Line data    Source code

       1             : /* crypto/ecdh/ec_kdf.c */
       2             : /*
       3             :  * Written by Stephen Henson for the OpenSSL project.
       4             :  */
       5             : /* ====================================================================
       6             :  * Copyright (c) 2013 The OpenSSL Project.  All rights reserved.
       7             :  *
       8             :  * Redistribution and use in source and binary forms, with or without
       9             :  * modification, are permitted provided that the following conditions
      10             :  * are met:
      11             :  *
      12             :  * 1. Redistributions of source code must retain the above copyright
      13             :  *    notice, this list of conditions and the following disclaimer.
      14             :  *
      15             :  * 2. Redistributions in binary form must reproduce the above copyright
      16             :  *    notice, this list of conditions and the following disclaimer in
      17             :  *    the documentation and/or other materials provided with the
      18             :  *    distribution.
      19             :  *
      20             :  * 3. All advertising materials mentioning features or use of this
      21             :  *    software must display the following acknowledgment:
      22             :  *    "This product includes software developed by the OpenSSL Project
      23             :  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
      24             :  *
      25             :  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
      26             :  *    endorse or promote products derived from this software without
      27             :  *    prior written permission. For written permission, please contact
      28             :  *    openssl-core@openssl.org.
      29             :  *
      30             :  * 5. Products derived from this software may not be called "OpenSSL"
      31             :  *    nor may "OpenSSL" appear in their names without prior written
      32             :  *    permission of the OpenSSL Project.
      33             :  *
      34             :  * 6. Redistributions of any form whatsoever must retain the following
      35             :  *    acknowledgment:
      36             :  *    "This product includes software developed by the OpenSSL Project
      37             :  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
      38             :  *
      39             :  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
      40             :  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
      41             :  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
      42             :  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
      43             :  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
      44             :  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
      45             :  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
      46             :  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
      47             :  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
      48             :  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
      49             :  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
      50             :  * OF THE POSSIBILITY OF SUCH DAMAGE.
      51             :  * ====================================================================
      52             :  */
      53             : 
      54             : #define OPENSSL_FIPSAPI
      55             : 
      56             : #include <string.h>
      57             : #include <openssl/ecdh.h>
      58             : #include <openssl/evp.h>
      59             : 
      60             : /* Key derivation function from X9.62/SECG */
      61             : /* Way more than we will ever need */
      62             : #define ECDH_KDF_MAX    (1 << 30)
      63             : 
      64           0 : int ECDH_KDF_X9_62(unsigned char *out, size_t outlen,
      65             :                    const unsigned char *Z, size_t Zlen,
      66             :                    const unsigned char *sinfo, size_t sinfolen,
      67             :                    const EVP_MD *md)
      68             : {
      69             :     EVP_MD_CTX mctx;
      70             :     int rv = 0;
      71             :     unsigned int i;
      72             :     size_t mdlen;
      73             :     unsigned char ctr[4];
      74           0 :     if (sinfolen > ECDH_KDF_MAX || outlen > ECDH_KDF_MAX
      75           0 :         || Zlen > ECDH_KDF_MAX)
      76             :         return 0;
      77           0 :     mdlen = EVP_MD_size(md);
      78           0 :     EVP_MD_CTX_init(&mctx);
      79           0 :     for (i = 1;; i++) {
      80             :         unsigned char mtmp[EVP_MAX_MD_SIZE];
      81           0 :         EVP_DigestInit_ex(&mctx, md, NULL);
      82           0 :         ctr[3] = i & 0xFF;
      83           0 :         ctr[2] = (i >> 8) & 0xFF;
      84           0 :         ctr[1] = (i >> 16) & 0xFF;
      85           0 :         ctr[0] = (i >> 24) & 0xFF;
      86           0 :         if (!EVP_DigestUpdate(&mctx, Z, Zlen))
      87             :             goto err;
      88           0 :         if (!EVP_DigestUpdate(&mctx, ctr, sizeof(ctr)))
      89             :             goto err;
      90           0 :         if (!EVP_DigestUpdate(&mctx, sinfo, sinfolen))
      91             :             goto err;
      92           0 :         if (outlen >= mdlen) {
      93           0 :             if (!EVP_DigestFinal(&mctx, out, NULL))
      94             :                 goto err;
      95           0 :             outlen -= mdlen;
      96           0 :             if (outlen == 0)
      97             :                 break;
      98           0 :             out += mdlen;
      99             :         } else {
     100           0 :             if (!EVP_DigestFinal(&mctx, mtmp, NULL))
     101             :                 goto err;
     102             :             memcpy(out, mtmp, outlen);
     103           0 :             OPENSSL_cleanse(mtmp, mdlen);
     104           0 :             break;
     105             :         }
     106           0 :     }
     107             :     rv = 1;
     108             :  err:
     109           0 :     EVP_MD_CTX_cleanup(&mctx);
     110           0 :     return rv;
     111             : }