EVP_KDF-X942-ASN1 - The X9.42-2003 asn1 EVP_KDF implementation
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).
"X942KDF-ASN1" or "X942KDF" is the name for this
  implementation; it can be used with the EVP_KDF_fetch() function.
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".
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.
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);
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)
This functionality was added in OpenSSL 3.0.
Copyright 2019-2022 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>.