AppleCSP/open_ssl/dh/dh_check.c

   1 /*
   2  * Copyright (c) 2000-2002 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18 /* crypto/dh/dh_check.c */
  19 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  20  * All rights reserved.
  21  *
  22  * This package is an SSL implementation written
  23  * by Eric Young (eay@cryptsoft.com).
  24  * The implementation was written so as to conform with Netscapes SSL.
  25  *
  26  * This library is free for commercial and non-commercial use as long as
  27  * the following conditions are aheared to.  The following conditions
  28  * apply to all code found in this distribution, be it the RC4, RSA,
  29  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  30  * included with this distribution is covered by the same copyright terms
  31  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  32  *
  33  * Copyright remains Eric Young's, and as such any Copyright notices in
  34  * the code are not to be removed.
  35  * If this package is used in a product, Eric Young should be given attribution
  36  * as the author of the parts of the library used.
  37  * This can be in the form of a textual message at program startup or
  38  * in documentation (online or textual) provided with the package.
  39  *
  40  * Redistribution and use in source and binary forms, with or without
  41  * modification, are permitted provided that the following conditions
  42  * are met:
  43  * 1. Redistributions of source code must retain the copyright
  44  *    notice, this list of conditions and the following disclaimer.
  45  * 2. Redistributions in binary form must reproduce the above copyright
  46  *    notice, this list of conditions and the following disclaimer in the
  47  *    documentation and/or other materials provided with the distribution.
  48  * 3. All advertising materials mentioning features or use of this software
  49  *    must display the following acknowledgement:
  50  *    "This product includes cryptographic software written by
  51  *     Eric Young (eay@cryptsoft.com)"
  52  *    The word 'cryptographic' can be left out if the rouines from the library
  53  *    being used are not cryptographic related :-).
  54  * 4. If you include any Windows specific code (or a derivative thereof) from
  55  *    the apps directory (application code) you must include an acknowledgement:
  56  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  57  *
  58  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  59  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  60  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  61  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  62  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  63  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  64  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  65  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  66  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  67  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  68  * SUCH DAMAGE.
  69  *
  70  * The licence and distribution terms for any publically available version or
  71  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  72  * copied and put under another distribution licence
  73  * [including the GNU Public Licence.]
  74  */
  75
  76 #include <stdio.h>
  77 #include "cryptlib.h"
  78 #include <openssl/bn.h>
  79 #include <openssl/dh.h>
  80
  81 /* Check that p is a safe prime and
  82  * if g is 2, 3 or 5, check that is is a suitable generator
  83  * where
  84  * for 2, p mod 24 == 11
  85  * for 3, p mod 12 == 5
  86  * for 5, p mod 10 == 3 or 7
  87  * should hold.
  88  */
  89
  90 int DH_check(DH *dh, int *ret)
  91         {
  92         int ok=0;
  93         BN_CTX *ctx=NULL;
  94         BN_ULONG l;
  95         BIGNUM *q=NULL;
  96
  97         *ret=0;
  98         ctx=BN_CTX_new();
  99         if (ctx == NULL) goto err;
 100         q=BN_new();
 101         if (q == NULL) goto err;
 102
 103         if (BN_is_word(dh->g,DH_GENERATOR_2))
 104                 {
 105                 l=BN_mod_word(dh->p,24);
 106                 if (l != 11) *ret|=DH_NOT_SUITABLE_GENERATOR;
 107                 }
 108 #if 0
 109         else if (BN_is_word(dh->g,DH_GENERATOR_3))
 110                 {
 111                 l=BN_mod_word(dh->p,12);
 112                 if (l != 5) *ret|=DH_NOT_SUITABLE_GENERATOR;
 113                 }
 114 #endif
 115         else if (BN_is_word(dh->g,DH_GENERATOR_5))
 116                 {
 117                 l=BN_mod_word(dh->p,10);
 118                 if ((l != 3) && (l != 7))
 119                         *ret|=DH_NOT_SUITABLE_GENERATOR;
 120                 }
 121         else
 122                 *ret|=DH_UNABLE_TO_CHECK_GENERATOR;
 123
 124         if (!BN_is_prime(dh->p,BN_prime_checks,NULL,ctx,NULL))
 125                 *ret|=DH_CHECK_P_NOT_PRIME;
 126         else
 127                 {
 128                 if (!BN_rshift1(q,dh->p)) goto err;
 129                 if (!BN_is_prime(q,BN_prime_checks,NULL,ctx,NULL))
 130                         *ret|=DH_CHECK_P_NOT_SAFE_PRIME;
 131                 }
 132         ok=1;
 133 err:
 134         if (ctx != NULL) BN_CTX_free(ctx);
 135         if (q != NULL) BN_free(q);
 136         return(ok);
 137         }