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    EVP_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    EVP_sha1()
  70 #endif
  71
  72 #include <openssl/opensslconf.h> /* To see if OPENSSL_NO_SHA is defined */
  73
  74 #ifndef OPENSSL_NO_SHA
  75
  76 #include <stdio.h>
  77 #include "cryptlib.h"
  78 #include <openssl/evp.h>
  79 #include <openssl/bn.h>
  80 #include <openssl/rand.h>
  81 #include <openssl/sha.h>
  82 #include "dsa_locl.h"
  83
  84 int DSA_generate_parameters_ex(DSA *ret, int bits,
  85                 const unsigned char *seed_in, int seed_len,
  86                 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
  87         {
  88         if(ret->meth->dsa_paramgen)
  89                 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
  90                                 counter_ret, h_ret, cb);
  91         else
  92                 {
  93                 const EVP_MD *evpmd;
  94                 size_t qbits = bits >= 2048 ? 256 : 160;
  95
  96                 if (bits >= 2048)
  97                         {
  98                         qbits = 256;
  99                         evpmd = EVP_sha256();
 100                         }
 101                 else
 102                         {
 103                         qbits = 160;
 104                         evpmd = EVP_sha1();
 105                         }
 106
 107                 return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
 108                                 seed_in, seed_len, counter_ret, h_ret, cb);
 109                 }
 110         }
 111
 112 int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
 113         const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
 114         int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
 115         {
 116         int ok=0;
 117         unsigned char seed[SHA256_DIGEST_LENGTH];
 118         unsigned char md[SHA256_DIGEST_LENGTH];
 119         unsigned char buf[SHA256_DIGEST_LENGTH],buf2[SHA256_DIGEST_LENGTH];
 120         BIGNUM *r0,*W,*X,*c,*test;
 121         BIGNUM *g=NULL,*q=NULL,*p=NULL;
 122         BN_MONT_CTX *mont=NULL;
 123         int i, k,n=0,b,m=0, qsize = qbits >> 3;
 124         int counter=0;
 125         int r=0;
 126         BN_CTX *ctx=NULL;
 127         unsigned int h=2;
 128
 129         if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
 130             qsize != SHA256_DIGEST_LENGTH)
 131                 /* invalid q size */
 132                 return 0;
 133
 134         if (evpmd == NULL)
 135                 /* use SHA1 as default */
 136                 evpmd = EVP_sha1();
 137
 138         if (bits < 512)
 139                 bits = 512;
 140
 141         bits = (bits+63)/64*64;
 142
 143         /* NB: seed_len == 0 is special case: copy generated seed to
 144          * seed_in if it is not NULL.
 145          */
 146         if (seed_len && (seed_len < (size_t)qsize))
 147                 seed_in = NULL;         /* seed buffer too small -- ignore */
 148         if (seed_len > (size_t)qsize)
 149                 seed_len = qsize;       /* App. 2.2 of FIPS PUB 186 allows larger SEED,
 150                                          * but our internal buffers are restricted to 160 bits*/
 151         if (seed_in != NULL)
 152                 memcpy(seed, seed_in, seed_len);
 153
 154         if ((ctx=BN_CTX_new()) == NULL)
 155                 goto err;
 156
 157         if ((mont=BN_MONT_CTX_new()) == NULL)
 158                 goto err;
 159
 160         BN_CTX_start(ctx);
 161         r0 = BN_CTX_get(ctx);
 162         g = BN_CTX_get(ctx);
 163         W = BN_CTX_get(ctx);
 164         q = BN_CTX_get(ctx);
 165         X = BN_CTX_get(ctx);
 166         c = BN_CTX_get(ctx);
 167         p = BN_CTX_get(ctx);
 168         test = BN_CTX_get(ctx);
 169
 170         if (!BN_lshift(test,BN_value_one(),bits-1))
 171                 goto err;
 172
 173         for (;;)
 174                 {
 175                 for (;;) /* find q */
 176                         {
 177                         int seed_is_random;
 178
 179                         /* step 1 */
 180                         if(!BN_GENCB_call(cb, 0, m++))
 181                                 goto err;
 182
 183                         if (!seed_len)
 184                                 {
 185                                 RAND_pseudo_bytes(seed, qsize);
 186                                 seed_is_random = 1;
 187                                 }
 188                         else
 189                                 {
 190                                 seed_is_random = 0;
 191                                 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
 192                                 }
 193                         memcpy(buf , seed, qsize);
 194                         memcpy(buf2, seed, qsize);
 195                         /* precompute "SEED + 1" for step 7: */
 196                         for (i = qsize-1; i >= 0; i--)
 197                                 {
 198                                 buf[i]++;
 199                                 if (buf[i] != 0)
 200                                         break;
 201                                 }
 202
 203                         /* step 2 */
 204                         EVP_Digest(seed, qsize, md,   NULL, evpmd, NULL);
 205                         EVP_Digest(buf,  qsize, buf2, NULL, evpmd, NULL);
 206                         for (i = 0; i < qsize; i++)
 207                                 md[i]^=buf2[i];
 208
 209                         /* step 3 */
 210                         md[0] |= 0x80;
 211                         md[qsize-1] |= 0x01;
 212                         if (!BN_bin2bn(md, qsize, q))
 213                                 goto err;
 214
 215                         /* step 4 */
 216                         r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
 217                                         seed_is_random, cb);
 218                         if (r > 0)
 219                                 break;
 220                         if (r != 0)
 221                                 goto err;
 222
 223                         /* do a callback call */
 224                         /* step 5 */
 225                         }
 226
 227                 if(!BN_GENCB_call(cb, 2, 0)) goto err;
 228                 if(!BN_GENCB_call(cb, 3, 0)) goto err;
 229
 230                 /* step 6 */
 231                 counter=0;
 232                 /* "offset = 2" */
 233
 234                 n=(bits-1)/160;
 235                 b=(bits-1)-n*160;
 236
 237                 for (;;)
 238                         {
 239                         if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 240                                 goto err;
 241
 242                         /* step 7 */
 243                         BN_zero(W);
 244                         /* now 'buf' contains "SEED + offset - 1" */
 245                         for (k=0; k<=n; k++)
 246                                 {
 247                                 /* obtain "SEED + offset + k" by incrementing: */
 248                                 for (i = qsize-1; i >= 0; i--)
 249                                         {
 250                                         buf[i]++;
 251                                         if (buf[i] != 0)
 252                                                 break;
 253                                         }
 254
 255                                 EVP_Digest(buf, qsize, md ,NULL, evpmd, NULL);
 256
 257                                 /* step 8 */
 258                                 if (!BN_bin2bn(md, qsize, r0))
 259                                         goto err;
 260                                 if (!BN_lshift(r0,r0,(qsize << 3)*k)) goto err;
 261                                 if (!BN_add(W,W,r0)) goto err;
 262                                 }
 263
 264                         /* more of step 8 */
 265                         if (!BN_mask_bits(W,bits-1)) goto err;
 266                         if (!BN_copy(X,W)) goto err;
 267                         if (!BN_add(X,X,test)) goto err;
 268
 269                         /* step 9 */
 270                         if (!BN_lshift1(r0,q)) goto err;
 271                         if (!BN_mod(c,X,r0,ctx)) goto err;
 272                         if (!BN_sub(r0,c,BN_value_one())) goto err;
 273                         if (!BN_sub(p,X,r0)) goto err;
 274
 275                         /* step 10 */
 276                         if (BN_cmp(p,test) >= 0)
 277                                 {
 278                                 /* step 11 */
 279                                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
 280                                                 ctx, 1, cb);
 281                                 if (r > 0)
 282                                                 goto end; /* found it */
 283                                 if (r != 0)
 284                                         goto err;
 285                                 }
 286
 287                         /* step 13 */
 288                         counter++;
 289                         /* "offset = offset + n + 1" */
 290
 291                         /* step 14 */
 292                         if (counter >= 4096) break;
 293                         }
 294                 }
 295 end:
 296         if(!BN_GENCB_call(cb, 2, 1))
 297                 goto err;
 298
 299         /* We now need to generate g */
 300         /* Set r0=(p-1)/q */
 301         if (!BN_sub(test,p,BN_value_one())) goto err;
 302         if (!BN_div(r0,NULL,test,q,ctx)) goto err;
 303
 304         if (!BN_set_word(test,h)) goto err;
 305         if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
 306
 307         for (;;)
 308                 {
 309                 /* g=test^r0%p */
 310                 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
 311                 if (!BN_is_one(g)) break;
 312                 if (!BN_add(test,test,BN_value_one())) goto err;
 313                 h++;
 314                 }
 315
 316         if(!BN_GENCB_call(cb, 3, 1))
 317                 goto err;
 318
 319         ok=1;
 320 err:
 321         if (ok)
 322                 {
 323                 if(ret->p) BN_free(ret->p);
 324                 if(ret->q) BN_free(ret->q);
 325                 if(ret->g) BN_free(ret->g);
 326                 ret->p=BN_dup(p);
 327                 ret->q=BN_dup(q);
 328                 ret->g=BN_dup(g);
 329                 if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
 330                         {
 331                         ok=0;
 332                         goto err;
 333                         }
 334                 if (counter_ret != NULL) *counter_ret=counter;
 335                 if (h_ret != NULL) *h_ret=h;
 336                 }
 337         if(ctx)
 338                 {
 339                 BN_CTX_end(ctx);
 340                 BN_CTX_free(ctx);
 341                 }
 342         if (mont != NULL) BN_MONT_CTX_free(mont);
 343         return ok;
 344         }
 345 #endif