crypto/dsa/dsa_gen.c

   1 /* crypto/dsa/dsa_gen.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 #undef GENUINE_DSA
  60
  61 #ifdef GENUINE_DSA
  62 #define HASH    SHA
  63 #else
  64 #define HASH    SHA1
  65 #endif
  66
  67 #include <stdio.h>
  68 #include <time.h>
  69 #include "cryptlib.h"
  70 #include "sha.h"
  71 #include "bn.h"
  72 #include "dsa.h"
  73 #include "rand.h"
  74
  75 DSA *DSA_generate_parameters(bits,seed_in,seed_len,counter_ret,h_ret,callback)
  76 int bits;
  77 unsigned char *seed_in;
  78 int seed_len;
  79 int *counter_ret;
  80 unsigned long *h_ret;
  81 void (*callback)();
  82         {
  83         int ok=0;
  84         unsigned char seed[SHA_DIGEST_LENGTH];
  85         unsigned char md[SHA_DIGEST_LENGTH];
  86         unsigned char buf[SHA_DIGEST_LENGTH],buf2[SHA_DIGEST_LENGTH];
  87         BIGNUM *r0,*W,*X,*c,*test;
  88         BIGNUM *g=NULL,*q=NULL,*p=NULL;
  89         int k,n=0,i,b,m=0;
  90         int counter=0;
  91         BN_CTX *ctx=NULL,*ctx2=NULL;
  92         unsigned int h=2;
  93         DSA *ret=NULL;
  94
  95         if (bits < 512) bits=512;
  96         bits=(bits+63)/64*64;
  97
  98         if ((seed_in != NULL) && (seed_len == 20))
  99                 memcpy(seed,seed_in,seed_len);
 100
 101         ctx=BN_CTX_new();
 102         if (ctx == NULL) goto err;
 103         ctx2=BN_CTX_new();
 104         if (ctx2 == NULL) goto err;
 105         ret=DSA_new();
 106         if (ret == NULL) goto err;
 107         r0=ctx2->bn[0];
 108         g=ctx2->bn[1];
 109         W=ctx2->bn[2];
 110         q=ctx2->bn[3];
 111         X=ctx2->bn[4];
 112         c=ctx2->bn[5];
 113         p=ctx2->bn[6];
 114         test=ctx2->bn[7];
 115
 116         BN_lshift(test,BN_value_one(),bits-1);
 117
 118         for (;;)
 119                 {
 120                 for (;;)
 121                         {
 122                         /* step 1 */
 123                         if (callback != NULL) callback(0,m++);
 124
 125                         if (!seed_len)
 126                                 RAND_bytes(seed,SHA_DIGEST_LENGTH);
 127                         else
 128                                 seed_len=0;
 129
 130                         memcpy(buf,seed,SHA_DIGEST_LENGTH);
 131                         memcpy(buf2,seed,SHA_DIGEST_LENGTH);
 132                         for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
 133                                 {
 134                                 buf[i]++;
 135                                 if (buf[i] != 0) break;
 136                                 }
 137
 138                         /* step 2 */
 139                         HASH(seed,SHA_DIGEST_LENGTH,md);
 140                         HASH(buf,SHA_DIGEST_LENGTH,buf2);
 141                         for (i=0; i<SHA_DIGEST_LENGTH; i++)
 142                                 md[i]^=buf2[i];
 143
 144                         /* step 3 */
 145                         md[0]|=0x80;
 146                         md[SHA_DIGEST_LENGTH-1]|=0x01;
 147                         if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,q)) abort();
 148
 149                         /* step 4 */
 150                         if (DSA_is_prime(q,callback) > 0) break;
 151                         /* do a callback call */
 152                         /* step 5 */
 153                         }
 154
 155                 if (callback != NULL) callback(2,0);
 156                 if (callback != NULL) callback(3,0);
 157
 158                 /* step 6 */
 159                 counter=0;
 160
 161                 n=(bits-1)/160;
 162                 b=(bits-1)-n*160;
 163
 164                 for (;;)
 165                         {
 166                         /* step 7 */
 167                         BN_zero(W);
 168                         for (k=0; k<=n; k++)
 169                                 {
 170                                 for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
 171                                         {
 172                                         buf[i]++;
 173                                         if (buf[i] != 0) break;
 174                                         }
 175
 176                                 HASH(buf,SHA_DIGEST_LENGTH,md);
 177
 178                                 /* step 8 */
 179                                 if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,r0)) abort();
 180                                 BN_lshift(r0,r0,160*k);
 181                                 BN_add(W,W,r0);
 182                                 }
 183
 184                         /* more of step 8 */
 185                         BN_mask_bits(W,bits-1);
 186                         BN_copy(X,W); /* this should be ok */
 187                         BN_add(X,X,test); /* this should be ok */
 188
 189                         /* step 9 */
 190                         BN_lshift1(r0,q);
 191                         BN_mod(c,X,r0,ctx);
 192                         BN_sub(r0,c,BN_value_one());
 193                         BN_sub(p,X,r0);
 194
 195                         /* step 10 */
 196                         if (BN_cmp(p,test) >= 0)
 197                                 {
 198                                 /* step 11 */
 199                                 if (DSA_is_prime(p,callback) > 0)
 200                                         goto end;
 201                                 }
 202
 203                         /* step 13 */
 204                         counter++;
 205
 206                         /* step 14 */
 207                         if (counter >= 4096) break;
 208
 209                         if (callback != NULL) callback(0,counter);
 210                         }
 211                 }
 212 end:
 213         if (callback != NULL) callback(2,1);
 214
 215         /* We now need to gernerate g */
 216         /* Set r0=(p-1)/q */
 217         BN_sub(test,p,BN_value_one());
 218         BN_div(r0,NULL,test,q,ctx);
 219
 220         BN_set_word(test,h);
 221         for (;;)
 222                 {
 223                 /* g=test^r0%p */
 224                 BN_mod_exp(g,test,r0,p,ctx);
 225                 if (!BN_is_one(g)) break;
 226                 BN_add(test,test,BN_value_one());
 227                 h++;
 228                 }
 229
 230         if (callback != NULL) callback(3,1);
 231
 232         ok=1;
 233 err:
 234         if (!ok)
 235                 {
 236                 if (ret != NULL) DSA_free(ret);
 237                 }
 238         else
 239                 {
 240                 ret->p=BN_dup(p);
 241                 ret->q=BN_dup(q);
 242                 ret->g=BN_dup(g);
 243                 if ((m > 1) && (seed_in != NULL)) memcpy(seed_in,seed,20);
 244                 if (counter_ret != NULL) *counter_ret=counter;
 245                 if (h_ret != NULL) *h_ret=h;
 246                 }
 247         BN_CTX_free(ctx);
 248         BN_CTX_free(ctx2);
 249         return(ok?ret:NULL);
 250         }
 251
 252 int DSA_is_prime(w, callback)
 253 BIGNUM *w;
 254 void (*callback)();
 255         {
 256         int ok= -1,j,i,n;
 257         BN_CTX *ctx=NULL,*ctx2=NULL;
 258         BIGNUM *w_1,*b,*m,*z;
 259         int a;
 260
 261         if (!BN_is_bit_set(w,0)) return(0);
 262
 263         ctx=BN_CTX_new();
 264         if (ctx == NULL) goto err;
 265         ctx2=BN_CTX_new();
 266         if (ctx2 == NULL) goto err;
 267
 268         m=  ctx2->bn[2];
 269         b=  ctx2->bn[3];
 270         z=  ctx2->bn[4];
 271         w_1=ctx2->bn[5];
 272
 273         /* step 1 */
 274         n=50;
 275
 276         /* step 2 */
 277         if (!BN_sub(w_1,w,BN_value_one())) goto err;
 278         for (a=1; !BN_is_bit_set(w_1,a); a++)
 279                 ;
 280         if (!BN_rshift(m,w_1,a)) goto err;
 281
 282         for (i=1; i < n; i++)
 283                 {
 284                 /* step 3 */
 285                 BN_rand(b,BN_num_bits(w)-2/*-1*/,0,0);
 286                 BN_set_word(b,0x10001L);
 287
 288                 /* step 4 */
 289                 j=0;
 290                 if (!BN_mod_exp(z,b,m,w,ctx)) goto err;
 291
 292                 /* step 5 */
 293                 for (;;)
 294                         {
 295                         if (((j == 0) && BN_is_one(z)) || (BN_cmp(z,w_1) == 0))
 296                                 break;
 297
 298                         /* step 6 */
 299                         if ((j > 0) && BN_is_one(z))
 300                                 {
 301                                 ok=0;
 302                                 goto err;
 303                                 }
 304
 305                         j++;
 306                         if (j >= a)
 307                                 {
 308                                 ok=0;
 309                                 goto err;
 310                                 }
 311
 312                         if (!BN_mod_mul(z,z,z,w,ctx)) goto err;
 313                         if (callback != NULL) callback(1,j);
 314                         }
 315                 }
 316
 317         ok=1;
 318 err:
 319         if (ok == -1) DSAerr(DSA_F_DSA_IS_PRIME,ERR_R_BN_LIB);
 320         BN_CTX_free(ctx);
 321         BN_CTX_free(ctx2);
 322
 323         return(ok);
 324         }
 325