NAME<\/a> EVP_KDF_TLS1_PRF \u2212 The TLS1 PRF EVP_KDF implementation<\/p>\n Support for computing the TLS1<\/small><\/b> PRF<\/small> through the EVP_KDF<\/small><\/b> API.<\/small><\/p>\n The EVP_KDF_TLS1_PRF<\/small> algorithm implements the PRF<\/small> used by TLS<\/small> versions up to and including TLS 1.2.<\/small><\/p>\n Numeric identity Supported controls<\/b> This control works as described in ” CONTROLS”<\/small> in EVP_KDF_CTX<\/small><\/b> (3).<\/p>\n The “EVP_KDF_CTRL_SET_MD” control is used to set the message digest associated with the TLS PRF.<\/small> EVP_md5_sha1()<\/b> is treated as a special case which uses the PRF<\/small> algorithm using both MD5<\/small><\/b> and SHA1<\/small><\/b> as used in TLS 1.0<\/small> and 1.1.<\/p>\n EVP_KDF_CTRL_SET_TLS_SECRET<\/small><\/b><\/p>\n This control expects two arguments: “unsigned char *sec”, “size_t seclen”<\/p>\n Sets the secret value of the TLS PRF<\/small> to seclen<\/b> bytes of the buffer sec<\/b>. Any existing secret value is replaced.<\/p>\n EVP_KDF_ctrl_str()<\/b> takes two type strings for this control: The value string is used as is.<\/p>\n “hexsecret”<\/p>\n The value string is expected to be a hexadecimal number, which will be decoded before being passed on as the control value.<\/p>\n EVP_KDF_CTRL_RESET_TLS_SEED<\/small><\/b><\/p>\n This control does not expect any arguments.<\/p>\n Resets the context seed buffer to zero length.<\/p>\n EVP_KDF_CTRL_ADD_TLS_SEED<\/small><\/b><\/p>\n This control expects two arguments: “unsigned char *seed”, “size_t seedlen”<\/p>\n Sets the seed to seedlen<\/b> bytes of seed<\/b>. If a seed is already set it is appended to the existing value.<\/p>\n The total length of the context seed buffer cannot exceed 1024 bytes; this should be more than enough for any normal use of the TLS PRF.<\/small><\/p>\n EVP_KDF_ctrl_str()<\/b> takes two type strings for this control: The value string is used as is.<\/p>\n “hexseed”<\/p>\n The value string is expected to be a hexadecimal number, which will be decoded before being passed on as the control value.<\/p>\n A context for the TLS PRF<\/small> can be obtained by calling:<\/p>\n EVP_KDF_CTX *kctx = EVP_KDF_CTX_new_id(EVP_KDF_TLS1_PRF, NULL);<\/p>\n The digest, secret value and seed must be set before a key is derived otherwise an error will occur.<\/p>\n The output length of the PRF<\/small> is specified by the “keylen” parameter to the EVP_KDF_derive()<\/b> function.<\/p>\n This example derives 10 bytes using SHA\u2212256<\/small> with the secret key “secret” and seed value “seed”:<\/p>\n EVP_KDF_CTX *kctx;
DESCRIPTION<\/a>
NOTES<\/a>
EXAMPLE<\/a>
SEE ALSO<\/a>
COPYRIGHT<\/a> <\/p>\n
\nNAME <\/a> <\/h2>\n
DESCRIPTION <\/a> <\/h2>\n
EVP_KDF_TLS1_PRF<\/small><\/b> is the numeric identity for this implementation; it can be used with the EVP_KDF_CTX_new_id()<\/b> function.<\/p>\n
The supported controls are:
EVP_KDF_CTRL_SET_MD<\/small><\/b><\/p>\n
“secret”<\/p>\n
“seed”<\/p>\nNOTES <\/a> <\/h2>\n
EXAMPLE <\/a> <\/h2>\n
unsigned char out[10];
kctx = EVP_KDF_CTX_new_id(EVP_KDF_TLS1_PRF);
if (EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_MD, EVP_sha256()) <= 0) {
error(“EVP_KDF_CTRL_SET_MD”);
}
if (EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_TLS_SECRET,
“secret”, (size_t)6) <= 0) {
error(“EVP_KDF_CTRL_SET_TLS_SECRET”);
}
if (EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_ADD_TLS_SEED, “seed”, (size_t)4) <= 0) {
error(“EVP_KDF_CTRL_ADD_TLS_SEED”);
}
if (EVP_KDF_derive(kctx, out, sizeof(out)) <= 0) {
error(“EVP_KDF_derive”);
}
EVP_KDF_CTX_free(kctx);<\/p>\nSEE ALSO <\/a> <\/h2>\n