crypto/dsa/dsa_key.c

   1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   2  * All rights reserved.
   3  *
   4  * This package is an SSL implementation written
   5  * by Eric Young (eay@cryptsoft.com).
   6  * The implementation was written so as to conform with Netscapes SSL.
   7  *
   8  * This library is free for commercial and non-commercial use as long as
   9  * the following conditions are aheared to.  The following conditions
  10  * apply to all code found in this distribution, be it the RC4, RSA,
  11  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  12  * included with this distribution is covered by the same copyright terms
  13  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  14  *
  15  * Copyright remains Eric Young's, and as such any Copyright notices in
  16  * the code are not to be removed.
  17  * If this package is used in a product, Eric Young should be given attribution
  18  * as the author of the parts of the library used.
  19  * This can be in the form of a textual message at program startup or
  20  * in documentation (online or textual) provided with the package.
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  * 3. All advertising materials mentioning features or use of this software
  31  *    must display the following acknowledgement:
  32  *    "This product includes cryptographic software written by
  33  *     Eric Young (eay@cryptsoft.com)"
  34  *    The word 'cryptographic' can be left out if the rouines from the library
  35  *    being used are not cryptographic related :-).
  36  * 4. If you include any Windows specific code (or a derivative thereof) from
  37  *    the apps directory (application code) you must include an acknowledgement:
  38  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  39  *
  40  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  50  * SUCH DAMAGE.
  51  *
  52  * The licence and distribution terms for any publically available version or
  53  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  54  * copied and put under another distribution licence
  55  * [including the GNU Public Licence.]
  56  */
  57
  58 #include <stdio.h>
  59 #include <time.h>
  60 #include "internal/cryptlib.h"
  61 #include <openssl/bn.h>
  62 #include <openssl/dsa.h>
  63 #include <openssl/rand.h>
  64
  65 static int dsa_builtin_keygen(DSA *dsa);
  66
  67 int DSA_generate_key(DSA *dsa)
  68 {
  69     if (dsa->meth->dsa_keygen)
  70         return dsa->meth->dsa_keygen(dsa);
  71     return dsa_builtin_keygen(dsa);
  72 }
  73
  74 static int dsa_builtin_keygen(DSA *dsa)
  75 {
  76     int ok = 0;
  77     BN_CTX *ctx = NULL;
  78     BIGNUM *pub_key = NULL, *priv_key = NULL;
  79
  80     if ((ctx = BN_CTX_new()) == NULL)
  81         goto err;
  82
  83     if (dsa->priv_key == NULL) {
  84         if ((priv_key = BN_secure_new()) == NULL)
  85             goto err;
  86     } else
  87         priv_key = dsa->priv_key;
  88
  89     do
  90         if (!BN_rand_range(priv_key, dsa->q))
  91             goto err;
  92     while (BN_is_zero(priv_key)) ;
  93
  94     if (dsa->pub_key == NULL) {
  95         if ((pub_key = BN_new()) == NULL)
  96             goto err;
  97     } else
  98         pub_key = dsa->pub_key;
  99
 100     {
 101         BIGNUM *local_prk = NULL;
 102         BIGNUM *prk;
 103
 104         if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
 105             local_prk = prk = BN_new();
 106             if (local_prk == NULL)
 107                 goto err;
 108             BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
 109         } else {
 110             prk = priv_key;
 111         }
 112
 113         if (!BN_mod_exp(pub_key, dsa->g, prk, dsa->p, ctx)) {
 114             BN_free(local_prk);
 115             goto err;
 116         }
 117         /* We MUST free local_prk before any further use of priv_key */
 118         BN_free(local_prk);
 119     }
 120
 121     dsa->priv_key = priv_key;
 122     dsa->pub_key = pub_key;
 123     ok = 1;
 124
 125  err:
 126     if (pub_key != dsa->pub_key)
 127         BN_free(pub_key);
 128     if (priv_key != dsa->priv_key)
 129         BN_free(priv_key);
 130     BN_CTX_free(ctx);
 131     return (ok);
 132 }