crypto/openssl-0.9/crypto/ec/ec_check.c

   1 /* crypto/ec/ec_check.c */
   2 /* ====================================================================
   3  * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  *
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in
  14  *    the documentation and/or other materials provided with the
  15  *    distribution.
  16  *
  17  * 3. All advertising materials mentioning features or use of this
  18  *    software must display the following acknowledgment:
  19  *    "This product includes software developed by the OpenSSL Project
  20  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  21  *
  22  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  23  *    endorse or promote products derived from this software without
  24  *    prior written permission. For written permission, please contact
  25  *    openssl-core@openssl.org.
  26  *
  27  * 5. Products derived from this software may not be called "OpenSSL"
  28  *    nor may "OpenSSL" appear in their names without prior written
  29  *    permission of the OpenSSL Project.
  30  *
  31  * 6. Redistributions of any form whatsoever must retain the following
  32  *    acknowledgment:
  33  *    "This product includes software developed by the OpenSSL Project
  34  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  35  *
  36  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  37  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  38  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  39  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  40  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  41  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  42  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  43  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  44  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  45  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  46  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  47  * OF THE POSSIBILITY OF SUCH DAMAGE.
  48  * ====================================================================
  49  *
  50  * This product includes cryptographic software written by Eric Young
  51  * (eay@cryptsoft.com).  This product includes software written by Tim
  52  * Hudson (tjh@cryptsoft.com).
  53  *
  54  */
  55
  56 #include "ec_lcl.h"
  57 #include <openssl/err.h>
  58
  59 int EC_GROUP_check(const EC_GROUP *group, BN_CTX *ctx)
  60         {
  61         int ret = 0;
  62         BIGNUM *order;
  63         BN_CTX *new_ctx = NULL;
  64         EC_POINT *point = NULL;
  65
  66         if (ctx == NULL)
  67                 {
  68                 ctx = new_ctx = BN_CTX_new();
  69                 if (ctx == NULL)
  70                         {
  71                         ECerr(EC_F_EC_GROUP_CHECK, ERR_R_MALLOC_FAILURE);
  72                         goto err;
  73                         }
  74                 }
  75         BN_CTX_start(ctx);
  76         if ((order = BN_CTX_get(ctx)) == NULL) goto err;
  77
  78         /* check the discriminant */
  79         if (!EC_GROUP_check_discriminant(group, ctx))
  80                 {
  81                 ECerr(EC_F_EC_GROUP_CHECK, EC_R_DISCRIMINANT_IS_ZERO);
  82                 goto err;
  83                 }
  84
  85         /* check the generator */
  86         if (group->generator == NULL)
  87                 {
  88                 ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_GENERATOR);
  89                 goto err;
  90                 }
  91         if (!EC_POINT_is_on_curve(group, group->generator, ctx))
  92                 {
  93                 ECerr(EC_F_EC_GROUP_CHECK, EC_R_POINT_IS_NOT_ON_CURVE);
  94                 goto err;
  95                 }
  96
  97         /* check the order of the generator */
  98         if ((point = EC_POINT_new(group)) == NULL) goto err;
  99         if (!EC_GROUP_get_order(group, order, ctx)) goto err;
 100         if (BN_is_zero(order))
 101                 {
 102                 ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_ORDER);
 103                 goto err;
 104                 }
 105
 106         if (!EC_POINT_mul(group, point, order, NULL, NULL, ctx)) goto err;
 107         if (!EC_POINT_is_at_infinity(group, point))
 108                 {
 109                 ECerr(EC_F_EC_GROUP_CHECK, EC_R_INVALID_GROUP_ORDER);
 110                 goto err;
 111                 }
 112
 113         ret = 1;
 114
 115 err:
 116         if (ctx != NULL)
 117                 BN_CTX_end(ctx);
 118         if (new_ctx != NULL)
 119                 BN_CTX_free(new_ctx);
 120         if (point)
 121                 EC_POINT_free(point);
 122         return ret;
 123         }