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 #define OPENSSL_FIPSAPI
  77
  78 #include <stdio.h>
  79 #include "cryptlib.h"
  80 #include <openssl/evp.h>
  81 #include <openssl/bn.h>
  82 #include <openssl/rand.h>
  83 #include <openssl/sha.h>
  84 #ifdef OPENSSL_FIPS
  85 #include <openssl/fips.h>
  86 #include <openssl/fips_rand.h>
  87 #endif
  88
  89 #include "dsa_locl.h"
  90
  91 int DSA_generate_parameters_ex(DSA *ret, int bits,
  92                 const unsigned char *seed_in, int seed_len,
  93                 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
  94         {
  95         if(ret->meth->dsa_paramgen)
  96                 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
  97                                 counter_ret, h_ret, cb);
  98         else
  99                 {
 100                 const EVP_MD *evpmd;
 101                 size_t qbits = bits >= 2048 ? 256 : 160;
 102
 103                 if (bits >= 2048)
 104                         {
 105                         qbits = 256;
 106                         evpmd = EVP_sha256();
 107                         }
 108                 else
 109                         {
 110                         qbits = 160;
 111                         evpmd = EVP_sha1();
 112                         }
 113
 114                 return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
 115                         seed_in, seed_len, NULL, counter_ret, h_ret, cb);
 116                 }
 117         }
 118
 119 int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
 120         const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
 121         unsigned char *seed_out,
 122         int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
 123         {
 124         int ok=0;
 125         unsigned char seed[SHA256_DIGEST_LENGTH];
 126         unsigned char md[SHA256_DIGEST_LENGTH];
 127         unsigned char buf[SHA256_DIGEST_LENGTH],buf2[SHA256_DIGEST_LENGTH];
 128         BIGNUM *r0,*W,*X,*c,*test;
 129         BIGNUM *g=NULL,*q=NULL,*p=NULL;
 130         BN_MONT_CTX *mont=NULL;
 131         int i, k, n=0, m=0, qsize = qbits >> 3;
 132         int counter=0;
 133         int r=0;
 134         BN_CTX *ctx=NULL;
 135         unsigned int h=2;
 136
 137 #ifdef OPENSSL_FIPS
 138         if(FIPS_selftest_failed())
 139             {
 140             FIPSerr(FIPS_F_DSA_BUILTIN_PARAMGEN, FIPS_R_FIPS_SELFTEST_FAILED);
 141             goto err;
 142             }
 143
 144         if (FIPS_mode() && !(ret->flags & DSA_FLAG_NON_FIPS_ALLOW)
 145                         && (bits < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS))
 146                 {
 147                 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN, DSA_R_KEY_SIZE_TOO_SMALL);
 148                 goto err;
 149                 }
 150 #endif
 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                                 if (RAND_pseudo_bytes(seed, qsize) < 0)
 209                                         goto err;
 210                                 seed_is_random = 1;
 211                                 }
 212                         else
 213                                 {
 214                                 seed_is_random = 0;
 215                                 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
 216                                 }
 217                         memcpy(buf , seed, qsize);
 218                         memcpy(buf2, seed, qsize);
 219                         /* precompute "SEED + 1" for step 7: */
 220                         for (i = qsize-1; i >= 0; i--)
 221                                 {
 222                                 buf[i]++;
 223                                 if (buf[i] != 0)
 224                                         break;
 225                                 }
 226
 227                         /* step 2 */
 228                         if (!EVP_Digest(seed, qsize, md,   NULL, evpmd, NULL))
 229                                 goto err;
 230                         if (!EVP_Digest(buf,  qsize, buf2, NULL, evpmd, NULL))
 231                                 goto err;
 232                         for (i = 0; i < qsize; i++)
 233                                 md[i]^=buf2[i];
 234
 235                         /* step 3 */
 236                         md[0] |= 0x80;
 237                         md[qsize-1] |= 0x01;
 238                         if (!BN_bin2bn(md, qsize, q))
 239                                 goto err;
 240
 241                         /* step 4 */
 242                         r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
 243                                         seed_is_random, cb);
 244                         if (r > 0)
 245                                 break;
 246                         if (r != 0)
 247                                 goto err;
 248
 249                         /* do a callback call */
 250                         /* step 5 */
 251                         }
 252
 253                 if(!BN_GENCB_call(cb, 2, 0)) goto err;
 254                 if(!BN_GENCB_call(cb, 3, 0)) goto err;
 255
 256                 /* step 6 */
 257                 counter=0;
 258                 /* "offset = 2" */
 259
 260                 n=(bits-1)/160;
 261
 262                 for (;;)
 263                         {
 264                         if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 265                                 goto err;
 266
 267                         /* step 7 */
 268                         BN_zero(W);
 269                         /* now 'buf' contains "SEED + offset - 1" */
 270                         for (k=0; k<=n; k++)
 271                                 {
 272                                 /* obtain "SEED + offset + k" by incrementing: */
 273                                 for (i = qsize-1; i >= 0; i--)
 274                                         {
 275                                         buf[i]++;
 276                                         if (buf[i] != 0)
 277                                                 break;
 278                                         }
 279
 280                                 if (!EVP_Digest(buf, qsize, md ,NULL, evpmd,
 281                                                                         NULL))
 282                                         goto err;
 283
 284                                 /* step 8 */
 285                                 if (!BN_bin2bn(md, qsize, r0))
 286                                         goto err;
 287                                 if (!BN_lshift(r0,r0,(qsize << 3)*k)) goto err;
 288                                 if (!BN_add(W,W,r0)) goto err;
 289                                 }
 290
 291                         /* more of step 8 */
 292                         if (!BN_mask_bits(W,bits-1)) goto err;
 293                         if (!BN_copy(X,W)) goto err;
 294                         if (!BN_add(X,X,test)) goto err;
 295
 296                         /* step 9 */
 297                         if (!BN_lshift1(r0,q)) goto err;
 298                         if (!BN_mod(c,X,r0,ctx)) goto err;
 299                         if (!BN_sub(r0,c,BN_value_one())) goto err;
 300                         if (!BN_sub(p,X,r0)) goto err;
 301
 302                         /* step 10 */
 303                         if (BN_cmp(p,test) >= 0)
 304                                 {
 305                                 /* step 11 */
 306                                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
 307                                                 ctx, 1, cb);
 308                                 if (r > 0)
 309                                                 goto end; /* found it */
 310                                 if (r != 0)
 311                                         goto err;
 312                                 }
 313
 314                         /* step 13 */
 315                         counter++;
 316                         /* "offset = offset + n + 1" */
 317
 318                         /* step 14 */
 319                         if (counter >= 4096) break;
 320                         }
 321                 }
 322 end:
 323         if(!BN_GENCB_call(cb, 2, 1))
 324                 goto err;
 325
 326         /* We now need to generate g */
 327         /* Set r0=(p-1)/q */
 328         if (!BN_sub(test,p,BN_value_one())) goto err;
 329         if (!BN_div(r0,NULL,test,q,ctx)) goto err;
 330
 331         if (!BN_set_word(test,h)) goto err;
 332         if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
 333
 334         for (;;)
 335                 {
 336                 /* g=test^r0%p */
 337                 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
 338                 if (!BN_is_one(g)) break;
 339                 if (!BN_add(test,test,BN_value_one())) goto err;
 340                 h++;
 341                 }
 342
 343         if(!BN_GENCB_call(cb, 3, 1))
 344                 goto err;
 345
 346         ok=1;
 347 err:
 348         if (ok)
 349                 {
 350                 if(ret->p) BN_free(ret->p);
 351                 if(ret->q) BN_free(ret->q);
 352                 if(ret->g) BN_free(ret->g);
 353                 ret->p=BN_dup(p);
 354                 ret->q=BN_dup(q);
 355                 ret->g=BN_dup(g);
 356                 if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
 357                         {
 358                         ok=0;
 359                         goto err;
 360                         }
 361                 if (counter_ret != NULL) *counter_ret=counter;
 362                 if (h_ret != NULL) *h_ret=h;
 363                 if (seed_out)
 364                         memcpy(seed_out, seed, qsize);
 365                 }
 366         if(ctx)
 367                 {
 368                 BN_CTX_end(ctx);
 369                 BN_CTX_free(ctx);
 370                 }
 371         if (mont != NULL) BN_MONT_CTX_free(mont);
 372         return ok;
 373         }
 374
 375 #ifdef OPENSSL_FIPS
 376
 377 /* Security strength of parameter values for (L,N): see FIPS186-3 4.2
 378  * and SP800-131A
 379  */
 380
 381
 382 static int fips_ffc_strength(size_t L, size_t N)
 383         {
 384         if (L >= 15360 && N >= 512)
 385                 return 256;
 386         if (L >= 7680 && N >= 384)
 387                 return 192;
 388         if (L >= 3072 && N >= 256)
 389                 return 128;
 390         if (L >= 2048 && N >= 224)
 391                 return 112;
 392         if (L >= 1024 && N >= 160)
 393                 return  80;
 394         return 0;
 395         }
 396
 397 /* Valid DSA2 parameters from FIPS 186-3 */
 398
 399 static int dsa2_valid_parameters(size_t L, size_t N)
 400         {
 401         if (L == 1024 && N == 160)
 402                 return 80;
 403         if (L == 2048 && N == 224)
 404                 return 112;
 405         if (L == 2048 && N == 256)
 406                 return 112;
 407         if (L == 3072 && N == 256)
 408                 return 112;
 409         return 0;
 410         }
 411
 412 int fips_check_dsa_prng(DSA *dsa, size_t L, size_t N)
 413         {
 414         int strength;
 415         if (!FIPS_mode())
 416                 return 1;
 417
 418         if (dsa->flags & (DSA_FLAG_NON_FIPS_ALLOW|DSA_FLAG_FIPS_CHECKED))
 419                 return 1;
 420
 421         if (!L || !N)
 422                 {
 423                 L = BN_num_bits(dsa->p);
 424                 N = BN_num_bits(dsa->q);
 425                 }
 426         if (!dsa2_valid_parameters(L, N))
 427                 {
 428                 FIPSerr(FIPS_F_FIPS_CHECK_DSA_PRNG, FIPS_R_INVALID_PARAMETERS);
 429                 return 0;
 430                 }
 431
 432         strength = fips_ffc_strength(L, N);
 433
 434         if (!strength)
 435                 {
 436                 FIPSerr(FIPS_F_FIPS_CHECK_DSA_PRNG,FIPS_R_KEY_TOO_SHORT);
 437                 return 0;
 438                 }
 439
 440         if (FIPS_rand_strength() >= strength)
 441                 return 1;
 442
 443         FIPSerr(FIPS_F_FIPS_CHECK_DSA_PRNG,FIPS_R_PRNG_STRENGTH_TOO_LOW);
 444         return 0;
 445
 446         }
 447 #endif /* OPENSSL_FIPS */
 448
 449 /* This is a parameter generation algorithm for the DSA2 algorithm as
 450  * described in FIPS 186-3.
 451  */
 452
 453 int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
 454         const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
 455         unsigned char *seed_out,
 456         int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
 457         {
 458         int ok=-1;
 459         unsigned char *seed = NULL;
 460         unsigned char md[EVP_MAX_MD_SIZE];
 461         int mdsize;
 462         BIGNUM *r0,*W,*X,*c,*test;
 463         BIGNUM *g=NULL,*q=NULL,*p=NULL;
 464         BN_MONT_CTX *mont=NULL;
 465         int i, k, n=0, m=0, qsize = N >> 3;
 466         int counter=0;
 467         int r=0;
 468         BN_CTX *ctx=NULL;
 469         unsigned int h=2;
 470
 471 #ifdef OPENSSL_FIPS
 472         if(FIPS_selftest_failed())
 473             {
 474             FIPSerr(FIPS_F_DSA_BUILTIN_PARAMGEN2,
 475                     FIPS_R_FIPS_SELFTEST_FAILED);
 476             goto err;
 477             }
 478
 479         if (!fips_check_dsa_prng(ret, L, N))
 480                 goto err;
 481 #endif
 482
 483         if (evpmd == NULL)
 484                 {
 485                 if (N == 160)
 486                         evpmd = EVP_sha1();
 487                 else if (N == 224)
 488                         evpmd = EVP_sha224();
 489                 else
 490                         evpmd = EVP_sha256();
 491                 }
 492
 493         mdsize = M_EVP_MD_size(evpmd);
 494
 495         if (seed_len == 0)
 496                 seed_len = mdsize;
 497
 498         seed = OPENSSL_malloc(seed_len);
 499
 500         if (!seed)
 501                 goto err;
 502
 503         if (seed_in)
 504                 memcpy(seed, seed_in, seed_len);
 505
 506         if ((ctx=BN_CTX_new()) == NULL)
 507                 goto err;
 508
 509         if ((mont=BN_MONT_CTX_new()) == NULL)
 510                 goto err;
 511
 512         BN_CTX_start(ctx);
 513         r0 = BN_CTX_get(ctx);
 514         g = BN_CTX_get(ctx);
 515         W = BN_CTX_get(ctx);
 516         q = BN_CTX_get(ctx);
 517         X = BN_CTX_get(ctx);
 518         c = BN_CTX_get(ctx);
 519         p = BN_CTX_get(ctx);
 520         test = BN_CTX_get(ctx);
 521
 522         if (!BN_lshift(test,BN_value_one(),L-1))
 523                 goto err;
 524         for (;;)
 525                 {
 526                 for (;;) /* find q */
 527                         {
 528                         unsigned char *pmd;
 529                         /* step 1 */
 530                         if(!BN_GENCB_call(cb, 0, m++))
 531                                 goto err;
 532
 533                         if (!seed_in)
 534                                 {
 535                                 if (RAND_pseudo_bytes(seed, seed_len) < 0)
 536                                         goto err;
 537                                 }
 538                         /* step 2 */
 539                         if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL))
 540                                 goto err;
 541                         /* Take least significant bits of md */
 542                         if (mdsize > qsize)
 543                                 pmd = md + mdsize - qsize;
 544                         else
 545                                 pmd = md;
 546
 547                         if (mdsize < qsize)
 548                                 memset(md + mdsize, 0, qsize - mdsize);
 549
 550                         /* step 3 */
 551                         pmd[0] |= 0x80;
 552                         pmd[qsize-1] |= 0x01;
 553                         if (!BN_bin2bn(pmd, qsize, q))
 554                                 goto err;
 555
 556                         /* step 4 */
 557                         r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
 558                                         seed_in ? 1 : 0, cb);
 559                         if (r > 0)
 560                                 break;
 561                         if (r != 0)
 562                                 goto err;
 563                         /* Provided seed didn't produce a prime: error */
 564                         if (seed_in)
 565                                 {
 566                                 ok = 0;
 567                                 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_Q_NOT_PRIME);
 568                                 goto err;
 569                                 }
 570
 571                         /* do a callback call */
 572                         /* step 5 */
 573                         }
 574                 /* Copy seed to seed_out before we mess with it */
 575                 if (seed_out)
 576                         memcpy(seed_out, seed, seed_len);
 577
 578                 if(!BN_GENCB_call(cb, 2, 0)) goto err;
 579                 if(!BN_GENCB_call(cb, 3, 0)) goto err;
 580
 581                 /* step 6 */
 582                 counter=0;
 583                 /* "offset = 1" */
 584
 585                 n=(L-1)/(mdsize << 3);
 586
 587                 for (;;)
 588                         {
 589                         if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 590                                 goto err;
 591
 592                         /* step 7 */
 593                         BN_zero(W);
 594                         /* now 'buf' contains "SEED + offset - 1" */
 595                         for (k=0; k<=n; k++)
 596                                 {
 597                                 /* obtain "SEED + offset + k" by incrementing: */
 598                                 for (i = seed_len-1; i >= 0; i--)
 599                                         {
 600                                         seed[i]++;
 601                                         if (seed[i] != 0)
 602                                                 break;
 603                                         }
 604
 605                                 if (!EVP_Digest(seed, seed_len, md ,NULL, evpmd,
 606                                                                         NULL))
 607                                         goto err;
 608
 609                                 /* step 8 */
 610                                 if (!BN_bin2bn(md, mdsize, r0))
 611                                         goto err;
 612                                 if (!BN_lshift(r0,r0,(mdsize << 3)*k)) goto err;
 613                                 if (!BN_add(W,W,r0)) goto err;
 614                                 }
 615
 616                         /* more of step 8 */
 617                         if (!BN_mask_bits(W,L-1)) goto err;
 618                         if (!BN_copy(X,W)) goto err;
 619                         if (!BN_add(X,X,test)) goto err;
 620
 621                         /* step 9 */
 622                         if (!BN_lshift1(r0,q)) goto err;
 623                         if (!BN_mod(c,X,r0,ctx)) goto err;
 624                         if (!BN_sub(r0,c,BN_value_one())) goto err;
 625                         if (!BN_sub(p,X,r0)) goto err;
 626
 627                         /* step 10 */
 628                         if (BN_cmp(p,test) >= 0)
 629                                 {
 630                                 /* step 11 */
 631                                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
 632                                                 ctx, 1, cb);
 633                                 if (r > 0)
 634                                                 goto end; /* found it */
 635                                 if (r != 0)
 636                                         goto err;
 637                                 }
 638
 639                         /* step 13 */
 640                         counter++;
 641                         /* "offset = offset + n + 1" */
 642
 643                         /* step 14 */
 644                         if (counter >= 4096) break;
 645                         }
 646                 }
 647 end:
 648         if(!BN_GENCB_call(cb, 2, 1))
 649                 goto err;
 650
 651         /* We now need to generate g */
 652         /* Set r0=(p-1)/q */
 653         if (!BN_sub(test,p,BN_value_one())) goto err;
 654         if (!BN_div(r0,NULL,test,q,ctx)) goto err;
 655
 656         if (!BN_set_word(test,h)) goto err;
 657         if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
 658
 659         for (;;)
 660                 {
 661                 /* g=test^r0%p */
 662                 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
 663                 if (!BN_is_one(g)) break;
 664                 if (!BN_add(test,test,BN_value_one())) goto err;
 665                 h++;
 666                 }
 667
 668         if(!BN_GENCB_call(cb, 3, 1))
 669                 goto err;
 670
 671         ok=1;
 672 err:
 673         if (ok == 1)
 674                 {
 675                 if(ret->p) BN_free(ret->p);
 676                 if(ret->q) BN_free(ret->q);
 677                 if(ret->g) BN_free(ret->g);
 678                 ret->p=BN_dup(p);
 679                 ret->q=BN_dup(q);
 680                 ret->g=BN_dup(g);
 681                 if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
 682                         {
 683                         ok=-1;
 684                         goto err;
 685                         }
 686                 if (counter_ret != NULL) *counter_ret=counter;
 687                 if (h_ret != NULL) *h_ret=h;
 688                 }
 689         if (seed)
 690                 OPENSSL_free(seed);
 691         if(ctx)
 692                 {
 693                 BN_CTX_end(ctx);
 694                 BN_CTX_free(ctx);
 695                 }
 696         if (mont != NULL) BN_MONT_CTX_free(mont);
 697         return ok;
 698         }
 699 #endif