EVP_KDF-X942-ASN1(7ossl) OpenSSL EVP_KDF-X942-ASN1(7ossl)
NAME
EVP_KDF-X942-ASN1 - The X9.42-2003 asn1 EVP_KDF implementation
DESCRIPTION
The EVP_KDF-X942-ASN1 algorithm implements the key derivation function
X942KDF-ASN1. It is used by DH KeyAgreement, to derive a key using
input such as a shared secret key and other info. The other info is DER
encoded data that contains a 32 bit counter as well as optional fields
for "partyu-info", "partyv-info", "supp-pubinfo" and "supp-privinfo".
This kdf is used by Cryptographic Message Syntax (CMS).
The output is considered to be keying material.
Identity
"X942KDF-ASN1" or "X942KDF" is the name for this implementation; it can
be used with the EVP_KDF_fetch() function.
Supported parameters
The supported parameters are:
"properties" (OSSL_KDF_PARAM_PROPERTIES) <UTF8 string>
"digest" (OSSL_KDF_PARAM_DIGEST) <UTF8 string>
These parameters work as described in "PARAMETERS" in EVP_KDF(3).
"secret" (OSSL_KDF_PARAM_SECRET) <octet string>
The shared secret used for key derivation. This parameter sets the
secret.
"acvp-info" (OSSL_KDF_PARAM_X942_ACVPINFO) <octet string>
This value should not be used in production and should only be used
for ACVP testing. It is an optional octet string containing a
combined DER encoded blob of any of the optional fields related to
"partyu-info", "partyv-info", "supp-pubinfo" and "supp-privinfo".
If it is specified then none of these other fields should be used.
"partyu-info" (OSSL_KDF_PARAM_X942_PARTYUINFO) <octet string>
An optional octet string containing public info contributed by the
initiator.
"ukm" (OSSL_KDF_PARAM_UKM) <octet string>
An alias for "partyu-info". In CMS this is the user keying
material.
"partyv-info" (OSSL_KDF_PARAM_X942_PARTYVINFO) <octet string>
An optional octet string containing public info contributed by the
responder.
"supp-pubinfo" (OSSL_KDF_PARAM_X942_SUPP_PUBINFO) <octet string>
An optional octet string containing some additional, mutually-known
public information. Setting this value also sets "use-keybits" to
0.
"use-keybits" (OSSL_KDF_PARAM_X942_USE_KEYBITS) <integer>
The default value of 1 will use the KEK key length (in bits) as the
"supp-pubinfo". A value of 0 disables setting the "supp-pubinfo".
"supp-privinfo" (OSSL_KDF_PARAM_X942_SUPP_PRIVINFO) <octet string>
An optional octet string containing some additional, mutually-known
private information.
"cekalg" (OSSL_KDF_PARAM_CEK_ALG) <UTF8 string>
This parameter sets the CEK wrapping algorithm name. Valid values
are "AES-128-WRAP", "AES-192-WRAP", "AES-256-WRAP" and "DES3-WRAP".
The OpenSSL FIPS provider also supports the following parameters:
"fips-indicator" (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 "key-check" parameter is set to 0 and the check fails.
"key-check" (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
(OSSL_KDF_PARAM_KEY) 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.
NOTES
A context for X942KDF can be obtained by calling:
EVP_KDF *kdf = EVP_KDF_fetch(NULL, "X942KDF", NULL);
EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);
The output length of an X942KDF is specified via the keylen parameter
to the EVP_KDF_derive(3) function.
EXAMPLES
This example derives 24 bytes, with the secret key "secret" and random
user keying material:
EVP_KDF_CTX *kctx;
EVP_KDF_CTX *kctx;
unsigned char out[192/8];
unsignred char ukm[64];
OSSL_PARAM params[5], *p = params;
if (RAND_bytes(ukm, sizeof(ukm)) <= 0)
error("RAND_bytes");
kdf = EVP_KDF_fetch(NULL, "X942KDF", NULL);
if (kctx == NULL)
error("EVP_KDF_fetch");
kctx = EVP_KDF_CTX_new(kdf);
EVP_KDF_free(kdf);
if (kctx == NULL)
error("EVP_KDF_CTX_new");
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST, "SHA256", 0);
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SECRET,
"secret", (size_t)6);
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_UKM, ukm, sizeof(ukm));
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_CEK_ALG, "AES-256-WRAP, 0);
*p = OSSL_PARAM_construct_end();
if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0)
error("EVP_KDF_derive");
EVP_KDF_CTX_free(kctx);
CONFORMING TO
ANS1 X9.42-2003 RFC 2631
SEE ALSO
EVP_KDF(3), EVP_KDF_CTX_new(3), EVP_KDF_CTX_free(3),
EVP_KDF_CTX_set_params(3), EVP_KDF_CTX_get_kdf_size(3),
EVP_KDF_derive(3), "PARAMETERS" in EVP_KDF(3)
HISTORY
This functionality was added in OpenSSL 3.0.
COPYRIGHT
Copyright 2019-2024 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
<https://www.openssl.org/source/license.html>.
3.4.0 2024-10-29 EVP_KDF-X942-ASN1(7ossl)
openssl 3.4.0 - Generated Thu Nov 21 14:23:05 CST 2024