 1.3.6.1.5.5.7.48.1 aka OCSP, or if accessLocation is not of
the "uniformResourceIdentifier" type. In that case @code{GNUTLS_E_UNKNOWN_ALGORITHM} 
will be returned, and  @code{seq} should be increased and this function
called again.

If  @code{what} is @code{GNUTLS_IA_CAISSUERS_URI} ,  @code{data} will hold the caIssuers
URI.  Requesting this  @code{what} value leads to an error if the
accessMethod is not 1.3.6.1.5.5.7.48.2 aka caIssuers, or if
accessLocation is not of the "uniformResourceIdentifier" type.
In that case handle as in @code{GNUTLS_IA_OCSP_URI} .

More  @code{what} values may be allocated in the future as needed.

If  @code{data} is NULL, the function does the same without storing the
output data, that is, it will set  @code{critical} and do error checking
as usual.

The value of the critical flag is returned in * @code{critical} .  Supply a
NULL  @code{critical} if you want the function to make sure the extension
is non-critical, as required by RFC 5280.

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  on success, @code{GNUTLS_E_INVALID_REQUEST}  on
invalid  @code{crt} , @code{GNUTLS_E_CONSTRAINT_ERROR}  if the extension is
incorrectly marked as critical (use a non-NULL  @code{critical} to
override), @code{GNUTLS_E_UNKNOWN_ALGORITHM}  if the requested OID does
not match (e.g., when using @code{GNUTLS_IA_OCSP_URI} ), otherwise a
negative error code.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_crt_get_authority_key_gn_serial
@anchor{gnutls_x509_crt_get_authority_key_gn_serial}
@deftypefun {int} {gnutls_x509_crt_get_authority_key_gn_serial} (gnutls_x509_crt_t @var{cert}, unsigned int @var{seq}, void * @var{alt}, size_t * @var{alt_size}, unsigned int * @var{alt_type}, void * @var{serial}, size_t * @var{serial_size}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{seq}: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

@var{alt}: is the place where the alternative name will be copied to

@var{alt_size}: holds the size of alt.

@var{alt_type}: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).

@var{serial}: buffer to store the serial number (may be null)

@var{serial_size}: Holds the size of the serial field (may be null)

@var{critical}: will be non-zero if the extension is marked as critical (may be null)

This function will return the X.509 authority key
identifier when stored as a general name (authorityCertIssuer)
and serial number.

Because more than one general names might be stored
 @code{seq} can be used as a counter to request them all until
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_crt_get_authority_key_id
@anchor{gnutls_x509_crt_get_authority_key_id}
@deftypefun {int} {gnutls_x509_crt_get_authority_key_id} (gnutls_x509_crt_t @var{cert}, void * @var{id}, size_t * @var{id_size}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{id}: The place where the identifier will be copied

@var{id_size}: Holds the size of the id field.

@var{critical}: will be non-zero if the extension is marked as critical (may be null)

This function will return the X.509v3 certificate authority's key
identifier.  This is obtained by the X.509 Authority Key
identifier extension field (2.5.29.35). Note that this function
only returns the keyIdentifier field of the extension and
@code{GNUTLS_E_X509_UNSUPPORTED_EXTENSION} , if the extension contains
the name and serial number of the certificate. In that case
@code{gnutls_x509_crt_get_authority_key_gn_serial()}  may be used.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.
@end deftypefun

@subheading gnutls_x509_crt_get_basic_constraints
@anchor{gnutls_x509_crt_get_basic_constraints}
@deftypefun {int} {gnutls_x509_crt_get_basic_constraints} (gnutls_x509_crt_t @var{cert}, unsigned int * @var{critical}, unsigned int * @var{ca}, int * @var{pathlen})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{critical}: will be non-zero if the extension is marked as critical

@var{ca}: pointer to output integer indicating CA status, may be NULL,
value is 1 if the certificate CA flag is set, 0 otherwise.

@var{pathlen}: pointer to output integer indicating path length (may be
NULL), non-negative error codes indicate a present pathLenConstraint
field and the actual value, -1 indicate that the field is absent.

This function will read the certificate's basic constraints, and
return the certificates CA status.  It reads the basicConstraints
X.509 extension (2.5.29.19).

@strong{Returns:} If the certificate is a CA a positive value will be
returned, or (0) if the certificate does not have CA flag set.  A
negative error code may be returned in case of errors.  If the
certificate does not contain the basicConstraints extension
GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
@end deftypefun

@subheading gnutls_x509_crt_get_ca_status
@anchor{gnutls_x509_crt_get_ca_status}
@deftypefun {int} {gnutls_x509_crt_get_ca_status} (gnutls_x509_crt_t @var{cert}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{critical}: will be non-zero if the extension is marked as critical

This function will return certificates CA status, by reading the
basicConstraints X.509 extension (2.5.29.19). If the certificate is
a CA a positive value will be returned, or (0) if the certificate
does not have CA flag set.

Use @code{gnutls_x509_crt_get_basic_constraints()}  if you want to read the
pathLenConstraint field too.

@strong{Returns:} If the certificate is a CA a positive value will be
returned, or (0) if the certificate does not have CA flag set.  A
negative error code may be returned in case of errors.  If the
certificate does not contain the basicConstraints extension
GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
@end deftypefun

@subheading gnutls_x509_crt_get_crl_dist_points
@anchor{gnutls_x509_crt_get_crl_dist_points}
@deftypefun {int} {gnutls_x509_crt_get_crl_dist_points} (gnutls_x509_crt_t @var{cert}, unsigned int @var{seq}, void * @var{san}, size_t * @var{san_size}, unsigned int * @var{reason_flags}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{seq}: specifies the sequence number of the distribution point (0 for the first one, 1 for the second etc.)

@var{san}: is the place where the distribution point will be copied to

@var{san_size}: holds the size of ret.

@var{reason_flags}: Revocation reasons. An ORed sequence of flags from @code{gnutls_x509_crl_reason_flags_t} .

@var{critical}: will be non-zero if the extension is marked as critical (may be null)

This function retrieves the CRL distribution points (2.5.29.31),
contained in the given certificate in the X509v3 Certificate
Extensions.

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  and updates  @code{ret_size} if
 @code{ret_size} is not enough to hold the distribution point, or the
type of the distribution point if everything was ok. The type is
one of the enumerated @code{gnutls_x509_subject_alt_name_t} .  If the
certificate does not have an Alternative name with the specified
sequence number then @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is
returned.
@end deftypefun

@subheading gnutls_x509_crt_get_dn
@anchor{gnutls_x509_crt_get_dn}
@deftypefun {int} {gnutls_x509_crt_get_dn} (gnutls_x509_crt_t @var{cert}, char * @var{buf}, size_t * @var{buf_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{buf}: a pointer to a structure to hold the name (may be null)

@var{buf_size}: initially holds the size of  @code{buf} 

This function will copy the name of the Certificate in the provided
buffer. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

The  @code{buf} returned will be null terminated and the  @code{buf_size} will account
for the trailing null. If  @code{buf} is null then only the size will be filled.

This function does not output a fully RFC4514 compliant string, if
that is required see @code{gnutls_x509_crt_get_dn3()} .

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is not
long enough, and in that case the  @code{buf_size} will be updated
with the required size. @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  if
the DN does not exist, or another error value on error. On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_dn2
@anchor{gnutls_x509_crt_get_dn2}
@deftypefun {int} {gnutls_x509_crt_get_dn2} (gnutls_x509_crt_t @var{cert}, gnutls_datum_t * @var{dn})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{dn}: a pointer to a structure to hold the name; must be freed using @code{gnutls_free()} 

This function will allocate buffer and copy the name of the Certificate.
The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

This function does not output a fully RFC4514 compliant string, if
that is required see @code{gnutls_x509_crt_get_dn3()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.1.10
@end deftypefun

@subheading gnutls_x509_crt_get_dn3
@anchor{gnutls_x509_crt_get_dn3}
@deftypefun {int} {gnutls_x509_crt_get_dn3} (gnutls_x509_crt_t @var{cert}, gnutls_datum_t * @var{dn}, unsigned @var{flags})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{dn}: a pointer to a structure to hold the name; must be freed using @code{gnutls_free()} 

@var{flags}: zero or @code{GNUTLS_X509_DN_FLAG_COMPAT} 

This function will allocate buffer and copy the name of the Certificate.
The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

When the flag @code{GNUTLS_X509_DN_FLAG_COMPAT}  is specified, the output
format will match the format output by previous to 3.5.6 versions of GnuTLS
which was not not fully RFC4514-compliant.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.5.7
@end deftypefun

@subheading gnutls_x509_crt_get_dn_by_oid
@anchor{gnutls_x509_crt_get_dn_by_oid}
@deftypefun {int} {gnutls_x509_crt_get_dn_by_oid} (gnutls_x509_crt_t @var{cert}, const char * @var{oid}, unsigned @var{indx}, unsigned int @var{raw_flag}, void * @var{buf}, size_t * @var{buf_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{oid}: holds an Object Identified in null terminated string

@var{indx}: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.

@var{raw_flag}: If non-zero returns the raw DER data of the DN part.

@var{buf}: a pointer where the DN part will be copied (may be null).

@var{buf_size}: initially holds the size of  @code{buf} 

This function will extract the part of the name of the Certificate
subject specified by the given OID. The output, if the raw flag is
not used, will be encoded as described in RFC4514. Thus a string
that is ASCII or UTF-8 encoded, depending on the certificate data.

Some helper macros with popular OIDs can be found in gnutls/x509.h
If raw flag is (0), this function will only return known OIDs as
text. Other OIDs will be DER encoded, as described in RFC4514 --
in hex format with a '#' prefix.  You can check about known OIDs
using @code{gnutls_x509_dn_oid_known()} .

If  @code{buf} is null then only the size will be filled. If the  @code{raw_flag} is not specified the output is always null terminated, although the
 @code{buf_size} will not include the null character.

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is not
long enough, and in that case the  @code{buf_size} will be updated with
the required size. @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  if there
are no data in the current index. On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_dn_oid
@anchor{gnutls_x509_crt_get_dn_oid}
@deftypefun {int} {gnutls_x509_crt_get_dn_oid} (gnutls_x509_crt_t @var{cert}, unsigned @var{indx}, void * @var{oid}, size_t * @var{oid_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{indx}: This specifies which OID to return. Use (0) to get the first one.

@var{oid}: a pointer to a buffer to hold the OID (may be null)

@var{oid_size}: initially holds the size of  @code{oid} 

This function will extract the OIDs of the name of the Certificate
subject specified by the given index.

If  @code{oid} is null then only the size will be filled. The  @code{oid} returned will be null terminated, although  @code{oid_size} will not
account for the trailing null.

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is not
long enough, and in that case the  @code{buf_size} will be updated with
the required size. @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  if there
are no data in the current index. On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_expiration_time
@anchor{gnutls_x509_crt_get_expiration_time}
@deftypefun {time_t} {gnutls_x509_crt_get_expiration_time} (gnutls_x509_crt_t @var{cert})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

This function will return the time this certificate was or will be
expired.

@strong{Returns:} expiration time, or (time_t)-1 on error.
@end deftypefun

@subheading gnutls_x509_crt_get_extension_by_oid
@anchor{gnutls_x509_crt_get_extension_by_oid}
@deftypefun {int} {gnutls_x509_crt_get_extension_by_oid} (gnutls_x509_crt_t @var{cert}, const char * @var{oid}, unsigned @var{indx}, void * @var{buf}, size_t * @var{buf_size}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{oid}: holds an Object Identified in null terminated string

@var{indx}: In case multiple same OIDs exist in the extensions, this specifies which to send. Use (0) to get the first one.

@var{buf}: a pointer to a structure to hold the name (may be null)

@var{buf_size}: initially holds the size of  @code{buf} 

@var{critical}: will be non-zero if the extension is marked as critical

This function will return the extension specified by the OID in the
certificate.  The extensions will be returned as binary data DER
encoded, in the provided buffer.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error code is returned. If the certificate does not
contain the specified extension
GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
@end deftypefun

@subheading gnutls_x509_crt_get_extension_by_oid2
@anchor{gnutls_x509_crt_get_extension_by_oid2}
@deftypefun {int} {gnutls_x509_crt_get_extension_by_oid2} (gnutls_x509_crt_t @var{cert}, const char * @var{oid}, unsigned @var{indx}, gnutls_datum_t * @var{output}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{oid}: holds an Object Identified in null terminated string

@var{indx}: In case multiple same OIDs exist in the extensions, this specifies which to send. Use (0) to get the first one.

@var{output}: will hold the allocated extension data

@var{critical}: will be non-zero if the extension is marked as critical

This function will return the extension specified by the OID in the
certificate.  The extensions will be returned as binary data DER
encoded, in the provided buffer.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error code is returned. If the certificate does not
contain the specified extension
GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

@strong{Since:} 3.3.8
@end deftypefun

@subheading gnutls_x509_crt_get_extension_data
@anchor{gnutls_x509_crt_get_extension_data}
@deftypefun {int} {gnutls_x509_crt_get_extension_data} (gnutls_x509_crt_t @var{cert}, unsigned @var{indx}, void * @var{data}, size_t * @var{sizeof_data})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{indx}: Specifies which extension OID to send. Use (0) to get the first one.

@var{data}: a pointer to a structure to hold the data (may be null)

@var{sizeof_data}: initially holds the size of  @code{data} 

This function will return the requested extension data in the
certificate.  The extension data will be stored in the
provided buffer.

Use @code{gnutls_x509_crt_get_extension_info()}  to extract the OID and
critical flag.  Use @code{gnutls_x509_crt_get_extension_by_oid()}  instead,
if you want to get data indexed by the extension OID rather than
sequence.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.
@end deftypefun

@subheading gnutls_x509_crt_get_extension_data2
@anchor{gnutls_x509_crt_get_extension_data2}
@deftypefun {int} {gnutls_x509_crt_get_extension_data2} (gnutls_x509_crt_t @var{cert}, unsigned @var{indx}, gnutls_datum_t * @var{data})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{indx}: Specifies which extension OID to read. Use (0) to get the first one.

@var{data}: will contain the extension DER-encoded data

This function will return the requested by the index extension data in the
certificate.  The extension data will be allocated using
@code{gnutls_malloc()} .

Use @code{gnutls_x509_crt_get_extension_info()}  to extract the OID.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.
@end deftypefun

@subheading gnutls_x509_crt_get_extension_info
@anchor{gnutls_x509_crt_get_extension_info}
@deftypefun {int} {gnutls_x509_crt_get_extension_info} (gnutls_x509_crt_t @var{cert}, unsigned @var{indx}, void * @var{oid}, size_t * @var{oid_size}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{indx}: Specifies which extension OID to send. Use (0) to get the first one.

@var{oid}: a pointer to a structure to hold the OID

@var{oid_size}: initially holds the maximum size of  @code{oid} , on return
holds actual size of  @code{oid} .

@var{critical}: output variable with critical flag, may be NULL.

This function will return the requested extension OID in the
certificate, and the critical flag for it.  The extension OID will
be stored as a string in the provided buffer.  Use
@code{gnutls_x509_crt_get_extension()}  to extract the data.

If the buffer provided is not long enough to hold the output, then
 @code{oid_size} is updated and @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  will be
returned. The  @code{oid} returned will be null terminated, although
 @code{oid_size} will not account for the trailing null (the latter is not
true for GnuTLS prior to 3.6.0).

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.
@end deftypefun

@subheading gnutls_x509_crt_get_extension_oid
@anchor{gnutls_x509_crt_get_extension_oid}
@deftypefun {int} {gnutls_x509_crt_get_extension_oid} (gnutls_x509_crt_t @var{cert}, unsigned @var{indx}, void * @var{oid}, size_t * @var{oid_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{indx}: Specifies which extension OID to send. Use (0) to get the first one.

@var{oid}: a pointer to a structure to hold the OID (may be null)

@var{oid_size}: initially holds the size of  @code{oid} 

This function will return the requested extension OID in the certificate.
The extension OID will be stored as a string in the provided buffer.

The  @code{oid} returned will be null terminated, although  @code{oid_size} will not
account for the trailing null.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
will be returned.
@end deftypefun

@subheading gnutls_x509_crt_get_fingerprint
@anchor{gnutls_x509_crt_get_fingerprint}
@deftypefun {int} {gnutls_x509_crt_get_fingerprint} (gnutls_x509_crt_t @var{cert}, gnutls_digest_algorithm_t @var{algo}, void * @var{buf}, size_t * @var{buf_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{algo}: is a digest algorithm

@var{buf}: a pointer to a structure to hold the fingerprint (may be null)

@var{buf_size}: initially holds the size of  @code{buf} 

This function will calculate and copy the certificate's fingerprint
in the provided buffer. The fingerprint is a hash of the DER-encoded
data of the certificate.

If the buffer is null then only the size will be filled.

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is
not long enough, and in that case the *buf_size will be updated
with the required size.  On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_inhibit_anypolicy
@anchor{gnutls_x509_crt_get_inhibit_anypolicy}
@deftypefun {int} {gnutls_x509_crt_get_inhibit_anypolicy} (gnutls_x509_crt_t @var{cert}, unsigned int * @var{skipcerts}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{skipcerts}: will hold the number of certificates after which anypolicy is no longer acceptable.

@var{critical}: will be non-zero if the extension is marked as critical

This function will return certificate's value of the SkipCerts, i.e.,
the Inhibit anyPolicy X.509 extension (2.5.29.54).

The returned value is the number of additional certificates that
may appear in the path before the anyPolicy is no longer acceptable.

@strong{Returns:} zero on success, or a negative error code in case of
parsing error.  If the certificate does not contain the Inhibit anyPolicy
extension @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  will be
returned.

@strong{Since:} 3.6.0
@end deftypefun

@subheading gnutls_x509_crt_get_issuer
@anchor{gnutls_x509_crt_get_issuer}
@deftypefun {int} {gnutls_x509_crt_get_issuer} (gnutls_x509_crt_t @var{cert}, gnutls_x509_dn_t * @var{dn})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{dn}: output variable with pointer to uint8_t DN

Return the Certificate's Issuer DN as a @code{gnutls_x509_dn_t}  data type,
that can be decoded using @code{gnutls_x509_dn_get_rdn_ava()} .

Note that  @code{dn} should be treated as constant. Because it points
into the  @code{cert} object, you should not use  @code{dn} after  @code{cert} is
deallocated.

@strong{Returns:} Returns 0 on success, or an error code.
@end deftypefun

@subheading gnutls_x509_crt_get_issuer_alt_name
@anchor{gnutls_x509_crt_get_issuer_alt_name}
@deftypefun {int} {gnutls_x509_crt_get_issuer_alt_name} (gnutls_x509_crt_t @var{cert}, unsigned int @var{seq}, void * @var{ian}, size_t * @var{ian_size}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{seq}: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

@var{ian}: is the place where the alternative name will be copied to

@var{ian_size}: holds the size of ian.

@var{critical}: will be non-zero if the extension is marked as critical (may be null)

This function retrieves the Issuer Alternative Name (2.5.29.18),
contained in the given certificate in the X509v3 Certificate
Extensions.

When the SAN type is otherName, it will extract the data in the
otherName's value field, and @code{GNUTLS_SAN_OTHERNAME}  is returned.
You may use @code{gnutls_x509_crt_get_subject_alt_othername_oid()}  to get
the corresponding OID and the "virtual" SAN types (e.g.,
@code{GNUTLS_SAN_OTHERNAME_XMPP} ).

If an otherName OID is known, the data will be decoded.  Otherwise
the returned data will be DER encoded, and you will have to decode
it yourself.  Currently, only the RFC 3920 id-on-xmppAddr Issuer
AltName is recognized.

@strong{Returns:} the alternative issuer name type on success, one of the
enumerated @code{gnutls_x509_subject_alt_name_t} .  It will return
@code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if  @code{ian_size} is not large enough
to hold the value.  In that case  @code{ian_size} will be updated with
the required size.  If the certificate does not have an
Alternative name with the specified sequence number then
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.

@strong{Since:} 2.10.0
@end deftypefun

@subheading gnutls_x509_crt_get_issuer_alt_name2
@anchor{gnutls_x509_crt_get_issuer_alt_name2}
@deftypefun {int} {gnutls_x509_crt_get_issuer_alt_name2} (gnutls_x509_crt_t @var{cert}, unsigned int @var{seq}, void * @var{ian}, size_t * @var{ian_size}, unsigned int * @var{ian_type}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{seq}: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

@var{ian}: is the place where the alternative name will be copied to

@var{ian_size}: holds the size of ret.

@var{ian_type}: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).

@var{critical}: will be non-zero if the extension is marked as critical (may be null)

This function will return the alternative names, contained in the
given certificate. It is the same as
@code{gnutls_x509_crt_get_issuer_alt_name()}  except for the fact that it
will return the type of the alternative name in  @code{ian_type} even if
the function fails for some reason (i.e.  the buffer provided is
not enough).

@strong{Returns:} the alternative issuer name type on success, one of the
enumerated @code{gnutls_x509_subject_alt_name_t} .  It will return
@code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if  @code{ian_size} is not large enough
to hold the value.  In that case  @code{ian_size} will be updated with
the required size.  If the certificate does not have an
Alternative name with the specified sequence number then
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.

@strong{Since:} 2.10.0
@end deftypefun

@subheading gnutls_x509_crt_get_issuer_alt_othername_oid
@anchor{gnutls_x509_crt_get_issuer_alt_othername_oid}
@deftypefun {int} {gnutls_x509_crt_get_issuer_alt_othername_oid} (gnutls_x509_crt_t @var{cert}, unsigned int @var{seq}, void * @var{ret}, size_t * @var{ret_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{seq}: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

@var{ret}: is the place where the otherName OID will be copied to

@var{ret_size}: holds the size of ret.

This function will extract the type OID of an otherName Subject
Alternative Name, contained in the given certificate, and return
the type as an enumerated element.

If  @code{oid} is null then only the size will be filled. The  @code{oid} returned will be null terminated, although  @code{oid_size} will not
account for the trailing null.

This function is only useful if
@code{gnutls_x509_crt_get_issuer_alt_name()}  returned
@code{GNUTLS_SAN_OTHERNAME} .

@strong{Returns:} the alternative issuer name type on success, one of the
enumerated gnutls_x509_subject_alt_name_t.  For supported OIDs, it
will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types,
e.g. @code{GNUTLS_SAN_OTHERNAME_XMPP} , and @code{GNUTLS_SAN_OTHERNAME}  for
unknown OIDs.  It will return @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if
 @code{ret_size} is not large enough to hold the value.  In that case
 @code{ret_size} will be updated with the required size.  If the
certificate does not have an Alternative name with the specified
sequence number and with the otherName type then
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.

@strong{Since:} 2.10.0
@end deftypefun

@subheading gnutls_x509_crt_get_issuer_dn
@anchor{gnutls_x509_crt_get_issuer_dn}
@deftypefun {int} {gnutls_x509_crt_get_issuer_dn} (gnutls_x509_crt_t @var{cert}, char * @var{buf}, size_t * @var{buf_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{buf}: a pointer to a structure to hold the name (may be null)

@var{buf_size}: initially holds the size of  @code{buf} 

This function will copy the name of the Certificate issuer in the
provided buffer. The name will be in the form
"C=xxxx,O=yyyy,CN=zzzz" as described in RFC4514. The output string
will be ASCII or UTF-8 encoded, depending on the certificate data.

If  @code{buf} is null then only the size will be filled.

This function does not output a fully RFC4514 compliant string, if
that is required see @code{gnutls_x509_crt_get_issuer_dn3()} .

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is not
long enough, and in that case the  @code{buf_size} will be updated
with the required size. @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  if
the DN does not exist, or another error value on error. On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_issuer_dn2
@anchor{gnutls_x509_crt_get_issuer_dn2}
@deftypefun {int} {gnutls_x509_crt_get_issuer_dn2} (gnutls_x509_crt_t @var{cert}, gnutls_datum_t * @var{dn})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{dn}: a pointer to a structure to hold the name; must be freed using @code{gnutls_free()} 

This function will allocate buffer and copy the name of issuer of the Certificate.
The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

This function does not output a fully RFC4514 compliant string, if
that is required see @code{gnutls_x509_crt_get_issuer_dn3()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.1.10
@end deftypefun

@subheading gnutls_x509_crt_get_issuer_dn3
@anchor{gnutls_x509_crt_get_issuer_dn3}
@deftypefun {int} {gnutls_x509_crt_get_issuer_dn3} (gnutls_x509_crt_t @var{cert}, gnutls_datum_t * @var{dn}, unsigned @var{flags})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{dn}: a pointer to a structure to hold the name; must be freed using @code{gnutls_free()} 

@var{flags}: zero or @code{GNUTLS_X509_DN_FLAG_COMPAT} 

This function will allocate buffer and copy the name of issuer of the Certificate.
The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

When the flag @code{GNUTLS_X509_DN_FLAG_COMPAT}  is specified, the output
format will match the format output by previous to 3.5.6 versions of GnuTLS
which was not not fully RFC4514-compliant.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.5.7
@end deftypefun

@subheading gnutls_x509_crt_get_issuer_dn_by_oid
@anchor{gnutls_x509_crt_get_issuer_dn_by_oid}
@deftypefun {int} {gnutls_x509_crt_get_issuer_dn_by_oid} (gnutls_x509_crt_t @var{cert}, const char * @var{oid}, unsigned @var{indx}, unsigned int @var{raw_flag}, void * @var{buf}, size_t * @var{buf_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{oid}: holds an Object Identified in null terminated string

@var{indx}: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.

@var{raw_flag}: If non-zero returns the raw DER data of the DN part.

@var{buf}: a pointer to a structure to hold the name (may be null)

@var{buf_size}: initially holds the size of  @code{buf} 

This function will extract the part of the name of the Certificate
issuer specified by the given OID. The output, if the raw flag is not
used, will be encoded as described in RFC4514. Thus a string that is
ASCII or UTF-8 encoded, depending on the certificate data.

Some helper macros with popular OIDs can be found in gnutls/x509.h
If raw flag is (0), this function will only return known OIDs as
text. Other OIDs will be DER encoded, as described in RFC4514 --
in hex format with a '#' prefix.  You can check about known OIDs
using @code{gnutls_x509_dn_oid_known()} .

If  @code{buf} is null then only the size will be filled. If the  @code{raw_flag} is not specified the output is always null terminated, although the
 @code{buf_size} will not include the null character.

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is not
long enough, and in that case the  @code{buf_size} will be updated with
the required size. @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  if there
are no data in the current index. On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_issuer_dn_oid
@anchor{gnutls_x509_crt_get_issuer_dn_oid}
@deftypefun {int} {gnutls_x509_crt_get_issuer_dn_oid} (gnutls_x509_crt_t @var{cert}, unsigned @var{indx}, void * @var{oid}, size_t * @var{oid_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{indx}: This specifies which OID to return. Use (0) to get the first one.

@var{oid}: a pointer to a buffer to hold the OID (may be null)

@var{oid_size}: initially holds the size of  @code{oid} 

This function will extract the OIDs of the name of the Certificate
issuer specified by the given index.

If  @code{oid} is null then only the size will be filled. The  @code{oid} returned will be null terminated, although  @code{oid_size} will not
account for the trailing null.

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is not
long enough, and in that case the  @code{buf_size} will be updated with
the required size. @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  if there
are no data in the current index. On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_issuer_unique_id
@anchor{gnutls_x509_crt_get_issuer_unique_id}
@deftypefun {int} {gnutls_x509_crt_get_issuer_unique_id} (gnutls_x509_crt_t @var{crt}, char * @var{buf}, size_t * @var{buf_size})
@var{crt}: Holds the certificate

@var{buf}: user allocated memory buffer, will hold the unique id

@var{buf_size}: size of user allocated memory buffer (on input), will hold
actual size of the unique ID on return.

This function will extract the issuerUniqueID value (if present) for
the given certificate.

If the user allocated memory buffer is not large enough to hold the
full subjectUniqueID, then a GNUTLS_E_SHORT_MEMORY_BUFFER error will be
returned, and buf_size will be set to the actual length.

This function had a bug prior to 3.4.8 that prevented the setting
of @code{NULL}   @code{buf} to discover the  @code{buf_size} . To use this function safely
with the older versions the  @code{buf} must be a valid buffer that can hold
at least a single byte if  @code{buf_size} is zero.

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  on success, otherwise a negative error code.

@strong{Since:} 2.12.0
@end deftypefun

@subheading gnutls_x509_crt_get_key_id
@anchor{gnutls_x509_crt_get_key_id}
@deftypefun {int} {gnutls_x509_crt_get_key_id} (gnutls_x509_crt_t @var{crt}, unsigned int @var{flags}, unsigned char * @var{output_data}, size_t * @var{output_data_size})
@var{crt}: Holds the certificate

@var{flags}: should be one of the flags from @code{gnutls_keyid_flags_t} 

@var{output_data}: will contain the key ID

@var{output_data_size}: holds the size of output_data (and will be
replaced by the actual size of parameters)

This function will return a unique ID that depends on the public
key parameters. This ID can be used in checking whether a
certificate corresponds to the given private key.

If the buffer provided is not long enough to hold the output, then
*output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
be returned.  The output will normally be a SHA-1 hash output,
which is 20 bytes.

@strong{Returns:} In case of failure a negative error code will be
returned, and 0 on success.
@end deftypefun

@subheading gnutls_x509_crt_get_key_purpose_oid
@anchor{gnutls_x509_crt_get_key_purpose_oid}
@deftypefun {int} {gnutls_x509_crt_get_key_purpose_oid} (gnutls_x509_crt_t @var{cert}, unsigned @var{indx}, void * @var{oid}, size_t * @var{oid_size}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{indx}: This specifies which OID to return. Use (0) to get the first one.

@var{oid}: a pointer to a buffer to hold the OID (may be null)

@var{oid_size}: initially holds the size of  @code{oid} 

@var{critical}: output flag to indicate criticality of extension

This function will extract the key purpose OIDs of the Certificate
specified by the given index.  These are stored in the Extended Key
Usage extension (2.5.29.37) See the GNUTLS_KP_* definitions for
human readable names.

If  @code{oid} is null then only the size will be filled. The  @code{oid} returned will be null terminated, although  @code{oid_size} will not
account for the trailing null.

@strong{Returns:} @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if the provided buffer is
not long enough, and in that case the *oid_size will be updated
with the required size.  On success 0 is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_key_usage
@anchor{gnutls_x509_crt_get_key_usage}
@deftypefun {int} {gnutls_x509_crt_get_key_usage} (gnutls_x509_crt_t @var{cert}, unsigned int * @var{key_usage}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{key_usage}: where the key usage bits will be stored

@var{critical}: will be non-zero if the extension is marked as critical

This function will return certificate's key usage, by reading the
keyUsage X.509 extension (2.5.29.15). The key usage value will ORed
values of the: @code{GNUTLS_KEY_DIGITAL_SIGNATURE} ,
@code{GNUTLS_KEY_NON_REPUDIATION} , @code{GNUTLS_KEY_KEY_ENCIPHERMENT} ,
@code{GNUTLS_KEY_DATA_ENCIPHERMENT} , @code{GNUTLS_KEY_KEY_AGREEMENT} ,
@code{GNUTLS_KEY_KEY_CERT_SIGN} , @code{GNUTLS_KEY_CRL_SIGN} ,
@code{GNUTLS_KEY_ENCIPHER_ONLY} , @code{GNUTLS_KEY_DECIPHER_ONLY} .

@strong{Returns:} zero on success, or a negative error code in case of
parsing error.  If the certificate does not contain the keyUsage
extension @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  will be
returned.
@end deftypefun

@subheading gnutls_x509_crt_get_name_constraints
@anchor{gnutls_x509_crt_get_name_constraints}
@deftypefun {int} {gnutls_x509_crt_get_name_constraints} (gnutls_x509_crt_t @var{crt}, gnutls_x509_name_constraints_t @var{nc}, unsigned int @var{flags}, unsigned int * @var{critical})
@var{crt}: should contain a @code{gnutls_x509_crt_t}  type

@var{nc}: The nameconstraints intermediate type

@var{flags}: zero or @code{GNUTLS_EXT_FLAG_APPEND} 

@var{critical}: the extension status

This function will return an intermediate type containing
the name constraints of the provided CA certificate. That
structure can be used in combination with @code{gnutls_x509_name_constraints_check()} 
to verify whether a server's name is in accordance with the constraints.

When the  @code{flags} is set to @code{GNUTLS_EXT_FLAG_APPEND} ,
then if the  @code{nc} structure is empty this function will behave
identically as if the flag was not set.
Otherwise if there are elements in the  @code{nc} structure then the
constraints will be merged with the existing constraints following
RFC5280 p6.1.4 (excluded constraints will be appended, permitted
will be intersected).

Note that  @code{nc} must be initialized prior to calling this function.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_crt_get_pk_algorithm
@anchor{gnutls_x509_crt_get_pk_algorithm}
@deftypefun {int} {gnutls_x509_crt_get_pk_algorithm} (gnutls_x509_crt_t @var{cert}, unsigned int * @var{bits})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{bits}: if bits is non null it will hold the size of the parameters' in bits

This function will return the public key algorithm of an X.509
certificate.

If bits is non null, it should have enough size to hold the parameters
size in bits. For RSA the bits returned is the modulus.
For DSA the bits returned are of the public
exponent.

Unknown/unsupported algorithms are mapped to @code{GNUTLS_PK_UNKNOWN} .

@strong{Returns:} a member of the @code{gnutls_pk_algorithm_t}  enumeration on
success, or a negative error code on error.
@end deftypefun

@subheading gnutls_x509_crt_get_pk_dsa_raw
@anchor{gnutls_x509_crt_get_pk_dsa_raw}
@deftypefun {int} {gnutls_x509_crt_get_pk_dsa_raw} (gnutls_x509_crt_t @var{crt}, gnutls_datum_t * @var{p}, gnutls_datum_t * @var{q}, gnutls_datum_t * @var{g}, gnutls_datum_t * @var{y})
@var{crt}: Holds the certificate

@var{p}: will hold the p

@var{q}: will hold the q

@var{g}: will hold the g

@var{y}: will hold the y

This function will export the DSA public key's parameters found in
the given certificate.  The new parameters will be allocated using
@code{gnutls_malloc()}  and will be stored in the appropriate datum.

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  on success, otherwise a negative error code.
@end deftypefun

@subheading gnutls_x509_crt_get_pk_ecc_raw
@anchor{gnutls_x509_crt_get_pk_ecc_raw}
@deftypefun {int} {gnutls_x509_crt_get_pk_ecc_raw} (gnutls_x509_crt_t @var{crt}, gnutls_ecc_curve_t * @var{curve}, gnutls_datum_t * @var{x}, gnutls_datum_t * @var{y})
@var{crt}: Holds the certificate

@var{curve}: will hold the curve

@var{x}: will hold the x-coordinate

@var{y}: will hold the y-coordinate

This function will export the ECC public key's parameters found in
the given certificate.  The new parameters will be allocated using
@code{gnutls_malloc()}  and will be stored in the appropriate datum.

In EdDSA curves the  @code{y} parameter will be @code{NULL}  and the other parameters
will be in the native format for the curve.

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  on success, otherwise a negative error code.

@strong{Since:} 3.4.1
@end deftypefun

@subheading gnutls_x509_crt_get_pk_gost_raw
@anchor{gnutls_x509_crt_get_pk_gost_raw}
@deftypefun {int} {gnutls_x509_crt_get_pk_gost_raw} (gnutls_x509_crt_t @var{crt}, gnutls_ecc_curve_t * @var{curve}, gnutls_digest_algorithm_t * @var{digest}, gnutls_gost_paramset_t * @var{paramset}, gnutls_datum_t * @var{x}, gnutls_datum_t * @var{y})
@var{crt}: Holds the certificate

@var{curve}: will hold the curve

@var{digest}: will hold the digest

@var{paramset}: will hold the GOST parameter set ID

@var{x}: will hold the x-coordinate

@var{y}: will hold the y-coordinate

This function will export the GOST public key's parameters found in
the given certificate.  The new parameters will be allocated using
@code{gnutls_malloc()}  and will be stored in the appropriate datum.

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  on success, otherwise a negative error code.

@strong{Since:} 3.6.3
@end deftypefun

@subheading gnutls_x509_crt_get_pk_oid
@anchor{gnutls_x509_crt_get_pk_oid}
@deftypefun {int} {gnutls_x509_crt_get_pk_oid} (gnutls_x509_crt_t @var{cert}, char * @var{oid}, size_t * @var{oid_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{oid}: a pointer to a buffer to hold the OID (may be null)

@var{oid_size}: initially holds the size of  @code{oid} 

This function will return the OID of the public key algorithm
on that certificate. This is function
is useful in the case @code{gnutls_x509_crt_get_pk_algorithm()} 
returned @code{GNUTLS_PK_UNKNOWN} .

@strong{Returns:} zero or a negative error code on error.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_crt_get_pk_rsa_raw
@anchor{gnutls_x509_crt_get_pk_rsa_raw}
@deftypefun {int} {gnutls_x509_crt_get_pk_rsa_raw} (gnutls_x509_crt_t @var{crt}, gnutls_datum_t * @var{m}, gnutls_datum_t * @var{e})
@var{crt}: Holds the certificate

@var{m}: will hold the modulus

@var{e}: will hold the public exponent

This function will export the RSA public key's parameters found in
the given structure.  The new parameters will be allocated using
@code{gnutls_malloc()}  and will be stored in the appropriate datum.

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  on success, otherwise a negative error code.
@end deftypefun

@subheading gnutls_x509_crt_get_policy
@anchor{gnutls_x509_crt_get_policy}
@deftypefun {int} {gnutls_x509_crt_get_policy} (gnutls_x509_crt_t @var{crt}, unsigned @var{indx}, struct gnutls_x509_policy_st * @var{policy}, unsigned int * @var{critical})
@var{crt}: should contain a @code{gnutls_x509_crt_t}  type

@var{indx}: This specifies which policy to return. Use (0) to get the first one.

@var{policy}: A pointer to a policy structure.

@var{critical}: will be non-zero if the extension is marked as critical

This function will extract the certificate policy (extension 2.5.29.32)
specified by the given index.

The policy returned by this function must be deinitialized by using
@code{gnutls_x509_policy_release()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.

@strong{Since:} 3.1.5
@end deftypefun

@subheading gnutls_x509_crt_get_private_key_usage_period
@anchor{gnutls_x509_crt_get_private_key_usage_period}
@deftypefun {int} {gnutls_x509_crt_get_private_key_usage_period} (gnutls_x509_crt_t @var{cert}, time_t * @var{activation}, time_t * @var{expiration}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{activation}: The activation time

@var{expiration}: The expiration time

@var{critical}: the extension status

This function will return the expiration and activation
times of the private key of the certificate. It relies on
the PKIX extension 2.5.29.16 being present.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.
@end deftypefun

@subheading gnutls_x509_crt_get_proxy
@anchor{gnutls_x509_crt_get_proxy}
@deftypefun {int} {gnutls_x509_crt_get_proxy} (gnutls_x509_crt_t @var{cert}, unsigned int * @var{critical}, int * @var{pathlen}, char ** @var{policyLanguage}, char ** @var{policy}, size_t * @var{sizeof_policy})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{critical}: will be non-zero if the extension is marked as critical

@var{pathlen}: pointer to output integer indicating path length (may be
NULL), non-negative error codes indicate a present pCPathLenConstraint
field and the actual value, -1 indicate that the field is absent.

@var{policyLanguage}: output variable with OID of policy language

@var{policy}: output variable with policy data

@var{sizeof_policy}: output variable size of policy data

This function will get information from a proxy certificate.  It
reads the ProxyCertInfo X.509 extension (1.3.6.1.5.5.7.1.14).

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error code is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_raw_dn
@anchor{gnutls_x509_crt_get_raw_dn}
@deftypefun {int} {gnutls_x509_crt_get_raw_dn} (gnutls_x509_crt_t @var{cert}, gnutls_datum_t * @var{dn})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{dn}: will hold the starting point of the DN

This function will return a pointer to the DER encoded DN structure and
the length. This points to allocated data that must be free'd using @code{gnutls_free()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value. or a negative error code on error.
@end deftypefun

@subheading gnutls_x509_crt_get_raw_issuer_dn
@anchor{gnutls_x509_crt_get_raw_issuer_dn}
@deftypefun {int} {gnutls_x509_crt_get_raw_issuer_dn} (gnutls_x509_crt_t @var{cert}, gnutls_datum_t * @var{dn})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{dn}: will hold the starting point of the DN

This function will return a pointer to the DER encoded DN structure
and the length. This points to allocated data that must be free'd using @code{gnutls_free()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.or a negative error code on error.
@end deftypefun

@subheading gnutls_x509_crt_get_serial
@anchor{gnutls_x509_crt_get_serial}
@deftypefun {int} {gnutls_x509_crt_get_serial} (gnutls_x509_crt_t @var{cert}, void * @var{result}, size_t * @var{result_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{result}: The place where the serial number will be copied

@var{result_size}: Holds the size of the result field.

This function will return the X.509 certificate's serial number.
This is obtained by the X509 Certificate serialNumber field. Serial
is not always a 32 or 64bit number. Some CAs use large serial
numbers, thus it may be wise to handle it as something uint8_t.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_get_signature
@anchor{gnutls_x509_crt_get_signature}
@deftypefun {int} {gnutls_x509_crt_get_signature} (gnutls_x509_crt_t @var{cert}, char * @var{sig}, size_t * @var{sig_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{sig}: a pointer where the signature part will be copied (may be null).

@var{sig_size}: initially holds the size of  @code{sig} 

This function will extract the signature field of a certificate.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_get_signature_algorithm
@anchor{gnutls_x509_crt_get_signature_algorithm}
@deftypefun {int} {gnutls_x509_crt_get_signature_algorithm} (gnutls_x509_crt_t @var{cert})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

This function will return a value of the @code{gnutls_sign_algorithm_t} 
enumeration that is the signature algorithm that has been used to
sign this certificate.

Since 3.6.0 this function never returns a negative error code.
Error cases and unknown/unsupported signature algorithms are
mapped to @code{GNUTLS_SIGN_UNKNOWN} .

@strong{Returns:} a @code{gnutls_sign_algorithm_t}  value
@end deftypefun

@subheading gnutls_x509_crt_get_signature_oid
@anchor{gnutls_x509_crt_get_signature_oid}
@deftypefun {int} {gnutls_x509_crt_get_signature_oid} (gnutls_x509_crt_t @var{cert}, char * @var{oid}, size_t * @var{oid_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{oid}: a pointer to a buffer to hold the OID (may be null)

@var{oid_size}: initially holds the size of  @code{oid} 

This function will return the OID of the signature algorithm
that has been used to sign this certificate. This is function
is useful in the case @code{gnutls_x509_crt_get_signature_algorithm()} 
returned @code{GNUTLS_SIGN_UNKNOWN} .

@strong{Returns:} zero or a negative error code on error.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_crt_get_spki
@anchor{gnutls_x509_crt_get_spki}
@deftypefun {int} {gnutls_x509_crt_get_spki} (gnutls_x509_crt_t @var{cert}, gnutls_x509_spki_t @var{spki}, unsigned int @var{flags})
@var{cert}: a certificate of type @code{gnutls_x509_crt_t} 

@var{spki}: a SubjectPublicKeyInfo structure of type @code{gnutls_x509_spki_t} 

@var{flags}: must be zero

This function will return the public key information of an X.509
certificate. The provided  @code{spki} must be initialized.

@strong{Since:} 3.6.0
@end deftypefun

@subheading gnutls_x509_crt_get_subject
@anchor{gnutls_x509_crt_get_subject}
@deftypefun {int} {gnutls_x509_crt_get_subject} (gnutls_x509_crt_t @var{cert}, gnutls_x509_dn_t * @var{dn})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{dn}: output variable with pointer to uint8_t DN.

Return the Certificate's Subject DN as a @code{gnutls_x509_dn_t}  data type,
that can be decoded using @code{gnutls_x509_dn_get_rdn_ava()} .

Note that  @code{dn} should be treated as constant. Because it points
into the  @code{cert} object, you should not use  @code{dn} after  @code{cert} is
deallocated.

@strong{Returns:} Returns 0 on success, or an error code.
@end deftypefun

@subheading gnutls_x509_crt_get_subject_alt_name
@anchor{gnutls_x509_crt_get_subject_alt_name}
@deftypefun {int} {gnutls_x509_crt_get_subject_alt_name} (gnutls_x509_crt_t @var{cert}, unsigned int @var{seq}, void * @var{san}, size_t * @var{san_size}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{seq}: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

@var{san}: is the place where the alternative name will be copied to

@var{san_size}: holds the size of san.

@var{critical}: will be non-zero if the extension is marked as critical (may be null)

This function retrieves the Alternative Name (2.5.29.17), contained
in the given certificate in the X509v3 Certificate Extensions.

When the SAN type is otherName, it will extract the data in the
otherName's value field, and @code{GNUTLS_SAN_OTHERNAME}  is returned.
You may use @code{gnutls_x509_crt_get_subject_alt_othername_oid()}  to get
the corresponding OID and the "virtual" SAN types (e.g.,
@code{GNUTLS_SAN_OTHERNAME_XMPP} ).

If an otherName OID is known, the data will be decoded.  Otherwise
the returned data will be DER encoded, and you will have to decode
it yourself.  Currently, only the RFC 3920 id-on-xmppAddr SAN is
recognized.

@strong{Returns:} the alternative subject name type on success, one of the
enumerated @code{gnutls_x509_subject_alt_name_t} .  It will return
@code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if  @code{san_size} is not large enough to
hold the value.  In that case  @code{san_size} will be updated with the
required size.  If the certificate does not have an Alternative
name with the specified sequence number then
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_subject_alt_name2
@anchor{gnutls_x509_crt_get_subject_alt_name2}
@deftypefun {int} {gnutls_x509_crt_get_subject_alt_name2} (gnutls_x509_crt_t @var{cert}, unsigned int @var{seq}, void * @var{san}, size_t * @var{san_size}, unsigned int * @var{san_type}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{seq}: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

@var{san}: is the place where the alternative name will be copied to

@var{san_size}: holds the size of ret.

@var{san_type}: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).

@var{critical}: will be non-zero if the extension is marked as critical (may be null)

This function will return the alternative names, contained in the
given certificate. It is the same as
@code{gnutls_x509_crt_get_subject_alt_name()}  except for the fact that it
will return the type of the alternative name in  @code{san_type} even if
the function fails for some reason (i.e.  the buffer provided is
not enough).

@strong{Returns:} the alternative subject name type on success, one of the
enumerated @code{gnutls_x509_subject_alt_name_t} .  It will return
@code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if  @code{san_size} is not large enough
to hold the value.  In that case  @code{san_size} will be updated with
the required size.  If the certificate does not have an
Alternative name with the specified sequence number then
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_subject_alt_othername_oid
@anchor{gnutls_x509_crt_get_subject_alt_othername_oid}
@deftypefun {int} {gnutls_x509_crt_get_subject_alt_othername_oid} (gnutls_x509_crt_t @var{cert}, unsigned int @var{seq}, void * @var{oid}, size_t * @var{oid_size})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{seq}: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)

@var{oid}: is the place where the otherName OID will be copied to

@var{oid_size}: holds the size of ret.

This function will extract the type OID of an otherName Subject
Alternative Name, contained in the given certificate, and return
the type as an enumerated element.

This function is only useful if
@code{gnutls_x509_crt_get_subject_alt_name()}  returned
@code{GNUTLS_SAN_OTHERNAME} .

If  @code{oid} is null then only the size will be filled. The  @code{oid} returned will be null terminated, although  @code{oid_size} will not
account for the trailing null.

@strong{Returns:} the alternative subject name type on success, one of the
enumerated gnutls_x509_subject_alt_name_t.  For supported OIDs, it
will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types,
e.g. @code{GNUTLS_SAN_OTHERNAME_XMPP} , and @code{GNUTLS_SAN_OTHERNAME}  for
unknown OIDs.  It will return @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  if
 @code{ian_size} is not large enough to hold the value.  In that case
 @code{ian_size} will be updated with the required size.  If the
certificate does not have an Alternative name with the specified
sequence number and with the otherName type then
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned.
@end deftypefun

@subheading gnutls_x509_crt_get_subject_key_id
@anchor{gnutls_x509_crt_get_subject_key_id}
@deftypefun {int} {gnutls_x509_crt_get_subject_key_id} (gnutls_x509_crt_t @var{cert}, void * @var{ret}, size_t * @var{ret_size}, unsigned int * @var{critical})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

@var{ret}: The place where the identifier will be copied

@var{ret_size}: Holds the size of the result field.

@var{critical}: will be non-zero if the extension is marked as critical (may be null)

This function will return the X.509v3 certificate's subject key
identifier.  This is obtained by the X.509 Subject Key identifier
extension field (2.5.29.14).

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.
@end deftypefun

@subheading gnutls_x509_crt_get_subject_unique_id
@anchor{gnutls_x509_crt_get_subject_unique_id}
@deftypefun {int} {gnutls_x509_crt_get_subject_unique_id} (gnutls_x509_crt_t @var{crt}, char * @var{buf}, size_t * @var{buf_size})
@var{crt}: Holds the certificate

@var{buf}: user allocated memory buffer, will hold the unique id

@var{buf_size}: size of user allocated memory buffer (on input), will hold
actual size of the unique ID on return.

This function will extract the subjectUniqueID value (if present) for
the given certificate.

If the user allocated memory buffer is not large enough to hold the
full subjectUniqueID, then a GNUTLS_E_SHORT_MEMORY_BUFFER error will be
returned, and buf_size will be set to the actual length.

This function had a bug prior to 3.4.8 that prevented the setting
of @code{NULL}   @code{buf} to discover the  @code{buf_size} . To use this function safely
with the older versions the  @code{buf} must be a valid buffer that can hold
at least a single byte if  @code{buf_size} is zero.

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  on success, otherwise a negative error code.
@end deftypefun

@subheading gnutls_x509_crt_get_tlsfeatures
@anchor{gnutls_x509_crt_get_tlsfeatures}
@deftypefun {int} {gnutls_x509_crt_get_tlsfeatures} (gnutls_x509_crt_t @var{crt}, gnutls_x509_tlsfeatures_t @var{features}, unsigned int @var{flags}, unsigned int * @var{critical})
@var{crt}: A X.509 certificate

@var{features}: If the function succeeds, the
features will be stored in this variable.

@var{flags}: zero or @code{GNUTLS_EXT_FLAG_APPEND} 

@var{critical}: the extension status

This function will get the X.509 TLS features
extension structure from the certificate. The
returned structure needs to be freed using
@code{gnutls_x509_tlsfeatures_deinit()} .

When the  @code{flags} is set to @code{GNUTLS_EXT_FLAG_APPEND} ,
then if the  @code{features} structure is empty this function will behave
identically as if the flag was not set. Otherwise if there are elements 
in the  @code{features} structure then they will be merged with.

Note that  @code{features} must be initialized prior to calling this function.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error value.

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_crt_get_version
@anchor{gnutls_x509_crt_get_version}
@deftypefun {int} {gnutls_x509_crt_get_version} (gnutls_x509_crt_t @var{cert})
@var{cert}: should contain a @code{gnutls_x509_crt_t}  type

This function will return the version of the specified Certificate.

@strong{Returns:} version of certificate, or a negative error code on error.
@end deftypefun

@subheading gnutls_x509_crt_import
@anchor{gnutls_x509_crt_import}
@deftypefun {int} {gnutls_x509_crt_import} (gnutls_x509_crt_t @var{cert}, const gnutls_datum_t * @var{data}, gnutls_x509_crt_fmt_t @var{format})
@var{cert}: The data to store the parsed certificate.

@var{data}: The DER or PEM encoded certificate.

@var{format}: One of DER or PEM

This function will convert the given DER or PEM encoded Certificate
to the native gnutls_x509_crt_t format. The output will be stored
in  @code{cert} .

If the Certificate is PEM encoded it should have a header of "X509
CERTIFICATE", or "CERTIFICATE".

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_import_url
@anchor{gnutls_x509_crt_import_url}
@deftypefun {int} {gnutls_x509_crt_import_url} (gnutls_x509_crt_t @var{crt}, const char * @var{url}, unsigned int @var{flags})
@var{crt}: A certificate of type @code{gnutls_x509_crt_t} 

@var{url}: A PKCS 11 url

@var{flags}: One of GNUTLS_PKCS11_OBJ_* flags for PKCS@code{11}  URLs or zero otherwise

This function will import a certificate present in a PKCS@code{11}  token
or any type of back-end that supports URLs.

In previous versions of gnutls this function was named
gnutls_x509_crt_import_pkcs11_url, and the old name is
an alias to this one.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.4.0
@end deftypefun

@subheading gnutls_x509_crt_init
@anchor{gnutls_x509_crt_init}
@deftypefun {int} {gnutls_x509_crt_init} (gnutls_x509_crt_t * @var{cert})
@var{cert}: A pointer to the type to be initialized

This function will initialize an X.509 certificate structure.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_list_import
@anchor{gnutls_x509_crt_list_import}
@deftypefun {int} {gnutls_x509_crt_list_import} (gnutls_x509_crt_t * @var{certs}, unsigned int * @var{cert_max}, const gnutls_datum_t * @var{data}, gnutls_x509_crt_fmt_t @var{format}, unsigned int @var{flags})
@var{certs}: Indicates where the parsed list will be copied to. Must not be initialized.

@var{cert_max}: Initially must hold the maximum number of certs. It will be updated with the number of certs available.

@var{data}: The PEM encoded certificate.

@var{format}: One of DER or PEM.

@var{flags}: must be (0) or an OR'd sequence of gnutls_certificate_import_flags.

This function will convert the given PEM encoded certificate list
to the native gnutls_x509_crt_t format. The output will be stored
in  @code{certs} .  They will be automatically initialized.

The flag @code{GNUTLS_X509_CRT_LIST_IMPORT_FAIL_IF_EXCEED}  will cause
import to fail if the certificates in the provided buffer are more
than the available structures. The @code{GNUTLS_X509_CRT_LIST_FAIL_IF_UNSORTED} 
flag will cause the function to fail if the provided list is not
sorted from subject to issuer.

If the Certificate is PEM encoded it should have a header of "X509
CERTIFICATE", or "CERTIFICATE".

@strong{Returns:} the number of certificates read or a negative error value.
@end deftypefun

@subheading gnutls_x509_crt_list_import2
@anchor{gnutls_x509_crt_list_import2}
@deftypefun {int} {gnutls_x509_crt_list_import2} (gnutls_x509_crt_t ** @var{certs}, unsigned int * @var{size}, const gnutls_datum_t * @var{data}, gnutls_x509_crt_fmt_t @var{format}, unsigned int @var{flags})
@var{certs}: Will hold the parsed certificate list.

@var{size}: It will contain the size of the list.

@var{data}: The PEM encoded certificate.

@var{format}: One of DER or PEM.

@var{flags}: must be (0) or an OR'd sequence of gnutls_certificate_import_flags.

This function will convert the given PEM encoded certificate list
to the native gnutls_x509_crt_t format. The output will be stored
in  @code{certs} which will be allocated and initialized.

If the Certificate is PEM encoded it should have a header of "X509
CERTIFICATE", or "CERTIFICATE".

To deinitialize  @code{certs} , you need to deinitialize each crt structure
independently, and use @code{gnutls_free()}  at  @code{certs} .

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  on success, otherwise a negative error code.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_crt_list_import_url
@anchor{gnutls_x509_crt_list_import_url}
@deftypefun {int} {gnutls_x509_crt_list_import_url} (gnutls_x509_crt_t ** @var{certs}, unsigned int * @var{size}, const char * @var{url}, gnutls_pin_callback_t @var{pin_fn}, void * @var{pin_fn_userdata}, unsigned int @var{flags})
@var{certs}: Will hold the allocated certificate list.

@var{size}: It will contain the size of the list.

@var{url}: A PKCS 11 url

@var{pin_fn}: a PIN callback if not globally set

@var{pin_fn_userdata}: parameter for the PIN callback

@var{flags}: One of GNUTLS_PKCS11_OBJ_* flags for PKCS@code{11}  URLs or zero otherwise

This function will import a certificate chain present in a PKCS@code{11}  token
or any type of back-end that supports URLs. The certificates
must be deinitialized afterwards using @code{gnutls_x509_crt_deinit()} 
and the returned pointer must be freed using @code{gnutls_free()} .

The URI provided must be the first certificate in the chain; subsequent
certificates will be retrieved using @code{gnutls_pkcs11_get_raw_issuer()}  or
equivalent functionality for the supported URI.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.6.3
@end deftypefun

@subheading gnutls_x509_crt_list_verify
@anchor{gnutls_x509_crt_list_verify}
@deftypefun {int} {gnutls_x509_crt_list_verify} (const gnutls_x509_crt_t * @var{cert_list}, unsigned @var{cert_list_length}, const gnutls_x509_crt_t * @var{CA_list}, unsigned @var{CA_list_length}, const gnutls_x509_crl_t * @var{CRL_list}, unsigned @var{CRL_list_length}, unsigned int @var{flags}, unsigned int * @var{verify})
@var{cert_list}: is the certificate list to be verified

@var{cert_list_length}: holds the number of certificate in cert_list

@var{CA_list}: is the CA list which will be used in verification

@var{CA_list_length}: holds the number of CA certificate in CA_list

@var{CRL_list}: holds a list of CRLs.

@var{CRL_list_length}: the length of CRL list.

@var{flags}: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

@var{verify}: will hold the certificate verification output.


This function will try to verify the given certificate list and
return its status. The details of the verification are the same
as in @code{gnutls_x509_trust_list_verify_crt2()} .

You must check the peer's name in order to check if the verified
certificate belongs to the actual peer.

The certificate verification output will be put in  @code{verify} and will
be one or more of the gnutls_certificate_status_t enumerated
elements bitwise or'd.  For a more detailed verification status use
@code{gnutls_x509_crt_verify()}  per list element.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_print
@anchor{gnutls_x509_crt_print}
@deftypefun {int} {gnutls_x509_crt_print} (gnutls_x509_crt_t @var{cert}, gnutls_certificate_print_formats_t @var{format}, gnutls_datum_t * @var{out})
@var{cert}: The data to be printed

@var{format}: Indicate the format to use

@var{out}: Newly allocated datum with null terminated string.

This function will pretty print a X.509 certificate, suitable for
display to a human.

If the format is @code{GNUTLS_CRT_PRINT_FULL}  then all fields of the
certificate will be output, on multiple lines.  The
@code{GNUTLS_CRT_PRINT_ONELINE}  format will generate one line with some
selected fields, which is useful for logging purposes.

The output  @code{out} needs to be deallocated using @code{gnutls_free()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_activation_time
@anchor{gnutls_x509_crt_set_activation_time}
@deftypefun {int} {gnutls_x509_crt_set_activation_time} (gnutls_x509_crt_t @var{cert}, time_t @var{act_time})
@var{cert}: a certificate of type @code{gnutls_x509_crt_t} 

@var{act_time}: The actual time

This function will set the time this certificate was or will be
activated.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_authority_info_access
@anchor{gnutls_x509_crt_set_authority_info_access}
@deftypefun {int} {gnutls_x509_crt_set_authority_info_access} (gnutls_x509_crt_t @var{crt}, int @var{what}, gnutls_datum_t * @var{data})
@var{crt}: Holds the certificate

@var{what}: what data to get, a @code{gnutls_info_access_what_t}  type.

@var{data}: output data to be freed with @code{gnutls_free()} .

This function sets the Authority Information Access (AIA)
extension, see RFC 5280 section 4.2.2.1 for more information.  

The type of data stored in  @code{data} is specified via  @code{what} which
should be @code{gnutls_info_access_what_t}  values.

If  @code{what} is @code{GNUTLS_IA_OCSP_URI} ,  @code{data} will hold the OCSP URI.
If  @code{what} is @code{GNUTLS_IA_CAISSUERS_URI} ,  @code{data} will hold the caIssuers
URI.  

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_crt_set_authority_key_id
@anchor{gnutls_x509_crt_set_authority_key_id}
@deftypefun {int} {gnutls_x509_crt_set_authority_key_id} (gnutls_x509_crt_t @var{cert}, const void * @var{id}, size_t @var{id_size})
@var{cert}: a certificate of type @code{gnutls_x509_crt_t} 

@var{id}: The key ID

@var{id_size}: Holds the size of the key ID field.

This function will set the X.509 certificate's authority key ID extension.
Only the keyIdentifier field can be set with this function.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_basic_constraints
@anchor{gnutls_x509_crt_set_basic_constraints}
@deftypefun {int} {gnutls_x509_crt_set_basic_constraints} (gnutls_x509_crt_t @var{crt}, unsigned int @var{ca}, int @var{pathLenConstraint})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{ca}: true(1) or false(0). Depending on the Certificate authority status.

@var{pathLenConstraint}: non-negative error codes indicate maximum length of path,
and negative error codes indicate that the pathLenConstraints field should
not be present.

This function will set the basicConstraints certificate extension.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_ca_status
@anchor{gnutls_x509_crt_set_ca_status}
@deftypefun {int} {gnutls_x509_crt_set_ca_status} (gnutls_x509_crt_t @var{crt}, unsigned int @var{ca})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{ca}: true(1) or false(0). Depending on the Certificate authority status.

This function will set the basicConstraints certificate extension.
Use @code{gnutls_x509_crt_set_basic_constraints()}  if you want to control
the pathLenConstraint field too.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_crl_dist_points
@anchor{gnutls_x509_crt_set_crl_dist_points}
@deftypefun {int} {gnutls_x509_crt_set_crl_dist_points} (gnutls_x509_crt_t @var{crt}, gnutls_x509_subject_alt_name_t @var{type}, const void * @var{data_string}, unsigned int @var{reason_flags})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{type}: is one of the gnutls_x509_subject_alt_name_t enumerations

@var{data_string}: The data to be set

@var{reason_flags}: revocation reasons

This function will set the CRL distribution points certificate extension.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_crl_dist_points2
@anchor{gnutls_x509_crt_set_crl_dist_points2}
@deftypefun {int} {gnutls_x509_crt_set_crl_dist_points2} (gnutls_x509_crt_t @var{crt}, gnutls_x509_subject_alt_name_t @var{type}, const void * @var{data}, unsigned int @var{data_size}, unsigned int @var{reason_flags})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{type}: is one of the gnutls_x509_subject_alt_name_t enumerations

@var{data}: The data to be set

@var{data_size}: The data size

@var{reason_flags}: revocation reasons

This function will set the CRL distribution points certificate extension.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.6.0
@end deftypefun

@subheading gnutls_x509_crt_set_crq
@anchor{gnutls_x509_crt_set_crq}
@deftypefun {int} {gnutls_x509_crt_set_crq} (gnutls_x509_crt_t @var{crt}, gnutls_x509_crq_t @var{crq})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{crq}: holds a certificate request

This function will set the name and public parameters as well as
the extensions from the given certificate request to the certificate. 
Only RSA keys are currently supported.

Note that this function will only set the  @code{crq} if it is self
signed and the signature is correct. See @code{gnutls_x509_crq_sign2()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_crq_extension_by_oid
@anchor{gnutls_x509_crt_set_crq_extension_by_oid}
@deftypefun {int} {gnutls_x509_crt_set_crq_extension_by_oid} (gnutls_x509_crt_t @var{crt}, gnutls_x509_crq_t @var{crq}, const char * @var{oid}, unsigned @var{flags})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{crq}: holds a certificate request

@var{oid}: the object identifier of the OID to copy

@var{flags}: should be zero

This function will set the extension specify by  @code{oid} from the given request to the
certificate.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_crt_set_crq_extensions
@anchor{gnutls_x509_crt_set_crq_extensions}
@deftypefun {int} {gnutls_x509_crt_set_crq_extensions} (gnutls_x509_crt_t @var{crt}, gnutls_x509_crq_t @var{crq})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{crq}: holds a certificate request

This function will set the extensions from the given request to the
certificate.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.8.0
@end deftypefun

@subheading gnutls_x509_crt_set_dn
@anchor{gnutls_x509_crt_set_dn}
@deftypefun {int} {gnutls_x509_crt_set_dn} (gnutls_x509_crt_t @var{crt}, const char * @var{dn}, const char ** @var{err})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{dn}: a comma separated DN string (RFC4514)

@var{err}: indicates the error position (if any)

This function will set the DN on the provided certificate.
The input string should be plain ASCII or UTF-8 encoded. On
DN parsing error @code{GNUTLS_E_PARSING_ERROR}  is returned.

Note that DNs are not expected to hold DNS information, and thus
no automatic IDNA conversions are attempted when using this function.
If that is required (e.g., store a domain in CN), process the corresponding
input with @code{gnutls_idna_map()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_dn_by_oid
@anchor{gnutls_x509_crt_set_dn_by_oid}
@deftypefun {int} {gnutls_x509_crt_set_dn_by_oid} (gnutls_x509_crt_t @var{crt}, const char * @var{oid}, unsigned int @var{raw_flag}, const void * @var{name}, unsigned int @var{sizeof_name})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{oid}: holds an Object Identifier in a null terminated string

@var{raw_flag}: must be 0, or 1 if the data are DER encoded

@var{name}: a pointer to the name

@var{sizeof_name}: holds the size of  @code{name} 

This function will set the part of the name of the Certificate
subject, specified by the given OID. The input string should be
ASCII or UTF-8 encoded.

Some helper macros with popular OIDs can be found in gnutls/x509.h
With this function you can only set the known OIDs. You can test
for known OIDs using @code{gnutls_x509_dn_oid_known()} . For OIDs that are
not known (by gnutls) you should properly DER encode your data,
and call this function with  @code{raw_flag} set.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_expiration_time
@anchor{gnutls_x509_crt_set_expiration_time}
@deftypefun {int} {gnutls_x509_crt_set_expiration_time} (gnutls_x509_crt_t @var{cert}, time_t @var{exp_time})
@var{cert}: a certificate of type @code{gnutls_x509_crt_t} 

@var{exp_time}: The actual time

This function will set the time this Certificate will expire.
Setting an expiration time to (time_t)-1 will set
to the no well-defined expiration date value.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_extension_by_oid
@anchor{gnutls_x509_crt_set_extension_by_oid}
@deftypefun {int} {gnutls_x509_crt_set_extension_by_oid} (gnutls_x509_crt_t @var{crt}, const char * @var{oid}, const void * @var{buf}, size_t @var{sizeof_buf}, unsigned int @var{critical})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{oid}: holds an Object Identifier in null terminated string

@var{buf}: a pointer to a DER encoded data

@var{sizeof_buf}: holds the size of  @code{buf} 

@var{critical}: should be non-zero if the extension is to be marked as critical

This function will set an the extension, by the specified OID, in
the certificate.  The extension data should be binary data DER
encoded.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_flags
@anchor{gnutls_x509_crt_set_flags}
@deftypefun {void} {gnutls_x509_crt_set_flags} (gnutls_x509_crt_t @var{cert}, unsigned int @var{flags})
@var{cert}: A type @code{gnutls_x509_crt_t} 

@var{flags}: flags from the @code{gnutls_x509_crt_flags} 

This function will set flags for the specified certificate.
Currently this is useful for the @code{GNUTLS_X509_CRT_FLAG_IGNORE_SANITY} 
which allows importing certificates even if they have known issues.

@strong{Since:} 3.6.0
@end deftypefun

@subheading gnutls_x509_crt_set_inhibit_anypolicy
@anchor{gnutls_x509_crt_set_inhibit_anypolicy}
@deftypefun {int} {gnutls_x509_crt_set_inhibit_anypolicy} (gnutls_x509_crt_t @var{crt}, unsigned int @var{skipcerts})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{skipcerts}: number of certificates after which anypolicy is no longer acceptable.

This function will set the Inhibit anyPolicy certificate extension.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_issuer_alt_name
@anchor{gnutls_x509_crt_set_issuer_alt_name}
@deftypefun {int} {gnutls_x509_crt_set_issuer_alt_name} (gnutls_x509_crt_t @var{crt}, gnutls_x509_subject_alt_name_t @var{type}, const void * @var{data}, unsigned int @var{data_size}, unsigned int @var{flags})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{type}: is one of the gnutls_x509_subject_alt_name_t enumerations

@var{data}: The data to be set

@var{data_size}: The size of data to be set

@var{flags}: GNUTLS_FSAN_SET to clear previous data or GNUTLS_FSAN_APPEND to append. 

This function will set the issuer alternative name certificate
extension. It can set the same types as @code{gnutls_x509_crt_set_subject_alt_name()} .

Since version 3.5.7 the @code{GNUTLS_SAN_RFC822NAME} , @code{GNUTLS_SAN_DNSNAME} , and
@code{GNUTLS_SAN_OTHERNAME_XMPP}  are converted to ACE format when necessary.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_crt_set_issuer_alt_othername
@anchor{gnutls_x509_crt_set_issuer_alt_othername}
@deftypefun {int} {gnutls_x509_crt_set_issuer_alt_othername} (gnutls_x509_crt_t @var{crt}, const char * @var{oid}, const void * @var{data}, unsigned int @var{data_size}, unsigned int @var{flags})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{oid}: The other name OID

@var{data}: The data to be set

@var{data_size}: The size of data to be set

@var{flags}: GNUTLS_FSAN_SET to clear previous data or GNUTLS_FSAN_APPEND to append. 

This function will set an "othername" to the issuer alternative name certificate
extension.

The values set are set as binary values and are expected to have the proper DER encoding.
For convenience the flags @code{GNUTLS_FSAN_ENCODE_OCTET_STRING}  and @code{GNUTLS_FSAN_ENCODE_UTF8_STRING} 
can be used to encode the provided data.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_crt_set_issuer_dn
@anchor{gnutls_x509_crt_set_issuer_dn}
@deftypefun {int} {gnutls_x509_crt_set_issuer_dn} (gnutls_x509_crt_t @var{crt}, const char * @var{dn}, const char ** @var{err})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{dn}: a comma separated DN string (RFC4514)

@var{err}: indicates the error position (if any)

This function will set the DN on the provided certificate.
The input string should be plain ASCII or UTF-8 encoded. On
DN parsing error @code{GNUTLS_E_PARSING_ERROR}  is returned.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_issuer_dn_by_oid
@anchor{gnutls_x509_crt_set_issuer_dn_by_oid}
@deftypefun {int} {gnutls_x509_crt_set_issuer_dn_by_oid} (gnutls_x509_crt_t @var{crt}, const char * @var{oid}, unsigned int @var{raw_flag}, const void * @var{name}, unsigned int @var{sizeof_name})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{oid}: holds an Object Identifier in a null terminated string

@var{raw_flag}: must be 0, or 1 if the data are DER encoded

@var{name}: a pointer to the name

@var{sizeof_name}: holds the size of  @code{name} 

This function will set the part of the name of the Certificate
issuer, specified by the given OID.  The input string should be
ASCII or UTF-8 encoded.

Some helper macros with popular OIDs can be found in gnutls/x509.h
With this function you can only set the known OIDs. You can test
for known OIDs using @code{gnutls_x509_dn_oid_known()} . For OIDs that are
not known (by gnutls) you should properly DER encode your data,
and call this function with  @code{raw_flag} set.

Normally you do not need to call this function, since the signing
operation will copy the signer's name as the issuer of the
certificate.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_issuer_unique_id
@anchor{gnutls_x509_crt_set_issuer_unique_id}
@deftypefun {int} {gnutls_x509_crt_set_issuer_unique_id} (gnutls_x509_crt_t @var{cert}, const void * @var{id}, size_t @var{id_size})
@var{cert}: a certificate of type @code{gnutls_x509_crt_t} 

@var{id}: The unique ID

@var{id_size}: Holds the size of the unique ID.

This function will set the X.509 certificate's issuer unique ID field.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.4.7
@end deftypefun

@subheading gnutls_x509_crt_set_key
@anchor{gnutls_x509_crt_set_key}
@deftypefun {int} {gnutls_x509_crt_set_key} (gnutls_x509_crt_t @var{crt}, gnutls_x509_privkey_t @var{key})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{key}: holds a private key

This function will set the public parameters from the given
private key to the certificate.

To export the public key (i.e., the SubjectPublicKeyInfo part), check
@code{gnutls_pubkey_import_x509()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_key_purpose_oid
@anchor{gnutls_x509_crt_set_key_purpose_oid}
@deftypefun {int} {gnutls_x509_crt_set_key_purpose_oid} (gnutls_x509_crt_t @var{cert}, const void * @var{oid}, unsigned int @var{critical})
@var{cert}: a certificate of type @code{gnutls_x509_crt_t} 

@var{oid}: a pointer to a null terminated string that holds the OID

@var{critical}: Whether this extension will be critical or not

This function will set the key purpose OIDs of the Certificate.
These are stored in the Extended Key Usage extension (2.5.29.37)
See the GNUTLS_KP_* definitions for human readable names.

Subsequent calls to this function will append OIDs to the OID list.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error code is returned.
@end deftypefun

@subheading gnutls_x509_crt_set_key_usage
@anchor{gnutls_x509_crt_set_key_usage}
@deftypefun {int} {gnutls_x509_crt_set_key_usage} (gnutls_x509_crt_t @var{crt}, unsigned int @var{usage})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{usage}: an ORed sequence of the GNUTLS_KEY_* elements.

This function will set the keyUsage certificate extension.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_name_constraints
@anchor{gnutls_x509_crt_set_name_constraints}
@deftypefun {int} {gnutls_x509_crt_set_name_constraints} (gnutls_x509_crt_t @var{crt}, gnutls_x509_name_constraints_t @var{nc}, unsigned int @var{critical})
@var{crt}: The certificate

@var{nc}: The nameconstraints structure

@var{critical}: whether this extension will be critical

This function will set the provided name constraints to
the certificate extension list. This extension is always
marked as critical.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_crt_set_pin_function
@anchor{gnutls_x509_crt_set_pin_function}
@deftypefun {void} {gnutls_x509_crt_set_pin_function} (gnutls_x509_crt_t @var{crt}, gnutls_pin_callback_t @var{fn}, void * @var{userdata})
@var{crt}: The certificate structure

@var{fn}: the callback

@var{userdata}: data associated with the callback

This function will set a callback function to be used when
it is required to access a protected object. This function overrides
the global function set using @code{gnutls_pkcs11_set_pin_function()} .

Note that this callback is currently used only during the import
of a PKCS @code{11}  certificate with @code{gnutls_x509_crt_import_url()} .

@strong{Since:} 3.1.0
@end deftypefun

@subheading gnutls_x509_crt_set_policy
@anchor{gnutls_x509_crt_set_policy}
@deftypefun {int} {gnutls_x509_crt_set_policy} (gnutls_x509_crt_t @var{crt}, const struct gnutls_x509_policy_st * @var{policy}, unsigned int @var{critical})
@var{crt}: should contain a @code{gnutls_x509_crt_t}  type

@var{policy}: A pointer to a policy

@var{critical}: use non-zero if the extension is marked as critical

This function will set the certificate policy extension (2.5.29.32).
Multiple calls to this function append a new policy.

Note the maximum text size for the qualifier @code{GNUTLS_X509_QUALIFIER_NOTICE} 
is 200 characters. This function will fail with @code{GNUTLS_E_INVALID_REQUEST} 
if this is exceeded.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.1.5
@end deftypefun

@subheading gnutls_x509_crt_set_private_key_usage_period
@anchor{gnutls_x509_crt_set_private_key_usage_period}
@deftypefun {int} {gnutls_x509_crt_set_private_key_usage_period} (gnutls_x509_crt_t @var{crt}, time_t @var{activation}, time_t @var{expiration})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{activation}: The activation time

@var{expiration}: The expiration time

This function will set the private key usage period extension (2.5.29.16).

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_proxy
@anchor{gnutls_x509_crt_set_proxy}
@deftypefun {int} {gnutls_x509_crt_set_proxy} (gnutls_x509_crt_t @var{crt}, int @var{pathLenConstraint}, const char * @var{policyLanguage}, const char * @var{policy}, size_t @var{sizeof_policy})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{pathLenConstraint}: non-negative error codes indicate maximum length of path,
and negative error codes indicate that the pathLenConstraints field should
not be present.

@var{policyLanguage}: OID describing the language of  @code{policy} .

@var{policy}: uint8_t byte array with policy language, can be @code{NULL} 

@var{sizeof_policy}: size of  @code{policy} .

This function will set the proxyCertInfo extension.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_proxy_dn
@anchor{gnutls_x509_crt_set_proxy_dn}
@deftypefun {int} {gnutls_x509_crt_set_proxy_dn} (gnutls_x509_crt_t @var{crt}, gnutls_x509_crt_t @var{eecrt}, unsigned int @var{raw_flag}, const void * @var{name}, unsigned int @var{sizeof_name})
@var{crt}: a gnutls_x509_crt_t type with the new proxy cert

@var{eecrt}: the end entity certificate that will be issuing the proxy

@var{raw_flag}: must be 0, or 1 if the CN is DER encoded

@var{name}: a pointer to the CN name, may be NULL (but MUST then be added later)

@var{sizeof_name}: holds the size of  @code{name} 

This function will set the subject in  @code{crt} to the end entity's
 @code{eecrt} subject name, and add a single Common Name component  @code{name} of size  @code{sizeof_name} .  This corresponds to the required proxy
certificate naming style.  Note that if  @code{name} is @code{NULL} , you MUST
set it later by using @code{gnutls_x509_crt_set_dn_by_oid()}  or similar.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_serial
@anchor{gnutls_x509_crt_set_serial}
@deftypefun {int} {gnutls_x509_crt_set_serial} (gnutls_x509_crt_t @var{cert}, const void * @var{serial}, size_t @var{serial_size})
@var{cert}: a certificate of type @code{gnutls_x509_crt_t} 

@var{serial}: The serial number

@var{serial_size}: Holds the size of the serial field.

This function will set the X.509 certificate's serial number.
While the serial number is an integer, it is often handled
as an opaque field by several CAs. For this reason this function
accepts any kind of data as a serial number. To be consistent
with the X.509/PKIX specifications the provided  @code{serial} should be 
a big-endian positive number (i.e. its leftmost bit should be zero).

The size of the serial is restricted to 20 bytes maximum by RFC5280.
This function allows writing more than 20 bytes but the generated
certificates in that case may be rejected by other implementations.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_spki
@anchor{gnutls_x509_crt_set_spki}
@deftypefun {int} {gnutls_x509_crt_set_spki} (gnutls_x509_crt_t @var{crt}, const gnutls_x509_spki_t @var{spki}, unsigned int @var{flags})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{spki}: a SubjectPublicKeyInfo structure of type @code{gnutls_x509_spki_t} 

@var{flags}: must be zero

This function will set the certificate's subject public key
information explicitly. This is intended to be used in the cases
where a single public key (e.g., RSA) can be used for multiple
signature algorithms (RSA PKCS1-1.5, and RSA-PSS).

To export the public key (i.e., the SubjectPublicKeyInfo part), check
@code{gnutls_pubkey_import_x509()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.6.0
@end deftypefun

@subheading gnutls_x509_crt_set_subject_alt_name
@anchor{gnutls_x509_crt_set_subject_alt_name}
@deftypefun {int} {gnutls_x509_crt_set_subject_alt_name} (gnutls_x509_crt_t @var{crt}, gnutls_x509_subject_alt_name_t @var{type}, const void * @var{data}, unsigned int @var{data_size}, unsigned int @var{flags})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{type}: is one of the gnutls_x509_subject_alt_name_t enumerations

@var{data}: The data to be set

@var{data_size}: The size of data to be set

@var{flags}: GNUTLS_FSAN_SET to clear previous data or GNUTLS_FSAN_APPEND to append. 

This function will set the subject alternative name certificate
extension. It can set the following types: @code{GNUTLS_SAN_DNSNAME}  as a text string,
@code{GNUTLS_SAN_RFC822NAME}  as a text string, @code{GNUTLS_SAN_URI}  as a text string,
@code{GNUTLS_SAN_IPADDRESS}  as a binary IP address (4 or 16 bytes),
@code{GNUTLS_SAN_OTHERNAME_XMPP}  as a UTF8 string (since 3.5.0).

Since version 3.5.7 the @code{GNUTLS_SAN_RFC822NAME} , @code{GNUTLS_SAN_DNSNAME} , and
@code{GNUTLS_SAN_OTHERNAME_XMPP}  are converted to ACE format when necessary.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.6.0
@end deftypefun

@subheading gnutls_x509_crt_set_subject_alt_othername
@anchor{gnutls_x509_crt_set_subject_alt_othername}
@deftypefun {int} {gnutls_x509_crt_set_subject_alt_othername} (gnutls_x509_crt_t @var{crt}, const char * @var{oid}, const void * @var{data}, unsigned int @var{data_size}, unsigned int @var{flags})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{oid}: The other name OID

@var{data}: The data to be set

@var{data_size}: The size of data to be set

@var{flags}: GNUTLS_FSAN_SET to clear previous data or GNUTLS_FSAN_APPEND to append. 

This function will set an "othername" to the subject alternative name certificate
extension.

The values set are set as binary values and are expected to have the proper DER encoding.
For convenience the flags @code{GNUTLS_FSAN_ENCODE_OCTET_STRING}  and @code{GNUTLS_FSAN_ENCODE_UTF8_STRING} 
can be used to encode the provided data.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_crt_set_subject_alternative_name
@anchor{gnutls_x509_crt_set_subject_alternative_name}
@deftypefun {int} {gnutls_x509_crt_set_subject_alternative_name} (gnutls_x509_crt_t @var{crt}, gnutls_x509_subject_alt_name_t           @var{type}, const char * @var{data_string})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{type}: is one of the gnutls_x509_subject_alt_name_t enumerations

@var{data_string}: The data to be set, a (0) terminated string

This function will set the subject alternative name certificate
extension. This function assumes that data can be expressed as a null
terminated string.

The name of the function is unfortunate since it is inconsistent with
@code{gnutls_x509_crt_get_subject_alt_name()} .

See @code{gnutls_x509_crt_set_subject_alt_name()}  for more information.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_subject_key_id
@anchor{gnutls_x509_crt_set_subject_key_id}
@deftypefun {int} {gnutls_x509_crt_set_subject_key_id} (gnutls_x509_crt_t @var{cert}, const void * @var{id}, size_t @var{id_size})
@var{cert}: a certificate of type @code{gnutls_x509_crt_t} 

@var{id}: The key ID

@var{id_size}: Holds the size of the subject key ID field.

This function will set the X.509 certificate's subject key ID
extension.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_set_subject_unique_id
@anchor{gnutls_x509_crt_set_subject_unique_id}
@deftypefun {int} {gnutls_x509_crt_set_subject_unique_id} (gnutls_x509_crt_t @var{cert}, const void * @var{id}, size_t @var{id_size})
@var{cert}: a certificate of type @code{gnutls_x509_crt_t} 

@var{id}: The unique ID

@var{id_size}: Holds the size of the unique ID.

This function will set the X.509 certificate's subject unique ID field.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.4.7
@end deftypefun

@subheading gnutls_x509_crt_set_tlsfeatures
@anchor{gnutls_x509_crt_set_tlsfeatures}
@deftypefun {int} {gnutls_x509_crt_set_tlsfeatures} (gnutls_x509_crt_t @var{crt}, gnutls_x509_tlsfeatures_t @var{features})
@var{crt}: A X.509 certificate

@var{features}: If the function succeeds, the
features will be added to the certificate.

This function will set the certificates
X.509 TLS extension from the given structure.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error value.

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_crt_set_version
@anchor{gnutls_x509_crt_set_version}
@deftypefun {int} {gnutls_x509_crt_set_version} (gnutls_x509_crt_t @var{crt}, unsigned int @var{version})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{version}: holds the version number. For X.509v1 certificates must be 1.

This function will set the version of the certificate.  This must
be one for X.509 version 1, and so on.  Plain certificates without
extensions must have version set to one.

To create well-formed certificates, you must specify version 3 if
you use any certificate extensions.  Extensions are created by
functions such as @code{gnutls_x509_crt_set_subject_alt_name()} 
or @code{gnutls_x509_crt_set_key_usage()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_sign
@anchor{gnutls_x509_crt_sign}
@deftypefun {int} {gnutls_x509_crt_sign} (gnutls_x509_crt_t @var{crt}, gnutls_x509_crt_t @var{issuer}, gnutls_x509_privkey_t @var{issuer_key})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{issuer}: is the certificate of the certificate issuer

@var{issuer_key}: holds the issuer's private key

This function is the same a @code{gnutls_x509_crt_sign2()}  with no flags,
and an appropriate hash algorithm. The hash algorithm used may
vary between versions of GnuTLS, and it is tied to the security
level of the issuer's public key.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_sign2
@anchor{gnutls_x509_crt_sign2}
@deftypefun {int} {gnutls_x509_crt_sign2} (gnutls_x509_crt_t @var{crt}, gnutls_x509_crt_t @var{issuer}, gnutls_x509_privkey_t @var{issuer_key}, gnutls_digest_algorithm_t @var{dig}, unsigned int @var{flags})
@var{crt}: a certificate of type @code{gnutls_x509_crt_t} 

@var{issuer}: is the certificate of the certificate issuer

@var{issuer_key}: holds the issuer's private key

@var{dig}: The message digest to use, @code{GNUTLS_DIG_SHA256}  is a safe choice

@var{flags}: must be 0

This function will sign the certificate with the issuer's private key, and
will copy the issuer's information into the certificate.

This must be the last step in a certificate generation since all
the previously set parameters are now signed.

A known limitation of this function is, that a newly-signed certificate will not
be fully functional (e.g., for signature verification), until it
is exported an re-imported.

After GnuTLS 3.6.1 the value of  @code{dig} may be @code{GNUTLS_DIG_UNKNOWN} ,
and in that case, a suitable but reasonable for the key algorithm will be selected.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_verify
@anchor{gnutls_x509_crt_verify}
@deftypefun {int} {gnutls_x509_crt_verify} (gnutls_x509_crt_t @var{cert}, const gnutls_x509_crt_t * @var{CA_list}, unsigned @var{CA_list_length}, unsigned int @var{flags}, unsigned int * @var{verify})
@var{cert}: is the certificate to be verified

@var{CA_list}: is one certificate that is considered to be trusted one

@var{CA_list_length}: holds the number of CA certificate in CA_list

@var{flags}: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

@var{verify}: will hold the certificate verification output.

This function will try to verify the given certificate and return
its status. Note that a verification error does not imply a negative
return status. In that case the  @code{verify} status is set.

The details of the verification are the same
as in @code{gnutls_x509_trust_list_verify_crt2()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_crt_verify_data2
@anchor{gnutls_x509_crt_verify_data2}
@deftypefun {int} {gnutls_x509_crt_verify_data2} (gnutls_x509_crt_t @var{crt}, gnutls_sign_algorithm_t @var{algo}, unsigned int @var{flags}, const gnutls_datum_t * @var{data}, const gnutls_datum_t * @var{signature})
@var{crt}: Holds the certificate to verify with

@var{algo}: The signature algorithm used

@var{flags}: Zero or an OR list of @code{gnutls_certificate_verify_flags} 

@var{data}: holds the signed data

@var{signature}: contains the signature

This function will verify the given signed data, using the
parameters from the certificate.

@strong{Returns:} In case of a verification failure @code{GNUTLS_E_PK_SIG_VERIFY_FAILED} 
is returned, @code{GNUTLS_E_EXPIRED}  or @code{GNUTLS_E_NOT_YET_ACTIVATED}  on expired
or not yet activated certificate and zero or positive code on success.

Note that since GnuTLS 3.5.6 this function introduces checks in the
end certificate ( @code{crt} ), including time checks and key usage checks.

@strong{Since:} 3.4.0
@end deftypefun

@subheading gnutls_x509_ct_sct_get
@anchor{gnutls_x509_ct_sct_get}
@deftypefun {int} {gnutls_x509_ct_sct_get} (const gnutls_x509_ct_scts_t @var{scts}, unsigned @var{idx}, time_t * @var{timestamp}, gnutls_datum_t * @var{logid}, gnutls_sign_algorithm_t * @var{sigalg}, gnutls_datum_t * @var{signature})
@var{scts}: A list of SCTs

@var{idx}: The index of the target SCT in the list

@var{timestamp}: The timestamp of the SCT

@var{logid}: The LogID field of the SCT; must be freed with @code{gnutls_free()} 

@var{sigalg}: The signature algorithm

@var{signature}: The signature of the SCT; must be freed with @code{gnutls_free()} 

This function will return a specific SCT (Signed Certificate Timestamp)
stored in the SCT list  @code{scts} .

The datums holding the SCT's LogId and signature will be allocated
using @code{gnutls_malloc()} .

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  (0) will be returned on success,
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  if  @code{idx} exceeds the number of SCTs in the list
or a negative error value.
@end deftypefun

@subheading gnutls_x509_ct_sct_get_version
@anchor{gnutls_x509_ct_sct_get_version}
@deftypefun {int} {gnutls_x509_ct_sct_get_version} (gnutls_x509_ct_scts_t @var{scts}, unsigned @var{idx}, unsigned int * @var{version_out})
@var{scts}: A list of SCTs

@var{idx}: The index of the target SCT in the list

@var{version_out}: The version of the target SCT.

This function obtains the version of the SCT at the given position
in the SCT list.

The version of that SCT will be placed on  @code{version_out} .

Return : @code{GNUTLS_E_SUCCESS}  (0) is returned on success,
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  if  @code{idx} exceeds the number of SCTs in the list
and @code{GNUTLS_E_INVALID_REQUEST}  if the SCT's version is different than 1, as that's currently
the only defined version.
@end deftypefun

@subheading gnutls_x509_dn_deinit
@anchor{gnutls_x509_dn_deinit}
@deftypefun {void} {gnutls_x509_dn_deinit} (gnutls_x509_dn_t @var{dn})
@var{dn}: a DN uint8_t object pointer.

This function deallocates the DN object as returned by
@code{gnutls_x509_dn_import()} .

@strong{Since:} 2.4.0
@end deftypefun

@subheading gnutls_x509_dn_export
@anchor{gnutls_x509_dn_export}
@deftypefun {int} {gnutls_x509_dn_export} (gnutls_x509_dn_t @var{dn}, gnutls_x509_crt_fmt_t @var{format}, void * @var{output_data}, size_t * @var{output_data_size})
@var{dn}: Holds the uint8_t DN object

@var{format}: the format of output params. One of PEM or DER.

@var{output_data}: will contain a DN PEM or DER encoded

@var{output_data_size}: holds the size of output_data (and will be
replaced by the actual size of parameters)

This function will export the DN to DER or PEM format.

If the buffer provided is not long enough to hold the output, then
* @code{output_data_size} is updated and @code{GNUTLS_E_SHORT_MEMORY_BUFFER} 
will be returned.

If the structure is PEM encoded, it will have a header
of "BEGIN NAME".

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_dn_export2
@anchor{gnutls_x509_dn_export2}
@deftypefun {int} {gnutls_x509_dn_export2} (gnutls_x509_dn_t @var{dn}, gnutls_x509_crt_fmt_t @var{format}, gnutls_datum_t * @var{out})
@var{dn}: Holds the uint8_t DN object

@var{format}: the format of output params. One of PEM or DER.

@var{out}: will contain a DN PEM or DER encoded

This function will export the DN to DER or PEM format.

The output buffer is allocated using @code{gnutls_malloc()} .

If the structure is PEM encoded, it will have a header
of "BEGIN NAME".

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.1.3
@end deftypefun

@subheading gnutls_x509_dn_get_rdn_ava
@anchor{gnutls_x509_dn_get_rdn_ava}
@deftypefun {int} {gnutls_x509_dn_get_rdn_ava} (gnutls_x509_dn_t @var{dn}, int @var{irdn}, int @var{iava}, gnutls_x509_ava_st * @var{ava})
@var{dn}: a pointer to DN

@var{irdn}: index of RDN

@var{iava}: index of AVA.

@var{ava}: Pointer to structure which will hold output information.

Get pointers to data within the DN. The format of the  @code{ava} structure
is shown below.

struct gnutls_x509_ava_st @{
gnutls_datum_t oid;
gnutls_datum_t value;
unsigned long value_tag;
@};

The X.509 distinguished name is a sequence of sequences of strings
and this is what the  @code{irdn} and  @code{iava} indexes model.

Note that  @code{ava} will contain pointers into the  @code{dn} structure which
in turns points to the original certificate. Thus you should not
modify any data or deallocate any of those.

This is a low-level function that requires the caller to do the
value conversions when necessary (e.g. from UCS-2).

@strong{Returns:} Returns 0 on success, or an error code.
@end deftypefun

@subheading gnutls_x509_dn_get_str
@anchor{gnutls_x509_dn_get_str}
@deftypefun {int} {gnutls_x509_dn_get_str} (gnutls_x509_dn_t @var{dn}, gnutls_datum_t * @var{str})
@var{dn}: a pointer to DN

@var{str}: a datum that will hold the name

This function will allocate buffer and copy the name in the provided DN.
The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.4.2
@end deftypefun

@subheading gnutls_x509_dn_get_str2
@anchor{gnutls_x509_dn_get_str2}
@deftypefun {int} {gnutls_x509_dn_get_str2} (gnutls_x509_dn_t @var{dn}, gnutls_datum_t * @var{str}, unsigned @var{flags})
@var{dn}: a pointer to DN

@var{str}: a datum that will hold the name

@var{flags}: zero or @code{GNUTLS_X509_DN_FLAG_COMPAT} 

This function will allocate buffer and copy the name in the provided DN.
The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.

When the flag @code{GNUTLS_X509_DN_FLAG_COMPAT}  is specified, the output
format will match the format output by previous to 3.5.6 versions of GnuTLS
which was not not fully RFC4514-compliant.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.5.7
@end deftypefun

@subheading gnutls_x509_dn_import
@anchor{gnutls_x509_dn_import}
@deftypefun {int} {gnutls_x509_dn_import} (gnutls_x509_dn_t @var{dn}, const gnutls_datum_t * @var{data})
@var{dn}: the structure that will hold the imported DN

@var{data}: should contain a DER encoded RDN sequence

This function parses an RDN sequence and stores the result to a
@code{gnutls_x509_dn_t}  type. The data must have been initialized
with @code{gnutls_x509_dn_init()} . You may use @code{gnutls_x509_dn_get_rdn_ava()}  to
decode the DN.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.4.0
@end deftypefun

@subheading gnutls_x509_dn_init
@anchor{gnutls_x509_dn_init}
@deftypefun {int} {gnutls_x509_dn_init} (gnutls_x509_dn_t * @var{dn})
@var{dn}: the object to be initialized

This function initializes a @code{gnutls_x509_dn_t}  type.

The object returned must be deallocated using
@code{gnutls_x509_dn_deinit()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.4.0
@end deftypefun

@subheading gnutls_x509_dn_oid_known
@anchor{gnutls_x509_dn_oid_known}
@deftypefun {int} {gnutls_x509_dn_oid_known} (const char * @var{oid})
@var{oid}: holds an Object Identifier in a null terminated string

This function will inform about known DN OIDs. This is useful since
functions like @code{gnutls_x509_crt_set_dn_by_oid()}  use the information
on known OIDs to properly encode their input. Object Identifiers
that are not known are not encoded by these functions, and their
input is stored directly into the ASN.1 structure. In that case of
unknown OIDs, you have the responsibility of DER encoding your
data.

@strong{Returns:} 1 on known OIDs and 0 otherwise.
@end deftypefun

@subheading gnutls_x509_dn_oid_name
@anchor{gnutls_x509_dn_oid_name}
@deftypefun {const char *} {gnutls_x509_dn_oid_name} (const char * @var{oid}, unsigned int @var{flags})
@var{oid}: holds an Object Identifier in a null terminated string

@var{flags}: 0 or GNUTLS_X509_DN_OID_*

This function will return the name of a known DN OID. If
@code{GNUTLS_X509_DN_OID_RETURN_OID}  is specified this function
will return the given OID if no descriptive name has been
found.

@strong{Returns:} A null terminated string or NULL otherwise.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_dn_set_str
@anchor{gnutls_x509_dn_set_str}
@deftypefun {int} {gnutls_x509_dn_set_str} (gnutls_x509_dn_t @var{dn}, const char * @var{str}, const char ** @var{err})
@var{dn}: a pointer to DN

@var{str}: a comma separated DN string (RFC4514)

@var{err}: indicates the error position (if any)

This function will set the DN on the provided DN structure.
The input string should be plain ASCII or UTF-8 encoded. On
DN parsing error @code{GNUTLS_E_PARSING_ERROR}  is returned.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.5.3
@end deftypefun

@subheading gnutls_x509_ext_ct_export_scts
@anchor{gnutls_x509_ext_ct_export_scts}
@deftypefun {int} {gnutls_x509_ext_ct_export_scts} (const gnutls_x509_ct_scts_t @var{scts}, gnutls_datum_t * @var{ext})
@var{scts}: An initialized SCT list

@var{ext}: The DER-encoded extension data; must be freed with @code{gnutls_free()} 

This function will convert the provided list of SCTs to a DER-encoded
SignedCertificateTimestampList extension (1.3.6.1.4.1.11129.2.4.2).
The output data in  @code{ext} will be allocated using @code{gnutls_malloc()} .

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  (0) on success or a negative error value.
@end deftypefun

@subheading gnutls_x509_ext_ct_import_scts
@anchor{gnutls_x509_ext_ct_import_scts}
@deftypefun {int} {gnutls_x509_ext_ct_import_scts} (const gnutls_datum_t * @var{ext}, gnutls_x509_ct_scts_t @var{scts}, unsigned int @var{flags})
@var{ext}: a DER-encoded extension

@var{scts}: The SCT list

@var{flags}: should be zero

This function will read a SignedCertificateTimestampList structure
from the DER data of the X.509 Certificate Transparency SCT extension
(OID 1.3.6.1.4.1.11129.2.4.2).

The list of SCTs (Signed Certificate Timestamps) is placed on  @code{scts} ,
which must be previously initialized with @code{gnutls_x509_ext_ct_scts_init()} .

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  (0) on success or a negative error value.
@end deftypefun

@subheading gnutls_x509_ext_ct_scts_deinit
@anchor{gnutls_x509_ext_ct_scts_deinit}
@deftypefun {void} {gnutls_x509_ext_ct_scts_deinit} (gnutls_x509_ct_scts_t @var{scts})
@var{scts}: The SCT list

This function will deinitialize a Certificate Transparency SCT list.
@end deftypefun

@subheading gnutls_x509_ext_ct_scts_init
@anchor{gnutls_x509_ext_ct_scts_init}
@deftypefun {int} {gnutls_x509_ext_ct_scts_init} (gnutls_x509_ct_scts_t * @var{scts})
@var{scts}: The SCT list

This function will initialize a Certificate Transparency SCT list.

@strong{Returns:} @code{GNUTLS_E_SUCCESS}  (0) on success, otherwise a negative error value.
@end deftypefun

@subheading gnutls_x509_ext_deinit
@anchor{gnutls_x509_ext_deinit}
@deftypefun {void} {gnutls_x509_ext_deinit} (gnutls_x509_ext_st * @var{ext})
@var{ext}: The extensions structure

This function will deinitialize an extensions structure.

@strong{Since:} 3.3.8
@end deftypefun

@subheading gnutls_x509_ext_export_aia
@anchor{gnutls_x509_ext_export_aia}
@deftypefun {int} {gnutls_x509_ext_export_aia} (gnutls_x509_aia_t @var{aia}, gnutls_datum_t * @var{ext})
@var{aia}: The authority info access

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will DER encode the Authority Information Access (AIA)
extension; see RFC 5280 section 4.2.2.1 for more information on the
extension.  

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_authority_key_id
@anchor{gnutls_x509_ext_export_authority_key_id}
@deftypefun {int} {gnutls_x509_ext_export_authority_key_id} (gnutls_x509_aki_t @var{aki}, gnutls_datum_t * @var{ext})
@var{aki}: An initialized authority key identifier

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the provided key identifier to a
DER-encoded PKIX AuthorityKeyIdentifier extension. 
The output data in  @code{ext} will be allocated using
@code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_basic_constraints
@anchor{gnutls_x509_ext_export_basic_constraints}
@deftypefun {int} {gnutls_x509_ext_export_basic_constraints} (unsigned int @var{ca}, int @var{pathlen}, gnutls_datum_t * @var{ext})
@var{ca}: non-zero for a CA

@var{pathlen}: The path length constraint (set to -1 for no constraint)

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the parameters provided to a basic constraints
DER encoded extension (2.5.29.19).
The  @code{ext} data will be allocated using
@code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_crl_dist_points
@anchor{gnutls_x509_ext_export_crl_dist_points}
@deftypefun {int} {gnutls_x509_ext_export_crl_dist_points} (gnutls_x509_crl_dist_points_t @var{cdp}, gnutls_datum_t * @var{ext})
@var{cdp}: A pointer to an initialized CRL distribution points.

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the provided policies, to a certificate policy
DER encoded extension (2.5.29.31).

The  @code{ext} data will be allocated using @code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_inhibit_anypolicy
@anchor{gnutls_x509_ext_export_inhibit_anypolicy}
@deftypefun {int} {gnutls_x509_ext_export_inhibit_anypolicy} (unsigned int @var{skipcerts}, gnutls_datum_t * @var{ext})
@var{skipcerts}: number of certificates after which anypolicy is no longer acceptable.

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the  @code{skipcerts} value to a DER
encoded Inhibit AnyPolicy PKIX extension. The  @code{ext} data will be allocated using
@code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.6.0
@end deftypefun

@subheading gnutls_x509_ext_export_key_purposes
@anchor{gnutls_x509_ext_export_key_purposes}
@deftypefun {int} {gnutls_x509_ext_export_key_purposes} (gnutls_x509_key_purposes_t @var{p}, gnutls_datum_t * @var{ext})
@var{p}: The key purposes

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the key purposes type to a
DER-encoded PKIX ExtKeyUsageSyntax (2.5.29.37) extension. The output data in 
 @code{ext} will be allocated using @code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_key_usage
@anchor{gnutls_x509_ext_export_key_usage}
@deftypefun {int} {gnutls_x509_ext_export_key_usage} (unsigned int @var{usage}, gnutls_datum_t * @var{ext})
@var{usage}: an ORed sequence of the GNUTLS_KEY_* elements.

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the keyUsage bit string to a DER
encoded PKIX extension. The  @code{ext} data will be allocated using
@code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_name_constraints
@anchor{gnutls_x509_ext_export_name_constraints}
@deftypefun {int} {gnutls_x509_ext_export_name_constraints} (gnutls_x509_name_constraints_t @var{nc}, gnutls_datum_t * @var{ext})
@var{nc}: The nameconstraints

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the provided name constraints type to a
DER-encoded PKIX NameConstraints (2.5.29.30) extension. The output data in 
 @code{ext} will be allocated using @code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_policies
@anchor{gnutls_x509_ext_export_policies}
@deftypefun {int} {gnutls_x509_ext_export_policies} (gnutls_x509_policies_t @var{policies}, gnutls_datum_t * @var{ext})
@var{policies}: A pointer to an initialized policies.

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the provided policies, to a certificate policy
DER encoded extension (2.5.29.32).

The  @code{ext} data will be allocated using @code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_private_key_usage_period
@anchor{gnutls_x509_ext_export_private_key_usage_period}
@deftypefun {int} {gnutls_x509_ext_export_private_key_usage_period} (time_t @var{activation}, time_t @var{expiration}, gnutls_datum_t * @var{ext})
@var{activation}: The activation time

@var{expiration}: The expiration time

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the periods provided to a private key
usage DER encoded extension (2.5.29.16).
The  @code{ext} data will be allocated using
@code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_proxy
@anchor{gnutls_x509_ext_export_proxy}
@deftypefun {int} {gnutls_x509_ext_export_proxy} (int @var{pathLenConstraint}, const char * @var{policyLanguage}, const char * @var{policy}, size_t @var{sizeof_policy}, gnutls_datum_t * @var{ext})
@var{pathLenConstraint}: A negative value will remove the path length constraint,
while non-negative values will be set as the length of the pathLenConstraints field.

@var{policyLanguage}: OID describing the language of  @code{policy} .

@var{policy}: uint8_t byte array with policy language, can be @code{NULL} 

@var{sizeof_policy}: size of  @code{policy} .

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the parameters provided to a proxyCertInfo extension.

The  @code{ext} data will be allocated using @code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_subject_alt_names
@anchor{gnutls_x509_ext_export_subject_alt_names}
@deftypefun {int} {gnutls_x509_ext_export_subject_alt_names} (gnutls_subject_alt_names_t @var{sans}, gnutls_datum_t * @var{ext})
@var{sans}: The alternative names

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the provided alternative names structure to a
DER-encoded SubjectAltName PKIX extension. The output data in  @code{ext} will be allocated using
@code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_subject_key_id
@anchor{gnutls_x509_ext_export_subject_key_id}
@deftypefun {int} {gnutls_x509_ext_export_subject_key_id} (const gnutls_datum_t * @var{id}, gnutls_datum_t * @var{ext})
@var{id}: The key identifier

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the provided key identifier to a
DER-encoded PKIX SubjectKeyIdentifier extension. 
The output data in  @code{ext} will be allocated using
@code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_export_tlsfeatures
@anchor{gnutls_x509_ext_export_tlsfeatures}
@deftypefun {int} {gnutls_x509_ext_export_tlsfeatures} (gnutls_x509_tlsfeatures_t @var{f}, gnutls_datum_t * @var{ext})
@var{f}: The features structure

@var{ext}: The DER-encoded extension data; must be freed using @code{gnutls_free()} .

This function will convert the provided TLS features structure structure to a
DER-encoded TLS features PKIX extension. The output data in  @code{ext} will be allocated using
@code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_ext_import_aia
@anchor{gnutls_x509_ext_import_aia}
@deftypefun {int} {gnutls_x509_ext_import_aia} (const gnutls_datum_t * @var{ext}, gnutls_x509_aia_t @var{aia}, unsigned int @var{flags})
@var{ext}: The DER-encoded extension data

@var{aia}: The authority info access

@var{flags}: should be zero

This function extracts the Authority Information Access (AIA)
extension from the provided DER-encoded data; see RFC 5280 section 4.2.2.1 
for more information on the extension.  The
AIA extension holds a sequence of AccessDescription (AD) data.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_authority_key_id
@anchor{gnutls_x509_ext_import_authority_key_id}
@deftypefun {int} {gnutls_x509_ext_import_authority_key_id} (const gnutls_datum_t * @var{ext}, gnutls_x509_aki_t @var{aki}, unsigned int @var{flags})
@var{ext}: a DER encoded extension

@var{aki}: An initialized authority key identifier type

@var{flags}: should be zero

This function will return the subject key ID stored in the provided
AuthorityKeyIdentifier extension.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_basic_constraints
@anchor{gnutls_x509_ext_import_basic_constraints}
@deftypefun {int} {gnutls_x509_ext_import_basic_constraints} (const gnutls_datum_t * @var{ext}, unsigned int * @var{ca}, int * @var{pathlen})
@var{ext}: the DER encoded extension data

@var{ca}: will be non zero if the CA status is true

@var{pathlen}: the path length constraint; will be set to -1 for no limit

This function will return the CA status and path length constraint
as written in the PKIX extension 2.5.29.19.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_crl_dist_points
@anchor{gnutls_x509_ext_import_crl_dist_points}
@deftypefun {int} {gnutls_x509_ext_import_crl_dist_points} (const gnutls_datum_t * @var{ext}, gnutls_x509_crl_dist_points_t @var{cdp}, unsigned int @var{flags})
@var{ext}: the DER encoded extension data

@var{cdp}: A pointer to an initialized CRL distribution points.

@var{flags}: should be zero

This function will extract the CRL distribution points extension (2.5.29.31) 
and store it into the provided type.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_inhibit_anypolicy
@anchor{gnutls_x509_ext_import_inhibit_anypolicy}
@deftypefun {int} {gnutls_x509_ext_import_inhibit_anypolicy} (const gnutls_datum_t * @var{ext}, unsigned int * @var{skipcerts})
@var{ext}: the DER encoded extension data

@var{skipcerts}: will hold the number of certificates after which anypolicy is no longer acceptable.

This function will return certificate's value of SkipCerts,
by reading the DER data of the Inhibit anyPolicy X.509 extension (2.5.29.54).

The  @code{skipcerts} value is the number of additional certificates that
may appear in the path before the anyPolicy (@code{GNUTLS_X509_OID_POLICY_ANY} )
is no longer acceptable.

@strong{Returns:} zero, or a negative error code in case of
parsing error.  If the certificate does not contain the Inhibit anyPolicy
extension @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  will be
returned.

@strong{Since:} 3.6.0
@end deftypefun

@subheading gnutls_x509_ext_import_key_purposes
@anchor{gnutls_x509_ext_import_key_purposes}
@deftypefun {int} {gnutls_x509_ext_import_key_purposes} (const gnutls_datum_t * @var{ext}, gnutls_x509_key_purposes_t @var{p}, unsigned int @var{flags})
@var{ext}: The DER-encoded extension data

@var{p}: The key purposes

@var{flags}: should be zero

This function will extract the key purposes in the provided DER-encoded
ExtKeyUsageSyntax PKIX extension, to a @code{gnutls_x509_key_purposes_t}  type. 
The data must be initialized.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_key_usage
@anchor{gnutls_x509_ext_import_key_usage}
@deftypefun {int} {gnutls_x509_ext_import_key_usage} (const gnutls_datum_t * @var{ext}, unsigned int * @var{key_usage})
@var{ext}: the DER encoded extension data

@var{key_usage}: where the key usage bits will be stored

This function will return certificate's key usage, by reading the DER
data of the keyUsage X.509 extension (2.5.29.15). The key usage value will ORed
values of the: @code{GNUTLS_KEY_DIGITAL_SIGNATURE} ,
@code{GNUTLS_KEY_NON_REPUDIATION} , @code{GNUTLS_KEY_KEY_ENCIPHERMENT} ,
@code{GNUTLS_KEY_DATA_ENCIPHERMENT} , @code{GNUTLS_KEY_KEY_AGREEMENT} ,
@code{GNUTLS_KEY_KEY_CERT_SIGN} , @code{GNUTLS_KEY_CRL_SIGN} ,
@code{GNUTLS_KEY_ENCIPHER_ONLY} , @code{GNUTLS_KEY_DECIPHER_ONLY} .

@strong{Returns:} the certificate key usage, or a negative error code in case of
parsing error.  If the certificate does not contain the keyUsage
extension @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  will be
returned.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_name_constraints
@anchor{gnutls_x509_ext_import_name_constraints}
@deftypefun {int} {gnutls_x509_ext_import_name_constraints} (const gnutls_datum_t * @var{ext}, gnutls_x509_name_constraints_t @var{nc}, unsigned int @var{flags})
@var{ext}: a DER encoded extension

@var{nc}: The nameconstraints

@var{flags}: zero or @code{GNUTLS_NAME_CONSTRAINTS_FLAG_APPEND} 

This function will return an intermediate type containing
the name constraints of the provided NameConstraints extension. That
can be used in combination with @code{gnutls_x509_name_constraints_check()} 
to verify whether a server's name is in accordance with the constraints.

When the  @code{flags} is set to @code{GNUTLS_NAME_CONSTRAINTS_FLAG_APPEND} , then if 
the  @code{nc} type is empty this function will behave identically as if the flag was not set.
Otherwise if there are elements in the  @code{nc} structure then the
constraints will be merged with the existing constraints following
RFC5280 p6.1.4 (excluded constraints will be appended, permitted
will be intersected).

Note that  @code{nc} must be initialized prior to calling this function.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_policies
@anchor{gnutls_x509_ext_import_policies}
@deftypefun {int} {gnutls_x509_ext_import_policies} (const gnutls_datum_t * @var{ext}, gnutls_x509_policies_t @var{policies}, unsigned int @var{flags})
@var{ext}: the DER encoded extension data

@var{policies}: A pointer to an initialized policies.

@var{flags}: should be zero

This function will extract the certificate policy extension (2.5.29.32) 
and store it the provided policies.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_private_key_usage_period
@anchor{gnutls_x509_ext_import_private_key_usage_period}
@deftypefun {int} {gnutls_x509_ext_import_private_key_usage_period} (const gnutls_datum_t * @var{ext}, time_t * @var{activation}, time_t * @var{expiration})
@var{ext}: the DER encoded extension data

@var{activation}: Will hold the activation time

@var{expiration}: Will hold the expiration time

This function will return the expiration and activation
times of the private key as written in the
PKIX extension 2.5.29.16.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_proxy
@anchor{gnutls_x509_ext_import_proxy}
@deftypefun {int} {gnutls_x509_ext_import_proxy} (const gnutls_datum_t * @var{ext}, int * @var{pathlen}, char ** @var{policyLanguage}, char ** @var{policy}, size_t * @var{sizeof_policy})
@var{ext}: the DER encoded extension data

@var{pathlen}: pointer to output integer indicating path length (may be
NULL), non-negative error codes indicate a present pCPathLenConstraint
field and the actual value, -1 indicate that the field is absent.

@var{policyLanguage}: output variable with OID of policy language

@var{policy}: output variable with policy data

@var{sizeof_policy}: output variable with size of policy data

This function will return the information from a proxy certificate
extension. It reads the ProxyCertInfo X.509 extension (1.3.6.1.5.5.7.1.14).
The  @code{policyLanguage} and  @code{policy} values must be deinitialized using @code{gnutls_free()}  after use.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_subject_alt_names
@anchor{gnutls_x509_ext_import_subject_alt_names}
@deftypefun {int} {gnutls_x509_ext_import_subject_alt_names} (const gnutls_datum_t * @var{ext}, gnutls_subject_alt_names_t @var{sans}, unsigned int @var{flags})
@var{ext}: The DER-encoded extension data

@var{sans}: The alternative names

@var{flags}: should be zero

This function will export the alternative names in the provided DER-encoded
SubjectAltName PKIX extension, to a @code{gnutls_subject_alt_names_t}  type.  @code{sans} must be initialized.

This function will succeed even if there no subject alternative names
in the structure.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_subject_key_id
@anchor{gnutls_x509_ext_import_subject_key_id}
@deftypefun {int} {gnutls_x509_ext_import_subject_key_id} (const gnutls_datum_t * @var{ext}, gnutls_datum_t * @var{id})
@var{ext}: a DER encoded extension

@var{id}: will contain the subject key ID

This function will return the subject key ID stored in the provided
SubjectKeyIdentifier extension. The ID will be allocated using
@code{gnutls_malloc()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_ext_import_tlsfeatures
@anchor{gnutls_x509_ext_import_tlsfeatures}
@deftypefun {int} {gnutls_x509_ext_import_tlsfeatures} (const gnutls_datum_t * @var{ext}, gnutls_x509_tlsfeatures_t @var{f}, unsigned int @var{flags})
@var{ext}: The DER-encoded extension data

@var{f}: The features structure

@var{flags}: zero or @code{GNUTLS_EXT_FLAG_APPEND} 

This function will export the features in the provided DER-encoded
TLS Features PKIX extension, to a @code{gnutls_x509_tlsfeatures_t}  type.  @code{f} must be initialized.

When the  @code{flags} is set to @code{GNUTLS_EXT_FLAG_APPEND} ,
then if the  @code{features} structure is empty this function will behave
identically as if the flag was not set. Otherwise if there are elements 
in the  @code{features} structure then they will be merged with.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_ext_print
@anchor{gnutls_x509_ext_print}
@deftypefun {int} {gnutls_x509_ext_print} (gnutls_x509_ext_st * @var{exts}, unsigned int @var{exts_size}, gnutls_certificate_print_formats_t @var{format}, gnutls_datum_t * @var{out})
@var{exts}: The data to be printed

@var{exts_size}: the number of available structures

@var{format}: Indicate the format to use

@var{out}: Newly allocated datum with null terminated string.

This function will pretty print X.509 certificate extensions,
suitable for display to a human.

The output  @code{out} needs to be deallocated using @code{gnutls_free()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_key_purpose_deinit
@anchor{gnutls_x509_key_purpose_deinit}
@deftypefun {void} {gnutls_x509_key_purpose_deinit} (gnutls_x509_key_purposes_t @var{p})
@var{p}: The key purposes

This function will deinitialize a key purposes type.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_key_purpose_get
@anchor{gnutls_x509_key_purpose_get}
@deftypefun {int} {gnutls_x509_key_purpose_get} (gnutls_x509_key_purposes_t @var{p}, unsigned @var{idx}, gnutls_datum_t * @var{oid})
@var{p}: The key purposes

@var{idx}: The index of the key purpose to retrieve

@var{oid}: Will hold the object identifier of the key purpose (to be treated as constant)

This function will retrieve the specified by the index key purpose in the
purposes type. The object identifier will be a null terminated string.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the index is out of bounds, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_key_purpose_init
@anchor{gnutls_x509_key_purpose_init}
@deftypefun {int} {gnutls_x509_key_purpose_init} (gnutls_x509_key_purposes_t * @var{p})
@var{p}: The key purposes

This function will initialize an alternative names type.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_key_purpose_set
@anchor{gnutls_x509_key_purpose_set}
@deftypefun {int} {gnutls_x509_key_purpose_set} (gnutls_x509_key_purposes_t @var{p}, const char * @var{oid})
@var{p}: The key purposes

@var{oid}: The object identifier of the key purpose

This function will store the specified key purpose in the
purposes.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0), otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_name_constraints_add_excluded
@anchor{gnutls_x509_name_constraints_add_excluded}
@deftypefun {int} {gnutls_x509_name_constraints_add_excluded} (gnutls_x509_name_constraints_t @var{nc}, gnutls_x509_subject_alt_name_t @var{type}, const gnutls_datum_t * @var{name})
@var{nc}: The nameconstraints

@var{type}: The type of the constraints

@var{name}: The data of the constraints

This function will add a name constraint to the list of excluded
constraints. The constraints  @code{type} can be any of the following types:
@code{GNUTLS_SAN_DNSNAME} , @code{GNUTLS_SAN_RFC822NAME} , @code{GNUTLS_SAN_DN} ,
@code{GNUTLS_SAN_URI} , @code{GNUTLS_SAN_IPADDRESS} . For the latter, an IP address
in network byte order is expected, followed by its network mask (which is
4 bytes in IPv4 or 16-bytes in IPv6).

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_name_constraints_add_permitted
@anchor{gnutls_x509_name_constraints_add_permitted}
@deftypefun {int} {gnutls_x509_name_constraints_add_permitted} (gnutls_x509_name_constraints_t @var{nc}, gnutls_x509_subject_alt_name_t @var{type}, const gnutls_datum_t * @var{name})
@var{nc}: The nameconstraints

@var{type}: The type of the constraints

@var{name}: The data of the constraints

This function will add a name constraint to the list of permitted
constraints. The constraints  @code{type} can be any of the following types:
@code{GNUTLS_SAN_DNSNAME} , @code{GNUTLS_SAN_RFC822NAME} , @code{GNUTLS_SAN_DN} ,
@code{GNUTLS_SAN_URI} , @code{GNUTLS_SAN_IPADDRESS} . For the latter, an IP address
in network byte order is expected, followed by its network mask.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_name_constraints_check
@anchor{gnutls_x509_name_constraints_check}
@deftypefun {unsigned} {gnutls_x509_name_constraints_check} (gnutls_x509_name_constraints_t @var{nc}, gnutls_x509_subject_alt_name_t @var{type}, const gnutls_datum_t * @var{name})
@var{nc}: the extracted name constraints

@var{type}: the type of the constraint to check (of type gnutls_x509_subject_alt_name_t)

@var{name}: the name to be checked

This function will check the provided name against the constraints in
 @code{nc} using the RFC5280 rules. Currently this function is limited to DNS
names, emails and IP addresses (of type @code{GNUTLS_SAN_DNSNAME} ,
@code{GNUTLS_SAN_RFC822NAME}  and @code{GNUTLS_SAN_IPADDRESS} ).

@strong{Returns:} zero if the provided name is not acceptable, and non-zero otherwise.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_name_constraints_check_crt
@anchor{gnutls_x509_name_constraints_check_crt}
@deftypefun {unsigned} {gnutls_x509_name_constraints_check_crt} (gnutls_x509_name_constraints_t @var{nc}, gnutls_x509_subject_alt_name_t @var{type}, gnutls_x509_crt_t @var{cert})
@var{nc}: the extracted name constraints

@var{type}: the type of the constraint to check (of type gnutls_x509_subject_alt_name_t)

@var{cert}: the certificate to be checked

This function will check the provided certificate names against the constraints in
 @code{nc} using the RFC5280 rules. It will traverse all the certificate's names and
alternative names.

Currently this function is limited to DNS
names and emails (of type @code{GNUTLS_SAN_DNSNAME}  and @code{GNUTLS_SAN_RFC822NAME} ).

@strong{Returns:} zero if the provided name is not acceptable, and non-zero otherwise.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_name_constraints_deinit
@anchor{gnutls_x509_name_constraints_deinit}
@deftypefun {void} {gnutls_x509_name_constraints_deinit} (gnutls_x509_name_constraints_t @var{nc})
@var{nc}: The nameconstraints

This function will deinitialize a name constraints type.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_name_constraints_get_excluded
@anchor{gnutls_x509_name_constraints_get_excluded}
@deftypefun {int} {gnutls_x509_name_constraints_get_excluded} (gnutls_x509_name_constraints_t @var{nc}, unsigned @var{idx}, unsigned * @var{type}, gnutls_datum_t * @var{name})
@var{nc}: the extracted name constraints

@var{idx}: the index of the constraint

@var{type}: the type of the constraint (of type gnutls_x509_subject_alt_name_t)

@var{name}: the name in the constraint (of the specific type)

This function will return an intermediate type containing
the name constraints of the provided CA certificate. That
structure can be used in combination with @code{gnutls_x509_name_constraints_check()} 
to verify whether a server's name is in accordance with the constraints.

The name should be treated as constant and valid for the lifetime of  @code{nc} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_name_constraints_get_permitted
@anchor{gnutls_x509_name_constraints_get_permitted}
@deftypefun {int} {gnutls_x509_name_constraints_get_permitted} (gnutls_x509_name_constraints_t @var{nc}, unsigned @var{idx}, unsigned * @var{type}, gnutls_datum_t * @var{name})
@var{nc}: the extracted name constraints

@var{idx}: the index of the constraint

@var{type}: the type of the constraint (of type gnutls_x509_subject_alt_name_t)

@var{name}: the name in the constraint (of the specific type)

This function will return an intermediate type containing
the name constraints of the provided CA certificate. That
structure can be used in combination with @code{gnutls_x509_name_constraints_check()} 
to verify whether a server's name is in accordance with the constraints.

The name should be treated as constant and valid for the lifetime of  @code{nc} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the extension is not present, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_name_constraints_init
@anchor{gnutls_x509_name_constraints_init}
@deftypefun {int} {gnutls_x509_name_constraints_init} (gnutls_x509_name_constraints_t * @var{nc})
@var{nc}: The nameconstraints

This function will initialize a name constraints type.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_othername_to_virtual
@anchor{gnutls_x509_othername_to_virtual}
@deftypefun {int} {gnutls_x509_othername_to_virtual} (const char * @var{oid}, const gnutls_datum_t * @var{othername}, unsigned int * @var{virt_type}, gnutls_datum_t * @var{virt})
@var{oid}: The othername object identifier

@var{othername}: The othername data

@var{virt_type}: GNUTLS_SAN_OTHERNAME_XXX

@var{virt}: allocated printable data

This function will parse and convert the othername data to a virtual
type supported by gnutls.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.8
@end deftypefun

@subheading gnutls_x509_policies_deinit
@anchor{gnutls_x509_policies_deinit}
@deftypefun {void} {gnutls_x509_policies_deinit} (gnutls_x509_policies_t @var{policies})
@var{policies}: The authority key identifier

This function will deinitialize an authority key identifier type.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_policies_get
@anchor{gnutls_x509_policies_get}
@deftypefun {int} {gnutls_x509_policies_get} (gnutls_x509_policies_t @var{policies}, unsigned int @var{seq}, struct gnutls_x509_policy_st * @var{policy})
@var{policies}: The policies

@var{seq}: The index of the name to get

@var{policy}: Will hold the policy

This function will return a specific policy as stored in
the  @code{policies} type. The returned values should be treated as constant
and valid for the lifetime of  @code{policies} .

The any policy OID is available as the @code{GNUTLS_X509_OID_POLICY_ANY}  macro.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
if the index is out of bounds, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_policies_init
@anchor{gnutls_x509_policies_init}
@deftypefun {int} {gnutls_x509_policies_init} (gnutls_x509_policies_t * @var{policies})
@var{policies}: The authority key ID

This function will initialize an authority key ID type.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_policies_set
@anchor{gnutls_x509_policies_set}
@deftypefun {int} {gnutls_x509_policies_set} (gnutls_x509_policies_t @var{policies}, const struct gnutls_x509_policy_st * @var{policy})
@var{policies}: An initialized policies

@var{policy}: Contains the policy to set

This function will store the specified policy in
the provided  @code{policies} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0), otherwise a negative error value.

@strong{Since:} 3.3.0
@end deftypefun

@subheading gnutls_x509_policy_release
@anchor{gnutls_x509_policy_release}
@deftypefun {void} {gnutls_x509_policy_release} (struct gnutls_x509_policy_st * @var{policy})
@var{policy}: a certificate policy

This function will deinitialize all memory associated with the provided
 @code{policy} . The policy is allocated using @code{gnutls_x509_crt_get_policy()} .

@strong{Since:} 3.1.5
@end deftypefun

@subheading gnutls_x509_privkey_cpy
@anchor{gnutls_x509_privkey_cpy}
@deftypefun {int} {gnutls_x509_privkey_cpy} (gnutls_x509_privkey_t @var{dst}, gnutls_x509_privkey_t @var{src})
@var{dst}: The destination key, which should be initialized.

@var{src}: The source key

This function will copy a private key from source to destination
key. Destination has to be initialized.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_deinit
@anchor{gnutls_x509_privkey_deinit}
@deftypefun {void} {gnutls_x509_privkey_deinit} (gnutls_x509_privkey_t @var{key})
@var{key}: The key to be deinitialized

This function will deinitialize a private key structure.
@end deftypefun

@subheading gnutls_x509_privkey_export
@anchor{gnutls_x509_privkey_export}
@deftypefun {int} {gnutls_x509_privkey_export} (gnutls_x509_privkey_t @var{key}, gnutls_x509_crt_fmt_t @var{format}, void * @var{output_data}, size_t * @var{output_data_size})
@var{key}: Holds the key

@var{format}: the format of output params. One of PEM or DER.

@var{output_data}: will contain a private key PEM or DER encoded

@var{output_data_size}: holds the size of output_data (and will be
replaced by the actual size of parameters)

This function will export the private key to a PKCS@code{1}  structure for
RSA or RSA-PSS keys, and integer sequence for DSA keys. Other keys types
will be exported in PKCS@code{8}  form.

If the structure is PEM encoded, it will have a header
of "BEGIN RSA PRIVATE KEY".

It is recommended to use @code{gnutls_x509_privkey_export_pkcs8()}  instead
of this function, when a consistent output format is required.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_export2
@anchor{gnutls_x509_privkey_export2}
@deftypefun {int} {gnutls_x509_privkey_export2} (gnutls_x509_privkey_t @var{key}, gnutls_x509_crt_fmt_t @var{format}, gnutls_datum_t * @var{out})
@var{key}: Holds the key

@var{format}: the format of output params. One of PEM or DER.

@var{out}: will contain a private key PEM or DER encoded

This function will export the private key to a PKCS@code{1}  structure for
RSA or RSA-PSS keys, and integer sequence for DSA keys. Other keys types
will be exported in PKCS@code{8}  form.

The output buffer is allocated using @code{gnutls_malloc()} .

It is recommended to use @code{gnutls_x509_privkey_export2_pkcs8()}  instead
of this function, when a consistent output format is required.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

Since 3.1.3
@end deftypefun

@subheading gnutls_x509_privkey_export2_pkcs8
@anchor{gnutls_x509_privkey_export2_pkcs8}
@deftypefun {int} {gnutls_x509_privkey_export2_pkcs8} (gnutls_x509_privkey_t @var{key}, gnutls_x509_crt_fmt_t @var{format}, const char * @var{password}, unsigned int @var{flags}, gnutls_datum_t * @var{out})
@var{key}: Holds the key

@var{format}: the format of output params. One of PEM or DER.

@var{password}: the password that will be used to encrypt the key.

@var{flags}: an ORed sequence of gnutls_pkcs_encrypt_flags_t

@var{out}: will contain a private key PEM or DER encoded

This function will export the private key to a PKCS8 structure.
Both RSA and DSA keys can be exported. For DSA keys we use
PKCS @code{11}  definitions. If the flags do not specify the encryption
cipher, then the default 3DES (PBES2) will be used.

The  @code{password} can be either ASCII or UTF-8 in the default PBES2
encryption schemas, or ASCII for the PKCS12 schemas.

The output buffer is allocated using @code{gnutls_malloc()} .

If the structure is PEM encoded, it will have a header
of "BEGIN ENCRYPTED PRIVATE KEY" or "BEGIN PRIVATE KEY" if
encryption is not used.

@strong{Returns:} In case of failure a negative error code will be
returned, and 0 on success.

Since 3.1.3
@end deftypefun

@subheading gnutls_x509_privkey_export_dsa_raw
@anchor{gnutls_x509_privkey_export_dsa_raw}
@deftypefun {int} {gnutls_x509_privkey_export_dsa_raw} (gnutls_x509_privkey_t @var{key}, gnutls_datum_t * @var{p}, gnutls_datum_t * @var{q}, gnutls_datum_t * @var{g}, gnutls_datum_t * @var{y}, gnutls_datum_t * @var{x})
@var{key}: a key

@var{p}: will hold the p

@var{q}: will hold the q

@var{g}: will hold the g

@var{y}: will hold the y

@var{x}: will hold the x

This function will export the DSA private key's parameters found
in the given structure. The new parameters will be allocated using
@code{gnutls_malloc()}  and will be stored in the appropriate datum.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_export_ecc_raw
@anchor{gnutls_x509_privkey_export_ecc_raw}
@deftypefun {int} {gnutls_x509_privkey_export_ecc_raw} (gnutls_x509_privkey_t @var{key}, gnutls_ecc_curve_t * @var{curve}, gnutls_datum_t * @var{x}, gnutls_datum_t * @var{y}, gnutls_datum_t * @var{k})
@var{key}: a key

@var{curve}: will hold the curve

@var{x}: will hold the x-coordinate

@var{y}: will hold the y-coordinate

@var{k}: will hold the private key

This function will export the ECC private key's parameters found
in the given structure. The new parameters will be allocated using
@code{gnutls_malloc()}  and will be stored in the appropriate datum.

In EdDSA curves the  @code{y} parameter will be @code{NULL}  and the other parameters
will be in the native format for the curve.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_privkey_export_gost_raw
@anchor{gnutls_x509_privkey_export_gost_raw}
@deftypefun {int} {gnutls_x509_privkey_export_gost_raw} (gnutls_x509_privkey_t @var{key}, gnutls_ecc_curve_t * @var{curve}, gnutls_digest_algorithm_t * @var{digest}, gnutls_gost_paramset_t * @var{paramset}, gnutls_datum_t * @var{x}, gnutls_datum_t * @var{y}, gnutls_datum_t * @var{k})
@var{key}: a key

@var{curve}: will hold the curve

@var{digest}: will hold the digest

@var{paramset}: will hold the GOST parameter set ID

@var{x}: will hold the x-coordinate

@var{y}: will hold the y-coordinate

@var{k}: will hold the private key

This function will export the GOST private key's parameters found
in the given structure. The new parameters will be allocated using
@code{gnutls_malloc()}  and will be stored in the appropriate datum.

@strong{Note:} parameters will be stored with least significant byte first. On
version 3.6.3 this was incorrectly returned in big-endian format.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.6.3
@end deftypefun

@subheading gnutls_x509_privkey_export_pkcs8
@anchor{gnutls_x509_privkey_export_pkcs8}
@deftypefun {int} {gnutls_x509_privkey_export_pkcs8} (gnutls_x509_privkey_t @var{key}, gnutls_x509_crt_fmt_t @var{format}, const char * @var{password}, unsigned int @var{flags}, void * @var{output_data}, size_t * @var{output_data_size})
@var{key}: Holds the key

@var{format}: the format of output params. One of PEM or DER.

@var{password}: the password that will be used to encrypt the key.

@var{flags}: an ORed sequence of gnutls_pkcs_encrypt_flags_t

@var{output_data}: will contain a private key PEM or DER encoded

@var{output_data_size}: holds the size of output_data (and will be
replaced by the actual size of parameters)

This function will export the private key to a PKCS8 structure.
Both RSA and DSA keys can be exported. For DSA keys we use
PKCS @code{11}  definitions. If the flags do not specify the encryption
cipher, then the default 3DES (PBES2) will be used.

The  @code{password} can be either ASCII or UTF-8 in the default PBES2
encryption schemas, or ASCII for the PKCS12 schemas.

If the buffer provided is not long enough to hold the output, then
*output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
be returned.

If the structure is PEM encoded, it will have a header
of "BEGIN ENCRYPTED PRIVATE KEY" or "BEGIN PRIVATE KEY" if
encryption is not used.

@strong{Returns:} In case of failure a negative error code will be
returned, and 0 on success.
@end deftypefun

@subheading gnutls_x509_privkey_export_rsa_raw
@anchor{gnutls_x509_privkey_export_rsa_raw}
@deftypefun {int} {gnutls_x509_privkey_export_rsa_raw} (gnutls_x509_privkey_t @var{key}, gnutls_datum_t * @var{m}, gnutls_datum_t * @var{e}, gnutls_datum_t * @var{d}, gnutls_datum_t * @var{p}, gnutls_datum_t * @var{q}, gnutls_datum_t * @var{u})
@var{key}: a key

@var{m}: will hold the modulus

@var{e}: will hold the public exponent

@var{d}: will hold the private exponent

@var{p}: will hold the first prime (p)

@var{q}: will hold the second prime (q)

@var{u}: will hold the coefficient

This function will export the RSA private key's parameters found
in the given structure. The new parameters will be allocated using
@code{gnutls_malloc()}  and will be stored in the appropriate datum.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_export_rsa_raw2
@anchor{gnutls_x509_privkey_export_rsa_raw2}
@deftypefun {int} {gnutls_x509_privkey_export_rsa_raw2} (gnutls_x509_privkey_t @var{key}, gnutls_datum_t * @var{m}, gnutls_datum_t * @var{e}, gnutls_datum_t * @var{d}, gnutls_datum_t * @var{p}, gnutls_datum_t * @var{q}, gnutls_datum_t * @var{u}, gnutls_datum_t * @var{e1}, gnutls_datum_t * @var{e2})
@var{key}: a key

@var{m}: will hold the modulus

@var{e}: will hold the public exponent

@var{d}: will hold the private exponent

@var{p}: will hold the first prime (p)

@var{q}: will hold the second prime (q)

@var{u}: will hold the coefficient

@var{e1}: will hold e1 = d mod (p-1)

@var{e2}: will hold e2 = d mod (q-1)

This function will export the RSA private key's parameters found
in the given structure. The new parameters will be allocated using
@code{gnutls_malloc()}  and will be stored in the appropriate datum.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 2.12.0
@end deftypefun

@subheading gnutls_x509_privkey_fix
@anchor{gnutls_x509_privkey_fix}
@deftypefun {int} {gnutls_x509_privkey_fix} (gnutls_x509_privkey_t @var{key})
@var{key}: a key

This function will recalculate the secondary parameters in a key.
In RSA keys, this can be the coefficient and exponent1,2.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_generate
@anchor{gnutls_x509_privkey_generate}
@deftypefun {int} {gnutls_x509_privkey_generate} (gnutls_x509_privkey_t @var{key}, gnutls_pk_algorithm_t @var{algo}, unsigned int @var{bits}, unsigned int @var{flags})
@var{key}: an initialized key

@var{algo}: is one of the algorithms in @code{gnutls_pk_algorithm_t} .

@var{bits}: the size of the parameters to generate

@var{flags}: Must be zero or flags from @code{gnutls_privkey_flags_t} .

This function will generate a random private key. Note that this
function must be called on an initialized private key.

The flag @code{GNUTLS_PRIVKEY_FLAG_PROVABLE} 
instructs the key generation process to use algorithms like Shawe-Taylor
(from FIPS PUB186-4) which generate provable parameters out of a seed
for RSA and DSA keys. See @code{gnutls_x509_privkey_generate2()}  for more
information.

Note that when generating an elliptic curve key, the curve
can be substituted in the place of the bits parameter using the
@code{GNUTLS_CURVE_TO_BITS()}  macro. The input to the macro is any curve from
@code{gnutls_ecc_curve_t} .

For DSA keys, if the subgroup size needs to be specified check
the @code{GNUTLS_SUBGROUP_TO_BITS()}  macro.

It is recommended to do not set the number of  @code{bits} directly, use @code{gnutls_sec_param_to_pk_bits()}  instead .

See also @code{gnutls_privkey_generate()} , @code{gnutls_x509_privkey_generate2()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_generate2
@anchor{gnutls_x509_privkey_generate2}
@deftypefun {int} {gnutls_x509_privkey_generate2} (gnutls_x509_privkey_t @var{key}, gnutls_pk_algorithm_t @var{algo}, unsigned int @var{bits}, unsigned int @var{flags}, const gnutls_keygen_data_st * @var{data}, unsigned @var{data_size})
@var{key}: a key

@var{algo}: is one of the algorithms in @code{gnutls_pk_algorithm_t} .

@var{bits}: the size of the modulus

@var{flags}: Must be zero or flags from @code{gnutls_privkey_flags_t} .

@var{data}: Allow specifying @code{gnutls_keygen_data_st}  types such as the seed to be used.

@var{data_size}: The number of  @code{data} available.

This function will generate a random private key. Note that this
function must be called on an initialized private key.

The flag @code{GNUTLS_PRIVKEY_FLAG_PROVABLE} 
instructs the key generation process to use algorithms like Shawe-Taylor
(from FIPS PUB186-4) which generate provable parameters out of a seed
for RSA and DSA keys. On DSA keys the PQG parameters are generated using the
seed, while on RSA the two primes. To specify an explicit seed
(by default a random seed is used), use the  @code{data} with a @code{GNUTLS_KEYGEN_SEED} 
type.

Note that when generating an elliptic curve key, the curve
can be substituted in the place of the bits parameter using the
@code{GNUTLS_CURVE_TO_BITS()}  macro.

To export the generated keys in memory or in files it is recommended to use the
PKCS@code{8}  form as it can handle all key types, and can store additional parameters
such as the seed, in case of provable RSA or DSA keys.
Generated keys can be exported in memory using @code{gnutls_privkey_export_x509()} ,
and then with @code{gnutls_x509_privkey_export2_pkcs8()} .

If key generation is part of your application, avoid setting the number
of bits directly, and instead use @code{gnutls_sec_param_to_pk_bits()} .
That way the generated keys will adapt to the security levels
of the underlying GnuTLS library.

See also @code{gnutls_privkey_generate2()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_get_key_id
@anchor{gnutls_x509_privkey_get_key_id}
@deftypefun {int} {gnutls_x509_privkey_get_key_id} (gnutls_x509_privkey_t @var{key}, unsigned int @var{flags}, unsigned char * @var{output_data}, size_t * @var{output_data_size})
@var{key}: a key

@var{flags}: should be one of the flags from @code{gnutls_keyid_flags_t} 

@var{output_data}: will contain the key ID

@var{output_data_size}: holds the size of output_data (and will be
replaced by the actual size of parameters)

This function will return a unique ID that depends on the public key
parameters. This ID can be used in checking whether a certificate
corresponds to the given key.

If the buffer provided is not long enough to hold the output, then
* @code{output_data_size} is updated and @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  will
be returned.  The output will normally be a SHA-1 hash output,
which is 20 bytes.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_get_pk_algorithm
@anchor{gnutls_x509_privkey_get_pk_algorithm}
@deftypefun {int} {gnutls_x509_privkey_get_pk_algorithm} (gnutls_x509_privkey_t @var{key})
@var{key}: should contain a @code{gnutls_x509_privkey_t}  type

This function will return the public key algorithm of a private
key.

@strong{Returns:} a member of the @code{gnutls_pk_algorithm_t}  enumeration on
success, or a negative error code on error.
@end deftypefun

@subheading gnutls_x509_privkey_get_pk_algorithm2
@anchor{gnutls_x509_privkey_get_pk_algorithm2}
@deftypefun {int} {gnutls_x509_privkey_get_pk_algorithm2} (gnutls_x509_privkey_t @var{key}, unsigned int * @var{bits})
@var{key}: should contain a @code{gnutls_x509_privkey_t}  type

@var{bits}: The number of bits in the public key algorithm

This function will return the public key algorithm of a private
key.

@strong{Returns:} a member of the @code{gnutls_pk_algorithm_t}  enumeration on
success, or a negative error code on error.
@end deftypefun

@subheading gnutls_x509_privkey_get_seed
@anchor{gnutls_x509_privkey_get_seed}
@deftypefun {int} {gnutls_x509_privkey_get_seed} (gnutls_x509_privkey_t @var{key}, gnutls_digest_algorithm_t * @var{digest}, void * @var{seed}, size_t * @var{seed_size})
@var{key}: should contain a @code{gnutls_x509_privkey_t}  type

@var{digest}: if non-NULL it will contain the digest algorithm used for key generation (if applicable)

@var{seed}: where seed will be copied to

@var{seed_size}: originally holds the size of  @code{seed} , will be updated with actual size

This function will return the seed that was used to generate the
given private key. That function will succeed only if the key was generated
as a provable key.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_privkey_get_spki
@anchor{gnutls_x509_privkey_get_spki}
@deftypefun {int} {gnutls_x509_privkey_get_spki} (gnutls_x509_privkey_t @var{key}, gnutls_x509_spki_t @var{spki}, unsigned int @var{flags})
@var{key}: should contain a @code{gnutls_x509_privkey_t}  type

@var{spki}: a SubjectPublicKeyInfo structure of type @code{gnutls_x509_spki_t} 

@var{flags}: must be zero

This function will return the public key information of a private
key. The provided  @code{spki} must be initialized.

@strong{Returns:} Zero on success, or a negative error code on error.
@end deftypefun

@subheading gnutls_x509_privkey_import
@anchor{gnutls_x509_privkey_import}
@deftypefun {int} {gnutls_x509_privkey_import} (gnutls_x509_privkey_t @var{key}, const gnutls_datum_t * @var{data}, gnutls_x509_crt_fmt_t @var{format})
@var{key}: The data to store the parsed key

@var{data}: The DER or PEM encoded certificate.

@var{format}: One of DER or PEM

This function will convert the given DER or PEM encoded key to the
native @code{gnutls_x509_privkey_t}  format. The output will be stored in
 @code{key} .

If the key is PEM encoded it should have a header that contains "PRIVATE
KEY". Note that this function falls back to PKCS @code{8}  decoding without
password, if the default format fails to import.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_import2
@anchor{gnutls_x509_privkey_import2}
@deftypefun {int} {gnutls_x509_privkey_import2} (gnutls_x509_privkey_t @var{key}, const gnutls_datum_t * @var{data}, gnutls_x509_crt_fmt_t @var{format}, const char * @var{password}, unsigned int @var{flags})
@var{key}: The data to store the parsed key

@var{data}: The DER or PEM encoded key.

@var{format}: One of DER or PEM

@var{password}: A password (optional)

@var{flags}: an ORed sequence of gnutls_pkcs_encrypt_flags_t

This function will import the given DER or PEM encoded key, to 
the native @code{gnutls_x509_privkey_t}  format, irrespective of the
input format. The input format is auto-detected.

The supported formats are basic unencrypted key, PKCS8, PKCS12,
and the openssl format.

If the provided key is encrypted but no password was given, then
@code{GNUTLS_E_DECRYPTION_FAILED}  is returned. Since GnuTLS 3.4.0 this
function will utilize the PIN callbacks if any.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_import_dsa_raw
@anchor{gnutls_x509_privkey_import_dsa_raw}
@deftypefun {int} {gnutls_x509_privkey_import_dsa_raw} (gnutls_x509_privkey_t @var{key}, const gnutls_datum_t * @var{p}, const gnutls_datum_t * @var{q}, const gnutls_datum_t * @var{g}, const gnutls_datum_t * @var{y}, const gnutls_datum_t * @var{x})
@var{key}: The data to store the parsed key

@var{p}: holds the p

@var{q}: holds the q

@var{g}: holds the g

@var{y}: holds the y (optional)

@var{x}: holds the x

This function will convert the given DSA raw parameters to the
native @code{gnutls_x509_privkey_t}  format.  The output will be stored
in  @code{key} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_import_ecc_raw
@anchor{gnutls_x509_privkey_import_ecc_raw}
@deftypefun {int} {gnutls_x509_privkey_import_ecc_raw} (gnutls_x509_privkey_t @var{key}, gnutls_ecc_curve_t @var{curve}, const gnutls_datum_t * @var{x}, const gnutls_datum_t * @var{y}, const gnutls_datum_t * @var{k})
@var{key}: The data to store the parsed key

@var{curve}: holds the curve

@var{x}: holds the x-coordinate

@var{y}: holds the y-coordinate

@var{k}: holds the k

This function will convert the given elliptic curve parameters to the
native @code{gnutls_x509_privkey_t}  format.  The output will be stored
in  @code{key} . For EdDSA keys, the  @code{x} and  @code{k} values must be in the
native to curve format.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_privkey_import_gost_raw
@anchor{gnutls_x509_privkey_import_gost_raw}
@deftypefun {int} {gnutls_x509_privkey_import_gost_raw} (gnutls_x509_privkey_t @var{key}, gnutls_ecc_curve_t @var{curve}, gnutls_digest_algorithm_t @var{digest}, gnutls_gost_paramset_t @var{paramset}, const gnutls_datum_t * @var{x}, const gnutls_datum_t * @var{y}, const gnutls_datum_t * @var{k})
@var{key}: The data to store the parsed key

@var{curve}: holds the curve

@var{digest}: will hold the digest

@var{paramset}: will hold the GOST parameter set ID

@var{x}: holds the x-coordinate

@var{y}: holds the y-coordinate

@var{k}: holds the k (private key)

This function will convert the given GOST private key's parameters to the
native @code{gnutls_x509_privkey_t}  format.  The output will be stored
in  @code{key} .   @code{digest} should be one of GNUTLS_DIG_GOSR_94,
GNUTLS_DIG_STREEBOG_256 or GNUTLS_DIG_STREEBOG_512.  If  @code{paramset} is set to
GNUTLS_GOST_PARAMSET_UNKNOWN default one will be selected depending on
 @code{digest} .

@strong{Note:} parameters should be stored with least significant byte first. On
version 3.6.3 big-endian format was used incorrectly.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.6.3
@end deftypefun

@subheading gnutls_x509_privkey_import_openssl
@anchor{gnutls_x509_privkey_import_openssl}
@deftypefun {int} {gnutls_x509_privkey_import_openssl} (gnutls_x509_privkey_t @var{key}, const gnutls_datum_t * @var{data}, const char * @var{password})
@var{key}: The data to store the parsed key

@var{data}: The DER or PEM encoded key.

@var{password}: the password to decrypt the key (if it is encrypted).

This function will convert the given PEM encrypted to 
the native gnutls_x509_privkey_t format. The
output will be stored in  @code{key} .  

The  @code{password} should be in ASCII. If the password is not provided
or wrong then @code{GNUTLS_E_DECRYPTION_FAILED}  will be returned.

If the Certificate is PEM encoded it should have a header of
"PRIVATE KEY" and the "DEK-Info" header. 

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_import_pkcs8
@anchor{gnutls_x509_privkey_import_pkcs8}
@deftypefun {int} {gnutls_x509_privkey_import_pkcs8} (gnutls_x509_privkey_t @var{key}, const gnutls_datum_t * @var{data}, gnutls_x509_crt_fmt_t @var{format}, const char * @var{password}, unsigned int @var{flags})
@var{key}: The data to store the parsed key

@var{data}: The DER or PEM encoded key.

@var{format}: One of DER or PEM

@var{password}: the password to decrypt the key (if it is encrypted).

@var{flags}: 0 if encrypted or GNUTLS_PKCS_PLAIN if not encrypted.

This function will convert the given DER or PEM encoded PKCS8 2.0
encrypted key to the native gnutls_x509_privkey_t format. The
output will be stored in  @code{key} .  Both RSA and DSA keys can be
imported, and flags can only be used to indicate an unencrypted
key.

The  @code{password} can be either ASCII or UTF-8 in the default PBES2
encryption schemas, or ASCII for the PKCS12 schemas.

If the Certificate is PEM encoded it should have a header of
"ENCRYPTED PRIVATE KEY", or "PRIVATE KEY". You only need to
specify the flags if the key is DER encoded, since in that case
the encryption status cannot be auto-detected.

If the @code{GNUTLS_PKCS_PLAIN}  flag is specified and the supplied data
are encrypted then @code{GNUTLS_E_DECRYPTION_FAILED}  is returned.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_import_rsa_raw
@anchor{gnutls_x509_privkey_import_rsa_raw}
@deftypefun {int} {gnutls_x509_privkey_import_rsa_raw} (gnutls_x509_privkey_t @var{key}, const gnutls_datum_t * @var{m}, const gnutls_datum_t * @var{e}, const gnutls_datum_t * @var{d}, const gnutls_datum_t * @var{p}, const gnutls_datum_t * @var{q}, const gnutls_datum_t * @var{u})
@var{key}: The data to store the parsed key

@var{m}: holds the modulus

@var{e}: holds the public exponent

@var{d}: holds the private exponent

@var{p}: holds the first prime (p)

@var{q}: holds the second prime (q)

@var{u}: holds the coefficient

This function will convert the given RSA raw parameters to the
native @code{gnutls_x509_privkey_t}  format.  The output will be stored in
 @code{key} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_import_rsa_raw2
@anchor{gnutls_x509_privkey_import_rsa_raw2}
@deftypefun {int} {gnutls_x509_privkey_import_rsa_raw2} (gnutls_x509_privkey_t @var{key}, const gnutls_datum_t * @var{m}, const gnutls_datum_t * @var{e}, const gnutls_datum_t * @var{d}, const gnutls_datum_t * @var{p}, const gnutls_datum_t * @var{q}, const gnutls_datum_t * @var{u}, const gnutls_datum_t * @var{e1}, const gnutls_datum_t * @var{e2})
@var{key}: The data to store the parsed key

@var{m}: holds the modulus

@var{e}: holds the public exponent

@var{d}: holds the private exponent

@var{p}: holds the first prime (p)

@var{q}: holds the second prime (q)

@var{u}: holds the coefficient (optional)

@var{e1}: holds e1 = d mod (p-1) (optional)

@var{e2}: holds e2 = d mod (q-1) (optional)

This function will convert the given RSA raw parameters to the
native @code{gnutls_x509_privkey_t}  format.  The output will be stored in
 @code{key} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_init
@anchor{gnutls_x509_privkey_init}
@deftypefun {int} {gnutls_x509_privkey_init} (gnutls_x509_privkey_t * @var{key})
@var{key}: A pointer to the type to be initialized

This function will initialize a private key type.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_sec_param
@anchor{gnutls_x509_privkey_sec_param}
@deftypefun {gnutls_sec_param_t} {gnutls_x509_privkey_sec_param} (gnutls_x509_privkey_t @var{key})
@var{key}: a key

This function will return the security parameter appropriate with
this private key.

@strong{Returns:} On success, a valid security parameter is returned otherwise
@code{GNUTLS_SEC_PARAM_UNKNOWN}  is returned.

@strong{Since:} 2.12.0
@end deftypefun

@subheading gnutls_x509_privkey_set_flags
@anchor{gnutls_x509_privkey_set_flags}
@deftypefun {void} {gnutls_x509_privkey_set_flags} (gnutls_x509_privkey_t @var{key}, unsigned int @var{flags})
@var{key}: A key of type @code{gnutls_x509_privkey_t} 

@var{flags}: flags from the @code{gnutls_privkey_flags} 

This function will set flags for the specified private key, after
it is generated. Currently this is useful for the @code{GNUTLS_PRIVKEY_FLAG_EXPORT_COMPAT} 
to allow exporting a "provable" private key in backwards compatible way.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_privkey_set_pin_function
@anchor{gnutls_x509_privkey_set_pin_function}
@deftypefun {void} {gnutls_x509_privkey_set_pin_function} (gnutls_x509_privkey_t @var{privkey}, gnutls_pin_callback_t @var{fn}, void * @var{userdata})
@var{privkey}: The certificate structure

@var{fn}: the callback

@var{userdata}: data associated with the callback

This function will set a callback function to be used when
it is required to access a protected object. This function overrides 
the global function set using @code{gnutls_pkcs11_set_pin_function()} .

Note that this callback is used when decrypting a key.

@strong{Since:} 3.4.0
@end deftypefun

@subheading gnutls_x509_privkey_set_spki
@anchor{gnutls_x509_privkey_set_spki}
@deftypefun {int} {gnutls_x509_privkey_set_spki} (gnutls_x509_privkey_t @var{key}, const gnutls_x509_spki_t @var{spki}, unsigned int @var{flags})
@var{key}: should contain a @code{gnutls_x509_privkey_t}  type

@var{spki}: a SubjectPublicKeyInfo structure of type @code{gnutls_x509_spki_t} 

@var{flags}: must be zero

This function will return the public key information of a private
key. The provided  @code{spki} must be initialized.

@strong{Returns:} Zero on success, or a negative error code on error.
@end deftypefun

@subheading gnutls_x509_privkey_sign_data
@anchor{gnutls_x509_privkey_sign_data}
@deftypefun {int} {gnutls_x509_privkey_sign_data} (gnutls_x509_privkey_t @var{key}, gnutls_digest_algorithm_t @var{digest}, unsigned int @var{flags}, const gnutls_datum_t * @var{data}, void * @var{signature}, size_t * @var{signature_size})
@var{key}: a key

@var{digest}: should be a digest algorithm

@var{flags}: should be 0 for now

@var{data}: holds the data to be signed

@var{signature}: will contain the signature

@var{signature_size}: holds the size of signature (and will be replaced
by the new size)

This function will sign the given data using a signature algorithm
supported by the private key. Signature algorithms are always used
together with a hash functions.  Different hash functions may be
used for the RSA algorithm, but only SHA-1 for the DSA keys.

If the buffer provided is not long enough to hold the output, then
* @code{signature_size} is updated and @code{GNUTLS_E_SHORT_MEMORY_BUFFER}  will
be returned.

Use @code{gnutls_x509_crt_get_preferred_hash_algorithm()}  to determine
the hash algorithm.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_verify_params
@anchor{gnutls_x509_privkey_verify_params}
@deftypefun {int} {gnutls_x509_privkey_verify_params} (gnutls_x509_privkey_t @var{key})
@var{key}: a key

This function will verify the private key parameters.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_privkey_verify_seed
@anchor{gnutls_x509_privkey_verify_seed}
@deftypefun {int} {gnutls_x509_privkey_verify_seed} (gnutls_x509_privkey_t @var{key}, gnutls_digest_algorithm_t @var{digest}, const void * @var{seed}, size_t @var{seed_size})
@var{key}: should contain a @code{gnutls_x509_privkey_t}  type

@var{digest}: it contains the digest algorithm used for key generation (if applicable)

@var{seed}: the seed of the key to be checked with

@var{seed_size}: holds the size of  @code{seed} 

This function will verify that the given private key was generated from
the provided seed. If  @code{seed} is @code{NULL}  then the seed stored in the  @code{key} 's structure
will be used for verification.

@strong{Returns:} In case of a verification failure @code{GNUTLS_E_PRIVKEY_VERIFICATION_ERROR} 
is returned, and zero or positive code on success.

@strong{Since:} 3.5.0
@end deftypefun

@subheading gnutls_x509_rdn_get
@anchor{gnutls_x509_rdn_get}
@deftypefun {int} {gnutls_x509_rdn_get} (const gnutls_datum_t * @var{idn}, char * @var{buf}, size_t * @var{buf_size})
@var{idn}: should contain a DER encoded RDN sequence

@var{buf}: a pointer to a structure to hold the peer's name

@var{buf_size}: holds the size of  @code{buf} 

This function will return the name of the given RDN sequence.  The
name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as described in
RFC4514.

This function does not output a fully RFC4514 compliant string, if
that is required see @code{gnutls_x509_rdn_get2()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, or
@code{GNUTLS_E_SHORT_MEMORY_BUFFER}  is returned and * @code{buf_size} is
updated if the provided buffer is not long enough, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_rdn_get2
@anchor{gnutls_x509_rdn_get2}
@deftypefun {int} {gnutls_x509_rdn_get2} (const gnutls_datum_t * @var{idn}, gnutls_datum_t * @var{str}, unsigned @var{flags})
@var{idn}: should contain a DER encoded RDN sequence

@var{str}: a datum that will hold the name

@var{flags}: zero of @code{GNUTLS_X509_DN_FLAG_COMPAT} 

This function will return the name of the given RDN sequence.  The
name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as described in
RFC4514.

When the flag @code{GNUTLS_X509_DN_FLAG_COMPAT}  is specified, the output
format will match the format output by previous to 3.5.6 versions of GnuTLS
which was not not fully RFC4514-compliant.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, or
@code{GNUTLS_E_SHORT_MEMORY_BUFFER}  is returned and * @code{buf_size} is
updated if the provided buffer is not long enough, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_rdn_get_by_oid
@anchor{gnutls_x509_rdn_get_by_oid}
@deftypefun {int} {gnutls_x509_rdn_get_by_oid} (const gnutls_datum_t * @var{idn}, const char * @var{oid}, unsigned @var{indx}, unsigned int @var{raw_flag}, void * @var{buf}, size_t * @var{buf_size})
@var{idn}: should contain a DER encoded RDN sequence

@var{oid}: an Object Identifier

@var{indx}: In case multiple same OIDs exist in the RDN indicates which
to send. Use 0 for the first one.

@var{raw_flag}: If non-zero then the raw DER data are returned.

@var{buf}: a pointer to a structure to hold the peer's name

@var{buf_size}: holds the size of  @code{buf} 

This function will return the name of the given Object identifier,
of the RDN sequence.  The name will be encoded using the rules
from RFC4514.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, or
@code{GNUTLS_E_SHORT_MEMORY_BUFFER}  is returned and * @code{buf_size} is
updated if the provided buffer is not long enough, otherwise a
negative error value.
@end deftypefun

@subheading gnutls_x509_rdn_get_oid
@anchor{gnutls_x509_rdn_get_oid}
@deftypefun {int} {gnutls_x509_rdn_get_oid} (const gnutls_datum_t * @var{idn}, unsigned @var{indx}, void * @var{buf}, size_t * @var{buf_size})
@var{idn}: should contain a DER encoded RDN sequence

@var{indx}: Indicates which OID to return. Use 0 for the first one.

@var{buf}: a pointer to a structure to hold the peer's name OID

@var{buf_size}: holds the size of  @code{buf} 

This function will return the specified Object identifier, of the
RDN sequence.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, or
@code{GNUTLS_E_SHORT_MEMORY_BUFFER}  is returned and * @code{buf_size} is
updated if the provided buffer is not long enough, otherwise a
negative error value.

@strong{Since:} 2.4.0
@end deftypefun

@subheading gnutls_x509_spki_deinit
@anchor{gnutls_x509_spki_deinit}
@deftypefun {void} {gnutls_x509_spki_deinit} (gnutls_x509_spki_t @var{spki})
@var{spki}: the SubjectPublicKeyInfo structure

This function will deinitialize a SubjectPublicKeyInfo structure.

@strong{Since:} 3.6.0
@end deftypefun

@subheading gnutls_x509_spki_get_rsa_pss_params
@anchor{gnutls_x509_spki_get_rsa_pss_params}
@deftypefun {int} {gnutls_x509_spki_get_rsa_pss_params} (gnutls_x509_spki_t @var{spki}, gnutls_digest_algorithm_t * @var{dig}, unsigned int * @var{salt_size})
@var{spki}: the SubjectPublicKeyInfo structure

@var{dig}: if non-NULL, it will hold the digest algorithm

@var{salt_size}: if non-NULL, it will hold the salt size

This function will get the public key algorithm parameters
of RSA-PSS type.

@strong{Returns:} zero if the parameters are present or a negative
value on error.

@strong{Since:} 3.6.0
@end deftypefun

@subheading gnutls_x509_spki_init
@anchor{gnutls_x509_spki_init}
@deftypefun {int} {gnutls_x509_spki_init} (gnutls_x509_spki_t * @var{spki})
@var{spki}: A pointer to the type to be initialized

This function will initialize a SubjectPublicKeyInfo structure used
in PKIX. The structure is used to set additional parameters
in the public key information field of a certificate.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.6.0
@end deftypefun

@subheading gnutls_x509_spki_set_rsa_pss_params
@anchor{gnutls_x509_spki_set_rsa_pss_params}
@deftypefun {void} {gnutls_x509_spki_set_rsa_pss_params} (gnutls_x509_spki_t @var{spki}, gnutls_digest_algorithm_t @var{dig}, unsigned int @var{salt_size})
@var{spki}: the SubjectPublicKeyInfo structure

@var{dig}: a digest algorithm of type @code{gnutls_digest_algorithm_t} 

@var{salt_size}: the size of salt string

This function will set the public key parameters for
an RSA-PSS algorithm, in the SubjectPublicKeyInfo structure.

@strong{Since:} 3.6.0
@end deftypefun

@subheading gnutls_x509_tlsfeatures_add
@anchor{gnutls_x509_tlsfeatures_add}
@deftypefun {int} {gnutls_x509_tlsfeatures_add} (gnutls_x509_tlsfeatures_t @var{f}, unsigned int @var{feature})
@var{f}: The TLS features

@var{feature}: The feature to add

This function will append a feature to the X.509 TLS features
extension structure.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error value.

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_tlsfeatures_check_crt
@anchor{gnutls_x509_tlsfeatures_check_crt}
@deftypefun {unsigned} {gnutls_x509_tlsfeatures_check_crt} (gnutls_x509_tlsfeatures_t @var{feat}, gnutls_x509_crt_t @var{cert})
@var{feat}: a set of TLSFeatures

@var{cert}: the certificate to be checked

This function will check the provided certificate against the TLSFeatures
set in  @code{feat} using the RFC7633 p.4.2.2 rules. It will check whether the certificate
contains the features in  @code{feat} or a superset.

@strong{Returns:} non-zero if the provided certificate complies, and zero otherwise.

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_tlsfeatures_deinit
@anchor{gnutls_x509_tlsfeatures_deinit}
@deftypefun {void} {gnutls_x509_tlsfeatures_deinit} (gnutls_x509_tlsfeatures_t @var{f})
@var{f}: The TLS features

This function will deinitialize a X.509 TLS features extension structure

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_tlsfeatures_get
@anchor{gnutls_x509_tlsfeatures_get}
@deftypefun {int} {gnutls_x509_tlsfeatures_get} (gnutls_x509_tlsfeatures_t @var{f}, unsigned @var{idx}, unsigned int * @var{feature})
@var{f}: The TLS features

@var{idx}: The index of the feature to get

@var{feature}: If the function succeeds, the feature will be stored in this variable

This function will get a feature from the X.509 TLS features
extension structure.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error value.

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_tlsfeatures_init
@anchor{gnutls_x509_tlsfeatures_init}
@deftypefun {int} {gnutls_x509_tlsfeatures_init} (gnutls_x509_tlsfeatures_t * @var{f})
@var{f}: The TLS features

This function will initialize a X.509 TLS features extension structure

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error value.

@strong{Since:} 3.5.1
@end deftypefun

@subheading gnutls_x509_trust_list_add_cas
@anchor{gnutls_x509_trust_list_add_cas}
@deftypefun {int} {gnutls_x509_trust_list_add_cas} (gnutls_x509_trust_list_t @var{list}, const gnutls_x509_crt_t * @var{clist}, unsigned @var{clist_size}, unsigned int @var{flags})
@var{list}: The list

@var{clist}: A list of CAs

@var{clist_size}: The length of the CA list

@var{flags}: flags from @code{gnutls_trust_list_flags_t} 

This function will add the given certificate authorities
to the trusted list. The CAs in  @code{clist} must not be deinitialized
during the lifetime of  @code{list} .

If the flag @code{GNUTLS_TL_NO_DUPLICATES}  is specified, then
this function will ensure that no duplicates will be
present in the final trust list.

If the flag @code{GNUTLS_TL_NO_DUPLICATE_KEY}  is specified, then
this function will ensure that no certificates with the
same key are present in the final trust list.

If either @code{GNUTLS_TL_NO_DUPLICATE_KEY}  or @code{GNUTLS_TL_NO_DUPLICATES} 
are given, @code{gnutls_x509_trust_list_deinit()}  must be called with parameter
 @code{all} being 1.

@strong{Returns:} The number of added elements is returned; that includes
duplicate entries.

@strong{Since:} 3.0.0
@end deftypefun

@subheading gnutls_x509_trust_list_add_crls
@anchor{gnutls_x509_trust_list_add_crls}
@deftypefun {int} {gnutls_x509_trust_list_add_crls} (gnutls_x509_trust_list_t @var{list}, const gnutls_x509_crl_t * @var{crl_list}, unsigned @var{crl_size}, unsigned int @var{flags}, unsigned int @var{verification_flags})
@var{list}: The list

@var{crl_list}: A list of CRLs

@var{crl_size}: The length of the CRL list

@var{flags}: flags from @code{gnutls_trust_list_flags_t} 

@var{verification_flags}: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL

This function will add the given certificate revocation lists
to the trusted list. The CRLs in  @code{crl_list} must not be deinitialized
during the lifetime of  @code{list} .

This function must be called after @code{gnutls_x509_trust_list_add_cas()} 
to allow verifying the CRLs for validity. If the flag @code{GNUTLS_TL_NO_DUPLICATES} 
is given, then the final CRL list will not contain duplicate entries.

If the flag @code{GNUTLS_TL_NO_DUPLICATES}  is given, @code{gnutls_x509_trust_list_deinit()}  must be
called with parameter  @code{all} being 1.

If flag @code{GNUTLS_TL_VERIFY_CRL}  is given the CRLs will be verified before being added,
and if verification fails, they will be skipped.

@strong{Returns:} The number of added elements is returned; that includes
duplicate entries.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_trust_list_add_named_crt
@anchor{gnutls_x509_trust_list_add_named_crt}
@deftypefun {int} {gnutls_x509_trust_list_add_named_crt} (gnutls_x509_trust_list_t @var{list}, gnutls_x509_crt_t @var{cert}, const void * @var{name}, size_t @var{name_size}, unsigned int @var{flags})
@var{list}: The list

@var{cert}: A certificate

@var{name}: An identifier for the certificate

@var{name_size}: The size of the identifier

@var{flags}: should be 0.

This function will add the given certificate to the trusted
list and associate it with a name. The certificate will not be
be used for verification with @code{gnutls_x509_trust_list_verify_crt()} 
but with @code{gnutls_x509_trust_list_verify_named_crt()}  or
@code{gnutls_x509_trust_list_verify_crt2()}  - the latter only since
GnuTLS 3.4.0 and if a hostname is provided.

In principle this function can be used to set individual "server"
certificates that are trusted by the user for that specific server
but for no other purposes.

The certificate  @code{cert} must not be deinitialized during the lifetime
of the  @code{list} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.0.0
@end deftypefun

@subheading gnutls_x509_trust_list_add_system_trust
@anchor{gnutls_x509_trust_list_add_system_trust}
@deftypefun {int} {gnutls_x509_trust_list_add_system_trust} (gnutls_x509_trust_list_t @var{list}, unsigned int @var{tl_flags}, unsigned int @var{tl_vflags})
@var{list}: The structure of the list

@var{tl_flags}: GNUTLS_TL_*

@var{tl_vflags}: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL

This function adds the system's default trusted certificate
authorities to the trusted list. Note that on unsupported systems
this function returns @code{GNUTLS_E_UNIMPLEMENTED_FEATURE} .

This function implies the flag @code{GNUTLS_TL_NO_DUPLICATES} .

@strong{Returns:} The number of added elements or a negative error code on error.

@strong{Since:} 3.1
@end deftypefun

@subheading gnutls_x509_trust_list_add_trust_dir
@anchor{gnutls_x509_trust_list_add_trust_dir}
@deftypefun {int} {gnutls_x509_trust_list_add_trust_dir} (gnutls_x509_trust_list_t @var{list}, const char * @var{ca_dir}, const char * @var{crl_dir}, gnutls_x509_crt_fmt_t @var{type}, unsigned int @var{tl_flags}, unsigned int @var{tl_vflags})
@var{list}: The list

@var{ca_dir}: A directory containing the CAs (optional)

@var{crl_dir}: A directory containing a list of CRLs (optional)

@var{type}: The format of the certificates

@var{tl_flags}: flags from @code{gnutls_trust_list_flags_t} 

@var{tl_vflags}: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL

This function will add the given certificate authorities
to the trusted list. Only directories are accepted by
this function.

@strong{Returns:} The number of added elements is returned.

@strong{Since:} 3.3.6
@end deftypefun

@subheading gnutls_x509_trust_list_add_trust_file
@anchor{gnutls_x509_trust_list_add_trust_file}
@deftypefun {int} {gnutls_x509_trust_list_add_trust_file} (gnutls_x509_trust_list_t @var{list}, const char * @var{ca_file}, const char * @var{crl_file}, gnutls_x509_crt_fmt_t @var{type}, unsigned int @var{tl_flags}, unsigned int @var{tl_vflags})
@var{list}: The list

@var{ca_file}: A file containing a list of CAs (optional)

@var{crl_file}: A file containing a list of CRLs (optional)

@var{type}: The format of the certificates

@var{tl_flags}: flags from @code{gnutls_trust_list_flags_t} 

@var{tl_vflags}: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL

This function will add the given certificate authorities
to the trusted list. PKCS @code{11}  URLs are also accepted, instead
of files, by this function. A PKCS @code{11}  URL implies a trust
database (a specially marked module in p11-kit); the URL "pkcs11:"
implies all trust databases in the system. Only a single URL specifying
trust databases can be set; they cannot be stacked with multiple calls.

@strong{Returns:} The number of added elements is returned.

@strong{Since:} 3.1
@end deftypefun

@subheading gnutls_x509_trust_list_add_trust_mem
@anchor{gnutls_x509_trust_list_add_trust_mem}
@deftypefun {int} {gnutls_x509_trust_list_add_trust_mem} (gnutls_x509_trust_list_t @var{list}, const gnutls_datum_t * @var{cas}, const gnutls_datum_t * @var{crls}, gnutls_x509_crt_fmt_t @var{type}, unsigned int @var{tl_flags}, unsigned int @var{tl_vflags})
@var{list}: The list

@var{cas}: A buffer containing a list of CAs (optional)

@var{crls}: A buffer containing a list of CRLs (optional)

@var{type}: The format of the certificates

@var{tl_flags}: flags from @code{gnutls_trust_list_flags_t} 

@var{tl_vflags}: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL

This function will add the given certificate authorities
to the trusted list. 

If this function is used @code{gnutls_x509_trust_list_deinit()}  must be called
with parameter  @code{all} being 1.

@strong{Returns:} The number of added elements is returned.

@strong{Since:} 3.1
@end deftypefun

@subheading gnutls_x509_trust_list_deinit
@anchor{gnutls_x509_trust_list_deinit}
@deftypefun {void} {gnutls_x509_trust_list_deinit} (gnutls_x509_trust_list_t @var{list}, unsigned int @var{all})
@var{list}: The list to be deinitialized

@var{all}: if non-zero it will deinitialize all the certificates and CRLs contained in the structure.

This function will deinitialize a trust list. Note that the
 @code{all} flag should be typically non-zero unless you have specified
your certificates using @code{gnutls_x509_trust_list_add_cas()}  and you
want to prevent them from being deinitialized by this function.

@strong{Since:} 3.0.0
@end deftypefun

@subheading gnutls_x509_trust_list_get_issuer
@anchor{gnutls_x509_trust_list_get_issuer}
@deftypefun {int} {gnutls_x509_trust_list_get_issuer} (gnutls_x509_trust_list_t @var{list}, gnutls_x509_crt_t @var{cert}, gnutls_x509_crt_t * @var{issuer}, unsigned int @var{flags})
@var{list}: The list

@var{cert}: is the certificate to find issuer for

@var{issuer}: Will hold the issuer if any. Should be treated as constant
unless @code{GNUTLS_TL_GET_COPY}  is set in  @code{flags} .

@var{flags}: flags from @code{gnutls_trust_list_flags_t}  (@code{GNUTLS_TL_GET_COPY}  is applicable)

This function will find the issuer of the given certificate.
If the flag @code{GNUTLS_TL_GET_COPY}  is specified a copy of the issuer
will be returned which must be freed using @code{gnutls_x509_crt_deinit()} .
In that case the provided  @code{issuer} must not be initialized.

Note that the flag @code{GNUTLS_TL_GET_COPY}  is required for this function
to work with PKCS@code{11}  trust lists in a thread-safe way.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_trust_list_get_issuer_by_dn
@anchor{gnutls_x509_trust_list_get_issuer_by_dn}
@deftypefun {int} {gnutls_x509_trust_list_get_issuer_by_dn} (gnutls_x509_trust_list_t @var{list}, const gnutls_datum_t * @var{dn}, gnutls_x509_crt_t * @var{issuer}, unsigned int @var{flags})
@var{list}: The list

@var{dn}: is the issuer's DN

@var{issuer}: Will hold the issuer if any. Should be deallocated after use.

@var{flags}: Use zero

This function will find the issuer with the given name, and
return a copy of the issuer, which must be freed using @code{gnutls_x509_crt_deinit()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.4.0
@end deftypefun

@subheading gnutls_x509_trust_list_get_issuer_by_subject_key_id
@anchor{gnutls_x509_trust_list_get_issuer_by_subject_key_id}
@deftypefun {int} {gnutls_x509_trust_list_get_issuer_by_subject_key_id} (gnutls_x509_trust_list_t @var{list}, const gnutls_datum_t * @var{dn}, const gnutls_datum_t * @var{spki}, gnutls_x509_crt_t * @var{issuer}, unsigned int @var{flags})
@var{list}: The list

@var{dn}: is the issuer's DN (may be @code{NULL} )

@var{spki}: is the subject key ID

@var{issuer}: Will hold the issuer if any. Should be deallocated after use.

@var{flags}: Use zero

This function will find the issuer with the given name and subject key ID, and
return a copy of the issuer, which must be freed using @code{gnutls_x509_crt_deinit()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.4.2
@end deftypefun

@subheading gnutls_x509_trust_list_get_ptr
@anchor{gnutls_x509_trust_list_get_ptr}
@deftypefun {void *} {gnutls_x509_trust_list_get_ptr} (gnutls_x509_trust_list_t @var{tlist})
@var{tlist}: is a @code{gnutls_x509_trust_list_t}  type.

Get user pointer for tlist. Useful in callback function
gnutls_x509_trust_list_set_getissuer_function.
This is the pointer set with @code{gnutls_x509_trust_list_set_ptr()} .

@strong{Returns:} the user given pointer from the tlist structure, or
@code{NULL}  if it was never set.

@strong{Since:} 3.7.0
@end deftypefun

@subheading gnutls_x509_trust_list_init
@anchor{gnutls_x509_trust_list_init}
@deftypefun {int} {gnutls_x509_trust_list_init} (gnutls_x509_trust_list_t * @var{list}, unsigned int @var{size})
@var{list}: A pointer to the type to be initialized

@var{size}: The size of the internal hash table. Use (0) for default size.

This function will initialize an X.509 trust list structure.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.0.0
@end deftypefun

@subheading gnutls_x509_trust_list_iter_deinit
@anchor{gnutls_x509_trust_list_iter_deinit}
@deftypefun {void} {gnutls_x509_trust_list_iter_deinit} (gnutls_x509_trust_list_iter_t @var{iter})
@var{iter}: The iterator structure to be deinitialized

This function will deinitialize an iterator structure.

@strong{Since:} 3.4.0
@end deftypefun

@subheading gnutls_x509_trust_list_iter_get_ca
@anchor{gnutls_x509_trust_list_iter_get_ca}
@deftypefun {int} {gnutls_x509_trust_list_iter_get_ca} (gnutls_x509_trust_list_t @var{list}, gnutls_x509_trust_list_iter_t * @var{iter}, gnutls_x509_crt_t * @var{crt})
@var{list}: The list

@var{iter}: A pointer to an iterator (initially the iterator should be @code{NULL} )

@var{crt}: where the certificate will be copied

This function obtains a certificate in the trust list and advances the
iterator to the next certificate. The certificate returned in  @code{crt} must be
deallocated with @code{gnutls_x509_crt_deinit()} .

When past the last element is accessed @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
is returned and the iterator is reset.

The iterator is deinitialized and reset to @code{NULL}  automatically by this
function after iterating through all elements until
@code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE}  is returned. If the iteration is
aborted early, it must be manually deinitialized using
@code{gnutls_x509_trust_list_iter_deinit()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.4.0
@end deftypefun

@subheading gnutls_x509_trust_list_remove_cas
@anchor{gnutls_x509_trust_list_remove_cas}
@deftypefun {int} {gnutls_x509_trust_list_remove_cas} (gnutls_x509_trust_list_t @var{list}, const gnutls_x509_crt_t * @var{clist}, unsigned @var{clist_size})
@var{list}: The list

@var{clist}: A list of CAs

@var{clist_size}: The length of the CA list

This function will remove the given certificate authorities
from the trusted list.

Note that this function can accept certificates and authorities
not yet known. In that case they will be kept in a separate
black list that will be used during certificate verification.
Unlike @code{gnutls_x509_trust_list_add_cas()}  there is no deinitialization
restriction for  certificate list provided in this function.

@strong{Returns:} The number of removed elements is returned.

@strong{Since:} 3.1.10
@end deftypefun

@subheading gnutls_x509_trust_list_remove_trust_file
@anchor{gnutls_x509_trust_list_remove_trust_file}
@deftypefun {int} {gnutls_x509_trust_list_remove_trust_file} (gnutls_x509_trust_list_t @var{list}, const char * @var{ca_file}, gnutls_x509_crt_fmt_t @var{type})
@var{list}: The list

@var{ca_file}: A file containing a list of CAs

@var{type}: The format of the certificates

This function will remove the given certificate authorities
from the trusted list, and add them into a black list when needed. 
PKCS 11 URLs are also accepted, instead
of files, by this function.

See also @code{gnutls_x509_trust_list_remove_cas()} .

@strong{Returns:} The number of added elements is returned.

@strong{Since:} 3.1.10
@end deftypefun

@subheading gnutls_x509_trust_list_remove_trust_mem
@anchor{gnutls_x509_trust_list_remove_trust_mem}
@deftypefun {int} {gnutls_x509_trust_list_remove_trust_mem} (gnutls_x509_trust_list_t @var{list}, const gnutls_datum_t * @var{cas}, gnutls_x509_crt_fmt_t @var{type})
@var{list}: The list

@var{cas}: A buffer containing a list of CAs (optional)

@var{type}: The format of the certificates

This function will remove the provided certificate authorities
from the trusted list, and add them into a black list when needed. 

See also @code{gnutls_x509_trust_list_remove_cas()} .

@strong{Returns:} The number of removed elements is returned.

@strong{Since:} 3.1.10
@end deftypefun

@subheading gnutls_x509_trust_list_set_getissuer_function
@anchor{gnutls_x509_trust_list_set_getissuer_function}
@deftypefun {void} {gnutls_x509_trust_list_set_getissuer_function} (gnutls_x509_trust_list_t @var{tlist}, gnutls_x509_trust_list_getissuer_function * @var{func})
@var{tlist}: is a @code{gnutls_x509_trust_list_t}  type.

@var{func}: is the callback function

This function sets a callback to be called when the peer's certificate
chain is incomplete due a missing intermediate certificate. The callback
may provide the missing certificate for use during verification.

The callback's function prototype is defined in gnutls/x509.h as:

int (*callback)(gnutls_x509_trust_list_t list,
const gnutls_x509_crt_t cert,
gnutls_x509_crt_t **issuers,
unsigned int *issuers_size);

If the callback function is provided then gnutls will call it during the
certificate verification procedure. The callback may wish to use
@code{gnutls_x509_crt_get_authority_info_access()}  to get a URI from which
to attempt to download the missing issuer certificate, if available.

On a successful call, the callback shall allocate the 'issuers' array with
@code{gnutls_x509_crt_list_import2()} . The ownership of both the array and the
elements is transferred to the caller and thus the application does not need
to maintain the memory after the call.

The callback function should return 0 if the missing issuer certificate
for 'crt' was properly populated and added to the 'issuers', or non-zero
to continue the certificate list verification but with issuer as @code{NULL} .

@strong{Since:} 3.7.0
@end deftypefun

@subheading gnutls_x509_trust_list_set_ptr
@anchor{gnutls_x509_trust_list_set_ptr}
@deftypefun {void} {gnutls_x509_trust_list_set_ptr} (gnutls_x509_trust_list_t @var{tlist}, void * @var{ptr})
@var{tlist}: is a @code{gnutls_x509_trust_list_t}  type.

@var{ptr}: is the user pointer

This function will set (associate) the user given pointer  @code{ptr} to
the tlist structure. This pointer can be accessed with
@code{gnutls_x509_trust_list_get_ptr()} . Useful in the callback function
gnutls_x509_trust_list_set_getissuer_function.

@strong{Since:} 3.7.0
@end deftypefun

@subheading gnutls_x509_trust_list_verify_crt
@anchor{gnutls_x509_trust_list_verify_crt}
@deftypefun {int} {gnutls_x509_trust_list_verify_crt} (gnutls_x509_trust_list_t @var{list}, gnutls_x509_crt_t * @var{cert_list}, unsigned int @var{cert_list_size}, unsigned int @var{flags}, unsigned int * @var{voutput}, gnutls_verify_output_function @var{func})
@var{list}: The list

@var{cert_list}: is the certificate list to be verified

@var{cert_list_size}: is the certificate list size

@var{flags}: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

@var{voutput}: will hold the certificate verification output.

@var{func}: If non-null will be called on each chain element verification with the output.

This function will try to verify the given certificate and return
its status. The  @code{voutput} parameter will hold an OR'ed sequence of
@code{gnutls_certificate_status_t}  flags.

The details of the verification are the same as in @code{gnutls_x509_trust_list_verify_crt2()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.0
@end deftypefun

@subheading gnutls_x509_trust_list_verify_crt2
@anchor{gnutls_x509_trust_list_verify_crt2}
@deftypefun {int} {gnutls_x509_trust_list_verify_crt2} (gnutls_x509_trust_list_t @var{list}, gnutls_x509_crt_t * @var{cert_list}, unsigned int @var{cert_list_size}, gnutls_typed_vdata_st * @var{data}, unsigned int @var{elements}, unsigned int @var{flags}, unsigned int * @var{voutput}, gnutls_verify_output_function @var{func})
@var{list}: The list

@var{cert_list}: is the certificate list to be verified

@var{cert_list_size}: is the certificate list size

@var{data}: an array of typed data

@var{elements}: the number of data elements

@var{flags}: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

@var{voutput}: will hold the certificate verification output.

@var{func}: If non-null will be called on each chain element verification with the output.

This function will attempt to verify the given certificate chain and return
its status. The  @code{voutput} parameter will hold an OR'ed sequence of
@code{gnutls_certificate_status_t}  flags.

When a certificate chain of  @code{cert_list_size} with more than one certificates is
provided, the verification status will apply to the first certificate in the chain
that failed verification. The verification process starts from the end of the chain
(from CA to end certificate). The first certificate in the chain must be the end-certificate
while the rest of the members may be sorted or not.

Additionally a certificate verification profile can be specified
from the ones in @code{gnutls_certificate_verification_profiles_t}  by
ORing the result of @code{GNUTLS_PROFILE_TO_VFLAGS()}  to the verification
flags.

Additional verification parameters are possible via the  @code{data} types; the
acceptable types are @code{GNUTLS_DT_DNS_HOSTNAME} , @code{GNUTLS_DT_IP_ADDRESS}  and @code{GNUTLS_DT_KEY_PURPOSE_OID} .
The former accepts as data a null-terminated hostname, and the latter a null-terminated
object identifier (e.g., @code{GNUTLS_KP_TLS_WWW_SERVER} ).
If a DNS hostname is provided then this function will compare
the hostname in the end certificate against the given. If names do not match the
@code{GNUTLS_CERT_UNEXPECTED_OWNER}  status flag will be set. In addition it
will consider certificates provided with @code{gnutls_x509_trust_list_add_named_crt()} .

If a key purpose OID is provided and the end-certificate contains the extended key
usage PKIX extension, it will be required to match the provided OID
or be marked for any purpose, otherwise verification will fail with 
@code{GNUTLS_CERT_PURPOSE_MISMATCH}  status.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value. Note that verification failure will not result to an
error code, only  @code{voutput} will be updated.

@strong{Since:} 3.3.8
@end deftypefun

@subheading gnutls_x509_trust_list_verify_named_crt
@anchor{gnutls_x509_trust_list_verify_named_crt}
@deftypefun {int} {gnutls_x509_trust_list_verify_named_crt} (gnutls_x509_trust_list_t @var{list}, gnutls_x509_crt_t @var{cert}, const void * @var{name}, size_t @var{name_size}, unsigned int @var{flags}, unsigned int * @var{voutput}, gnutls_verify_output_function @var{func})
@var{list}: The list

@var{cert}: is the certificate to be verified

@var{name}: is the certificate's name

@var{name_size}: is the certificate's name size

@var{flags}: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.

@var{voutput}: will hold the certificate verification output.

@var{func}: If non-null will be called on each chain element verification with the output.

This function will try to find a certificate that is associated with the provided
name --see @code{gnutls_x509_trust_list_add_named_crt()} . If a match is found the
certificate is considered valid. In addition to that this function will also 
check CRLs. The  @code{voutput} parameter will hold an OR'ed sequence of 
@code{gnutls_certificate_status_t}  flags.

Additionally a certificate verification profile can be specified
from the ones in @code{gnutls_certificate_verification_profiles_t}  by
ORing the result of @code{GNUTLS_PROFILE_TO_VFLAGS()}  to the verification
flags.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.

@strong{Since:} 3.0.0
@end deftypefun