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/* Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*!
* \file
*
* \addtogroup key
*
* \brief DNSSEC public and private key manipulation.
*
* The dnssec_key_t is an abstraction for a DNSSEC key pair. If the key
* key is initialized with a public key data only, it can be used only for
* signature verification. In order to use the key for signing, private key
* has to be loaded. If only a private key is loaded into the structure,
* the public key is automatically constructed.
*
* The module interface provides various functions to retrieve information
* about the key. But the key is mostly used by other modules of the library.
*
* The following example shows construction of a key from DNSKEY RDATA:
*
* ~~~~~ {.c}
*
* dnssec_binary_t rdata = // ...;
*
* int result;
* dnssec_key_t *key = NULL;
*
* // create new DNSSEC key
* result = dnssec_key_new(&key);
* if (result != DNSSEC_EOK) {
* return result;
* }
*
* // load the DNSKEY RDATA
* result = dnssec_key_set_rdata(key, &rdata);
* if (result != DNSSEC_EOK) {
* dnssec_key_free(key);
* return result;
* }
*
* // print key tag
* printf("key %s\n", dnssec_key_get_keytag(key));
*
* // make sure what we can do with the key
* assert(dnssec_key_can_verify(key) == true);
* assert(dnssec_key_can_sign(key) == false);
*
* // ...
*
* // cleanup
* dnssec_key_free(key);
*
* ~~~~~
*
* @{
*/
#pragma once
#include <stdbool.h>
#include <stdint.h>
#include <libdnssec/binary.h>
/*!
* DNSKEY algorithm numbers.
*
* \see https://www.iana.org/assignments/dns-sec-alg-numbers/dns-sec-alg-numbers.xhtml
*/
typedef enum dnssec_key_algorithm {
DNSSEC_KEY_ALGORITHM_INVALID = 0,
DNSSEC_KEY_ALGORITHM_RSA_SHA1 = 5,
DNSSEC_KEY_ALGORITHM_RSA_SHA1_NSEC3 = 7,
DNSSEC_KEY_ALGORITHM_RSA_SHA256 = 8,
DNSSEC_KEY_ALGORITHM_RSA_SHA512 = 10,
DNSSEC_KEY_ALGORITHM_ECDSA_P256_SHA256 = 13,
DNSSEC_KEY_ALGORITHM_ECDSA_P384_SHA384 = 14,
DNSSEC_KEY_ALGORITHM_ED25519 = 15,
DNSSEC_KEY_ALGORITHM_ED448 = 16,
} dnssec_key_algorithm_t;
struct dnssec_key;
/*!
* DNSSEC key.
*/
typedef struct dnssec_key dnssec_key_t;
/*!
* Check whether a DNSKEY algorithm is supported.
*
* @note: less secure algorithms may go unsupported on purpose.
*/
bool dnssec_algorithm_key_support(dnssec_key_algorithm_t algo);
/*!
* Allocate new DNSSEC key.
*
* The protocol field of the key is set to 3 (DNSSEC).
* The flags field of the key is set to 256 (zone key, no SEP).
*
* \return Error code, DNSSEC_EOK if successful.
*/
int dnssec_key_new(dnssec_key_t **key);
/*!
* Clear the DNSSEC key.
*
* Has the same effect as calling \ref dnssec_key_free and \ref dnssec_key_new.
*/
void dnssec_key_clear(dnssec_key_t *key);
/*!
* Free the key allocated by \ref dnssec_key_new.
*/
void dnssec_key_free(dnssec_key_t *key);
/*!
* Create a copy of a DNSSEC key.
*
* Only a public part of the key is copied.
*/
dnssec_key_t *dnssec_key_dup(const dnssec_key_t *key);
/*!
* Get the key tag of the DNSSEC key.
*/
uint16_t dnssec_key_get_keytag(const dnssec_key_t *key);
/*!
* Get the domain name of the DNSSEC key.
*/
const uint8_t *dnssec_key_get_dname(const dnssec_key_t *key);
/*!
* Set the domain name of the DNSSEC key.
*/
int dnssec_key_set_dname(dnssec_key_t *key, const uint8_t *dname);
/*!
* Get the flags field of the DNSSEC key.
*/
uint16_t dnssec_key_get_flags(const dnssec_key_t *key);
/*!
* Set the flags field of the DNSSEC key.
*/
int dnssec_key_set_flags(dnssec_key_t *key, uint16_t flags);
/*!
* Get the protocol field of the DNSSEC key.
*/
uint8_t dnssec_key_get_protocol(const dnssec_key_t *key);
/*!
* Get the protocol field of the DNSSEC key.
*/
int dnssec_key_set_protocol(dnssec_key_t *key, uint8_t protocol);
/*!
* Get the algorithm field of the DNSSEC key.
*/
uint8_t dnssec_key_get_algorithm(const dnssec_key_t *key);
/*!
* Set the algorithm field of the DNSSEC key.
*
* The function will fail if the algorithm is incompatible with the
* loaded key. This means, that the function can be used to set the initial
* algorithm and later, only the hashing algorithm can be changed.
*/
int dnssec_key_set_algorithm(dnssec_key_t *key, uint8_t algorithm);
/*!
* Get the public key field of the DNSSEC key.
*
* The returned content must not be modified by the caller. A reference
* to internally allocated structure is returned.
*/
int dnssec_key_get_pubkey(const dnssec_key_t *key, dnssec_binary_t *pubkey);
/*!
* Set the public key field of the DNSSEC key.
*
* A valid algorithm has to be set prior to calling this function.
*
* The function will fail if the key is already loaded in the structure.
*/
int dnssec_key_set_pubkey(dnssec_key_t *key, const dnssec_binary_t *pubkey);
/*!
* Get the bit size of the cryptographic key used with the DNSSEC key.
*/
unsigned dnssec_key_get_size(const dnssec_key_t *key);
/*!
* \brief Compute key ID from public key.
*
* \param key Key structure holding the public key.
* \param id Output: key ID in hex.
*
* \return DNSSEC_E*
*/
int dnssec_key_get_keyid(const dnssec_key_t *key, char **id);
/*!
* Get the RDATA of the DNSSEC key.
*
* The returned content must not be modified by the caller. A reference
* to internally allocated structure is returned.
*/
int dnssec_key_get_rdata(const dnssec_key_t *key, dnssec_binary_t *rdata);
/*!
* Set the RDATA of the DNSSEC key.
*
* Calling this function has the same effect as setting the individual
* fields of the key step-by-step. The same limitations apply.
*/
int dnssec_key_set_rdata(dnssec_key_t *key, const dnssec_binary_t *rdata);
/*!
* Load PKCS #8 private key in the unencrypted PEM format.
*
* At least an algorithm must be set prior to calling this function.
*
* The function will create public key, unless it was already set (using
* \ref dnssec_key_set_pubkey or \ref dnssec_key_set_rdata). If the public key
* was set, the function will prevent loading of non-matching private key.
*/
int dnssec_key_load_pkcs8(dnssec_key_t *key, const dnssec_binary_t *pem);
/*!
* Check if the key can be used for signing.
*/
bool dnssec_key_can_sign(const dnssec_key_t *key);
/*!
* Check if the key can be used for verification.
*/
bool dnssec_key_can_verify(const dnssec_key_t *key);
/*!
* Get private key size range for a DNSSEC algorithm.
*
* \param[in] algorithm DNSKEY algorithm.
* \param[out] min Minimal size of the private key (can be NULL).
* \param[out] max Maximal size of the private key (can be NULL).
*
* \return DNSSEC_EOK for valid parameters.
*/
int dnssec_algorithm_key_size_range(dnssec_key_algorithm_t algorithm,
unsigned *min, unsigned *max);
/*!
* Check if the private key size matches DNSKEY constraints.
*
* \param algorithm DNSKEY algorithm.
* \param bits Private key size.
*
* \return DNSKEY algorithm matches the key size constraints.
*/
bool dnssec_algorithm_key_size_check(dnssec_key_algorithm_t algorithm,
unsigned bits);
/*!
* Get default key size for given algorithm.
*
* The default size is balance between security and response lengths with
* respect to use in DNS.
*/
int dnssec_algorithm_key_size_default(dnssec_key_algorithm_t algorithm);
/*!
* DS algorithm numbers.
*
* \see https://www.iana.org/assignments/ds-rr-types/ds-rr-types.xhtml
*/
typedef enum dnssec_key_digest {
DNSSEC_KEY_DIGEST_INVALID = 0,
DNSSEC_KEY_DIGEST_SHA1 = 1,
DNSSEC_KEY_DIGEST_SHA256 = 2,
DNSSEC_KEY_DIGEST_SHA384 = 4,
} dnssec_key_digest_t;
/*!
* Check whether a DS algorithm is supported.
*
* @note: less secure algorithms may go unsupported on purpose.
*/
bool dnssec_algorithm_digest_support(dnssec_key_digest_t algo);
/*!
* Create DS (Delgation Signer) RDATA from DNSSEC key.
*
* \param[in] key DNSSEC key.
* \param[in] digest Digest algorithm to be used.
* \param[out] rdata Allocated DS RDATA.
*
* \return Error code, DNSSEC_EOK if successful.
*/
int dnssec_key_create_ds(const dnssec_key_t *key, dnssec_key_digest_t digest,
dnssec_binary_t *rdata);
/** @} */
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