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 /* Parameter generation follows the original release of FIPS PUB 186,
  63  * Appendix 2.2 (i.e. use SHA as defined in FIPS PUB 180) */
  64 #define HASH    SHA
  65 #else
  66 /* Parameter generation follows the updated Appendix 2.2 for FIPS PUB 186,
  67  * also Appendix 2.2 of FIPS PUB 186-1 (i.e. use SHA as defined in
  68  * FIPS PUB 180-1) */
  69 #define HASH    SHA1
  70 #endif
  71
  72 #ifndef NO_SHA
  73
  74 #include <stdio.h>
  75 #include <time.h>
  76 #include "cryptlib.h"
  77 #include <openssl/sha.h>
  78 #include <openssl/bn.h>
  79 #include <openssl/dsa.h>
  80 #include <openssl/rand.h>
  81
  82 DSA *DSA_generate_parameters(int bits, unsigned char *seed_in, int seed_len,
  83                 int *counter_ret, unsigned long *h_ret,
  84                 void (*callback)(int, int, void *),
  85                 void *cb_arg)
  86         {
  87         int ok=0;
  88         unsigned char seed[SHA_DIGEST_LENGTH];
  89         unsigned char md[SHA_DIGEST_LENGTH];
  90         unsigned char buf[SHA_DIGEST_LENGTH],buf2[SHA_DIGEST_LENGTH];
  91         BIGNUM *r0,*W,*X,*c,*test;
  92         BIGNUM *g=NULL,*q=NULL,*p=NULL;
  93         BN_MONT_CTX *mont=NULL;
  94         int k,n=0,i,b,m=0;
  95         int counter=0;
  96         int r=0;
  97         BN_CTX *ctx=NULL,*ctx2=NULL,*ctx3=NULL;
  98         unsigned int h=2;
  99         DSA *ret=NULL;
 100
 101         if (bits < 512) bits=512;
 102         bits=(bits+63)/64*64;
 103
 104         if (seed_len < 20)
 105                 seed_in = NULL; /* seed buffer too small -- ignore */
 106         if (seed_len > 20)
 107                 seed_len = 20; /* App. 2.2 of FIPS PUB 186 allows larger SEED,
 108                                 * but our internal buffers are restricted to 160 bits*/
 109         if ((seed_in != NULL) && (seed_len == 20))
 110                 memcpy(seed,seed_in,seed_len);
 111
 112         if ((ctx=BN_CTX_new()) == NULL) goto err;
 113         if ((ctx2=BN_CTX_new()) == NULL) goto err;
 114         if ((ctx3=BN_CTX_new()) == NULL) goto err;
 115         if ((ret=DSA_new()) == NULL) goto err;
 116
 117         if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
 118
 119         r0= &(ctx2->bn[0]);
 120         g= &(ctx2->bn[1]);
 121         W= &(ctx2->bn[2]);
 122         q= &(ctx2->bn[3]);
 123         X= &(ctx2->bn[4]);
 124         c= &(ctx2->bn[5]);
 125         p= &(ctx2->bn[6]);
 126         test= &(ctx2->bn[7]);
 127
 128         BN_lshift(test,BN_value_one(),bits-1);
 129
 130         for (;;)
 131                 {
 132                 for (;;) /* find q */
 133                         {
 134                         int seed_is_random;
 135
 136                         /* step 1 */
 137                         if (callback != NULL) callback(0,m++,cb_arg);
 138
 139                         if (!seed_len)
 140                                 {
 141                                 RAND_pseudo_bytes(seed,SHA_DIGEST_LENGTH);
 142                                 seed_is_random = 1;
 143                                 }
 144                         else
 145                                 {
 146                                 seed_is_random = 0;
 147                                 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
 148                                 }
 149                         memcpy(buf,seed,SHA_DIGEST_LENGTH);
 150                         memcpy(buf2,seed,SHA_DIGEST_LENGTH);
 151                         /* precompute "SEED + 1" for step 7: */
 152                         for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
 153                                 {
 154                                 buf[i]++;
 155                                 if (buf[i] != 0) break;
 156                                 }
 157
 158                         /* step 2 */
 159                         HASH(seed,SHA_DIGEST_LENGTH,md);
 160                         HASH(buf,SHA_DIGEST_LENGTH,buf2);
 161                         for (i=0; i<SHA_DIGEST_LENGTH; i++)
 162                                 md[i]^=buf2[i];
 163
 164                         /* step 3 */
 165                         md[0]|=0x80;
 166                         md[SHA_DIGEST_LENGTH-1]|=0x01;
 167                         if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,q)) goto err;
 168
 169                         /* step 4 */
 170                         r = BN_is_prime_fasttest(q, DSS_prime_checks, callback, ctx3, cb_arg, seed_is_random);
 171                         if (ctx3->tos)
 172                                 goto err;
 173                         if (r > 0)
 174                                 break;
 175                         if (r != 0)
 176                                 goto err;
 177
 178                         /* do a callback call */
 179                         /* step 5 */
 180                         }
 181
 182                 if (callback != NULL) callback(2,0,cb_arg);
 183                 if (callback != NULL) callback(3,0,cb_arg);
 184
 185                 /* step 6 */
 186                 counter=0;
 187                 /* "offset = 2" */
 188
 189                 n=(bits-1)/160;
 190                 b=(bits-1)-n*160;
 191
 192                 for (;;)
 193                         {
 194                         if (callback != NULL && counter != 0)
 195                                 callback(0,counter,cb_arg);
 196
 197                         /* step 7 */
 198                         BN_zero(W);
 199                         /* now 'buf' contains "SEED + offset - 1" */
 200                         for (k=0; k<=n; k++)
 201                                 {
 202                                 /* obtain "SEED + offset + k" by incrementing: */
 203                                 for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
 204                                         {
 205                                         buf[i]++;
 206                                         if (buf[i] != 0) break;
 207                                         }
 208
 209                                 HASH(buf,SHA_DIGEST_LENGTH,md);
 210
 211                                 /* step 8 */
 212                                 if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,r0))
 213                                         goto err;
 214                                 BN_lshift(r0,r0,160*k);
 215                                 BN_add(W,W,r0);
 216                                 }
 217
 218                         /* more of step 8 */
 219                         BN_mask_bits(W,bits-1);
 220                         BN_copy(X,W); /* this should be ok */
 221                         BN_add(X,X,test); /* this should be ok */
 222
 223                         /* step 9 */
 224                         BN_lshift1(r0,q);
 225                         BN_mod(c,X,r0,ctx);
 226                         BN_sub(r0,c,BN_value_one());
 227                         BN_sub(p,X,r0);
 228
 229                         /* step 10 */
 230                         if (BN_cmp(p,test) >= 0)
 231                                 {
 232                                 /* step 11 */
 233                                 r = BN_is_prime_fasttest(p, DSS_prime_checks, callback, ctx3, cb_arg, 1);
 234                                 if (r > 0)
 235                                                 goto end; /* found it */
 236                                 if (r != 0)
 237                                         goto err;
 238                                 }
 239
 240                         /* step 13 */
 241                         counter++;
 242                         /* "offset = offset + n + 1" */
 243
 244                         /* step 14 */
 245                         if (counter >= 4096) break;
 246                         }
 247                 }
 248 end:
 249         if (callback != NULL) callback(2,1,cb_arg);
 250
 251         /* We now need to generate g */
 252         /* Set r0=(p-1)/q */
 253         BN_sub(test,p,BN_value_one());
 254         BN_div(r0,NULL,test,q,ctx);
 255
 256         BN_set_word(test,h);
 257         BN_MONT_CTX_set(mont,p,ctx);
 258
 259         for (;;)
 260                 {
 261                 /* g=test^r0%p */
 262                 BN_mod_exp_mont(g,test,r0,p,ctx,mont);
 263                 if (!BN_is_one(g)) break;
 264                 BN_add(test,test,BN_value_one());
 265                 h++;
 266                 }
 267
 268         if (callback != NULL) callback(3,1,cb_arg);
 269
 270         ok=1;
 271 err:
 272         if (!ok)
 273                 {
 274                 if (ret != NULL) DSA_free(ret);
 275                 }
 276         else
 277                 {
 278                 ret->p=BN_dup(p);
 279                 ret->q=BN_dup(q);
 280                 ret->g=BN_dup(g);
 281                 if ((m > 1) && (seed_in != NULL)) memcpy(seed_in,seed,20);
 282                 if (counter_ret != NULL) *counter_ret=counter;
 283                 if (h_ret != NULL) *h_ret=h;
 284                 }
 285         if (ctx != NULL) BN_CTX_free(ctx);
 286         if (ctx2 != NULL) BN_CTX_free(ctx2);
 287         if (ctx3 != NULL) BN_CTX_free(ctx3);
 288         if (mont != NULL) BN_MONT_CTX_free(mont);
 289         return(ok?ret:NULL);
 290         }
 291 #endif