crypto/ecdh/ech_ossl.c

   1 /* crypto/ecdh/ech_ossl.c */
   2 /* ====================================================================
   3  * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
   4  *
   5  * The Elliptic Curve Public-Key Crypto Library (ECC Code) included
   6  * herein is developed by SUN MICROSYSTEMS, INC., and is contributed
   7  * to the OpenSSL project.
   8  *
   9  * The ECC Code is licensed pursuant to the OpenSSL open source
  10  * license provided below.
  11  *
  12  * The ECDH software is originally written by Douglas Stebila of
  13  * Sun Microsystems Laboratories.
  14  *
  15  */
  16 /* ====================================================================
  17  * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.
  18  *
  19  * Redistribution and use in source and binary forms, with or without
  20  * modification, are permitted provided that the following conditions
  21  * are met:
  22  *
  23  * 1. Redistributions of source code must retain the above copyright
  24  *    notice, this list of conditions and the following disclaimer.
  25  *
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in
  28  *    the documentation and/or other materials provided with the
  29  *    distribution.
  30  *
  31  * 3. All advertising materials mentioning features or use of this
  32  *    software must display the following acknowledgment:
  33  *    "This product includes software developed by the OpenSSL Project
  34  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  35  *
  36  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  37  *    endorse or promote products derived from this software without
  38  *    prior written permission. For written permission, please contact
  39  *    openssl-core@OpenSSL.org.
  40  *
  41  * 5. Products derived from this software may not be called "OpenSSL"
  42  *    nor may "OpenSSL" appear in their names without prior written
  43  *    permission of the OpenSSL Project.
  44  *
  45  * 6. Redistributions of any form whatsoever must retain the following
  46  *    acknowledgment:
  47  *    "This product includes software developed by the OpenSSL Project
  48  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  49  *
  50  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  51  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  52  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  53  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  54  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  55  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  56  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  57  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  58  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  59  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  60  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  61  * OF THE POSSIBILITY OF SUCH DAMAGE.
  62  * ====================================================================
  63  *
  64  * This product includes cryptographic software written by Eric Young
  65  * (eay@cryptsoft.com).  This product includes software written by Tim
  66  * Hudson (tjh@cryptsoft.com).
  67  *
  68  */
  69
  70
  71 #include "ecdh.h"
  72 #include <openssl/err.h>
  73 #include <openssl/sha.h>
  74 #include <openssl/obj_mac.h>
  75
  76 static int ecdh_compute_key(unsigned char *key, const EC_POINT *pub_key, EC_KEY *ecdh);
  77
  78 static ECDH_METHOD openssl_ecdh_meth = {
  79         "OpenSSL ECDH method",
  80         ecdh_compute_key,
  81 #if 0
  82         NULL, /* init     */
  83         NULL, /* finish   */
  84 #endif
  85         0,    /* flags    */
  86         NULL  /* app_data */
  87 };
  88
  89 const ECDH_METHOD *ECDH_OpenSSL(void)
  90         {
  91         return &openssl_ecdh_meth;
  92         }
  93
  94
  95 /* This implementation is based on the following primitives in the IEEE 1363 standard:
  96  *  - ECKAS-DH1
  97  *  - ECSVDP-DH
  98  *  - KDF1 with SHA-1
  99  */
 100 static int ecdh_compute_key(unsigned char *key, const EC_POINT *pub_key, EC_KEY *ecdh)
 101         {
 102         BN_CTX *ctx;
 103         EC_POINT *tmp=NULL;
 104         BIGNUM *x=NULL, *y=NULL;
 105         int ret= -1, len;
 106         unsigned char *buf=NULL;
 107
 108         if ((ctx = BN_CTX_new()) == NULL) goto err;
 109         BN_CTX_start(ctx);
 110         x = BN_CTX_get(ctx);
 111         y = BN_CTX_get(ctx);
 112
 113         if (ecdh->priv_key == NULL)
 114                 {
 115                 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_NO_PRIVATE_VALUE);
 116                 goto err;
 117                 }
 118
 119         if ((tmp=EC_POINT_new(ecdh->group)) == NULL)
 120                 {
 121                 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE);
 122                 goto err;
 123                 }
 124
 125         if (!EC_POINT_mul(ecdh->group, tmp, NULL, pub_key, ecdh->priv_key, ctx))
 126                 {
 127                 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE);
 128                 goto err;
 129                 }
 130
 131         if (EC_METHOD_get_field_type(EC_GROUP_method_of(ecdh->group)) == NID_X9_62_prime_field)
 132                 {
 133                 if (!EC_POINT_get_affine_coordinates_GFp(ecdh->group, tmp, x, y, ctx))
 134                         {
 135                         ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE);
 136                         goto err;
 137                         }
 138                 }
 139         else
 140                 {
 141                 if (!EC_POINT_get_affine_coordinates_GF2m(ecdh->group, tmp, x, y, ctx))
 142                         {
 143                         ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE);
 144                         goto err;
 145                         }
 146                 }
 147
 148         if ((buf = (unsigned char *)OPENSSL_malloc(sizeof(unsigned char) * BN_num_bytes(x))) == NULL)
 149                 {
 150                 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE);
 151                 goto err;
 152                 }
 153
 154         if ((len = BN_bn2bin(x,buf)) <= 0)
 155                 {
 156                 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_BN_LIB);
 157                 goto err;
 158                 }
 159
 160         if ((SHA1(buf, len, key) == NULL))
 161                 {
 162                 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_SHA1_DIGEST_FAILED);
 163                 goto err;
 164                 }
 165
 166         ret = 20;
 167
 168 err:
 169         if (tmp) EC_POINT_free(tmp);
 170         if (ctx) BN_CTX_end(ctx);
 171         if (ctx) BN_CTX_free(ctx);
 172         if (buf) OPENSSL_free(buf);
 173         return(ret);
 174         }