crypto/ec/ecdh_kdf.c

   1 /*
   2  * Copyright 2015-2019 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <string.h>
  11 #include <openssl/core_names.h>
  12 #include <openssl/ec.h>
  13 #include <openssl/evp.h>
  14 #include <openssl/kdf.h>
  15 #include "ec_lcl.h"
  16
  17 /* Key derivation function from X9.63/SECG */
  18 int ecdh_KDF_X9_63(unsigned char *out, size_t outlen,
  19                    const unsigned char *Z, size_t Zlen,
  20                    const unsigned char *sinfo, size_t sinfolen,
  21                    const EVP_MD *md)
  22 {
  23     int ret = 0;
  24     EVP_KDF_CTX *kctx = NULL;
  25     OSSL_PARAM params[4], *p = params;
  26     const char *mdname = EVP_MD_name(md);
  27     EVP_KDF *kdf = EVP_KDF_fetch(NULL, OSSL_KDF_NAME_X963KDF, NULL);
  28
  29     if ((kctx = EVP_KDF_CTX_new(kdf)) != NULL) {
  30         *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
  31                                                 (char *)mdname,
  32                                                 strlen(mdname) + 1);
  33         *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
  34                                                  (void *)Z, Zlen);
  35         *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
  36                                                  (void *)sinfo, sinfolen);
  37         *p = OSSL_PARAM_construct_end();
  38
  39         ret = EVP_KDF_CTX_set_params(kctx, params) > 0
  40             && EVP_KDF_derive(kctx, out, outlen) > 0;
  41         EVP_KDF_CTX_free(kctx);
  42     }
  43     EVP_KDF_free(kdf);
  44     return ret;
  45 }
  46
  47 /*-
  48  * The old name for ecdh_KDF_X9_63
  49  * Retained for ABI compatibility
  50  */
  51 #if !OPENSSL_API_3
  52 int ECDH_KDF_X9_62(unsigned char *out, size_t outlen,
  53                    const unsigned char *Z, size_t Zlen,
  54                    const unsigned char *sinfo, size_t sinfolen,
  55                    const EVP_MD *md)
  56 {
  57     return ecdh_KDF_X9_63(out, outlen, Z, Zlen, sinfo, sinfolen, md);
  58 }
  59 #endif