=pod =head1 NAME EVP_KDF-TLS1_PRF - The TLS1 PRF EVP_KDF implementation =head1 DESCRIPTION Support for computing the B PRF through the B API. The EVP_KDF-TLS1_PRF algorithm implements the PRF used by TLS versions up to and including TLS 1.2. =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 B ("properties") =item B ("digest") These parameters work as described in L. The C 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 and B as used in TLS 1.0 and 1.1. =item B ("secret") This parameter sets the secret value of the TLS PRF. Any existing secret value is replaced. =item B ("seed") 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 =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 C 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_set_params(kctx, params) <= 0) { error("EVP_KDF_set_params"); } if (EVP_KDF_derive(kctx, out, sizeof(out)) <= 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, L, L, L, L, L =head1 COPYRIGHT Copyright 2018-2019 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. =cut