release/src/router/openssl/crypto/srp/srp_vfy.c

   1 /* crypto/srp/srp_vfy.c */
   2 /*
   3  * Written by Christophe Renou (christophe.renou@edelweb.fr) with the
   4  * precious help of Peter Sylvester (peter.sylvester@edelweb.fr) for the
   5  * EdelKey project and contributed to the OpenSSL project 2004.
   6  */
   7 /* ====================================================================
   8  * Copyright (c) 2004 The OpenSSL Project.  All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  *
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  *
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in
  19  *    the documentation and/or other materials provided with the
  20  *    distribution.
  21  *
  22  * 3. All advertising materials mentioning features or use of this
  23  *    software must display the following acknowledgment:
  24  *    "This product includes software developed by the OpenSSL Project
  25  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  26  *
  27  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  28  *    endorse or promote products derived from this software without
  29  *    prior written permission. For written permission, please contact
  30  *    licensing@OpenSSL.org.
  31  *
  32  * 5. Products derived from this software may not be called "OpenSSL"
  33  *    nor may "OpenSSL" appear in their names without prior written
  34  *    permission of the OpenSSL Project.
  35  *
  36  * 6. Redistributions of any form whatsoever must retain the following
  37  *    acknowledgment:
  38  *    "This product includes software developed by the OpenSSL Project
  39  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  42  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  44  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  45  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  46  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  47  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  48  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  50  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  51  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  52  * OF THE POSSIBILITY OF SUCH DAMAGE.
  53  * ====================================================================
  54  *
  55  * This product includes cryptographic software written by Eric Young
  56  * (eay@cryptsoft.com).  This product includes software written by Tim
  57  * Hudson (tjh@cryptsoft.com).
  58  *
  59  */
  60 #ifndef OPENSSL_NO_SRP
  61 # include "cryptlib.h"
  62 # include "srp_lcl.h"
  63 # include <openssl/srp.h>
  64 # include <openssl/evp.h>
  65 # include <openssl/buffer.h>
  66 # include <openssl/rand.h>
  67 # include <openssl/txt_db.h>
  68
  69 # define SRP_RANDOM_SALT_LEN 20
  70 # define MAX_LEN 2500
  71
  72 static char b64table[] =
  73     "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz./";
  74
  75 /*
  76  * the following two conversion routines have been inspired by code from
  77  * Stanford
  78  */
  79
  80 /*
  81  * Convert a base64 string into raw byte array representation.
  82  */
  83 static int t_fromb64(unsigned char *a, const char *src)
  84 {
  85     char *loc;
  86     int i, j;
  87     int size;
  88
  89     while (*src && (*src == ' ' || *src == '\t' || *src == '\n'))
  90         ++src;
  91     size = strlen(src);
  92     i = 0;
  93     while (i < size) {
  94         loc = strchr(b64table, src[i]);
  95         if (loc == (char *)0)
  96             break;
  97         else
  98             a[i] = loc - b64table;
  99         ++i;
 100     }
 101     /* if nothing valid to process we have a zero length response */
 102     if (i == 0)
 103         return 0;
 104     size = i;
 105     i = size - 1;
 106     j = size;
 107     while (1) {
 108         a[j] = a[i];
 109         if (--i < 0)
 110             break;
 111         a[j] |= (a[i] & 3) << 6;
 112         --j;
 113         a[j] = (unsigned char)((a[i] & 0x3c) >> 2);
 114         if (--i < 0)
 115             break;
 116         a[j] |= (a[i] & 0xf) << 4;
 117         --j;
 118         a[j] = (unsigned char)((a[i] & 0x30) >> 4);
 119         if (--i < 0)
 120             break;
 121         a[j] |= (a[i] << 2);
 122
 123         a[--j] = 0;
 124         if (--i < 0)
 125             break;
 126     }
 127     while (a[j] == 0 && j <= size)
 128         ++j;
 129     i = 0;
 130     while (j <= size)
 131         a[i++] = a[j++];
 132     return i;
 133 }
 134
 135 /*
 136  * Convert a raw byte string into a null-terminated base64 ASCII string.
 137  */
 138 static char *t_tob64(char *dst, const unsigned char *src, int size)
 139 {
 140     int c, pos = size % 3;
 141     unsigned char b0 = 0, b1 = 0, b2 = 0, notleading = 0;
 142     char *olddst = dst;
 143
 144     switch (pos) {
 145     case 1:
 146         b2 = src[0];
 147         break;
 148     case 2:
 149         b1 = src[0];
 150         b2 = src[1];
 151         break;
 152     }
 153
 154     while (1) {
 155         c = (b0 & 0xfc) >> 2;
 156         if (notleading || c != 0) {
 157             *dst++ = b64table[c];
 158             notleading = 1;
 159         }
 160         c = ((b0 & 3) << 4) | ((b1 & 0xf0) >> 4);
 161         if (notleading || c != 0) {
 162             *dst++ = b64table[c];
 163             notleading = 1;
 164         }
 165         c = ((b1 & 0xf) << 2) | ((b2 & 0xc0) >> 6);
 166         if (notleading || c != 0) {
 167             *dst++ = b64table[c];
 168             notleading = 1;
 169         }
 170         c = b2 & 0x3f;
 171         if (notleading || c != 0) {
 172             *dst++ = b64table[c];
 173             notleading = 1;
 174         }
 175         if (pos >= size)
 176             break;
 177         else {
 178             b0 = src[pos++];
 179             b1 = src[pos++];
 180             b2 = src[pos++];
 181         }
 182     }
 183
 184     *dst++ = '\0';
 185     return olddst;
 186 }
 187
 188 static void SRP_user_pwd_free(SRP_user_pwd *user_pwd)
 189 {
 190     if (user_pwd == NULL)
 191         return;
 192     BN_free(user_pwd->s);
 193     BN_clear_free(user_pwd->v);
 194     OPENSSL_free(user_pwd->id);
 195     OPENSSL_free(user_pwd->info);
 196     OPENSSL_free(user_pwd);
 197 }
 198
 199 static SRP_user_pwd *SRP_user_pwd_new()
 200 {
 201     SRP_user_pwd *ret = OPENSSL_malloc(sizeof(SRP_user_pwd));
 202     if (ret == NULL)
 203         return NULL;
 204     ret->N = NULL;
 205     ret->g = NULL;
 206     ret->s = NULL;
 207     ret->v = NULL;
 208     ret->id = NULL;
 209     ret->info = NULL;
 210     return ret;
 211 }
 212
 213 static void SRP_user_pwd_set_gN(SRP_user_pwd *vinfo, const BIGNUM *g,
 214                                 const BIGNUM *N)
 215 {
 216     vinfo->N = N;
 217     vinfo->g = g;
 218 }
 219
 220 static int SRP_user_pwd_set_ids(SRP_user_pwd *vinfo, const char *id,
 221                                 const char *info)
 222 {
 223     if (id != NULL && NULL == (vinfo->id = BUF_strdup(id)))
 224         return 0;
 225     return (info == NULL || NULL != (vinfo->info = BUF_strdup(info)));
 226 }
 227
 228 static int SRP_user_pwd_set_sv(SRP_user_pwd *vinfo, const char *s,
 229                                const char *v)
 230 {
 231     unsigned char tmp[MAX_LEN];
 232     int len;
 233
 234     if (strlen(s) > MAX_LEN || strlen(v) > MAX_LEN)
 235         return 0;
 236     len = t_fromb64(tmp, v);
 237     if (NULL == (vinfo->v = BN_bin2bn(tmp, len, NULL)))
 238         return 0;
 239     len = t_fromb64(tmp, s);
 240     return ((vinfo->s = BN_bin2bn(tmp, len, NULL)) != NULL);
 241 }
 242
 243 static int SRP_user_pwd_set_sv_BN(SRP_user_pwd *vinfo, BIGNUM *s, BIGNUM *v)
 244 {
 245     vinfo->v = v;
 246     vinfo->s = s;
 247     return (vinfo->s != NULL && vinfo->v != NULL);
 248 }
 249
 250 SRP_VBASE *SRP_VBASE_new(char *seed_key)
 251 {
 252     SRP_VBASE *vb = (SRP_VBASE *)OPENSSL_malloc(sizeof(SRP_VBASE));
 253
 254     if (vb == NULL)
 255         return NULL;
 256     if (!(vb->users_pwd = sk_SRP_user_pwd_new_null()) ||
 257         !(vb->gN_cache = sk_SRP_gN_cache_new_null())) {
 258         OPENSSL_free(vb);
 259         return NULL;
 260     }
 261     vb->default_g = NULL;
 262     vb->default_N = NULL;
 263     vb->seed_key = NULL;
 264     if ((seed_key != NULL) && (vb->seed_key = BUF_strdup(seed_key)) == NULL) {
 265         sk_SRP_user_pwd_free(vb->users_pwd);
 266         sk_SRP_gN_cache_free(vb->gN_cache);
 267         OPENSSL_free(vb);
 268         return NULL;
 269     }
 270     return vb;
 271 }
 272
 273 int SRP_VBASE_free(SRP_VBASE *vb)
 274 {
 275     sk_SRP_user_pwd_pop_free(vb->users_pwd, SRP_user_pwd_free);
 276     sk_SRP_gN_cache_free(vb->gN_cache);
 277     OPENSSL_free(vb->seed_key);
 278     OPENSSL_free(vb);
 279     return 0;
 280 }
 281
 282 static SRP_gN_cache *SRP_gN_new_init(const char *ch)
 283 {
 284     unsigned char tmp[MAX_LEN];
 285     int len;
 286
 287     SRP_gN_cache *newgN =
 288         (SRP_gN_cache *)OPENSSL_malloc(sizeof(SRP_gN_cache));
 289     if (newgN == NULL)
 290         return NULL;
 291
 292     if ((newgN->b64_bn = BUF_strdup(ch)) == NULL)
 293         goto err;
 294
 295     len = t_fromb64(tmp, ch);
 296     if ((newgN->bn = BN_bin2bn(tmp, len, NULL)))
 297         return newgN;
 298
 299     OPENSSL_free(newgN->b64_bn);
 300  err:
 301     OPENSSL_free(newgN);
 302     return NULL;
 303 }
 304
 305 static void SRP_gN_free(SRP_gN_cache *gN_cache)
 306 {
 307     if (gN_cache == NULL)
 308         return;
 309     OPENSSL_free(gN_cache->b64_bn);
 310     BN_free(gN_cache->bn);
 311     OPENSSL_free(gN_cache);
 312 }
 313
 314 static SRP_gN *SRP_get_gN_by_id(const char *id, STACK_OF(SRP_gN) *gN_tab)
 315 {
 316     int i;
 317
 318     SRP_gN *gN;
 319     if (gN_tab != NULL)
 320         for (i = 0; i < sk_SRP_gN_num(gN_tab); i++) {
 321             gN = sk_SRP_gN_value(gN_tab, i);
 322             if (gN && (id == NULL || strcmp(gN->id, id) == 0))
 323                 return gN;
 324         }
 325
 326     return SRP_get_default_gN(id);
 327 }
 328
 329 static BIGNUM *SRP_gN_place_bn(STACK_OF(SRP_gN_cache) *gN_cache, char *ch)
 330 {
 331     int i;
 332     if (gN_cache == NULL)
 333         return NULL;
 334
 335     /* search if we have already one... */
 336     for (i = 0; i < sk_SRP_gN_cache_num(gN_cache); i++) {
 337         SRP_gN_cache *cache = sk_SRP_gN_cache_value(gN_cache, i);
 338         if (strcmp(cache->b64_bn, ch) == 0)
 339             return cache->bn;
 340     }
 341     {                           /* it is the first time that we find it */
 342         SRP_gN_cache *newgN = SRP_gN_new_init(ch);
 343         if (newgN) {
 344             if (sk_SRP_gN_cache_insert(gN_cache, newgN, 0) > 0)
 345                 return newgN->bn;
 346             SRP_gN_free(newgN);
 347         }
 348     }
 349     return NULL;
 350 }
 351
 352 /*
 353  * this function parses verifier file. Format is:
 354  * string(index):base64(N):base64(g):0
 355  * string(username):base64(v):base64(salt):int(index)
 356  */
 357
 358 int SRP_VBASE_init(SRP_VBASE *vb, char *verifier_file)
 359 {
 360     int error_code;
 361     STACK_OF(SRP_gN) *SRP_gN_tab = sk_SRP_gN_new_null();
 362     char *last_index = NULL;
 363     int i;
 364     char **pp;
 365
 366     SRP_gN *gN = NULL;
 367     SRP_user_pwd *user_pwd = NULL;
 368
 369     TXT_DB *tmpdb = NULL;
 370     BIO *in = BIO_new(BIO_s_file());
 371
 372     error_code = SRP_ERR_OPEN_FILE;
 373
 374     if (in == NULL || BIO_read_filename(in, verifier_file) <= 0)
 375         goto err;
 376
 377     error_code = SRP_ERR_VBASE_INCOMPLETE_FILE;
 378
 379     if ((tmpdb = TXT_DB_read(in, DB_NUMBER)) == NULL)
 380         goto err;
 381
 382     error_code = SRP_ERR_MEMORY;
 383
 384     if (vb->seed_key) {
 385         last_index = SRP_get_default_gN(NULL)->id;
 386     }
 387     for (i = 0; i < sk_OPENSSL_PSTRING_num(tmpdb->data); i++) {
 388         pp = sk_OPENSSL_PSTRING_value(tmpdb->data, i);
 389         if (pp[DB_srptype][0] == DB_SRP_INDEX) {
 390             /*
 391              * we add this couple in the internal Stack
 392              */
 393
 394             if ((gN = (SRP_gN *) OPENSSL_malloc(sizeof(SRP_gN))) == NULL)
 395                 goto err;
 396
 397             if (!(gN->id = BUF_strdup(pp[DB_srpid]))
 398                 || !(gN->N =
 399                      SRP_gN_place_bn(vb->gN_cache, pp[DB_srpverifier]))
 400                 || !(gN->g = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpsalt]))
 401                 || sk_SRP_gN_insert(SRP_gN_tab, gN, 0) == 0)
 402                 goto err;
 403
 404             gN = NULL;
 405
 406             if (vb->seed_key != NULL) {
 407                 last_index = pp[DB_srpid];
 408             }
 409         } else if (pp[DB_srptype][0] == DB_SRP_VALID) {
 410             /* it is a user .... */
 411             SRP_gN *lgN;
 412             if ((lgN = SRP_get_gN_by_id(pp[DB_srpgN], SRP_gN_tab)) != NULL) {
 413                 error_code = SRP_ERR_MEMORY;
 414                 if ((user_pwd = SRP_user_pwd_new()) == NULL)
 415                     goto err;
 416
 417                 SRP_user_pwd_set_gN(user_pwd, lgN->g, lgN->N);
 418                 if (!SRP_user_pwd_set_ids
 419                     (user_pwd, pp[DB_srpid], pp[DB_srpinfo]))
 420                     goto err;
 421
 422                 error_code = SRP_ERR_VBASE_BN_LIB;
 423                 if (!SRP_user_pwd_set_sv
 424                     (user_pwd, pp[DB_srpsalt], pp[DB_srpverifier]))
 425                     goto err;
 426
 427                 if (sk_SRP_user_pwd_insert(vb->users_pwd, user_pwd, 0) == 0)
 428                     goto err;
 429                 user_pwd = NULL; /* abandon responsability */
 430             }
 431         }
 432     }
 433
 434     if (last_index != NULL) {
 435         /* this means that we want to simulate a default user */
 436
 437         if (((gN = SRP_get_gN_by_id(last_index, SRP_gN_tab)) == NULL)) {
 438             error_code = SRP_ERR_VBASE_BN_LIB;
 439             goto err;
 440         }
 441         vb->default_g = gN->g;
 442         vb->default_N = gN->N;
 443         gN = NULL;
 444     }
 445     error_code = SRP_NO_ERROR;
 446
 447  err:
 448     /*
 449      * there may be still some leaks to fix, if this fails, the application
 450      * terminates most likely
 451      */
 452
 453     if (gN != NULL) {
 454         OPENSSL_free(gN->id);
 455         OPENSSL_free(gN);
 456     }
 457
 458     SRP_user_pwd_free(user_pwd);
 459
 460     if (tmpdb)
 461         TXT_DB_free(tmpdb);
 462     if (in)
 463         BIO_free_all(in);
 464
 465     sk_SRP_gN_free(SRP_gN_tab);
 466
 467     return error_code;
 468
 469 }
 470
 471 SRP_user_pwd *SRP_VBASE_get_by_user(SRP_VBASE *vb, char *username)
 472 {
 473     int i;
 474     SRP_user_pwd *user;
 475     unsigned char digv[SHA_DIGEST_LENGTH];
 476     unsigned char digs[SHA_DIGEST_LENGTH];
 477     EVP_MD_CTX ctxt;
 478
 479     if (vb == NULL)
 480         return NULL;
 481     for (i = 0; i < sk_SRP_user_pwd_num(vb->users_pwd); i++) {
 482         user = sk_SRP_user_pwd_value(vb->users_pwd, i);
 483         if (strcmp(user->id, username) == 0)
 484             return user;
 485     }
 486     if ((vb->seed_key == NULL) ||
 487         (vb->default_g == NULL) || (vb->default_N == NULL))
 488         return NULL;
 489
 490 /* if the user is unknown we set parameters as well if we have a seed_key */
 491
 492     if ((user = SRP_user_pwd_new()) == NULL)
 493         return NULL;
 494
 495     SRP_user_pwd_set_gN(user, vb->default_g, vb->default_N);
 496
 497     if (!SRP_user_pwd_set_ids(user, username, NULL))
 498         goto err;
 499
 500     if (RAND_pseudo_bytes(digv, SHA_DIGEST_LENGTH) < 0)
 501         goto err;
 502     EVP_MD_CTX_init(&ctxt);
 503     EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
 504     EVP_DigestUpdate(&ctxt, vb->seed_key, strlen(vb->seed_key));
 505     EVP_DigestUpdate(&ctxt, username, strlen(username));
 506     EVP_DigestFinal_ex(&ctxt, digs, NULL);
 507     EVP_MD_CTX_cleanup(&ctxt);
 508     if (SRP_user_pwd_set_sv_BN
 509         (user, BN_bin2bn(digs, SHA_DIGEST_LENGTH, NULL),
 510          BN_bin2bn(digv, SHA_DIGEST_LENGTH, NULL)))
 511         return user;
 512
 513  err:SRP_user_pwd_free(user);
 514     return NULL;
 515 }
 516
 517 /*
 518  * create a verifier (*salt,*verifier,g and N are in base64)
 519  */
 520 char *SRP_create_verifier(const char *user, const char *pass, char **salt,
 521                           char **verifier, const char *N, const char *g)
 522 {
 523     int len;
 524     char *result = NULL;
 525     char *vf;
 526     BIGNUM *N_bn = NULL, *g_bn = NULL, *s = NULL, *v = NULL;
 527     unsigned char tmp[MAX_LEN];
 528     unsigned char tmp2[MAX_LEN];
 529     char *defgNid = NULL;
 530
 531     if ((user == NULL) ||
 532         (pass == NULL) || (salt == NULL) || (verifier == NULL))
 533         goto err;
 534
 535     if (N) {
 536         if (!(len = t_fromb64(tmp, N)))
 537             goto err;
 538         N_bn = BN_bin2bn(tmp, len, NULL);
 539         if (!(len = t_fromb64(tmp, g)))
 540             goto err;
 541         g_bn = BN_bin2bn(tmp, len, NULL);
 542         defgNid = "*";
 543     } else {
 544         SRP_gN *gN = SRP_get_gN_by_id(g, NULL);
 545         if (gN == NULL)
 546             goto err;
 547         N_bn = gN->N;
 548         g_bn = gN->g;
 549         defgNid = gN->id;
 550     }
 551
 552     if (*salt == NULL) {
 553         if (RAND_pseudo_bytes(tmp2, SRP_RANDOM_SALT_LEN) < 0)
 554             goto err;
 555
 556         s = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
 557     } else {
 558         if (!(len = t_fromb64(tmp2, *salt)))
 559             goto err;
 560         s = BN_bin2bn(tmp2, len, NULL);
 561     }
 562
 563     if (!SRP_create_verifier_BN(user, pass, &s, &v, N_bn, g_bn))
 564         goto err;
 565
 566     BN_bn2bin(v, tmp);
 567     if (((vf = OPENSSL_malloc(BN_num_bytes(v) * 2)) == NULL))
 568         goto err;
 569     t_tob64(vf, tmp, BN_num_bytes(v));
 570
 571     *verifier = vf;
 572     if (*salt == NULL) {
 573         char *tmp_salt;
 574
 575         if ((tmp_salt = OPENSSL_malloc(SRP_RANDOM_SALT_LEN * 2)) == NULL) {
 576             OPENSSL_free(vf);
 577             goto err;
 578         }
 579         t_tob64(tmp_salt, tmp2, SRP_RANDOM_SALT_LEN);
 580         *salt = tmp_salt;
 581     }
 582
 583     result = defgNid;
 584
 585  err:
 586     if (N) {
 587         BN_free(N_bn);
 588         BN_free(g_bn);
 589     }
 590     return result;
 591 }
 592
 593 /*
 594  * create a verifier (*salt,*verifier,g and N are BIGNUMs)
 595  */
 596 int SRP_create_verifier_BN(const char *user, const char *pass, BIGNUM **salt,
 597                            BIGNUM **verifier, BIGNUM *N, BIGNUM *g)
 598 {
 599     int result = 0;
 600     BIGNUM *x = NULL;
 601     BN_CTX *bn_ctx = BN_CTX_new();
 602     unsigned char tmp2[MAX_LEN];
 603
 604     if ((user == NULL) ||
 605         (pass == NULL) ||
 606         (salt == NULL) ||
 607         (verifier == NULL) || (N == NULL) || (g == NULL) || (bn_ctx == NULL))
 608         goto err;
 609
 610     srp_bn_print(N);
 611     srp_bn_print(g);
 612
 613     if (*salt == NULL) {
 614         if (RAND_pseudo_bytes(tmp2, SRP_RANDOM_SALT_LEN) < 0)
 615             goto err;
 616
 617         *salt = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
 618     }
 619
 620     x = SRP_Calc_x(*salt, user, pass);
 621
 622     *verifier = BN_new();
 623     if (*verifier == NULL)
 624         goto err;
 625
 626     if (!BN_mod_exp(*verifier, g, x, N, bn_ctx)) {
 627         BN_clear_free(*verifier);
 628         goto err;
 629     }
 630
 631     srp_bn_print(*verifier);
 632
 633     result = 1;
 634
 635  err:
 636
 637     BN_clear_free(x);
 638     BN_CTX_free(bn_ctx);
 639     return result;
 640 }
 641
 642 #endif