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 #endif
  87
  88 #include "dsa_locl.h"
  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         if(ret->meth->dsa_paramgen)
  95                 return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
  96                                 counter_ret, h_ret, cb);
  97         else
  98                 {
  99                 const EVP_MD *evpmd;
 100                 size_t qbits = bits >= 2048 ? 256 : 160;
 101
 102                 if (bits >= 2048)
 103                         {
 104                         qbits = 256;
 105                         evpmd = EVP_sha256();
 106                         }
 107                 else
 108                         {
 109                         qbits = 160;
 110                         evpmd = EVP_sha1();
 111                         }
 112
 113                 return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
 114                         seed_in, seed_len, NULL, counter_ret, h_ret, cb);
 115                 }
 116         }
 117
 118 int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
 119         const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
 120         unsigned char *seed_out,
 121         int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
 122         {
 123         int ok=0;
 124         unsigned char seed[SHA256_DIGEST_LENGTH];
 125         unsigned char md[SHA256_DIGEST_LENGTH];
 126         unsigned char buf[SHA256_DIGEST_LENGTH],buf2[SHA256_DIGEST_LENGTH];
 127         BIGNUM *r0,*W,*X,*c,*test;
 128         BIGNUM *g=NULL,*q=NULL,*p=NULL;
 129         BN_MONT_CTX *mont=NULL;
 130         int i, k, n=0, m=0, qsize = qbits >> 3;
 131         int counter=0;
 132         int r=0;
 133         BN_CTX *ctx=NULL;
 134         unsigned int h=2;
 135
 136 #ifdef OPENSSL_FIPS
 137         if(FIPS_selftest_failed())
 138             {
 139             FIPSerr(FIPS_F_DSA_BUILTIN_PARAMGEN, FIPS_R_FIPS_SELFTEST_FAILED);
 140             goto err;
 141             }
 142
 143         if (FIPS_mode() && (bits < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS))
 144                 {
 145                 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN, DSA_R_KEY_SIZE_TOO_SMALL);
 146                 goto err;
 147                 }
 148 #endif
 149
 150         if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
 151             qsize != SHA256_DIGEST_LENGTH)
 152                 /* invalid q size */
 153                 return 0;
 154
 155         if (evpmd == NULL)
 156                 /* use SHA1 as default */
 157                 evpmd = EVP_sha1();
 158
 159         if (bits < 512)
 160                 bits = 512;
 161
 162         bits = (bits+63)/64*64;
 163
 164         /* NB: seed_len == 0 is special case: copy generated seed to
 165          * seed_in if it is not NULL.
 166          */
 167         if (seed_len && (seed_len < (size_t)qsize))
 168                 seed_in = NULL;         /* seed buffer too small -- ignore */
 169         if (seed_len > (size_t)qsize)
 170                 seed_len = qsize;       /* App. 2.2 of FIPS PUB 186 allows larger SEED,
 171                                          * but our internal buffers are restricted to 160 bits*/
 172         if (seed_in != NULL)
 173                 memcpy(seed, seed_in, seed_len);
 174
 175         if ((ctx=BN_CTX_new()) == NULL)
 176                 goto err;
 177
 178         if ((mont=BN_MONT_CTX_new()) == NULL)
 179                 goto err;
 180
 181         BN_CTX_start(ctx);
 182         r0 = BN_CTX_get(ctx);
 183         g = BN_CTX_get(ctx);
 184         W = BN_CTX_get(ctx);
 185         q = BN_CTX_get(ctx);
 186         X = BN_CTX_get(ctx);
 187         c = BN_CTX_get(ctx);
 188         p = BN_CTX_get(ctx);
 189         test = BN_CTX_get(ctx);
 190
 191         if (!BN_lshift(test,BN_value_one(),bits-1))
 192                 goto err;
 193
 194         for (;;)
 195                 {
 196                 for (;;) /* find q */
 197                         {
 198                         int seed_is_random;
 199
 200                         /* step 1 */
 201                         if(!BN_GENCB_call(cb, 0, m++))
 202                                 goto err;
 203
 204                         if (!seed_len)
 205                                 {
 206                                 RAND_pseudo_bytes(seed, qsize);
 207                                 seed_is_random = 1;
 208                                 }
 209                         else
 210                                 {
 211                                 seed_is_random = 0;
 212                                 seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
 213                                 }
 214                         memcpy(buf , seed, qsize);
 215                         memcpy(buf2, seed, qsize);
 216                         /* precompute "SEED + 1" for step 7: */
 217                         for (i = qsize-1; i >= 0; i--)
 218                                 {
 219                                 buf[i]++;
 220                                 if (buf[i] != 0)
 221                                         break;
 222                                 }
 223
 224                         /* step 2 */
 225                         if (!EVP_Digest(seed, qsize, md,   NULL, evpmd, NULL))
 226                                 goto err;
 227                         if (!EVP_Digest(buf,  qsize, buf2, NULL, evpmd, NULL))
 228                                 goto err;
 229                         for (i = 0; i < qsize; i++)
 230                                 md[i]^=buf2[i];
 231
 232                         /* step 3 */
 233                         md[0] |= 0x80;
 234                         md[qsize-1] |= 0x01;
 235                         if (!BN_bin2bn(md, qsize, q))
 236                                 goto err;
 237
 238                         /* step 4 */
 239                         r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
 240                                         seed_is_random, cb);
 241                         if (r > 0)
 242                                 break;
 243                         if (r != 0)
 244                                 goto err;
 245
 246                         /* do a callback call */
 247                         /* step 5 */
 248                         }
 249
 250                 if(!BN_GENCB_call(cb, 2, 0)) goto err;
 251                 if(!BN_GENCB_call(cb, 3, 0)) goto err;
 252
 253                 /* step 6 */
 254                 counter=0;
 255                 /* "offset = 2" */
 256
 257                 n=(bits-1)/160;
 258
 259                 for (;;)
 260                         {
 261                         if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 262                                 goto err;
 263
 264                         /* step 7 */
 265                         BN_zero(W);
 266                         /* now 'buf' contains "SEED + offset - 1" */
 267                         for (k=0; k<=n; k++)
 268                                 {
 269                                 /* obtain "SEED + offset + k" by incrementing: */
 270                                 for (i = qsize-1; i >= 0; i--)
 271                                         {
 272                                         buf[i]++;
 273                                         if (buf[i] != 0)
 274                                                 break;
 275                                         }
 276
 277                                 if (!EVP_Digest(buf, qsize, md ,NULL, evpmd,
 278                                                                         NULL))
 279                                         goto err;
 280
 281                                 /* step 8 */
 282                                 if (!BN_bin2bn(md, qsize, r0))
 283                                         goto err;
 284                                 if (!BN_lshift(r0,r0,(qsize << 3)*k)) goto err;
 285                                 if (!BN_add(W,W,r0)) goto err;
 286                                 }
 287
 288                         /* more of step 8 */
 289                         if (!BN_mask_bits(W,bits-1)) goto err;
 290                         if (!BN_copy(X,W)) goto err;
 291                         if (!BN_add(X,X,test)) goto err;
 292
 293                         /* step 9 */
 294                         if (!BN_lshift1(r0,q)) goto err;
 295                         if (!BN_mod(c,X,r0,ctx)) goto err;
 296                         if (!BN_sub(r0,c,BN_value_one())) goto err;
 297                         if (!BN_sub(p,X,r0)) goto err;
 298
 299                         /* step 10 */
 300                         if (BN_cmp(p,test) >= 0)
 301                                 {
 302                                 /* step 11 */
 303                                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
 304                                                 ctx, 1, cb);
 305                                 if (r > 0)
 306                                                 goto end; /* found it */
 307                                 if (r != 0)
 308                                         goto err;
 309                                 }
 310
 311                         /* step 13 */
 312                         counter++;
 313                         /* "offset = offset + n + 1" */
 314
 315                         /* step 14 */
 316                         if (counter >= 4096) break;
 317                         }
 318                 }
 319 end:
 320         if(!BN_GENCB_call(cb, 2, 1))
 321                 goto err;
 322
 323         /* We now need to generate g */
 324         /* Set r0=(p-1)/q */
 325         if (!BN_sub(test,p,BN_value_one())) goto err;
 326         if (!BN_div(r0,NULL,test,q,ctx)) goto err;
 327
 328         if (!BN_set_word(test,h)) goto err;
 329         if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
 330
 331         for (;;)
 332                 {
 333                 /* g=test^r0%p */
 334                 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
 335                 if (!BN_is_one(g)) break;
 336                 if (!BN_add(test,test,BN_value_one())) goto err;
 337                 h++;
 338                 }
 339
 340         if(!BN_GENCB_call(cb, 3, 1))
 341                 goto err;
 342
 343         ok=1;
 344 err:
 345         if (ok)
 346                 {
 347                 if(ret->p) BN_free(ret->p);
 348                 if(ret->q) BN_free(ret->q);
 349                 if(ret->g) BN_free(ret->g);
 350                 ret->p=BN_dup(p);
 351                 ret->q=BN_dup(q);
 352                 ret->g=BN_dup(g);
 353                 if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
 354                         {
 355                         ok=0;
 356                         goto err;
 357                         }
 358                 if (counter_ret != NULL) *counter_ret=counter;
 359                 if (h_ret != NULL) *h_ret=h;
 360                 if (seed_out)
 361                         memcpy(seed_out, seed, qsize);
 362                 }
 363         if(ctx)
 364                 {
 365                 BN_CTX_end(ctx);
 366                 BN_CTX_free(ctx);
 367                 }
 368         if (mont != NULL) BN_MONT_CTX_free(mont);
 369         return ok;
 370         }
 371
 372 /* Permissible parameter values for (L,N): see FIPS186-3 4.2 */
 373
 374 static int dsa2_check_params(size_t L, size_t N)
 375         {
 376         if (L == 1024 && N == 160)
 377                 return 1;
 378         if (L == 2048 && N == 224)
 379                 return 1;
 380         if (L == 2048 && N == 256)
 381                 return 1;
 382         if (L == 3072 && N == 256)
 383                 return 1;
 384         return 0;
 385         }
 386
 387 /* This is a parameter generation algorithm for the DSA2 algorithm as
 388  * described in FIPS 186-3.
 389  */
 390
 391 int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
 392         const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
 393         unsigned char *seed_out,
 394         int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
 395         {
 396         int ok=-1;
 397         unsigned char *seed = NULL;
 398         unsigned char md[EVP_MAX_MD_SIZE];
 399         int mdsize;
 400         BIGNUM *r0,*W,*X,*c,*test;
 401         BIGNUM *g=NULL,*q=NULL,*p=NULL;
 402         BN_MONT_CTX *mont=NULL;
 403         int i, k, n=0, m=0, qsize = N >> 3;
 404         int counter=0;
 405         int r=0;
 406         BN_CTX *ctx=NULL;
 407         unsigned int h=2;
 408
 409 #ifdef OPENSSL_FIPS
 410         if(FIPS_selftest_failed())
 411             {
 412             FIPSerr(FIPS_F_DSA_BUILTIN_PARAMGEN2,
 413                     FIPS_R_FIPS_SELFTEST_FAILED);
 414             goto err;
 415             }
 416 #endif
 417         if (!dsa2_check_params(L, N))
 418                 {
 419                 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS);
 420                 ok = 0;
 421                 goto err;
 422                 }
 423
 424         if (evpmd == NULL)
 425                 {
 426                 if (N == 160)
 427                         evpmd = EVP_sha1();
 428                 else if (N == 224)
 429                         evpmd = EVP_sha224();
 430                 else
 431                         evpmd = EVP_sha256();
 432                 }
 433
 434         mdsize = M_EVP_MD_size(evpmd);
 435
 436         if (seed_len == 0)
 437                 seed_len = mdsize;
 438
 439         seed = OPENSSL_malloc(seed_len);
 440
 441         if (!seed)
 442                 goto err;
 443
 444         if (seed_in)
 445                 memcpy(seed, seed_in, seed_len);
 446
 447         if ((ctx=BN_CTX_new()) == NULL)
 448                 goto err;
 449
 450         if ((mont=BN_MONT_CTX_new()) == NULL)
 451                 goto err;
 452
 453         BN_CTX_start(ctx);
 454         r0 = BN_CTX_get(ctx);
 455         g = BN_CTX_get(ctx);
 456         W = BN_CTX_get(ctx);
 457         q = BN_CTX_get(ctx);
 458         X = BN_CTX_get(ctx);
 459         c = BN_CTX_get(ctx);
 460         p = BN_CTX_get(ctx);
 461         test = BN_CTX_get(ctx);
 462
 463         if (!BN_lshift(test,BN_value_one(),L-1))
 464                 goto err;
 465         for (;;)
 466                 {
 467                 for (;;) /* find q */
 468                         {
 469                         unsigned char *pmd;
 470                         /* step 1 */
 471                         if(!BN_GENCB_call(cb, 0, m++))
 472                                 goto err;
 473
 474                         if (!seed_in)
 475                                 RAND_pseudo_bytes(seed, seed_len);
 476                         /* step 2 */
 477                         if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL))
 478                                 goto err;
 479                         /* Take least significant bits of md */
 480                         if (mdsize > qsize)
 481                                 pmd = md + mdsize - qsize;
 482                         else
 483                                 pmd = md;
 484
 485                         if (mdsize < qsize)
 486                                 memset(md + mdsize, 0, qsize - mdsize);
 487
 488                         /* step 3 */
 489                         pmd[0] |= 0x80;
 490                         pmd[qsize-1] |= 0x01;
 491                         if (!BN_bin2bn(pmd, qsize, q))
 492                                 goto err;
 493
 494                         /* step 4 */
 495                         r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
 496                                         seed_in ? 1 : 0, cb);
 497                         if (r > 0)
 498                                 break;
 499                         if (r != 0)
 500                                 goto err;
 501                         /* Provided seed didn't produce a prime: error */
 502                         if (seed_in)
 503                                 {
 504                                 ok = 0;
 505                                 DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_Q_NOT_PRIME);
 506                                 goto err;
 507                                 }
 508
 509                         /* do a callback call */
 510                         /* step 5 */
 511                         }
 512                 /* Copy seed to seed_out before we mess with it */
 513                 if (seed_out)
 514                         memcpy(seed_out, seed, seed_len);
 515
 516                 if(!BN_GENCB_call(cb, 2, 0)) goto err;
 517                 if(!BN_GENCB_call(cb, 3, 0)) goto err;
 518
 519                 /* step 6 */
 520                 counter=0;
 521                 /* "offset = 1" */
 522
 523                 n=(L-1)/(mdsize << 3);
 524
 525                 for (;;)
 526                         {
 527                         if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
 528                                 goto err;
 529
 530                         /* step 7 */
 531                         BN_zero(W);
 532                         /* now 'buf' contains "SEED + offset - 1" */
 533                         for (k=0; k<=n; k++)
 534                                 {
 535                                 /* obtain "SEED + offset + k" by incrementing: */
 536                                 for (i = seed_len-1; i >= 0; i--)
 537                                         {
 538                                         seed[i]++;
 539                                         if (seed[i] != 0)
 540                                                 break;
 541                                         }
 542
 543                                 if (!EVP_Digest(seed, seed_len, md ,NULL, evpmd,
 544                                                                         NULL))
 545                                         goto err;
 546
 547                                 /* step 8 */
 548                                 if (!BN_bin2bn(md, mdsize, r0))
 549                                         goto err;
 550                                 if (!BN_lshift(r0,r0,(mdsize << 3)*k)) goto err;
 551                                 if (!BN_add(W,W,r0)) goto err;
 552                                 }
 553
 554                         /* more of step 8 */
 555                         if (!BN_mask_bits(W,L-1)) goto err;
 556                         if (!BN_copy(X,W)) goto err;
 557                         if (!BN_add(X,X,test)) goto err;
 558
 559                         /* step 9 */
 560                         if (!BN_lshift1(r0,q)) goto err;
 561                         if (!BN_mod(c,X,r0,ctx)) goto err;
 562                         if (!BN_sub(r0,c,BN_value_one())) goto err;
 563                         if (!BN_sub(p,X,r0)) goto err;
 564
 565                         /* step 10 */
 566                         if (BN_cmp(p,test) >= 0)
 567                                 {
 568                                 /* step 11 */
 569                                 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
 570                                                 ctx, 1, cb);
 571                                 if (r > 0)
 572                                                 goto end; /* found it */
 573                                 if (r != 0)
 574                                         goto err;
 575                                 }
 576
 577                         /* step 13 */
 578                         counter++;
 579                         /* "offset = offset + n + 1" */
 580
 581                         /* step 14 */
 582                         if (counter >= 4096) break;
 583                         }
 584                 }
 585 end:
 586         if(!BN_GENCB_call(cb, 2, 1))
 587                 goto err;
 588
 589         /* We now need to generate g */
 590         /* Set r0=(p-1)/q */
 591         if (!BN_sub(test,p,BN_value_one())) goto err;
 592         if (!BN_div(r0,NULL,test,q,ctx)) goto err;
 593
 594         if (!BN_set_word(test,h)) goto err;
 595         if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
 596
 597         for (;;)
 598                 {
 599                 /* g=test^r0%p */
 600                 if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
 601                 if (!BN_is_one(g)) break;
 602                 if (!BN_add(test,test,BN_value_one())) goto err;
 603                 h++;
 604                 }
 605
 606         if(!BN_GENCB_call(cb, 3, 1))
 607                 goto err;
 608
 609         ok=1;
 610 err:
 611         if (ok == 1)
 612                 {
 613                 if(ret->p) BN_free(ret->p);
 614                 if(ret->q) BN_free(ret->q);
 615                 if(ret->g) BN_free(ret->g);
 616                 ret->p=BN_dup(p);
 617                 ret->q=BN_dup(q);
 618                 ret->g=BN_dup(g);
 619                 if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
 620                         {
 621                         ok=-1;
 622                         goto err;
 623                         }
 624                 if (counter_ret != NULL) *counter_ret=counter;
 625                 if (h_ret != NULL) *h_ret=h;
 626                 }
 627         if (seed)
 628                 OPENSSL_free(seed);
 629         if(ctx)
 630                 {
 631                 BN_CTX_end(ctx);
 632                 BN_CTX_free(ctx);
 633                 }
 634         if (mont != NULL) BN_MONT_CTX_free(mont);
 635         return ok;
 636         }
 637 #endif