crypto/dsa/dsa_key.c

   1 /* crypto/dsa/dsa_key.c */
   2 /* Copyright (C) 1995-1997 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 "cryptlib.h"
  62 #include "sha.h"
  63 #include "bn.h"
  64 #include "dsa.h"
  65 #include "rand.h"
  66
  67 int DSA_generate_key(dsa)
  68 DSA *dsa;
  69         {
  70         int ok=0;
  71         unsigned int i;
  72         BN_CTX *ctx=NULL;
  73         BIGNUM *pub_key=NULL,*priv_key=NULL;
  74
  75         if ((ctx=BN_CTX_new()) == NULL) goto err;
  76
  77         if (dsa->priv_key == NULL)
  78                 {
  79                 if ((priv_key=BN_new()) == NULL) goto err;
  80                 }
  81         else
  82                 priv_key=dsa->priv_key;
  83
  84         i=BN_num_bits(dsa->q);
  85         for (;;)
  86                 {
  87                 BN_rand(priv_key,i,1,0);
  88                 if (BN_cmp(priv_key,dsa->q) >= 0)
  89                         BN_sub(priv_key,priv_key,dsa->q);
  90                 if (!BN_is_zero(priv_key)) break;
  91                 }
  92
  93         if (dsa->pub_key == NULL)
  94                 {
  95                 if ((pub_key=BN_new()) == NULL) goto err;
  96                 }
  97         else
  98                 pub_key=dsa->pub_key;
  99
 100         if (!BN_mod_exp(pub_key,dsa->g,priv_key,dsa->p,ctx)) goto err;
 101
 102         dsa->priv_key=priv_key;
 103         dsa->pub_key=pub_key;
 104         ok=1;
 105
 106 err:
 107         if ((pub_key != NULL) && (dsa->pub_key == NULL)) BN_free(pub_key);
 108         if ((priv_key != NULL) && (dsa->priv_key == NULL)) BN_free(priv_key);
 109         if (ctx != NULL) BN_CTX_free(ctx);
 110         return(ok);
 111         }
 112