crypto/dsa/dsa_key.c

   1 /* crypto/dsa/dsa_key.c */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58
  59 #include <stdio.h>
  60 #include <time.h>
  61 #include "internal/cryptlib.h"
  62 #include <openssl/bn.h>
  63 #include <openssl/dsa.h>
  64 #include <openssl/rand.h>
  65
  66 static int dsa_builtin_keygen(DSA *dsa);
  67
  68 int DSA_generate_key(DSA *dsa)
  69 {
  70     if (dsa->meth->dsa_keygen)
  71         return dsa->meth->dsa_keygen(dsa);
  72     return dsa_builtin_keygen(dsa);
  73 }
  74
  75 static int dsa_builtin_keygen(DSA *dsa)
  76 {
  77     int ok = 0;
  78     BN_CTX *ctx = NULL;
  79     BIGNUM *pub_key = NULL, *priv_key = NULL;
  80
  81     if ((ctx = BN_CTX_new()) == NULL)
  82         goto err;
  83
  84     if (dsa->priv_key == NULL) {
  85         if ((priv_key = BN_secure_new()) == NULL)
  86             goto err;
  87     } else
  88         priv_key = dsa->priv_key;
  89
  90     do
  91         if (!BN_rand_range(priv_key, dsa->q))
  92             goto err;
  93     while (BN_is_zero(priv_key)) ;
  94
  95     if (dsa->pub_key == NULL) {
  96         if ((pub_key = BN_new()) == NULL)
  97             goto err;
  98     } else
  99         pub_key = dsa->pub_key;
 100
 101     {
 102         BIGNUM *local_prk = NULL;
 103         BIGNUM *prk;
 104
 105         if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
 106             local_prk = prk = BN_new();
 107             if (!local_prk)
 108                 goto err;
 109             BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
 110         } else
 111             prk = priv_key;
 112
 113         if (!BN_mod_exp(pub_key, dsa->g, prk, dsa->p, ctx)) {
 114             BN_free(local_prk);
 115             goto err;
 116         }
 117         BN_free(local_prk);
 118     }
 119
 120     dsa->priv_key = priv_key;
 121     dsa->pub_key = pub_key;
 122     ok = 1;
 123
 124  err:
 125     if (pub_key != dsa->pub_key)
 126         BN_free(pub_key);
 127     if (priv_key != dsa->priv_key)
 128         BN_free(priv_key);
 129     BN_CTX_free(ctx);
 130     return (ok);
 131 }