crypto/srp/srp_vfy.c

   1 /*
   2  * Written by Christophe Renou (christophe.renou@edelweb.fr) with the
   3  * precious help of Peter Sylvester (peter.sylvester@edelweb.fr) for the
   4  * EdelKey project and contributed to the OpenSSL project 2004.
   5  */
   6 /* ====================================================================
   7  * Copyright (c) 2004 The OpenSSL Project.  All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  *
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  *
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in
  18  *    the documentation and/or other materials provided with the
  19  *    distribution.
  20  *
  21  * 3. All advertising materials mentioning features or use of this
  22  *    software must display the following acknowledgment:
  23  *    "This product includes software developed by the OpenSSL Project
  24  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  25  *
  26  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  27  *    endorse or promote products derived from this software without
  28  *    prior written permission. For written permission, please contact
  29  *    licensing@OpenSSL.org.
  30  *
  31  * 5. Products derived from this software may not be called "OpenSSL"
  32  *    nor may "OpenSSL" appear in their names without prior written
  33  *    permission of the OpenSSL Project.
  34  *
  35  * 6. Redistributions of any form whatsoever must retain the following
  36  *    acknowledgment:
  37  *    "This product includes software developed by the OpenSSL Project
  38  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  39  *
  40  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  41  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  43  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  44  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  45  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  46  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  47  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  49  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  50  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  51  * OF THE POSSIBILITY OF SUCH DAMAGE.
  52  * ====================================================================
  53  *
  54  * This product includes cryptographic software written by Eric Young
  55  * (eay@cryptsoft.com).  This product includes software written by Tim
  56  * Hudson (tjh@cryptsoft.com).
  57  *
  58  */
  59 #ifndef OPENSSL_NO_SRP
  60 # include "internal/cryptlib.h"
  61 # include <openssl/sha.h>
  62 # include <openssl/srp.h>
  63 # include <openssl/evp.h>
  64 # include <openssl/buffer.h>
  65 # include <openssl/rand.h>
  66 # include <openssl/txt_db.h>
  67
  68 # define SRP_RANDOM_SALT_LEN 20
  69 # define MAX_LEN 2500
  70
  71 static char b64table[] =
  72     "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz./";
  73
  74 /*
  75  * the following two conversion routines have been inspired by code from
  76  * Stanford
  77  */
  78
  79 /*
  80  * Convert a base64 string into raw byte array representation.
  81  */
  82 static int t_fromb64(unsigned char *a, const char *src)
  83 {
  84     char *loc;
  85     int i, j;
  86     int size;
  87
  88     while (*src && (*src == ' ' || *src == '\t' || *src == '\n'))
  89         ++src;
  90     size = strlen(src);
  91     i = 0;
  92     while (i < size) {
  93         loc = strchr(b64table, src[i]);
  94         if (loc == (char *)0)
  95             break;
  96         else
  97             a[i] = loc - b64table;
  98         ++i;
  99     }
 100     /* if nothing valid to process we have a zero length response */
 101     if (i == 0)
 102         return 0;
 103     size = i;
 104     i = size - 1;
 105     j = size;
 106     while (1) {
 107         a[j] = a[i];
 108         if (--i < 0)
 109             break;
 110         a[j] |= (a[i] & 3) << 6;
 111         --j;
 112         a[j] = (unsigned char)((a[i] & 0x3c) >> 2);
 113         if (--i < 0)
 114             break;
 115         a[j] |= (a[i] & 0xf) << 4;
 116         --j;
 117         a[j] = (unsigned char)((a[i] & 0x30) >> 4);
 118         if (--i < 0)
 119             break;
 120         a[j] |= (a[i] << 2);
 121
 122         a[--j] = 0;
 123         if (--i < 0)
 124             break;
 125     }
 126     while (a[j] == 0 && j <= size)
 127         ++j;
 128     i = 0;
 129     while (j <= size)
 130         a[i++] = a[j++];
 131     return i;
 132 }
 133
 134 /*
 135  * Convert a raw byte string into a null-terminated base64 ASCII string.
 136  */
 137 static char *t_tob64(char *dst, const unsigned char *src, int size)
 138 {
 139     int c, pos = size % 3;
 140     unsigned char b0 = 0, b1 = 0, b2 = 0, notleading = 0;
 141     char *olddst = dst;
 142
 143     switch (pos) {
 144     case 1:
 145         b2 = src[0];
 146         break;
 147     case 2:
 148         b1 = src[0];
 149         b2 = src[1];
 150         break;
 151     }
 152
 153     while (1) {
 154         c = (b0 & 0xfc) >> 2;
 155         if (notleading || c != 0) {
 156             *dst++ = b64table[c];
 157             notleading = 1;
 158         }
 159         c = ((b0 & 3) << 4) | ((b1 & 0xf0) >> 4);
 160         if (notleading || c != 0) {
 161             *dst++ = b64table[c];
 162             notleading = 1;
 163         }
 164         c = ((b1 & 0xf) << 2) | ((b2 & 0xc0) >> 6);
 165         if (notleading || c != 0) {
 166             *dst++ = b64table[c];
 167             notleading = 1;
 168         }
 169         c = b2 & 0x3f;
 170         if (notleading || c != 0) {
 171             *dst++ = b64table[c];
 172             notleading = 1;
 173         }
 174         if (pos >= size)
 175             break;
 176         else {
 177             b0 = src[pos++];
 178             b1 = src[pos++];
 179             b2 = src[pos++];
 180         }
 181     }
 182
 183     *dst++ = '\0';
 184     return olddst;
 185 }
 186
 187 void SRP_user_pwd_free(SRP_user_pwd *user_pwd)
 188 {
 189     if (user_pwd == NULL)
 190         return;
 191     BN_free(user_pwd->s);
 192     BN_clear_free(user_pwd->v);
 193     OPENSSL_free(user_pwd->id);
 194     OPENSSL_free(user_pwd->info);
 195     OPENSSL_free(user_pwd);
 196 }
 197
 198 static SRP_user_pwd *SRP_user_pwd_new(void)
 199 {
 200     SRP_user_pwd *ret = OPENSSL_malloc(sizeof(*ret));
 201     if (ret == NULL)
 202         return NULL;
 203     ret->N = NULL;
 204     ret->g = NULL;
 205     ret->s = NULL;
 206     ret->v = NULL;
 207     ret->id = NULL;
 208     ret->info = NULL;
 209     return ret;
 210 }
 211
 212 static void SRP_user_pwd_set_gN(SRP_user_pwd *vinfo, const BIGNUM *g,
 213                                 const BIGNUM *N)
 214 {
 215     vinfo->N = N;
 216     vinfo->g = g;
 217 }
 218
 219 static int SRP_user_pwd_set_ids(SRP_user_pwd *vinfo, const char *id,
 220                                 const char *info)
 221 {
 222     if (id != NULL && NULL == (vinfo->id = OPENSSL_strdup(id)))
 223         return 0;
 224     return (info == NULL || NULL != (vinfo->info = OPENSSL_strdup(info)));
 225 }
 226
 227 static int SRP_user_pwd_set_sv(SRP_user_pwd *vinfo, const char *s,
 228                                const char *v)
 229 {
 230     unsigned char tmp[MAX_LEN];
 231     int len;
 232
 233     if (strlen(s) > MAX_LEN || strlen(v) > MAX_LEN)
 234         return 0;
 235     len = t_fromb64(tmp, v);
 236     if (NULL == (vinfo->v = BN_bin2bn(tmp, len, NULL)))
 237         return 0;
 238     len = t_fromb64(tmp, s);
 239     return ((vinfo->s = BN_bin2bn(tmp, len, NULL)) != NULL);
 240 }
 241
 242 static int SRP_user_pwd_set_sv_BN(SRP_user_pwd *vinfo, BIGNUM *s, BIGNUM *v)
 243 {
 244     vinfo->v = v;
 245     vinfo->s = s;
 246     return (vinfo->s != NULL && vinfo->v != NULL);
 247 }
 248
 249 static SRP_user_pwd *srp_user_pwd_dup(SRP_user_pwd *src)
 250 {
 251     SRP_user_pwd *ret;
 252
 253     if (src == NULL)
 254         return NULL;
 255     if ((ret = SRP_user_pwd_new()) == NULL)
 256         return NULL;
 257
 258     SRP_user_pwd_set_gN(ret, src->g, src->N);
 259     if (!SRP_user_pwd_set_ids(ret, src->id, src->info)
 260         || !SRP_user_pwd_set_sv_BN(ret, BN_dup(src->s), BN_dup(src->v))) {
 261             SRP_user_pwd_free(ret);
 262             return NULL;
 263     }
 264     return ret;
 265 }
 266
 267 SRP_VBASE *SRP_VBASE_new(char *seed_key)
 268 {
 269     SRP_VBASE *vb = OPENSSL_malloc(sizeof(*vb));
 270
 271     if (vb == NULL)
 272         return NULL;
 273     if ((vb->users_pwd = sk_SRP_user_pwd_new_null()) == NULL
 274         || (vb->gN_cache = sk_SRP_gN_cache_new_null()) == NULL) {
 275         OPENSSL_free(vb);
 276         return NULL;
 277     }
 278     vb->default_g = NULL;
 279     vb->default_N = NULL;
 280     vb->seed_key = NULL;
 281     if ((seed_key != NULL) && (vb->seed_key = OPENSSL_strdup(seed_key)) == NULL) {
 282         sk_SRP_user_pwd_free(vb->users_pwd);
 283         sk_SRP_gN_cache_free(vb->gN_cache);
 284         OPENSSL_free(vb);
 285         return NULL;
 286     }
 287     return vb;
 288 }
 289
 290 void SRP_VBASE_free(SRP_VBASE *vb)
 291 {
 292     if (!vb)
 293         return;
 294     sk_SRP_user_pwd_pop_free(vb->users_pwd, SRP_user_pwd_free);
 295     sk_SRP_gN_cache_free(vb->gN_cache);
 296     OPENSSL_free(vb->seed_key);
 297     OPENSSL_free(vb);
 298 }
 299
 300 static SRP_gN_cache *SRP_gN_new_init(const char *ch)
 301 {
 302     unsigned char tmp[MAX_LEN];
 303     int len;
 304     SRP_gN_cache *newgN = OPENSSL_malloc(sizeof(*newgN));
 305
 306     if (newgN == NULL)
 307         return NULL;
 308
 309     if ((newgN->b64_bn = OPENSSL_strdup(ch)) == NULL)
 310         goto err;
 311
 312     len = t_fromb64(tmp, ch);
 313     if ((newgN->bn = BN_bin2bn(tmp, len, NULL)))
 314         return newgN;
 315
 316     OPENSSL_free(newgN->b64_bn);
 317  err:
 318     OPENSSL_free(newgN);
 319     return NULL;
 320 }
 321
 322 static void SRP_gN_free(SRP_gN_cache *gN_cache)
 323 {
 324     if (gN_cache == NULL)
 325         return;
 326     OPENSSL_free(gN_cache->b64_bn);
 327     BN_free(gN_cache->bn);
 328     OPENSSL_free(gN_cache);
 329 }
 330
 331 static SRP_gN *SRP_get_gN_by_id(const char *id, STACK_OF(SRP_gN) *gN_tab)
 332 {
 333     int i;
 334
 335     SRP_gN *gN;
 336     if (gN_tab != NULL)
 337         for (i = 0; i < sk_SRP_gN_num(gN_tab); i++) {
 338             gN = sk_SRP_gN_value(gN_tab, i);
 339             if (gN && (id == NULL || strcmp(gN->id, id) == 0))
 340                 return gN;
 341         }
 342
 343     return SRP_get_default_gN(id);
 344 }
 345
 346 static BIGNUM *SRP_gN_place_bn(STACK_OF(SRP_gN_cache) *gN_cache, char *ch)
 347 {
 348     int i;
 349     if (gN_cache == NULL)
 350         return NULL;
 351
 352     /* search if we have already one... */
 353     for (i = 0; i < sk_SRP_gN_cache_num(gN_cache); i++) {
 354         SRP_gN_cache *cache = sk_SRP_gN_cache_value(gN_cache, i);
 355         if (strcmp(cache->b64_bn, ch) == 0)
 356             return cache->bn;
 357     }
 358     {                           /* it is the first time that we find it */
 359         SRP_gN_cache *newgN = SRP_gN_new_init(ch);
 360         if (newgN) {
 361             if (sk_SRP_gN_cache_insert(gN_cache, newgN, 0) > 0)
 362                 return newgN->bn;
 363             SRP_gN_free(newgN);
 364         }
 365     }
 366     return NULL;
 367 }
 368
 369 /*
 370  * this function parses verifier file. Format is:
 371  * string(index):base64(N):base64(g):0
 372  * string(username):base64(v):base64(salt):int(index)
 373  */
 374
 375 int SRP_VBASE_init(SRP_VBASE *vb, char *verifier_file)
 376 {
 377     int error_code;
 378     STACK_OF(SRP_gN) *SRP_gN_tab = sk_SRP_gN_new_null();
 379     char *last_index = NULL;
 380     int i;
 381     char **pp;
 382
 383     SRP_gN *gN = NULL;
 384     SRP_user_pwd *user_pwd = NULL;
 385
 386     TXT_DB *tmpdb = NULL;
 387     BIO *in = BIO_new(BIO_s_file());
 388
 389     error_code = SRP_ERR_OPEN_FILE;
 390
 391     if (in == NULL || BIO_read_filename(in, verifier_file) <= 0)
 392         goto err;
 393
 394     error_code = SRP_ERR_VBASE_INCOMPLETE_FILE;
 395
 396     if ((tmpdb = TXT_DB_read(in, DB_NUMBER)) == NULL)
 397         goto err;
 398
 399     error_code = SRP_ERR_MEMORY;
 400
 401     if (vb->seed_key) {
 402         last_index = SRP_get_default_gN(NULL)->id;
 403     }
 404     for (i = 0; i < sk_OPENSSL_PSTRING_num(tmpdb->data); i++) {
 405         pp = sk_OPENSSL_PSTRING_value(tmpdb->data, i);
 406         if (pp[DB_srptype][0] == DB_SRP_INDEX) {
 407             /*
 408              * we add this couple in the internal Stack
 409              */
 410
 411             if ((gN = OPENSSL_malloc(sizeof(*gN))) == NULL)
 412                 goto err;
 413
 414             if ((gN->id = OPENSSL_strdup(pp[DB_srpid])) == NULL
 415                 || (gN->N = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpverifier]))
 416                         == NULL
 417                 || (gN->g = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpsalt]))
 418                         == NULL
 419                 || sk_SRP_gN_insert(SRP_gN_tab, gN, 0) == 0)
 420                 goto err;
 421
 422             gN = NULL;
 423
 424             if (vb->seed_key != NULL) {
 425                 last_index = pp[DB_srpid];
 426             }
 427         } else if (pp[DB_srptype][0] == DB_SRP_VALID) {
 428             /* it is a user .... */
 429             const SRP_gN *lgN;
 430
 431             if ((lgN = SRP_get_gN_by_id(pp[DB_srpgN], SRP_gN_tab)) != NULL) {
 432                 error_code = SRP_ERR_MEMORY;
 433                 if ((user_pwd = SRP_user_pwd_new()) == NULL)
 434                     goto err;
 435
 436                 SRP_user_pwd_set_gN(user_pwd, lgN->g, lgN->N);
 437                 if (!SRP_user_pwd_set_ids
 438                     (user_pwd, pp[DB_srpid], pp[DB_srpinfo]))
 439                     goto err;
 440
 441                 error_code = SRP_ERR_VBASE_BN_LIB;
 442                 if (!SRP_user_pwd_set_sv
 443                     (user_pwd, pp[DB_srpsalt], pp[DB_srpverifier]))
 444                     goto err;
 445
 446                 if (sk_SRP_user_pwd_insert(vb->users_pwd, user_pwd, 0) == 0)
 447                     goto err;
 448                 user_pwd = NULL; /* abandon responsibility */
 449             }
 450         }
 451     }
 452
 453     if (last_index != NULL) {
 454         /* this means that we want to simulate a default user */
 455
 456         if (((gN = SRP_get_gN_by_id(last_index, SRP_gN_tab)) == NULL)) {
 457             error_code = SRP_ERR_VBASE_BN_LIB;
 458             goto err;
 459         }
 460         vb->default_g = gN->g;
 461         vb->default_N = gN->N;
 462         gN = NULL;
 463     }
 464     error_code = SRP_NO_ERROR;
 465
 466  err:
 467     /*
 468      * there may be still some leaks to fix, if this fails, the application
 469      * terminates most likely
 470      */
 471
 472     if (gN != NULL) {
 473         OPENSSL_free(gN->id);
 474         OPENSSL_free(gN);
 475     }
 476
 477     SRP_user_pwd_free(user_pwd);
 478
 479     TXT_DB_free(tmpdb);
 480     BIO_free_all(in);
 481
 482     sk_SRP_gN_free(SRP_gN_tab);
 483
 484     return error_code;
 485
 486 }
 487
 488 static SRP_user_pwd *find_user(SRP_VBASE *vb, char *username)
 489 {
 490     int i;
 491     SRP_user_pwd *user;
 492
 493     if (vb == NULL)
 494         return NULL;
 495
 496     for (i = 0; i < sk_SRP_user_pwd_num(vb->users_pwd); i++) {
 497         user = sk_SRP_user_pwd_value(vb->users_pwd, i);
 498         if (strcmp(user->id, username) == 0)
 499             return user;
 500     }
 501
 502     return NULL;
 503 }
 504
 505  #if OPENSSL_API_COMPAT < 0x10100000L
 506 /*
 507  * DEPRECATED: use SRP_VBASE_get1_by_user instead.
 508  * This method ignores the configured seed and fails for an unknown user.
 509  * Ownership of the returned pointer is not released to the caller.
 510  * In other words, caller must not free the result.
 511  */
 512 SRP_user_pwd *SRP_VBASE_get_by_user(SRP_VBASE *vb, char *username)
 513 {
 514     return find_user(vb, username);
 515 }
 516 #endif
 517
 518 /*
 519  * Ownership of the returned pointer is released to the caller.
 520  * In other words, caller must free the result once done.
 521  */
 522 SRP_user_pwd *SRP_VBASE_get1_by_user(SRP_VBASE *vb, char *username)
 523 {
 524     SRP_user_pwd *user;
 525     unsigned char digv[SHA_DIGEST_LENGTH];
 526     unsigned char digs[SHA_DIGEST_LENGTH];
 527     EVP_MD_CTX *ctxt = NULL;
 528
 529     if (vb == NULL)
 530         return NULL;
 531
 532     if ((user = find_user(vb, username)) != NULL)
 533         return srp_user_pwd_dup(user);
 534
 535     if ((vb->seed_key == NULL) ||
 536         (vb->default_g == NULL) || (vb->default_N == NULL))
 537         return NULL;
 538
 539 /* if the user is unknown we set parameters as well if we have a seed_key */
 540
 541     if ((user = SRP_user_pwd_new()) == NULL)
 542         return NULL;
 543
 544     SRP_user_pwd_set_gN(user, vb->default_g, vb->default_N);
 545
 546     if (!SRP_user_pwd_set_ids(user, username, NULL))
 547         goto err;
 548
 549     if (RAND_bytes(digv, SHA_DIGEST_LENGTH) <= 0)
 550         goto err;
 551     ctxt = EVP_MD_CTX_new();
 552     EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL);
 553     EVP_DigestUpdate(ctxt, vb->seed_key, strlen(vb->seed_key));
 554     EVP_DigestUpdate(ctxt, username, strlen(username));
 555     EVP_DigestFinal_ex(ctxt, digs, NULL);
 556     EVP_MD_CTX_free(ctxt);
 557     ctxt = NULL;
 558     if (SRP_user_pwd_set_sv_BN(user,
 559                                BN_bin2bn(digs, SHA_DIGEST_LENGTH, NULL),
 560                                BN_bin2bn(digv, SHA_DIGEST_LENGTH, NULL)))
 561         return user;
 562
 563  err:
 564     EVP_MD_CTX_free(ctxt);
 565     SRP_user_pwd_free(user);
 566     return NULL;
 567 }
 568
 569 /*
 570  * create a verifier (*salt,*verifier,g and N are in base64)
 571  */
 572 char *SRP_create_verifier(const char *user, const char *pass, char **salt,
 573                           char **verifier, const char *N, const char *g)
 574 {
 575     int len;
 576     char *result = NULL, *vf = NULL;
 577     BIGNUM *N_bn = NULL, *g_bn = NULL, *s = NULL, *v = NULL;
 578     unsigned char tmp[MAX_LEN];
 579     unsigned char tmp2[MAX_LEN];
 580     char *defgNid = NULL;
 581     int vfsize = 0;
 582
 583     if ((user == NULL) ||
 584         (pass == NULL) || (salt == NULL) || (verifier == NULL))
 585         goto err;
 586
 587     if (N) {
 588         if ((len = t_fromb64(tmp, N)) == 0)
 589             goto err;
 590         N_bn = BN_bin2bn(tmp, len, NULL);
 591         if ((len = t_fromb64(tmp, g)) == 0)
 592             goto err;
 593         g_bn = BN_bin2bn(tmp, len, NULL);
 594         defgNid = "*";
 595     } else {
 596         SRP_gN *gN = SRP_get_gN_by_id(g, NULL);
 597         if (gN == NULL)
 598             goto err;
 599         N_bn = gN->N;
 600         g_bn = gN->g;
 601         defgNid = gN->id;
 602     }
 603
 604     if (*salt == NULL) {
 605         if (RAND_bytes(tmp2, SRP_RANDOM_SALT_LEN) <= 0)
 606             goto err;
 607
 608         s = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
 609     } else {
 610         if ((len = t_fromb64(tmp2, *salt)) == 0)
 611             goto err;
 612         s = BN_bin2bn(tmp2, len, NULL);
 613     }
 614
 615     if (!SRP_create_verifier_BN(user, pass, &s, &v, N_bn, g_bn))
 616         goto err;
 617
 618     BN_bn2bin(v, tmp);
 619     vfsize = BN_num_bytes(v) * 2;
 620     if (((vf = OPENSSL_malloc(vfsize)) == NULL))
 621         goto err;
 622     t_tob64(vf, tmp, BN_num_bytes(v));
 623
 624     if (*salt == NULL) {
 625         char *tmp_salt;
 626
 627         if ((tmp_salt = OPENSSL_malloc(SRP_RANDOM_SALT_LEN * 2)) == NULL) {
 628             goto err;
 629         }
 630         t_tob64(tmp_salt, tmp2, SRP_RANDOM_SALT_LEN);
 631         *salt = tmp_salt;
 632     }
 633
 634     *verifier = vf;
 635     vf = NULL;
 636     result = defgNid;
 637
 638  err:
 639     if (N) {
 640         BN_free(N_bn);
 641         BN_free(g_bn);
 642     }
 643     OPENSSL_clear_free(vf, vfsize);
 644     BN_clear_free(s);
 645     BN_clear_free(v);
 646     return result;
 647 }
 648
 649 /*
 650  * create a verifier (*salt,*verifier,g and N are BIGNUMs). If *salt != NULL
 651  * then the provided salt will be used. On successful exit *verifier will point
 652  * to a newly allocated BIGNUM containing the verifier and (if a salt was not
 653  * provided) *salt will be populated with a newly allocated BIGNUM containing a
 654  * random salt.
 655  * The caller is responsible for freeing the allocated *salt and *verifier
 656  * BIGNUMS.
 657  */
 658 int SRP_create_verifier_BN(const char *user, const char *pass, BIGNUM **salt,
 659                            BIGNUM **verifier, const BIGNUM *N,
 660                            const BIGNUM *g)
 661 {
 662     int result = 0;
 663     BIGNUM *x = NULL;
 664     BN_CTX *bn_ctx = BN_CTX_new();
 665     unsigned char tmp2[MAX_LEN];
 666     BIGNUM *salttmp = NULL;
 667
 668     if ((user == NULL) ||
 669         (pass == NULL) ||
 670         (salt == NULL) ||
 671         (verifier == NULL) || (N == NULL) || (g == NULL) || (bn_ctx == NULL))
 672         goto err;
 673
 674     if (*salt == NULL) {
 675         if (RAND_bytes(tmp2, SRP_RANDOM_SALT_LEN) <= 0)
 676             goto err;
 677
 678         salttmp = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
 679     } else {
 680         salttmp = *salt;
 681     }
 682
 683     x = SRP_Calc_x(salttmp, user, pass);
 684
 685     *verifier = BN_new();
 686     if (*verifier == NULL)
 687         goto err;
 688
 689     if (!BN_mod_exp(*verifier, g, x, N, bn_ctx)) {
 690         BN_clear_free(*verifier);
 691         goto err;
 692     }
 693
 694     result = 1;
 695     *salt = salttmp;
 696
 697  err:
 698     if (salt != NULL && *salt != salttmp)
 699         BN_clear_free(salttmp);
 700     BN_clear_free(x);
 701     BN_CTX_free(bn_ctx);
 702     return result;
 703 }
 704
 705 #endif