mirror of
https://github.com/openssl/openssl.git
synced 2025-04-06 20:20:50 +08:00
6f08353a4b
Explicitely document what semantic meaning do various EVP_KDF algorithms produce. PBKDF2 produces cryptographic keys that are subject to cryptographic security measures, for example as defined in NIST SP 800-132. All other algorithms produce keying material, not subject to explicit output length checks in any known standards. Reviewed-by: Paul Dale <ppzgs1@gmail.com> Reviewed-by: Tomas Mraz <tomas@openssl.org> (Merged from https://github.com/openssl/openssl/pull/25610)
159 lines
4.6 KiB
Plaintext
159 lines
4.6 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
EVP_KDF-TLS1_PRF - The TLS1 PRF EVP_KDF implementation
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
Support for computing the B<TLS1> PRF through the B<EVP_KDF> API.
|
|
|
|
The EVP_KDF-TLS1_PRF algorithm implements the PRF used by TLS versions up to
|
|
and including TLS 1.2.
|
|
|
|
The output is considered to be keying material.
|
|
|
|
=head2 Identity
|
|
|
|
"TLS1-PRF" is the name for this implementation; it
|
|
can be used with the EVP_KDF_fetch() function.
|
|
|
|
=head2 Supported parameters
|
|
|
|
The supported parameters are:
|
|
|
|
=over 4
|
|
|
|
=item "properties" (B<OSSL_KDF_PARAM_PROPERTIES>) <UTF8 string>
|
|
|
|
=item "digest" (B<OSSL_KDF_PARAM_DIGEST>) <UTF8 string>
|
|
|
|
These parameters work as described in L<EVP_KDF(3)/PARAMETERS>.
|
|
|
|
The B<OSSL_KDF_PARAM_DIGEST> parameter is used to set the message digest
|
|
associated with the TLS PRF.
|
|
EVP_md5_sha1() is treated as a special case which uses the
|
|
PRF algorithm using both B<MD5> and B<SHA1> as used in TLS 1.0 and 1.1.
|
|
|
|
=item "secret" (B<OSSL_KDF_PARAM_SECRET>) <octet string>
|
|
|
|
This parameter sets the secret value of the TLS PRF.
|
|
Any existing secret value is replaced.
|
|
|
|
=item "seed" (B<OSSL_KDF_PARAM_SEED>) <octet string>
|
|
|
|
This parameter sets the context seed.
|
|
The length of the context seed cannot exceed 1024 bytes;
|
|
this should be more than enough for any normal use of the TLS PRF.
|
|
|
|
=back
|
|
|
|
The OpenSSL FIPS provider also supports the following parameters:
|
|
|
|
=over 4
|
|
|
|
=item "fips-indicator" (B<OSSL_KDF_PARAM_FIPS_APPROVED_INDICATOR>) <integer>
|
|
|
|
A getter that returns 1 if the operation is FIPS approved, or 0 otherwise.
|
|
This may be used after calling EVP_KDF_derive. It returns 0 if any "***-check"
|
|
related parameter is set to 0 and the check fails.
|
|
|
|
=item "ems_check" (B<OSSL_KDF_PARAM_FIPS_EMS_CHECK>) <integer>
|
|
|
|
The default value of 1 causes an error during EVP_KDF_derive() if
|
|
"master secret" is used instead of "extended master secret" Setting this to zero
|
|
will ignore the error and set the approved "fips-indicator" to 0.
|
|
This option breaks FIPS compliance if it causes the approved "fips-indicator"
|
|
to return 0.
|
|
|
|
=item "digest-check" (B<OSSL_KDF_PARAM_FIPS_DIGEST_CHECK>) <integer>
|
|
|
|
The default value of 1 causes an error during EVP_KDF_CTX_set_params() if
|
|
used digest is not approved.
|
|
Setting this to zero will ignore the error and set the approved
|
|
"fips-indicator" to 0.
|
|
This option breaks FIPS compliance if it causes the approved "fips-indicator"
|
|
to return 0.
|
|
|
|
According to SP 800-135r1, the following are approved digest algorithms:
|
|
SHA2-256, SHA2-384, SHA2-512.
|
|
|
|
=item "key-check" (B<OSSL_KDF_PARAM_FIPS_KEY_CHECK>) <integer>
|
|
|
|
The default value of 1 causes an error during EVP_KDF_CTX_set_params() if the
|
|
length of used key-derivation key (B<OSSL_KDF_PARAM_SECRET>) is shorter than 112
|
|
bits.
|
|
Setting this to zero will ignore the error and set the approved
|
|
"fips-indicator" to 0.
|
|
This option breaks FIPS compliance if it causes the approved "fips-indicator"
|
|
to return 0.
|
|
|
|
=back
|
|
|
|
=head1 NOTES
|
|
|
|
A context for the TLS PRF can be obtained by calling:
|
|
|
|
EVP_KDF *kdf = EVP_KDF_fetch(NULL, "TLS1-PRF", NULL);
|
|
EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);
|
|
|
|
The digest, secret value and seed must be set before a key is derived otherwise
|
|
an error will occur.
|
|
|
|
The output length of the PRF is specified by the I<keylen> parameter to the
|
|
EVP_KDF_derive() function.
|
|
|
|
=head1 EXAMPLES
|
|
|
|
This example derives 10 bytes using SHA-256 with the secret key "secret"
|
|
and seed value "seed":
|
|
|
|
EVP_KDF *kdf;
|
|
EVP_KDF_CTX *kctx;
|
|
unsigned char out[10];
|
|
OSSL_PARAM params[4], *p = params;
|
|
|
|
kdf = EVP_KDF_fetch(NULL, "TLS1-PRF", 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_SECRET,
|
|
"secret", (size_t)6);
|
|
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SEED,
|
|
"seed", (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);
|
|
|
|
=head1 CONFORMING TO
|
|
|
|
RFC 2246, RFC 5246 and NIST SP 800-135 r1
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<EVP_KDF(3)>,
|
|
L<EVP_KDF_CTX_new(3)>,
|
|
L<EVP_KDF_CTX_free(3)>,
|
|
L<EVP_KDF_CTX_set_params(3)>,
|
|
L<EVP_KDF_derive(3)>,
|
|
L<EVP_KDF(3)/PARAMETERS>
|
|
|
|
=head1 HISTORY
|
|
|
|
This functionality was added in OpenSSL 3.0.
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2018-2024 The OpenSSL Project Authors. All Rights Reserved.
|
|
|
|
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
|
|
L<https://www.openssl.org/source/license.html>.
|
|
|
|
=cut
|