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Diffstat (limited to 'upstream/archlinux/man7/EVP_KDF-HKDF.7ssl')
| -rw-r--r-- | upstream/archlinux/man7/EVP_KDF-HKDF.7ssl | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/upstream/archlinux/man7/EVP_KDF-HKDF.7ssl b/upstream/archlinux/man7/EVP_KDF-HKDF.7ssl new file mode 100644 index 00000000..f2ff8db4 --- /dev/null +++ b/upstream/archlinux/man7/EVP_KDF-HKDF.7ssl @@ -0,0 +1,200 @@ +.\" -*- mode: troff; coding: utf-8 -*- +.\" Automatically generated by Pod::Man 5.01 (Pod::Simple 3.43) +.\" +.\" Standard preamble: +.\" ======================================================================== +.de Sp \" Vertical space (when we can't use .PP) +.if t .sp .5v +.if n .sp +.. +.de Vb \" Begin verbatim text +.ft CW +.nf +.ne \\$1 +.. +.de Ve \" End verbatim text +.ft R +.fi +.. +.\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>. +.ie n \{\ +. ds C` "" +. ds C' "" +'br\} +.el\{\ +. ds C` +. ds C' +'br\} +.\" +.\" Escape single quotes in literal strings from groff's Unicode transform. +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" +.\" If the F register is >0, we'll generate index entries on stderr for +.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index +.\" entries marked with X<> in POD. Of course, you'll have to process the +.\" output yourself in some meaningful fashion. +.\" +.\" Avoid warning from groff about undefined register 'F'. +.de IX +.. +.nr rF 0 +.if \n(.g .if rF .nr rF 1 +.if (\n(rF:(\n(.g==0)) \{\ +. if \nF \{\ +. de IX +. tm Index:\\$1\t\\n%\t"\\$2" +.. +. if !\nF==2 \{\ +. nr % 0 +. nr F 2 +. \} +. \} +.\} +.rr rF +.\" ======================================================================== +.\" +.IX Title "EVP_KDF-HKDF 7ssl" +.TH EVP_KDF-HKDF 7ssl 2024-01-30 3.2.1 OpenSSL +.\" For nroff, turn off justification. Always turn off hyphenation; it makes +.\" way too many mistakes in technical documents. +.if n .ad l +.nh +.SH NAME +EVP_KDF\-HKDF \- The HKDF EVP_KDF implementation +.SH DESCRIPTION +.IX Header "DESCRIPTION" +Support for computing the \fBHKDF\fR KDF through the \fBEVP_KDF\fR API. +.PP +The EVP_KDF\-HKDF algorithm implements the HKDF key derivation function. +HKDF follows the "extract-then-expand" paradigm, where the KDF logically +consists of two modules. The first stage takes the input keying material +and "extracts" from it a fixed-length pseudorandom key K. The second stage +"expands" the key K into several additional pseudorandom keys (the output +of the KDF). +.SS Identity +.IX Subsection "Identity" +"HKDF" is the name for this implementation; it +can be used with the \fBEVP_KDF_fetch()\fR function. +.SS "Supported parameters" +.IX Subsection "Supported parameters" +The supported parameters are: +.IP """properties"" (\fBOSSL_KDF_PARAM_PROPERTIES\fR) <UTF8 string>" 4 +.IX Item """properties"" (OSSL_KDF_PARAM_PROPERTIES) <UTF8 string>" +.PD 0 +.IP """digest"" (\fBOSSL_KDF_PARAM_DIGEST\fR) <UTF8 string>" 4 +.IX Item """digest"" (OSSL_KDF_PARAM_DIGEST) <UTF8 string>" +.IP """key"" (\fBOSSL_KDF_PARAM_KEY\fR) <octet string>" 4 +.IX Item """key"" (OSSL_KDF_PARAM_KEY) <octet string>" +.IP """salt"" (\fBOSSL_KDF_PARAM_SALT\fR) <octet string>" 4 +.IX Item """salt"" (OSSL_KDF_PARAM_SALT) <octet string>" +.PD +These parameters work as described in "PARAMETERS" in \fBEVP_KDF\fR\|(3). +.IP """info"" (\fBOSSL_KDF_PARAM_INFO\fR) <octet string>" 4 +.IX Item """info"" (OSSL_KDF_PARAM_INFO) <octet string>" +This parameter sets the info value. +The length of the context info buffer cannot exceed 1024 bytes; +this should be more than enough for any normal use of HKDF. +.IP """mode"" (\fBOSSL_KDF_PARAM_MODE\fR) <UTF8 string> or <integer>" 4 +.IX Item """mode"" (OSSL_KDF_PARAM_MODE) <UTF8 string> or <integer>" +This parameter sets the mode for the HKDF operation. +There are three modes that are currently defined: +.RS 4 +.IP """EXTRACT_AND_EXPAND"" or \fBEVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND\fR" 4 +.IX Item """EXTRACT_AND_EXPAND"" or EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND" +This is the default mode. Calling \fBEVP_KDF_derive\fR\|(3) on an EVP_KDF_CTX set +up for HKDF will perform an extract followed by an expand operation in one go. +The derived key returned will be the result after the expand operation. The +intermediate fixed-length pseudorandom key K is not returned. +.Sp +In this mode the digest, key, salt and info values must be set before a key is +derived otherwise an error will occur. +.IP """EXTRACT_ONLY"" or \fBEVP_KDF_HKDF_MODE_EXTRACT_ONLY\fR" 4 +.IX Item """EXTRACT_ONLY"" or EVP_KDF_HKDF_MODE_EXTRACT_ONLY" +In this mode calling \fBEVP_KDF_derive\fR\|(3) will just perform the extract +operation. The value returned will be the intermediate fixed-length pseudorandom +key K. The \fIkeylen\fR parameter must match the size of K, which can be looked +up by calling \fBEVP_KDF_CTX_get_kdf_size()\fR after setting the mode and digest. +.Sp +The digest, key and salt values must be set before a key is derived otherwise +an error will occur. +.IP """EXPAND_ONLY"" or \fBEVP_KDF_HKDF_MODE_EXPAND_ONLY\fR" 4 +.IX Item """EXPAND_ONLY"" or EVP_KDF_HKDF_MODE_EXPAND_ONLY" +In this mode calling \fBEVP_KDF_derive\fR\|(3) will just perform the expand +operation. The input key should be set to the intermediate fixed-length +pseudorandom key K returned from a previous extract operation. +.Sp +The digest, key and info values must be set before a key is derived otherwise +an error will occur. +.RE +.RS 4 +.RE +.SH NOTES +.IX Header "NOTES" +A context for HKDF can be obtained by calling: +.PP +.Vb 2 +\& EVP_KDF *kdf = EVP_KDF_fetch(NULL, "HKDF", NULL); +\& EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf); +.Ve +.PP +The output length of an HKDF expand operation is specified via the \fIkeylen\fR +parameter to the \fBEVP_KDF_derive\fR\|(3) function. When using +EVP_KDF_HKDF_MODE_EXTRACT_ONLY the \fIkeylen\fR parameter must equal the size of +the intermediate fixed-length pseudorandom key otherwise an error will occur. +For that mode, the fixed output size can be looked up by calling \fBEVP_KDF_CTX_get_kdf_size()\fR +after setting the mode and digest on the \fBEVP_KDF_CTX\fR. +.SH EXAMPLES +.IX Header "EXAMPLES" +This example derives 10 bytes using SHA\-256 with the secret key "secret", +salt value "salt" and info value "label": +.PP +.Vb 4 +\& EVP_KDF *kdf; +\& EVP_KDF_CTX *kctx; +\& unsigned char out[10]; +\& OSSL_PARAM params[5], *p = params; +\& +\& kdf = EVP_KDF_fetch(NULL, "HKDF", NULL); +\& kctx = EVP_KDF_CTX_new(kdf); +\& EVP_KDF_free(kdf); +\& +\& *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST, +\& SN_sha256, strlen(SN_sha256)); +\& *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY, +\& "secret", (size_t)6); +\& *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO, +\& "label", (size_t)5); +\& *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT, +\& "salt", (size_t)4); +\& *p = OSSL_PARAM_construct_end(); +\& if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0) { +\& error("EVP_KDF_derive"); +\& } +\& +\& EVP_KDF_CTX_free(kctx); +.Ve +.SH "CONFORMING TO" +.IX Header "CONFORMING TO" +RFC 5869 +.SH "SEE ALSO" +.IX Header "SEE ALSO" +\&\fBEVP_KDF\fR\|(3), +\&\fBEVP_KDF_CTX_new\fR\|(3), +\&\fBEVP_KDF_CTX_free\fR\|(3), +\&\fBEVP_KDF_CTX_get_kdf_size\fR\|(3), +\&\fBEVP_KDF_CTX_set_params\fR\|(3), +\&\fBEVP_KDF_derive\fR\|(3), +"PARAMETERS" in \fBEVP_KDF\fR\|(3), +\&\fBEVP_KDF\-TLS13_KDF\fR\|(7) +.SH HISTORY +.IX Header "HISTORY" +This functionality was added in OpenSSL 3.0. +.SH COPYRIGHT +.IX Header "COPYRIGHT" +Copyright 2016\-2021 The OpenSSL Project Authors. All Rights Reserved. +.PP +Licensed under the Apache License 2.0 (the "License"). You may not use +this file except in compliance with the License. You can obtain a copy +in the file LICENSE in the source distribution or at +<https://www.openssl.org/source/license.html>. |