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 #ifdef OPENSSL_FIPS
  85 /* Workaround bug in prototype */
  86 #define fips_dsa_builtin_paramgen2 fips_dsa_paramgen_bad
  87 #include <openssl/fips.h>
  88 #endif
  89
  90 int DSA_generate_parameters_ex(DSA *ret, int bits,
  91                 const unsigned char *seed_in, int seed_len,
  92                 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
  93         {
  94 #ifdef OPENSSL_FIPS
  95         if (FIPS_mode() && !(ret->meth->flags & DSA_FLAG_FIPS_METHOD)
  96                         && !(ret->flags & DSA_FLAG_NON_FIPS_ALLOW))
  97                 {
  98                 DSAerr(DSA_F_DSA_GENERATE_PARAMETERS_EX, DSA_R_NON_FIPS_DSA_METHOD);
  99                 return 0;
 100                 }
 101 #endif
 102         if(ret->meth->dsa_paramgen)
 103                 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
 104                                 counter_ret, h_ret, cb);
 105 #ifdef OPENSSL_FIPS
 106         else if (FIPS_mode())
 107                 {
 108                 return FIPS_dsa_generate_parameters_ex(ret, bits,
 109                                                         seed_in, seed_len,
 110                                                         counter_ret, h_ret, cb);
 111                 }
 112 #endif
 113         else
 114                 {
 115                 const EVP_MD *evpmd;
 116                 size_t qbits = bits >= 2048 ? 256 : 160;
 117
 118                 if (bits >= 2048)
 119                         {
 120                         qbits = 256;
 121                         evpmd = EVP_sha256();
 122                         }
 123                 else
 124                         {
 125                         qbits = 160;
 126                         evpmd = EVP_sha1();
 127                         }
 128
 129                 return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
 130                         seed_in, seed_len, NULL, counter_ret, h_ret, cb);
 131                 }
 132         }
 133
 134 int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
 135         const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
 136         unsigned char *seed_out,
 137         int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
 138         {
 139         int ok=0;
 140         unsigned char seed[SHA256_DIGEST_LENGTH];
 141         unsigned char md[SHA256_DIGEST_LENGTH];
 142         unsigned char buf[SHA256_DIGEST_LENGTH],buf2[SHA256_DIGEST_LENGTH];
 143         BIGNUM *r0,*W,*X,*c,*test;
 144         BIGNUM *g=NULL,*q=NULL,*p=NULL;
 145         BN_MONT_CTX *mont=NULL;
 146         int i, k, n=0, m=0, qsize = qbits >> 3;
 147         int counter=0;
 148         int r=0;
 149         BN_CTX *ctx=NULL;
 150         unsigned int h=2;
 151
 152         if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
 153             qsize != SHA256_DIGEST_LENGTH)
 154                 /* invalid q size */
 155                 return 0;
 156
 157         if (evpmd == NULL)
 158                 /* use SHA1 as default */
 159                 evpmd = EVP_sha1();
 160
 161         if (bits < 512)
 162                 bits = 512;
 163
 164         bits = (bits+63)/64*64;
 165
 166         /* NB: seed_len == 0 is special case: copy generated seed to
 167          * seed_in if it is not NULL.
 168          */
 169         if (seed_len && (seed_len < (size_t)qsize))
 170                 seed_in = NULL;         /* seed buffer too small -- ignore */
 171         if (seed_len > (size_t)qsize)
 172                 seed_len = qsize;       /* App. 2.2 of FIPS PUB 186 allows larger SEED,
 173                                          * but our internal buffers are restricted to 160 bits*/
 174         if (seed_in != NULL)
 175                 memcpy(seed, seed_in, seed_len);
 176
 177         if ((ctx=BN_CTX_new()) == NULL)
 178                 goto err;
 179
 180         if ((mont=BN_MONT_CTX_new()) == NULL)
 181                 goto err;
 182
 183         BN_CTX_start(ctx);
 184         r0 = BN_CTX_get(ctx);
 185         g = BN_CTX_get(ctx);
 186         W = BN_CTX_get(ctx);
 187         q = BN_CTX_get(ctx);
 188         X = BN_CTX_get(ctx);
 189         c = BN_CTX_get(ctx);
 190         p = BN_CTX_get(ctx);
 191         test = BN_CTX_get(ctx);
 192
 193         if (!BN_lshift(test,BN_value_one(),bits-1))
 194                 goto err;
 195
 196         for (;;)
 197                 {
 198                 for (;;) /* find q */
 199                         {
 200                         int seed_is_random;
 201
 202                         /* step 1 */
 203                         if(!BN_GENCB_call(cb, 0, m++))
 204                                 goto err;
 205
 206                         if (!seed_len)
 207                                 {
 208                                 RAND_pseudo_bytes(seed, qsize);
 209                                 seed_is_random = 1;
 210                                 }
 211                         else
 212                                 {
 213                                 seed_is_random = 0;
 214                                 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
 215                                 }
 216                         memcpy(buf , seed, qsize);
 217                         memcpy(buf2, seed, qsize);
 218                         /* precompute "SEED + 1" for step 7: */
 219                         for (i = qsize-1; i >= 0; i--)
 220                                 {
 221                                 buf[i]++;
 222                                 if (buf[i] != 0)
 223                                         break;
 224                                 }
 225
 226                         /* step 2 */
 227                         if (!EVP_Digest(seed, qsize, md,   NULL, evpmd, NULL))
 228                                 goto err;
 229                         if (!EVP_Digest(buf,  qsize, buf2, NULL, evpmd, NULL))
 230                                 goto err;
 231                         for (i = 0; i < qsize; i++)
 232                                 md[i]^=buf2[i];
 233
 234                         /* step 3 */
 235                         md[0] |= 0x80;
 236                         md[qsize-1] |= 0x01;
 237                         if (!BN_bin2bn(md, qsize, q))
 238                                 goto err;
 239
 240                         /* step 4 */
 241                         r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
 242                                         seed_is_random, cb);
 243                         if (r > 0)
 244                                 break;
 245                         if (r != 0)
 246                                 goto err;
 247
 248                         /* do a callback call */
 249                         /* step 5 */
 250                         }
 251
 252                 if(!BN_GENCB_call(cb, 2, 0)) goto err;
 253                 if(!BN_GENCB_call(cb, 3, 0)) goto err;
 254
 255                 /* step 6 */
 256                 counter=0;
 257                 /* "offset = 2" */
 258
 259                 n=(bits-1)/160;
 260
 261                 for (;;)
 262                         {
 263                         if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 264                                 goto err;
 265
 266                         /* step 7 */
 267                         BN_zero(W);
 268                         /* now 'buf' contains "SEED + offset - 1" */
 269                         for (k=0; k<=n; k++)
 270                                 {
 271                                 /* obtain "SEED + offset + k" by incrementing: */
 272                                 for (i = qsize-1; i >= 0; i--)
 273                                         {
 274                                         buf[i]++;
 275                                         if (buf[i] != 0)
 276                                                 break;
 277                                         }
 278
 279                                 if (!EVP_Digest(buf, qsize, md ,NULL, evpmd,
 280                                                                         NULL))
 281                                         goto err;
 282
 283                                 /* step 8 */
 284                                 if (!BN_bin2bn(md, qsize, r0))
 285                                         goto err;
 286                                 if (!BN_lshift(r0,r0,(qsize << 3)*k)) goto err;
 287                                 if (!BN_add(W,W,r0)) goto err;
 288                                 }
 289
 290                         /* more of step 8 */
 291                         if (!BN_mask_bits(W,bits-1)) goto err;
 292                         if (!BN_copy(X,W)) goto err;
 293                         if (!BN_add(X,X,test)) goto err;
 294
 295                         /* step 9 */
 296                         if (!BN_lshift1(r0,q)) goto err;
 297                         if (!BN_mod(c,X,r0,ctx)) goto err;
 298                         if (!BN_sub(r0,c,BN_value_one())) goto err;
 299                         if (!BN_sub(p,X,r0)) goto err;
 300
 301                         /* step 10 */
 302                         if (BN_cmp(p,test) >= 0)
 303                                 {
 304                                 /* step 11 */
 305                                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
 306                                                 ctx, 1, cb);
 307                                 if (r > 0)
 308                                                 goto end; /* found it */
 309                                 if (r != 0)
 310                                         goto err;
 311                                 }
 312
 313                         /* step 13 */
 314                         counter++;
 315                         /* "offset = offset + n + 1" */
 316
 317                         /* step 14 */
 318                         if (counter >= 4096) break;
 319                         }
 320                 }
 321 end:
 322         if(!BN_GENCB_call(cb, 2, 1))
 323                 goto err;
 324
 325         /* We now need to generate g */
 326         /* Set r0=(p-1)/q */
 327         if (!BN_sub(test,p,BN_value_one())) goto err;
 328         if (!BN_div(r0,NULL,test,q,ctx)) goto err;
 329
 330         if (!BN_set_word(test,h)) goto err;
 331         if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
 332
 333         for (;;)
 334                 {
 335                 /* g=test^r0%p */
 336                 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
 337                 if (!BN_is_one(g)) break;
 338                 if (!BN_add(test,test,BN_value_one())) goto err;
 339                 h++;
 340                 }
 341
 342         if(!BN_GENCB_call(cb, 3, 1))
 343                 goto err;
 344
 345         ok=1;
 346 err:
 347         if (ok)
 348                 {
 349                 if(ret->p) BN_free(ret->p);
 350                 if(ret->q) BN_free(ret->q);
 351                 if(ret->g) BN_free(ret->g);
 352                 ret->p=BN_dup(p);
 353                 ret->q=BN_dup(q);
 354                 ret->g=BN_dup(g);
 355                 if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
 356                         {
 357                         ok=0;
 358                         goto err;
 359                         }
 360                 if (counter_ret != NULL) *counter_ret=counter;
 361                 if (h_ret != NULL) *h_ret=h;
 362                 if (seed_out)
 363                         memcpy(seed_out, seed, qsize);
 364                 }
 365         if(ctx)
 366                 {
 367                 BN_CTX_end(ctx);
 368                 BN_CTX_free(ctx);
 369                 }
 370         if (mont != NULL) BN_MONT_CTX_free(mont);
 371         return ok;
 372         }
 373
 374 #ifdef OPENSSL_FIPS
 375 #undef fips_dsa_builtin_paramgen2
 376 extern int fips_dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
 377         const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
 378         int idx, unsigned char *seed_out,
 379         int *counter_ret, unsigned long *h_ret, BN_GENCB *cb);
 380 #endif
 381
 382 /* This is a parameter generation algorithm for the DSA2 algorithm as
 383  * described in FIPS 186-3.
 384  */
 385
 386 int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
 387         const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
 388         int idx, unsigned char *seed_out,
 389         int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
 390         {
 391         int ok=-1;
 392         unsigned char *seed = NULL, *seed_tmp = NULL;
 393         unsigned char md[EVP_MAX_MD_SIZE];
 394         int mdsize;
 395         BIGNUM *r0,*W,*X,*c,*test;
 396         BIGNUM *g=NULL,*q=NULL,*p=NULL;
 397         BN_MONT_CTX *mont=NULL;
 398         int i, k, n=0, m=0, qsize = N >> 3;
 399         int counter=0;
 400         int r=0;
 401         BN_CTX *ctx=NULL;
 402         EVP_MD_CTX mctx;
 403         unsigned int h=2;
 404
 405 #ifdef OPENSSL_FIPS
 406
 407         if (FIPS_mode())
 408                 return fips_dsa_builtin_paramgen2(ret, L, N, evpmd,
 409                                                   seed_in, seed_len, idx,
 410                                                   seed_out, counter_ret,
 411                                                   h_ret, cb);
 412 #endif
 413
 414         EVP_MD_CTX_init(&mctx);
 415
 416         if (evpmd == NULL)
 417                 {
 418                 if (N == 160)
 419                         evpmd = EVP_sha1();
 420                 else if (N == 224)
 421                         evpmd = EVP_sha224();
 422                 else
 423                         evpmd = EVP_sha256();
 424                 }
 425
 426         mdsize = EVP_MD_size(evpmd);
 427         /* If unverificable g generation only don't need seed */
 428         if (!ret->p || !ret->q || idx >= 0)
 429                 {
 430                 if (seed_len == 0)
 431                         seed_len = mdsize;
 432
 433                 seed = OPENSSL_malloc(seed_len);
 434
 435                 if (seed_out)
 436                         seed_tmp = seed_out;
 437                 else
 438                         seed_tmp = OPENSSL_malloc(seed_len);
 439
 440                 if (!seed || !seed_tmp)
 441                         goto err;
 442
 443                 if (seed_in)
 444                         memcpy(seed, seed_in, seed_len);
 445
 446                 }
 447
 448         if ((ctx=BN_CTX_new()) == NULL)
 449                 goto err;
 450
 451         if ((mont=BN_MONT_CTX_new()) == NULL)
 452                 goto err;
 453
 454         BN_CTX_start(ctx);
 455         r0 = BN_CTX_get(ctx);
 456         g = BN_CTX_get(ctx);
 457         W = BN_CTX_get(ctx);
 458         X = BN_CTX_get(ctx);
 459         c = BN_CTX_get(ctx);
 460         test = BN_CTX_get(ctx);
 461
 462         /* if p, q already supplied generate g only */
 463         if (ret->p && ret->q)
 464                 {
 465                 p = ret->p;
 466                 q = ret->q;
 467                 if (idx >= 0)
 468                         memcpy(seed_tmp, seed, seed_len);
 469                 goto g_only;
 470                 }
 471         else
 472                 {
 473                 p = BN_CTX_get(ctx);
 474                 q = BN_CTX_get(ctx);
 475                 }
 476
 477         if (!BN_lshift(test,BN_value_one(),L-1))
 478                 goto err;
 479         for (;;)
 480                 {
 481                 for (;;) /* find q */
 482                         {
 483                         unsigned char *pmd;
 484                         /* step 1 */
 485                         if(!BN_GENCB_call(cb, 0, m++))
 486                                 goto err;
 487
 488                         if (!seed_in)
 489                                 {
 490                                 if (RAND_pseudo_bytes(seed, seed_len) < 0)
 491                                         goto err;
 492                                 }
 493                         /* step 2 */
 494                         if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL))
 495                                 goto err;
 496                         /* Take least significant bits of md */
 497                         if (mdsize > qsize)
 498                                 pmd = md + mdsize - qsize;
 499                         else
 500                                 pmd = md;
 501
 502                         if (mdsize < qsize)
 503                                 memset(md + mdsize, 0, qsize - mdsize);
 504
 505                         /* step 3 */
 506                         pmd[0] |= 0x80;
 507                         pmd[qsize-1] |= 0x01;
 508                         if (!BN_bin2bn(pmd, qsize, q))
 509                                 goto err;
 510
 511                         /* step 4 */
 512                         r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
 513                                         seed_in ? 1 : 0, cb);
 514                         if (r > 0)
 515                                 break;
 516                         if (r != 0)
 517                                 goto err;
 518                         /* Provided seed didn't produce a prime: error */
 519                         if (seed_in)
 520                                 {
 521                                 ok = 0;
 522                                 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_Q_NOT_PRIME);
 523                                 goto err;
 524                                 }
 525
 526                         /* do a callback call */
 527                         /* step 5 */
 528                         }
 529                 /* Copy seed to seed_out before we mess with it */
 530                 if (seed_out)
 531                         memcpy(seed_out, seed, seed_len);
 532
 533                 if(!BN_GENCB_call(cb, 2, 0)) goto err;
 534                 if(!BN_GENCB_call(cb, 3, 0)) goto err;
 535
 536                 /* step 6 */
 537                 counter=0;
 538                 /* "offset = 1" */
 539
 540                 n=(L-1)/(mdsize << 3);
 541
 542                 for (;;)
 543                         {
 544                         if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 545                                 goto err;
 546
 547                         /* step 7 */
 548                         BN_zero(W);
 549                         /* now 'buf' contains "SEED + offset - 1" */
 550                         for (k=0; k<=n; k++)
 551                                 {
 552                                 /* obtain "SEED + offset + k" by incrementing: */
 553                                 for (i = seed_len-1; i >= 0; i--)
 554                                         {
 555                                         seed[i]++;
 556                                         if (seed[i] != 0)
 557                                                 break;
 558                                         }
 559
 560                                 if (!EVP_Digest(seed, seed_len, md ,NULL, evpmd,
 561                                                                         NULL))
 562                                         goto err;
 563
 564                                 /* step 8 */
 565                                 if (!BN_bin2bn(md, mdsize, r0))
 566                                         goto err;
 567                                 if (!BN_lshift(r0,r0,(mdsize << 3)*k)) goto err;
 568                                 if (!BN_add(W,W,r0)) goto err;
 569                                 }
 570
 571                         /* more of step 8 */
 572                         if (!BN_mask_bits(W,L-1)) goto err;
 573                         if (!BN_copy(X,W)) goto err;
 574                         if (!BN_add(X,X,test)) goto err;
 575
 576                         /* step 9 */
 577                         if (!BN_lshift1(r0,q)) goto err;
 578                         if (!BN_mod(c,X,r0,ctx)) goto err;
 579                         if (!BN_sub(r0,c,BN_value_one())) goto err;
 580                         if (!BN_sub(p,X,r0)) goto err;
 581
 582                         /* step 10 */
 583                         if (BN_cmp(p,test) >= 0)
 584                                 {
 585                                 /* step 11 */
 586                                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
 587                                                 ctx, 1, cb);
 588                                 if (r > 0)
 589                                                 goto end; /* found it */
 590                                 if (r != 0)
 591                                         goto err;
 592                                 }
 593
 594                         /* step 13 */
 595                         counter++;
 596                         /* "offset = offset + n + 1" */
 597
 598                         /* step 14 */
 599                         if (counter >= (int)(4 * L)) break;
 600                         }
 601                 if (seed_in)
 602                         {
 603                         ok = 0;
 604                         DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS);
 605                         goto err;
 606                         }
 607                 }
 608 end:
 609         if(!BN_GENCB_call(cb, 2, 1))
 610                 goto err;
 611
 612         g_only:
 613
 614         /* We now need to generate g */
 615         /* Set r0=(p-1)/q */
 616         if (!BN_sub(test,p,BN_value_one())) goto err;
 617         if (!BN_div(r0,NULL,test,q,ctx)) goto err;
 618
 619         if (idx < 0)
 620                 {
 621                 if (!BN_set_word(test,h))
 622                         goto err;
 623                 }
 624         else
 625                 h = 1;
 626         if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
 627
 628         for (;;)
 629                 {
 630                 static const unsigned char ggen[4] = {0x67,0x67,0x65,0x6e};
 631                 if (idx >= 0)
 632                         {
 633                         md[0] = idx & 0xff;
 634                         md[1] = (h >> 8) & 0xff;
 635                         md[2] = h & 0xff;
 636                         if (!EVP_DigestInit_ex(&mctx, evpmd, NULL))
 637                                 goto err;
 638                         if (!EVP_DigestUpdate(&mctx, seed_tmp, seed_len))
 639                                 goto err;
 640                         if (!EVP_DigestUpdate(&mctx, ggen, sizeof(ggen)))
 641                                 goto err;
 642                         if (!EVP_DigestUpdate(&mctx, md, 3))
 643                                 goto err;
 644                         if (!EVP_DigestFinal_ex(&mctx, md, NULL))
 645                                 goto err;
 646                         if (!BN_bin2bn(md, mdsize, test))
 647                                 goto err;
 648                         }
 649                 /* g=test^r0%p */
 650                 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
 651                 if (!BN_is_one(g)) break;
 652                 if (idx < 0 && !BN_add(test,test,BN_value_one())) goto err;
 653                 h++;
 654                 if ( idx >= 0 && h > 0xffff)
 655                         goto err;
 656                 }
 657
 658         if(!BN_GENCB_call(cb, 3, 1))
 659                 goto err;
 660
 661         ok=1;
 662 err:
 663         if (ok == 1)
 664                 {
 665                 if (p != ret->p)
 666                         {
 667                         if(ret->p) BN_free(ret->p);
 668                         ret->p=BN_dup(p);
 669                         }
 670                 if (q != ret->q)
 671                         {
 672                         if(ret->q) BN_free(ret->q);
 673                         ret->q=BN_dup(q);
 674                         }
 675                 if(ret->g) BN_free(ret->g);
 676                 ret->g=BN_dup(g);
 677                 if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
 678                         {
 679                         ok=-1;
 680                         goto err;
 681                         }
 682                 if (counter_ret != NULL) *counter_ret=counter;
 683                 if (h_ret != NULL) *h_ret=h;
 684                 }
 685         if (seed)
 686                 OPENSSL_free(seed);
 687         if (seed_out != seed_tmp)
 688                 OPENSSL_free(seed_tmp);
 689         if(ctx)
 690                 {
 691                 BN_CTX_end(ctx);
 692                 BN_CTX_free(ctx);
 693                 }
 694         if (mont != NULL) BN_MONT_CTX_free(mont);
 695         EVP_MD_CTX_cleanup(&mctx);
 696         return ok;
 697         }
 698
 699 int dsa_paramgen_check_g(DSA *dsa)
 700         {
 701         BN_CTX *ctx;
 702         BIGNUM *tmp;
 703         BN_MONT_CTX *mont = NULL;
 704         int rv = -1;
 705         ctx = BN_CTX_new();
 706         if (!ctx)
 707                 return -1;
 708         BN_CTX_start(ctx);
 709         if (BN_cmp(dsa->g, BN_value_one()) <= 0)
 710                 return 0;
 711         if (BN_cmp(dsa->g, dsa->p) >= 0)
 712                 return 0;
 713         tmp = BN_CTX_get(ctx);
 714         if (!tmp)
 715                 goto err;
 716         if ((mont=BN_MONT_CTX_new()) == NULL)
 717                 goto err;
 718         if (!BN_MONT_CTX_set(mont,dsa->p,ctx))
 719                 goto err;
 720         /* Work out g^q mod p */
 721         if (!BN_mod_exp_mont(tmp,dsa->g,dsa->q, dsa->p, ctx, mont))
 722                 goto err;
 723         if (!BN_cmp(tmp, BN_value_one()))
 724                 rv = 1;
 725         else
 726                 rv = 0;
 727         err:
 728         BN_CTX_end(ctx);
 729         if (mont)
 730                 BN_MONT_CTX_free(mont);
 731         BN_CTX_free(ctx);
 732         return rv;
 733
 734         }
 735 #endif