crypto/dsa/dsa_gen.c

   1 /* crypto/dsa/dsa_gen.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 #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         cb_arg)
  77 int bits;
  78 unsigned char *seed_in;
  79 int seed_len;
  80 int *counter_ret;
  81 unsigned long *h_ret;
  82 void (*callback)();
  83 char *cb_arg;
  84         {
  85         int ok=0;
  86         unsigned char seed[SHA_DIGEST_LENGTH];
  87         unsigned char md[SHA_DIGEST_LENGTH];
  88         unsigned char buf[SHA_DIGEST_LENGTH],buf2[SHA_DIGEST_LENGTH];
  89         BIGNUM *r0,*W,*X,*c,*test;
  90         BIGNUM *g=NULL,*q=NULL,*p=NULL;
  91         BN_MONT_CTX *mont=NULL;
  92         int k,n=0,i,b,m=0;
  93         int counter=0;
  94         BN_CTX *ctx=NULL,*ctx2=NULL;
  95         unsigned int h=2;
  96         DSA *ret=NULL;
  97
  98         if (bits < 512) bits=512;
  99         bits=(bits+63)/64*64;
 100
 101         if ((seed_in != NULL) && (seed_len == 20))
 102                 memcpy(seed,seed_in,seed_len);
 103
 104         if ((ctx=BN_CTX_new()) == NULL) goto err;
 105         if ((ctx2=BN_CTX_new()) == NULL) goto err;
 106         if ((ret=DSA_new()) == NULL) goto err;
 107
 108         if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
 109
 110         r0= &(ctx2->bn[0]);
 111         g= &(ctx2->bn[1]);
 112         W= &(ctx2->bn[2]);
 113         q= &(ctx2->bn[3]);
 114         X= &(ctx2->bn[4]);
 115         c= &(ctx2->bn[5]);
 116         p= &(ctx2->bn[6]);
 117         test= &(ctx2->bn[7]);
 118
 119         BN_lshift(test,BN_value_one(),bits-1);
 120
 121         for (;;)
 122                 {
 123                 for (;;)
 124                         {
 125                         /* step 1 */
 126                         if (callback != NULL) callback(0,m++,cb_arg);
 127
 128                         if (!seed_len)
 129                                 RAND_bytes(seed,SHA_DIGEST_LENGTH);
 130                         else
 131                                 seed_len=0;
 132
 133                         memcpy(buf,seed,SHA_DIGEST_LENGTH);
 134                         memcpy(buf2,seed,SHA_DIGEST_LENGTH);
 135                         for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
 136                                 {
 137                                 buf[i]++;
 138                                 if (buf[i] != 0) break;
 139                                 }
 140
 141                         /* step 2 */
 142                         HASH(seed,SHA_DIGEST_LENGTH,md);
 143                         HASH(buf,SHA_DIGEST_LENGTH,buf2);
 144                         for (i=0; i<SHA_DIGEST_LENGTH; i++)
 145                                 md[i]^=buf2[i];
 146
 147                         /* step 3 */
 148                         md[0]|=0x80;
 149                         md[SHA_DIGEST_LENGTH-1]|=0x01;
 150                         if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,q)) abort();
 151
 152                         /* step 4 */
 153                         if (DSA_is_prime(q,callback,cb_arg) > 0) break;
 154                         /* do a callback call */
 155                         /* step 5 */
 156                         }
 157
 158                 if (callback != NULL) callback(2,0,cb_arg);
 159                 if (callback != NULL) callback(3,0,cb_arg);
 160
 161                 /* step 6 */
 162                 counter=0;
 163
 164                 n=(bits-1)/160;
 165                 b=(bits-1)-n*160;
 166
 167                 for (;;)
 168                         {
 169                         /* step 7 */
 170                         BN_zero(W);
 171                         for (k=0; k<=n; k++)
 172                                 {
 173                                 for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
 174                                         {
 175                                         buf[i]++;
 176                                         if (buf[i] != 0) break;
 177                                         }
 178
 179                                 HASH(buf,SHA_DIGEST_LENGTH,md);
 180
 181                                 /* step 8 */
 182                                 if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,r0)) abort();
 183                                 BN_lshift(r0,r0,160*k);
 184                                 BN_add(W,W,r0);
 185                                 }
 186
 187                         /* more of step 8 */
 188                         BN_mask_bits(W,bits-1);
 189                         BN_copy(X,W); /* this should be ok */
 190                         BN_add(X,X,test); /* this should be ok */
 191
 192                         /* step 9 */
 193                         BN_lshift1(r0,q);
 194                         BN_mod(c,X,r0,ctx);
 195                         BN_sub(r0,c,BN_value_one());
 196                         BN_sub(p,X,r0);
 197
 198                         /* step 10 */
 199                         if (BN_cmp(p,test) >= 0)
 200                                 {
 201                                 /* step 11 */
 202                                 if (DSA_is_prime(p,callback,cb_arg) > 0)
 203                                         goto end;
 204                                 }
 205
 206                         /* step 13 */
 207                         counter++;
 208
 209                         /* step 14 */
 210                         if (counter >= 4096) break;
 211
 212                         if (callback != NULL) callback(0,counter,cb_arg);
 213                         }
 214                 }
 215 end:
 216         if (callback != NULL) callback(2,1,cb_arg);
 217
 218         /* We now need to gernerate g */
 219         /* Set r0=(p-1)/q */
 220         BN_sub(test,p,BN_value_one());
 221         BN_div(r0,NULL,test,q,ctx);
 222
 223         BN_set_word(test,h);
 224         BN_MONT_CTX_set(mont,p,ctx);
 225
 226         for (;;)
 227                 {
 228                 /* g=test^r0%p */
 229                 BN_mod_exp_mont(g,test,r0,p,ctx,mont);
 230                 if (!BN_is_one(g)) break;
 231                 BN_add(test,test,BN_value_one());
 232                 h++;
 233                 }
 234
 235         if (callback != NULL) callback(3,1,cb_arg);
 236
 237         ok=1;
 238 err:
 239         if (!ok)
 240                 {
 241                 if (ret != NULL) DSA_free(ret);
 242                 }
 243         else
 244                 {
 245                 ret->p=BN_dup(p);
 246                 ret->q=BN_dup(q);
 247                 ret->g=BN_dup(g);
 248                 if ((m > 1) && (seed_in != NULL)) memcpy(seed_in,seed,20);
 249                 if (counter_ret != NULL) *counter_ret=counter;
 250                 if (h_ret != NULL) *h_ret=h;
 251                 }
 252         if (ctx != NULL) BN_CTX_free(ctx);
 253         if (ctx != NULL) BN_CTX_free(ctx2);
 254         if (mont != NULL) BN_MONT_CTX_free(mont);
 255         return(ok?ret:NULL);
 256         }
 257
 258 int DSA_is_prime(w, callback,cb_arg)
 259 BIGNUM *w;
 260 void (*callback)();
 261 char *cb_arg;
 262         {
 263         int ok= -1,j,i,n;
 264         BN_CTX *ctx=NULL,*ctx2=NULL;
 265         BIGNUM *w_1,*b,*m,*z,*tmp,*mont_1;
 266         int a;
 267         BN_MONT_CTX *mont=NULL;
 268
 269         if (!BN_is_bit_set(w,0)) return(0);
 270
 271         if ((ctx=BN_CTX_new()) == NULL) goto err;
 272         if ((ctx2=BN_CTX_new()) == NULL) goto err;
 273         if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
 274
 275         m=   &(ctx2->bn[2]);
 276         b=   &(ctx2->bn[3]);
 277         z=   &(ctx2->bn[4]);
 278         w_1= &(ctx2->bn[5]);
 279         tmp= &(ctx2->bn[6]);
 280         mont_1= &(ctx2->bn[7]);
 281
 282         /* step 1 */
 283         n=50;
 284
 285         /* step 2 */
 286         if (!BN_sub(w_1,w,BN_value_one())) goto err;
 287         for (a=1; !BN_is_bit_set(w_1,a); a++)
 288                 ;
 289         if (!BN_rshift(m,w_1,a)) goto err;
 290
 291         BN_MONT_CTX_set(mont,w,ctx);
 292         BN_to_montgomery(mont_1,BN_value_one(),mont,ctx);
 293         BN_to_montgomery(w_1,w_1,mont,ctx);
 294         for (i=1; i < n; i++)
 295                 {
 296                 /* step 3 */
 297                 BN_rand(b,BN_num_bits(w)-2/*-1*/,0,0);
 298                 /* BN_set_word(b,0x10001L); */
 299
 300                 /* step 4 */
 301                 j=0;
 302                 if (!BN_mod_exp_mont(z,b,m,w,ctx,mont)) goto err;
 303
 304                 if (!BN_to_montgomery(z,z,mont,ctx)) goto err;
 305
 306                 /* step 5 */
 307                 for (;;)
 308                         {
 309                         if (((j == 0) && (BN_cmp(z,mont_1) == 0)) ||
 310                                 (BN_cmp(z,w_1) == 0))
 311                                 break;
 312
 313                         /* step 6 */
 314                         if ((j > 0) && (BN_cmp(z,mont_1) == 0))
 315                                 {
 316                                 ok=0;
 317                                 goto err;
 318                                 }
 319
 320                         j++;
 321                         if (j >= a)
 322                                 {
 323                                 ok=0;
 324                                 goto err;
 325                                 }
 326
 327                         if (!BN_mod_mul_montgomery(z,z,z,mont,ctx)) goto err;
 328                         if (callback != NULL) callback(1,j,cb_arg);
 329                         }
 330                 }
 331
 332         ok=1;
 333 err:
 334         if (ok == -1) DSAerr(DSA_F_DSA_IS_PRIME,ERR_R_BN_LIB);
 335         BN_CTX_free(ctx);
 336         BN_CTX_free(ctx2);
 337
 338         return(ok);
 339         }
 340