crypto/srp/srp_vfy.c

   1 /*
   2  * Copyright 2004-2020 The OpenSSL Project Authors. All Rights Reserved.
   3  * Copyright (c) 2004, EdelKey Project. All Rights Reserved.
   4  *
   5  * Licensed under the Apache License 2.0 (the "License").  You may not use
   6  * this file except in compliance with the License.  You can obtain a copy
   7  * in the file LICENSE in the source distribution or at
   8  * https://www.openssl.org/source/license.html
   9  *
  10  * Originally written by Christophe Renou and Peter Sylvester,
  11  * for the EdelKey project.
  12  */
  13
  14 #ifndef OPENSSL_NO_SRP
  15 # include "internal/cryptlib.h"
  16 # include "crypto/evp.h"
  17 # include <openssl/sha.h>
  18 # include <openssl/srp.h>
  19 # include <openssl/evp.h>
  20 # include <openssl/buffer.h>
  21 # include <openssl/rand.h>
  22 # include <openssl/txt_db.h>
  23 # include <openssl/err.h>
  24
  25 # define SRP_RANDOM_SALT_LEN 20
  26 # define MAX_LEN 2500
  27
  28 DEFINE_STACK_OF(SRP_user_pwd)
  29 DEFINE_STACK_OF(SRP_gN_cache)
  30 DEFINE_STACK_OF(SRP_gN)
  31
  32 /*
  33  * Note that SRP uses its own variant of base 64 encoding. A different base64
  34  * alphabet is used and no padding '=' characters are added. Instead we pad to
  35  * the front with 0 bytes and subsequently strip off leading encoded padding.
  36  * This variant is used for compatibility with other SRP implementations -
  37  * notably libsrp, but also others. It is also required for backwards
  38  * compatibility in order to load verifier files from other OpenSSL versions.
  39  */
  40
  41 /*
  42  * Convert a base64 string into raw byte array representation.
  43  * Returns the length of the decoded data, or -1 on error.
  44  */
  45 static int t_fromb64(unsigned char *a, size_t alen, const char *src)
  46 {
  47     EVP_ENCODE_CTX *ctx;
  48     int outl = 0, outl2 = 0;
  49     size_t size, padsize;
  50     const unsigned char *pad = (const unsigned char *)"00";
  51
  52     while (*src == ' ' || *src == '\t' || *src == '\n')
  53         ++src;
  54     size = strlen(src);
  55     padsize = 4 - (size & 3);
  56     padsize &= 3;
  57
  58     /* Four bytes in src become three bytes output. */
  59     if (size > INT_MAX || ((size + padsize) / 4) * 3 > alen)
  60         return -1;
  61
  62     ctx = EVP_ENCODE_CTX_new();
  63     if (ctx == NULL)
  64         return -1;
  65
  66     /*
  67      * This should never occur because 1 byte of data always requires 2 bytes of
  68      * encoding, i.e.
  69      *  0 bytes unencoded = 0 bytes encoded
  70      *  1 byte unencoded  = 2 bytes encoded
  71      *  2 bytes unencoded = 3 bytes encoded
  72      *  3 bytes unencoded = 4 bytes encoded
  73      *  4 bytes unencoded = 6 bytes encoded
  74      *  etc
  75      */
  76     if (padsize == 3) {
  77         outl = -1;
  78         goto err;
  79     }
  80
  81     /* Valid padsize values are now 0, 1 or 2 */
  82
  83     EVP_DecodeInit(ctx);
  84     evp_encode_ctx_set_flags(ctx, EVP_ENCODE_CTX_USE_SRP_ALPHABET);
  85
  86     /* Add any encoded padding that is required */
  87     if (padsize != 0
  88             && EVP_DecodeUpdate(ctx, a, &outl, pad, padsize) < 0) {
  89         outl = -1;
  90         goto err;
  91     }
  92     if (EVP_DecodeUpdate(ctx, a, &outl2, (const unsigned char *)src, size) < 0) {
  93         outl = -1;
  94         goto err;
  95     }
  96     outl += outl2;
  97     EVP_DecodeFinal(ctx, a + outl, &outl2);
  98     outl += outl2;
  99
 100     /* Strip off the leading padding */
 101     if (padsize != 0) {
 102         if ((int)padsize >= outl) {
 103             outl = -1;
 104             goto err;
 105         }
 106
 107         /*
 108          * If we added 1 byte of padding prior to encoding then we have 2 bytes
 109          * of "real" data which gets spread across 4 encoded bytes like this:
 110          *   (6 bits pad)(2 bits pad | 4 bits data)(6 bits data)(6 bits data)
 111          * So 1 byte of pre-encoding padding results in 1 full byte of encoded
 112          * padding.
 113          * If we added 2 bytes of padding prior to encoding this gets encoded
 114          * as:
 115          *   (6 bits pad)(6 bits pad)(4 bits pad | 2 bits data)(6 bits data)
 116          * So 2 bytes of pre-encoding padding results in 2 full bytes of encoded
 117          * padding, i.e. we have to strip the same number of bytes of padding
 118          * from the encoded data as we added to the pre-encoded data.
 119          */
 120         memmove(a, a + padsize, outl - padsize);
 121         outl -= padsize;
 122     }
 123
 124  err:
 125     EVP_ENCODE_CTX_free(ctx);
 126
 127     return outl;
 128 }
 129
 130 /*
 131  * Convert a raw byte string into a null-terminated base64 ASCII string.
 132  * Returns 1 on success or 0 on error.
 133  */
 134 static int t_tob64(char *dst, const unsigned char *src, int size)
 135 {
 136     EVP_ENCODE_CTX *ctx = EVP_ENCODE_CTX_new();
 137     int outl = 0, outl2 = 0;
 138     unsigned char pad[2] = {0, 0};
 139     size_t leadz = 0;
 140
 141     if (ctx == NULL)
 142         return 0;
 143
 144     EVP_EncodeInit(ctx);
 145     evp_encode_ctx_set_flags(ctx, EVP_ENCODE_CTX_NO_NEWLINES
 146                                   | EVP_ENCODE_CTX_USE_SRP_ALPHABET);
 147
 148     /*
 149      * We pad at the front with zero bytes until the length is a multiple of 3
 150      * so that EVP_EncodeUpdate/EVP_EncodeFinal does not add any of its own "="
 151      * padding
 152      */
 153     leadz = 3 - (size % 3);
 154     if (leadz != 3
 155             && !EVP_EncodeUpdate(ctx, (unsigned char *)dst, &outl, pad,
 156                                  leadz)) {
 157         EVP_ENCODE_CTX_free(ctx);
 158         return 0;
 159     }
 160
 161     if (!EVP_EncodeUpdate(ctx, (unsigned char *)dst + outl, &outl2, src,
 162                           size)) {
 163         EVP_ENCODE_CTX_free(ctx);
 164         return 0;
 165     }
 166     outl += outl2;
 167     EVP_EncodeFinal(ctx, (unsigned char *)dst + outl, &outl2);
 168     outl += outl2;
 169
 170     /* Strip the encoded padding at the front */
 171     if (leadz != 3) {
 172         memmove(dst, dst + leadz, outl - leadz);
 173         dst[outl - leadz] = '\0';
 174     }
 175
 176     EVP_ENCODE_CTX_free(ctx);
 177     return 1;
 178 }
 179
 180 void SRP_user_pwd_free(SRP_user_pwd *user_pwd)
 181 {
 182     if (user_pwd == NULL)
 183         return;
 184     BN_free(user_pwd->s);
 185     BN_clear_free(user_pwd->v);
 186     OPENSSL_free(user_pwd->id);
 187     OPENSSL_free(user_pwd->info);
 188     OPENSSL_free(user_pwd);
 189 }
 190
 191 SRP_user_pwd *SRP_user_pwd_new(void)
 192 {
 193     SRP_user_pwd *ret;
 194
 195     if ((ret = OPENSSL_malloc(sizeof(*ret))) == NULL) {
 196         /* SRPerr(SRP_F_SRP_USER_PWD_NEW, ERR_R_MALLOC_FAILURE); */ /*ckerr_ignore*/
 197         return NULL;
 198     }
 199     ret->N = NULL;
 200     ret->g = NULL;
 201     ret->s = NULL;
 202     ret->v = NULL;
 203     ret->id = NULL;
 204     ret->info = NULL;
 205     return ret;
 206 }
 207
 208 void SRP_user_pwd_set_gN(SRP_user_pwd *vinfo, const BIGNUM *g,
 209                          const BIGNUM *N)
 210 {
 211     vinfo->N = N;
 212     vinfo->g = g;
 213 }
 214
 215 int SRP_user_pwd_set1_ids(SRP_user_pwd *vinfo, const char *id,
 216                           const char *info)
 217 {
 218     OPENSSL_free(vinfo->id);
 219     OPENSSL_free(vinfo->info);
 220     if (id != NULL && NULL == (vinfo->id = OPENSSL_strdup(id)))
 221         return 0;
 222     return (info == NULL || NULL != (vinfo->info = OPENSSL_strdup(info)));
 223 }
 224
 225 static int SRP_user_pwd_set_sv(SRP_user_pwd *vinfo, const char *s,
 226                                const char *v)
 227 {
 228     unsigned char tmp[MAX_LEN];
 229     int len;
 230
 231     vinfo->v = NULL;
 232     vinfo->s = NULL;
 233
 234     len = t_fromb64(tmp, sizeof(tmp), v);
 235     if (len < 0)
 236         return 0;
 237     if (NULL == (vinfo->v = BN_bin2bn(tmp, len, NULL)))
 238         return 0;
 239     len = t_fromb64(tmp, sizeof(tmp), s);
 240     if (len < 0)
 241         goto err;
 242     vinfo->s = BN_bin2bn(tmp, len, NULL);
 243     if (vinfo->s == NULL)
 244         goto err;
 245     return 1;
 246  err:
 247     BN_free(vinfo->v);
 248     vinfo->v = NULL;
 249     return 0;
 250 }
 251
 252 int SRP_user_pwd_set0_sv(SRP_user_pwd *vinfo, BIGNUM *s, BIGNUM *v)
 253 {
 254     BN_free(vinfo->s);
 255     BN_clear_free(vinfo->v);
 256     vinfo->v = v;
 257     vinfo->s = s;
 258     return (vinfo->s != NULL && vinfo->v != NULL);
 259 }
 260
 261 static SRP_user_pwd *srp_user_pwd_dup(SRP_user_pwd *src)
 262 {
 263     SRP_user_pwd *ret;
 264
 265     if (src == NULL)
 266         return NULL;
 267     if ((ret = SRP_user_pwd_new()) == NULL)
 268         return NULL;
 269
 270     SRP_user_pwd_set_gN(ret, src->g, src->N);
 271     if (!SRP_user_pwd_set1_ids(ret, src->id, src->info)
 272         || !SRP_user_pwd_set0_sv(ret, BN_dup(src->s), BN_dup(src->v))) {
 273             SRP_user_pwd_free(ret);
 274             return NULL;
 275     }
 276     return ret;
 277 }
 278
 279 SRP_VBASE *SRP_VBASE_new(char *seed_key)
 280 {
 281     SRP_VBASE *vb = OPENSSL_malloc(sizeof(*vb));
 282
 283     if (vb == NULL)
 284         return NULL;
 285     if ((vb->users_pwd = sk_SRP_user_pwd_new_null()) == NULL
 286         || (vb->gN_cache = sk_SRP_gN_cache_new_null()) == NULL) {
 287         OPENSSL_free(vb);
 288         return NULL;
 289     }
 290     vb->default_g = NULL;
 291     vb->default_N = NULL;
 292     vb->seed_key = NULL;
 293     if ((seed_key != NULL) && (vb->seed_key = OPENSSL_strdup(seed_key)) == NULL) {
 294         sk_SRP_user_pwd_free(vb->users_pwd);
 295         sk_SRP_gN_cache_free(vb->gN_cache);
 296         OPENSSL_free(vb);
 297         return NULL;
 298     }
 299     return vb;
 300 }
 301
 302 void SRP_VBASE_free(SRP_VBASE *vb)
 303 {
 304     if (!vb)
 305         return;
 306     sk_SRP_user_pwd_pop_free(vb->users_pwd, SRP_user_pwd_free);
 307     sk_SRP_gN_cache_free(vb->gN_cache);
 308     OPENSSL_free(vb->seed_key);
 309     OPENSSL_free(vb);
 310 }
 311
 312 static SRP_gN_cache *SRP_gN_new_init(const char *ch)
 313 {
 314     unsigned char tmp[MAX_LEN];
 315     int len;
 316     SRP_gN_cache *newgN = OPENSSL_malloc(sizeof(*newgN));
 317
 318     if (newgN == NULL)
 319         return NULL;
 320
 321     len = t_fromb64(tmp, sizeof(tmp), ch);
 322     if (len < 0)
 323         goto err;
 324
 325     if ((newgN->b64_bn = OPENSSL_strdup(ch)) == NULL)
 326         goto err;
 327
 328     if ((newgN->bn = BN_bin2bn(tmp, len, NULL)))
 329         return newgN;
 330
 331     OPENSSL_free(newgN->b64_bn);
 332  err:
 333     OPENSSL_free(newgN);
 334     return NULL;
 335 }
 336
 337 static void SRP_gN_free(SRP_gN_cache *gN_cache)
 338 {
 339     if (gN_cache == NULL)
 340         return;
 341     OPENSSL_free(gN_cache->b64_bn);
 342     BN_free(gN_cache->bn);
 343     OPENSSL_free(gN_cache);
 344 }
 345
 346 static SRP_gN *SRP_get_gN_by_id(const char *id, STACK_OF(SRP_gN) *gN_tab)
 347 {
 348     int i;
 349
 350     SRP_gN *gN;
 351     if (gN_tab != NULL) {
 352         for (i = 0; i < sk_SRP_gN_num(gN_tab); i++) {
 353             gN = sk_SRP_gN_value(gN_tab, i);
 354             if (gN && (id == NULL || strcmp(gN->id, id) == 0))
 355                 return gN;
 356         }
 357     }
 358
 359     return SRP_get_default_gN(id);
 360 }
 361
 362 static BIGNUM *SRP_gN_place_bn(STACK_OF(SRP_gN_cache) *gN_cache, char *ch)
 363 {
 364     int i;
 365     if (gN_cache == NULL)
 366         return NULL;
 367
 368     /* search if we have already one... */
 369     for (i = 0; i < sk_SRP_gN_cache_num(gN_cache); i++) {
 370         SRP_gN_cache *cache = sk_SRP_gN_cache_value(gN_cache, i);
 371         if (strcmp(cache->b64_bn, ch) == 0)
 372             return cache->bn;
 373     }
 374     {                           /* it is the first time that we find it */
 375         SRP_gN_cache *newgN = SRP_gN_new_init(ch);
 376         if (newgN) {
 377             if (sk_SRP_gN_cache_insert(gN_cache, newgN, 0) > 0)
 378                 return newgN->bn;
 379             SRP_gN_free(newgN);
 380         }
 381     }
 382     return NULL;
 383 }
 384
 385 /*
 386  * This function parses the verifier file generated by the srp app.
 387  * The format for each entry is:
 388  * V base64(verifier) base64(salt) username gNid userinfo(optional)
 389  * or
 390  * I base64(N) base64(g)
 391  * Note that base64 is the SRP variant of base64 encoding described
 392  * in t_fromb64().
 393  */
 394
 395 int SRP_VBASE_init(SRP_VBASE *vb, char *verifier_file)
 396 {
 397     int error_code;
 398     STACK_OF(SRP_gN) *SRP_gN_tab = sk_SRP_gN_new_null();
 399     char *last_index = NULL;
 400     int i;
 401     char **pp;
 402
 403     SRP_gN *gN = NULL;
 404     SRP_user_pwd *user_pwd = NULL;
 405
 406     TXT_DB *tmpdb = NULL;
 407     BIO *in = BIO_new(BIO_s_file());
 408
 409     error_code = SRP_ERR_OPEN_FILE;
 410
 411     if (in == NULL || BIO_read_filename(in, verifier_file) <= 0)
 412         goto err;
 413
 414     error_code = SRP_ERR_VBASE_INCOMPLETE_FILE;
 415
 416     if ((tmpdb = TXT_DB_read(in, DB_NUMBER)) == NULL)
 417         goto err;
 418
 419     error_code = SRP_ERR_MEMORY;
 420
 421     if (vb->seed_key) {
 422         last_index = SRP_get_default_gN(NULL)->id;
 423     }
 424     for (i = 0; i < sk_OPENSSL_PSTRING_num(tmpdb->data); i++) {
 425         pp = sk_OPENSSL_PSTRING_value(tmpdb->data, i);
 426         if (pp[DB_srptype][0] == DB_SRP_INDEX) {
 427             /*
 428              * we add this couple in the internal Stack
 429              */
 430
 431             if ((gN = OPENSSL_malloc(sizeof(*gN))) == NULL)
 432                 goto err;
 433
 434             if ((gN->id = OPENSSL_strdup(pp[DB_srpid])) == NULL
 435                 || (gN->N = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpverifier]))
 436                         == NULL
 437                 || (gN->g = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpsalt]))
 438                         == NULL
 439                 || sk_SRP_gN_insert(SRP_gN_tab, gN, 0) == 0)
 440                 goto err;
 441
 442             gN = NULL;
 443
 444             if (vb->seed_key != NULL) {
 445                 last_index = pp[DB_srpid];
 446             }
 447         } else if (pp[DB_srptype][0] == DB_SRP_VALID) {
 448             /* it is a user .... */
 449             const SRP_gN *lgN;
 450
 451             if ((lgN = SRP_get_gN_by_id(pp[DB_srpgN], SRP_gN_tab)) != NULL) {
 452                 error_code = SRP_ERR_MEMORY;
 453                 if ((user_pwd = SRP_user_pwd_new()) == NULL)
 454                     goto err;
 455
 456                 SRP_user_pwd_set_gN(user_pwd, lgN->g, lgN->N);
 457                 if (!SRP_user_pwd_set1_ids
 458                     (user_pwd, pp[DB_srpid], pp[DB_srpinfo]))
 459                     goto err;
 460
 461                 error_code = SRP_ERR_VBASE_BN_LIB;
 462                 if (!SRP_user_pwd_set_sv
 463                     (user_pwd, pp[DB_srpsalt], pp[DB_srpverifier]))
 464                     goto err;
 465
 466                 if (sk_SRP_user_pwd_insert(vb->users_pwd, user_pwd, 0) == 0)
 467                     goto err;
 468                 user_pwd = NULL; /* abandon responsibility */
 469             }
 470         }
 471     }
 472
 473     if (last_index != NULL) {
 474         /* this means that we want to simulate a default user */
 475
 476         if (((gN = SRP_get_gN_by_id(last_index, SRP_gN_tab)) == NULL)) {
 477             error_code = SRP_ERR_VBASE_BN_LIB;
 478             goto err;
 479         }
 480         vb->default_g = gN->g;
 481         vb->default_N = gN->N;
 482         gN = NULL;
 483     }
 484     error_code = SRP_NO_ERROR;
 485
 486  err:
 487     /*
 488      * there may be still some leaks to fix, if this fails, the application
 489      * terminates most likely
 490      */
 491
 492     if (gN != NULL) {
 493         OPENSSL_free(gN->id);
 494         OPENSSL_free(gN);
 495     }
 496
 497     SRP_user_pwd_free(user_pwd);
 498
 499     TXT_DB_free(tmpdb);
 500     BIO_free_all(in);
 501
 502     sk_SRP_gN_free(SRP_gN_tab);
 503
 504     return error_code;
 505
 506 }
 507
 508 static SRP_user_pwd *find_user(SRP_VBASE *vb, char *username)
 509 {
 510     int i;
 511     SRP_user_pwd *user;
 512
 513     if (vb == NULL)
 514         return NULL;
 515
 516     for (i = 0; i < sk_SRP_user_pwd_num(vb->users_pwd); i++) {
 517         user = sk_SRP_user_pwd_value(vb->users_pwd, i);
 518         if (strcmp(user->id, username) == 0)
 519             return user;
 520     }
 521
 522     return NULL;
 523 }
 524
 525 int SRP_VBASE_add0_user(SRP_VBASE *vb, SRP_user_pwd *user_pwd)
 526 {
 527     if (sk_SRP_user_pwd_push(vb->users_pwd, user_pwd) <= 0)
 528         return 0;
 529     return 1;
 530 }
 531
 532 # ifndef OPENSSL_NO_DEPRECATED_1_1_0
 533 /*
 534  * DEPRECATED: use SRP_VBASE_get1_by_user instead.
 535  * This method ignores the configured seed and fails for an unknown user.
 536  * Ownership of the returned pointer is not released to the caller.
 537  * In other words, caller must not free the result.
 538  */
 539 SRP_user_pwd *SRP_VBASE_get_by_user(SRP_VBASE *vb, char *username)
 540 {
 541     return find_user(vb, username);
 542 }
 543 # endif
 544
 545 /*
 546  * Ownership of the returned pointer is released to the caller.
 547  * In other words, caller must free the result once done.
 548  */
 549 SRP_user_pwd *SRP_VBASE_get1_by_user(SRP_VBASE *vb, char *username)
 550 {
 551     SRP_user_pwd *user;
 552     unsigned char digv[SHA_DIGEST_LENGTH];
 553     unsigned char digs[SHA_DIGEST_LENGTH];
 554     EVP_MD_CTX *ctxt = NULL;
 555
 556     if (vb == NULL)
 557         return NULL;
 558
 559     if ((user = find_user(vb, username)) != NULL)
 560         return srp_user_pwd_dup(user);
 561
 562     if ((vb->seed_key == NULL) ||
 563         (vb->default_g == NULL) || (vb->default_N == NULL))
 564         return NULL;
 565
 566 /* if the user is unknown we set parameters as well if we have a seed_key */
 567
 568     if ((user = SRP_user_pwd_new()) == NULL)
 569         return NULL;
 570
 571     SRP_user_pwd_set_gN(user, vb->default_g, vb->default_N);
 572
 573     if (!SRP_user_pwd_set1_ids(user, username, NULL))
 574         goto err;
 575
 576     if (RAND_priv_bytes(digv, SHA_DIGEST_LENGTH) <= 0)
 577         goto err;
 578     ctxt = EVP_MD_CTX_new();
 579     if (ctxt == NULL
 580         || !EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL)
 581         || !EVP_DigestUpdate(ctxt, vb->seed_key, strlen(vb->seed_key))
 582         || !EVP_DigestUpdate(ctxt, username, strlen(username))
 583         || !EVP_DigestFinal_ex(ctxt, digs, NULL))
 584         goto err;
 585     EVP_MD_CTX_free(ctxt);
 586     ctxt = NULL;
 587     if (SRP_user_pwd_set0_sv(user,
 588                                BN_bin2bn(digs, SHA_DIGEST_LENGTH, NULL),
 589                                BN_bin2bn(digv, SHA_DIGEST_LENGTH, NULL)))
 590         return user;
 591
 592  err:
 593     EVP_MD_CTX_free(ctxt);
 594     SRP_user_pwd_free(user);
 595     return NULL;
 596 }
 597
 598 /*
 599  * create a verifier (*salt,*verifier,g and N are in base64)
 600  */
 601 char *SRP_create_verifier_ex(const char *user, const char *pass, char **salt,
 602                              char **verifier, const char *N, const char *g,
 603                              OPENSSL_CTX *libctx, const char *propq)
 604 {
 605     int len;
 606     char *result = NULL, *vf = NULL;
 607     const BIGNUM *N_bn = NULL, *g_bn = NULL;
 608     BIGNUM *N_bn_alloc = NULL, *g_bn_alloc = NULL, *s = NULL, *v = NULL;
 609     unsigned char tmp[MAX_LEN];
 610     unsigned char tmp2[MAX_LEN];
 611     char *defgNid = NULL;
 612     int vfsize = 0;
 613
 614     if ((user == NULL) ||
 615         (pass == NULL) || (salt == NULL) || (verifier == NULL))
 616         goto err;
 617
 618     if (N) {
 619         if ((len = t_fromb64(tmp, sizeof(tmp), N)) <= 0)
 620             goto err;
 621         N_bn_alloc = BN_bin2bn(tmp, len, NULL);
 622         if (N_bn_alloc == NULL)
 623             goto err;
 624         N_bn = N_bn_alloc;
 625         if ((len = t_fromb64(tmp, sizeof(tmp) ,g)) <= 0)
 626             goto err;
 627         g_bn_alloc = BN_bin2bn(tmp, len, NULL);
 628         if (g_bn_alloc == NULL)
 629             goto err;
 630         g_bn = g_bn_alloc;
 631         defgNid = "*";
 632     } else {
 633         SRP_gN *gN = SRP_get_default_gN(g);
 634         if (gN == NULL)
 635             goto err;
 636         N_bn = gN->N;
 637         g_bn = gN->g;
 638         defgNid = gN->id;
 639     }
 640
 641     if (*salt == NULL) {
 642         if (RAND_bytes_ex(libctx, tmp2, SRP_RANDOM_SALT_LEN) <= 0)
 643             goto err;
 644
 645         s = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
 646     } else {
 647         if ((len = t_fromb64(tmp2, sizeof(tmp2), *salt)) <= 0)
 648             goto err;
 649         s = BN_bin2bn(tmp2, len, NULL);
 650     }
 651     if (s == NULL)
 652         goto err;
 653
 654     if (!SRP_create_verifier_BN_ex(user, pass, &s, &v, N_bn, g_bn, libctx,
 655                                    propq))
 656         goto err;
 657
 658     if (BN_bn2bin(v, tmp) < 0)
 659         goto err;
 660     vfsize = BN_num_bytes(v) * 2;
 661     if (((vf = OPENSSL_malloc(vfsize)) == NULL))
 662         goto err;
 663     if (!t_tob64(vf, tmp, BN_num_bytes(v)))
 664         goto err;
 665
 666     if (*salt == NULL) {
 667         char *tmp_salt;
 668
 669         if ((tmp_salt = OPENSSL_malloc(SRP_RANDOM_SALT_LEN * 2)) == NULL) {
 670             goto err;
 671         }
 672         if (!t_tob64(tmp_salt, tmp2, SRP_RANDOM_SALT_LEN)) {
 673             OPENSSL_free(tmp_salt);
 674             goto err;
 675         }
 676         *salt = tmp_salt;
 677     }
 678
 679     *verifier = vf;
 680     vf = NULL;
 681     result = defgNid;
 682
 683  err:
 684     BN_free(N_bn_alloc);
 685     BN_free(g_bn_alloc);
 686     OPENSSL_clear_free(vf, vfsize);
 687     BN_clear_free(s);
 688     BN_clear_free(v);
 689     return result;
 690 }
 691
 692 char *SRP_create_verifier(const char *user, const char *pass, char **salt,
 693                           char **verifier, const char *N, const char *g)
 694 {
 695     return SRP_create_verifier_ex(user, pass, salt, verifier, N, g, NULL, NULL);
 696 }
 697
 698 /*
 699  * create a verifier (*salt,*verifier,g and N are BIGNUMs). If *salt != NULL
 700  * then the provided salt will be used. On successful exit *verifier will point
 701  * to a newly allocated BIGNUM containing the verifier and (if a salt was not
 702  * provided) *salt will be populated with a newly allocated BIGNUM containing a
 703  * random salt.
 704  * The caller is responsible for freeing the allocated *salt and *verifier
 705  * BIGNUMS.
 706  */
 707 int SRP_create_verifier_BN_ex(const char *user, const char *pass, BIGNUM **salt,
 708                               BIGNUM **verifier, const BIGNUM *N,
 709                               const BIGNUM *g, OPENSSL_CTX *libctx,
 710                               const char *propq)
 711 {
 712     int result = 0;
 713     BIGNUM *x = NULL;
 714     BN_CTX *bn_ctx = BN_CTX_new_ex(libctx);
 715     unsigned char tmp2[MAX_LEN];
 716     BIGNUM *salttmp = NULL;
 717
 718     if ((user == NULL) ||
 719         (pass == NULL) ||
 720         (salt == NULL) ||
 721         (verifier == NULL) || (N == NULL) || (g == NULL) || (bn_ctx == NULL))
 722         goto err;
 723
 724     if (*salt == NULL) {
 725         if (RAND_bytes_ex(libctx, tmp2, SRP_RANDOM_SALT_LEN) <= 0)
 726             goto err;
 727
 728         salttmp = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
 729         if (salttmp == NULL)
 730             goto err;
 731     } else {
 732         salttmp = *salt;
 733     }
 734
 735     x = SRP_Calc_x_ex(salttmp, user, pass, libctx, propq);
 736     if (x == NULL)
 737         goto err;
 738
 739     *verifier = BN_new();
 740     if (*verifier == NULL)
 741         goto err;
 742
 743     if (!BN_mod_exp(*verifier, g, x, N, bn_ctx)) {
 744         BN_clear_free(*verifier);
 745         goto err;
 746     }
 747
 748     result = 1;
 749     *salt = salttmp;
 750
 751  err:
 752     if (salt != NULL && *salt != salttmp)
 753         BN_clear_free(salttmp);
 754     BN_clear_free(x);
 755     BN_CTX_free(bn_ctx);
 756     return result;
 757 }
 758
 759 int SRP_create_verifier_BN(const char *user, const char *pass, BIGNUM **salt,
 760                            BIGNUM **verifier, const BIGNUM *N,
 761                            const BIGNUM *g)
 762 {
 763     return SRP_create_verifier_BN_ex(user, pass, salt, verifier, N, g, NULL,
 764                                      NULL);
 765 }
 766 #endif