crypto/srp/srp_vfy.c

   1 /*
   2  * Copyright 2004-2018 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 "internal/evp_int.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 /*
  29  * Note that SRP uses its own variant of base 64 encoding. A different base64
  30  * alphabet is used and no padding '=' characters are added. Instead we pad to
  31  * the front with 0 bytes and subsequently strip off leading encoded padding.
  32  * This variant is used for compatibility with other SRP implementations -
  33  * notably libsrp, but also others. It is also required for backwards
  34  * compatibility in order to load verifier files from other OpenSSL versions.
  35  */
  36
  37 /*
  38  * Convert a base64 string into raw byte array representation.
  39  * Returns the length of the decoded data, or -1 on error.
  40  */
  41 static int t_fromb64(unsigned char *a, size_t alen, const char *src)
  42 {
  43     EVP_ENCODE_CTX *ctx;
  44     int outl = 0, outl2 = 0;
  45     size_t size, padsize;
  46     const unsigned char *pad = (const unsigned char *)"00";
  47
  48     while (*src == ' ' || *src == '\t' || *src == '\n')
  49         ++src;
  50     size = strlen(src);
  51     padsize = 4 - (size & 3);
  52     padsize &= 3;
  53
  54     /* Four bytes in src become three bytes output. */
  55     if (size > INT_MAX || ((size + padsize) / 4) * 3 > alen)
  56         return -1;
  57
  58     ctx = EVP_ENCODE_CTX_new();
  59     if (ctx == NULL)
  60         return -1;
  61
  62     /*
  63      * This should never occur because 1 byte of data always requires 2 bytes of
  64      * encoding, i.e.
  65      *  0 bytes unencoded = 0 bytes encoded
  66      *  1 byte unencoded  = 2 bytes encoded
  67      *  2 bytes unencoded = 3 bytes encoded
  68      *  3 bytes unencoded = 4 bytes encoded
  69      *  4 bytes unencoded = 6 bytes encoded
  70      *  etc
  71      */
  72     if (padsize == 3) {
  73         outl = -1;
  74         goto err;
  75     }
  76
  77     /* Valid padsize values are now 0, 1 or 2 */
  78
  79     EVP_DecodeInit(ctx);
  80     evp_encode_ctx_set_flags(ctx, EVP_ENCODE_CTX_USE_SRP_ALPHABET);
  81
  82     /* Add any encoded padding that is required */
  83     if (padsize != 0
  84             && EVP_DecodeUpdate(ctx, a, &outl, pad, padsize) < 0) {
  85         outl = -1;
  86         goto err;
  87     }
  88     if (EVP_DecodeUpdate(ctx, a, &outl2, (const unsigned char *)src, size) < 0) {
  89         outl = -1;
  90         goto err;
  91     }
  92     outl += outl2;
  93     EVP_DecodeFinal(ctx, a + outl, &outl2);
  94     outl += outl2;
  95
  96     /* Strip off the leading padding */
  97     if (padsize != 0) {
  98         if ((int)padsize >= outl) {
  99             outl = -1;
 100             goto err;
 101         }
 102
 103         /*
 104          * If we added 1 byte of padding prior to encoding then we have 2 bytes
 105          * of "real" data which gets spread across 4 encoded bytes like this:
 106          *   (6 bits pad)(2 bits pad | 4 bits data)(6 bits data)(6 bits data)
 107          * So 1 byte of pre-encoding padding results in 1 full byte of encoded
 108          * padding.
 109          * If we added 2 bytes of padding prior to encoding this gets encoded
 110          * as:
 111          *   (6 bits pad)(6 bits pad)(4 bits pad | 2 bits data)(6 bits data)
 112          * So 2 bytes of pre-encoding padding results in 2 full bytes of encoded
 113          * padding, i.e. we have to strip the same number of bytes of padding
 114          * from the encoded data as we added to the pre-encoded data.
 115          */
 116         memmove(a, a + padsize, outl - padsize);
 117         outl -= padsize;
 118     }
 119
 120  err:
 121     EVP_ENCODE_CTX_free(ctx);
 122
 123     return outl;
 124 }
 125
 126 /*
 127  * Convert a raw byte string into a null-terminated base64 ASCII string.
 128  * Returns 1 on success or 0 on error.
 129  */
 130 static int t_tob64(char *dst, const unsigned char *src, int size)
 131 {
 132     EVP_ENCODE_CTX *ctx = EVP_ENCODE_CTX_new();
 133     int outl = 0, outl2 = 0;
 134     unsigned char pad[2] = {0, 0};
 135     size_t leadz = 0;
 136
 137     if (ctx == NULL)
 138         return 0;
 139
 140     EVP_EncodeInit(ctx);
 141     evp_encode_ctx_set_flags(ctx, EVP_ENCODE_CTX_NO_NEWLINES
 142                                   | EVP_ENCODE_CTX_USE_SRP_ALPHABET);
 143
 144     /*
 145      * We pad at the front with zero bytes until the length is a multiple of 3
 146      * so that EVP_EncodeUpdate/EVP_EncodeFinal does not add any of its own "="
 147      * padding
 148      */
 149     leadz = 3 - (size % 3);
 150     if (leadz != 3
 151             && !EVP_EncodeUpdate(ctx, (unsigned char *)dst, &outl, pad,
 152                                  leadz)) {
 153         EVP_ENCODE_CTX_free(ctx);
 154         return 0;
 155     }
 156
 157     if (!EVP_EncodeUpdate(ctx, (unsigned char *)dst + outl, &outl2, src,
 158                           size)) {
 159         EVP_ENCODE_CTX_free(ctx);
 160         return 0;
 161     }
 162     outl += outl2;
 163     EVP_EncodeFinal(ctx, (unsigned char *)dst + outl, &outl2);
 164     outl += outl2;
 165
 166     /* Strip the encoded padding at the front */
 167     if (leadz != 3) {
 168         memmove(dst, dst + leadz, outl - leadz);
 169         dst[outl - leadz] = '\0';
 170     }
 171
 172     EVP_ENCODE_CTX_free(ctx);
 173     return 1;
 174 }
 175
 176 void SRP_user_pwd_free(SRP_user_pwd *user_pwd)
 177 {
 178     if (user_pwd == NULL)
 179         return;
 180     BN_free(user_pwd->s);
 181     BN_clear_free(user_pwd->v);
 182     OPENSSL_free(user_pwd->id);
 183     OPENSSL_free(user_pwd->info);
 184     OPENSSL_free(user_pwd);
 185 }
 186
 187 SRP_user_pwd *SRP_user_pwd_new(void)
 188 {
 189     SRP_user_pwd *ret;
 190
 191     if ((ret = OPENSSL_malloc(sizeof(*ret))) == NULL) {
 192         /* SRPerr(SRP_F_SRP_USER_PWD_NEW, ERR_R_MALLOC_FAILURE); */ /*ckerr_ignore*/
 193         return NULL;
 194     }
 195     ret->N = NULL;
 196     ret->g = NULL;
 197     ret->s = NULL;
 198     ret->v = NULL;
 199     ret->id = NULL;
 200     ret->info = NULL;
 201     return ret;
 202 }
 203
 204 void SRP_user_pwd_set_gN(SRP_user_pwd *vinfo, const BIGNUM *g,
 205                          const BIGNUM *N)
 206 {
 207     vinfo->N = N;
 208     vinfo->g = g;
 209 }
 210
 211 int SRP_user_pwd_set1_ids(SRP_user_pwd *vinfo, const char *id,
 212                           const char *info)
 213 {
 214     OPENSSL_free(vinfo->id);
 215     OPENSSL_free(vinfo->info);
 216     if (id != NULL && NULL == (vinfo->id = OPENSSL_strdup(id)))
 217         return 0;
 218     return (info == NULL || NULL != (vinfo->info = OPENSSL_strdup(info)));
 219 }
 220
 221 static int SRP_user_pwd_set_sv(SRP_user_pwd *vinfo, const char *s,
 222                                const char *v)
 223 {
 224     unsigned char tmp[MAX_LEN];
 225     int len;
 226
 227     vinfo->v = NULL;
 228     vinfo->s = NULL;
 229
 230     len = t_fromb64(tmp, sizeof(tmp), v);
 231     if (len < 0)
 232         return 0;
 233     if (NULL == (vinfo->v = BN_bin2bn(tmp, len, NULL)))
 234         return 0;
 235     len = t_fromb64(tmp, sizeof(tmp), s);
 236     if (len < 0)
 237         goto err;
 238     vinfo->s = BN_bin2bn(tmp, len, NULL);
 239     if (vinfo->s == NULL)
 240         goto err;
 241     return 1;
 242  err:
 243     BN_free(vinfo->v);
 244     vinfo->v = NULL;
 245     return 0;
 246 }
 247
 248 int SRP_user_pwd_set0_sv(SRP_user_pwd *vinfo, BIGNUM *s, BIGNUM *v)
 249 {
 250     BN_free(vinfo->s);
 251     BN_clear_free(vinfo->v);
 252     vinfo->v = v;
 253     vinfo->s = s;
 254     return (vinfo->s != NULL && vinfo->v != NULL);
 255 }
 256
 257 static SRP_user_pwd *srp_user_pwd_dup(SRP_user_pwd *src)
 258 {
 259     SRP_user_pwd *ret;
 260
 261     if (src == NULL)
 262         return NULL;
 263     if ((ret = SRP_user_pwd_new()) == NULL)
 264         return NULL;
 265
 266     SRP_user_pwd_set_gN(ret, src->g, src->N);
 267     if (!SRP_user_pwd_set1_ids(ret, src->id, src->info)
 268         || !SRP_user_pwd_set0_sv(ret, BN_dup(src->s), BN_dup(src->v))) {
 269             SRP_user_pwd_free(ret);
 270             return NULL;
 271     }
 272     return ret;
 273 }
 274
 275 SRP_VBASE *SRP_VBASE_new(char *seed_key)
 276 {
 277     SRP_VBASE *vb = OPENSSL_malloc(sizeof(*vb));
 278
 279     if (vb == NULL)
 280         return NULL;
 281     if ((vb->users_pwd = sk_SRP_user_pwd_new_null()) == NULL
 282         || (vb->gN_cache = sk_SRP_gN_cache_new_null()) == NULL) {
 283         OPENSSL_free(vb);
 284         return NULL;
 285     }
 286     vb->default_g = NULL;
 287     vb->default_N = NULL;
 288     vb->seed_key = NULL;
 289     if ((seed_key != NULL) && (vb->seed_key = OPENSSL_strdup(seed_key)) == NULL) {
 290         sk_SRP_user_pwd_free(vb->users_pwd);
 291         sk_SRP_gN_cache_free(vb->gN_cache);
 292         OPENSSL_free(vb);
 293         return NULL;
 294     }
 295     return vb;
 296 }
 297
 298 void SRP_VBASE_free(SRP_VBASE *vb)
 299 {
 300     if (!vb)
 301         return;
 302     sk_SRP_user_pwd_pop_free(vb->users_pwd, SRP_user_pwd_free);
 303     sk_SRP_gN_cache_free(vb->gN_cache);
 304     OPENSSL_free(vb->seed_key);
 305     OPENSSL_free(vb);
 306 }
 307
 308 static SRP_gN_cache *SRP_gN_new_init(const char *ch)
 309 {
 310     unsigned char tmp[MAX_LEN];
 311     int len;
 312     SRP_gN_cache *newgN = OPENSSL_malloc(sizeof(*newgN));
 313
 314     if (newgN == NULL)
 315         return NULL;
 316
 317     len = t_fromb64(tmp, sizeof(tmp), ch);
 318     if (len < 0)
 319         goto err;
 320
 321     if ((newgN->b64_bn = OPENSSL_strdup(ch)) == NULL)
 322         goto err;
 323
 324     if ((newgN->bn = BN_bin2bn(tmp, len, NULL)))
 325         return newgN;
 326
 327     OPENSSL_free(newgN->b64_bn);
 328  err:
 329     OPENSSL_free(newgN);
 330     return NULL;
 331 }
 332
 333 static void SRP_gN_free(SRP_gN_cache *gN_cache)
 334 {
 335     if (gN_cache == NULL)
 336         return;
 337     OPENSSL_free(gN_cache->b64_bn);
 338     BN_free(gN_cache->bn);
 339     OPENSSL_free(gN_cache);
 340 }
 341
 342 static SRP_gN *SRP_get_gN_by_id(const char *id, STACK_OF(SRP_gN) *gN_tab)
 343 {
 344     int i;
 345
 346     SRP_gN *gN;
 347     if (gN_tab != NULL) {
 348         for (i = 0; i < sk_SRP_gN_num(gN_tab); i++) {
 349             gN = sk_SRP_gN_value(gN_tab, i);
 350             if (gN && (id == NULL || strcmp(gN->id, id) == 0))
 351                 return gN;
 352         }
 353     }
 354
 355     return SRP_get_default_gN(id);
 356 }
 357
 358 static BIGNUM *SRP_gN_place_bn(STACK_OF(SRP_gN_cache) *gN_cache, char *ch)
 359 {
 360     int i;
 361     if (gN_cache == NULL)
 362         return NULL;
 363
 364     /* search if we have already one... */
 365     for (i = 0; i < sk_SRP_gN_cache_num(gN_cache); i++) {
 366         SRP_gN_cache *cache = sk_SRP_gN_cache_value(gN_cache, i);
 367         if (strcmp(cache->b64_bn, ch) == 0)
 368             return cache->bn;
 369     }
 370     {                           /* it is the first time that we find it */
 371         SRP_gN_cache *newgN = SRP_gN_new_init(ch);
 372         if (newgN) {
 373             if (sk_SRP_gN_cache_insert(gN_cache, newgN, 0) > 0)
 374                 return newgN->bn;
 375             SRP_gN_free(newgN);
 376         }
 377     }
 378     return NULL;
 379 }
 380
 381 /*
 382  * This function parses the verifier file generated by the srp app.
 383  * The format for each entry is:
 384  * V base64(verifier) base64(salt) username gNid userinfo(optional)
 385  * or
 386  * I base64(N) base64(g)
 387  * Note that base64 is the SRP variant of base64 encoding described
 388  * in t_fromb64().
 389  */
 390
 391 int SRP_VBASE_init(SRP_VBASE *vb, char *verifier_file)
 392 {
 393     int error_code;
 394     STACK_OF(SRP_gN) *SRP_gN_tab = sk_SRP_gN_new_null();
 395     char *last_index = NULL;
 396     int i;
 397     char **pp;
 398
 399     SRP_gN *gN = NULL;
 400     SRP_user_pwd *user_pwd = NULL;
 401
 402     TXT_DB *tmpdb = NULL;
 403     BIO *in = BIO_new(BIO_s_file());
 404
 405     error_code = SRP_ERR_OPEN_FILE;
 406
 407     if (in == NULL || BIO_read_filename(in, verifier_file) <= 0)
 408         goto err;
 409
 410     error_code = SRP_ERR_VBASE_INCOMPLETE_FILE;
 411
 412     if ((tmpdb = TXT_DB_read(in, DB_NUMBER)) == NULL)
 413         goto err;
 414
 415     error_code = SRP_ERR_MEMORY;
 416
 417     if (vb->seed_key) {
 418         last_index = SRP_get_default_gN(NULL)->id;
 419     }
 420     for (i = 0; i < sk_OPENSSL_PSTRING_num(tmpdb->data); i++) {
 421         pp = sk_OPENSSL_PSTRING_value(tmpdb->data, i);
 422         if (pp[DB_srptype][0] == DB_SRP_INDEX) {
 423             /*
 424              * we add this couple in the internal Stack
 425              */
 426
 427             if ((gN = OPENSSL_malloc(sizeof(*gN))) == NULL)
 428                 goto err;
 429
 430             if ((gN->id = OPENSSL_strdup(pp[DB_srpid])) == NULL
 431                 || (gN->N = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpverifier]))
 432                         == NULL
 433                 || (gN->g = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpsalt]))
 434                         == NULL
 435                 || sk_SRP_gN_insert(SRP_gN_tab, gN, 0) == 0)
 436                 goto err;
 437
 438             gN = NULL;
 439
 440             if (vb->seed_key != NULL) {
 441                 last_index = pp[DB_srpid];
 442             }
 443         } else if (pp[DB_srptype][0] == DB_SRP_VALID) {
 444             /* it is a user .... */
 445             const SRP_gN *lgN;
 446
 447             if ((lgN = SRP_get_gN_by_id(pp[DB_srpgN], SRP_gN_tab)) != NULL) {
 448                 error_code = SRP_ERR_MEMORY;
 449                 if ((user_pwd = SRP_user_pwd_new()) == NULL)
 450                     goto err;
 451
 452                 SRP_user_pwd_set_gN(user_pwd, lgN->g, lgN->N);
 453                 if (!SRP_user_pwd_set1_ids
 454                     (user_pwd, pp[DB_srpid], pp[DB_srpinfo]))
 455                     goto err;
 456
 457                 error_code = SRP_ERR_VBASE_BN_LIB;
 458                 if (!SRP_user_pwd_set_sv
 459                     (user_pwd, pp[DB_srpsalt], pp[DB_srpverifier]))
 460                     goto err;
 461
 462                 if (sk_SRP_user_pwd_insert(vb->users_pwd, user_pwd, 0) == 0)
 463                     goto err;
 464                 user_pwd = NULL; /* abandon responsibility */
 465             }
 466         }
 467     }
 468
 469     if (last_index != NULL) {
 470         /* this means that we want to simulate a default user */
 471
 472         if (((gN = SRP_get_gN_by_id(last_index, SRP_gN_tab)) == NULL)) {
 473             error_code = SRP_ERR_VBASE_BN_LIB;
 474             goto err;
 475         }
 476         vb->default_g = gN->g;
 477         vb->default_N = gN->N;
 478         gN = NULL;
 479     }
 480     error_code = SRP_NO_ERROR;
 481
 482  err:
 483     /*
 484      * there may be still some leaks to fix, if this fails, the application
 485      * terminates most likely
 486      */
 487
 488     if (gN != NULL) {
 489         OPENSSL_free(gN->id);
 490         OPENSSL_free(gN);
 491     }
 492
 493     SRP_user_pwd_free(user_pwd);
 494
 495     TXT_DB_free(tmpdb);
 496     BIO_free_all(in);
 497
 498     sk_SRP_gN_free(SRP_gN_tab);
 499
 500     return error_code;
 501
 502 }
 503
 504 static SRP_user_pwd *find_user(SRP_VBASE *vb, char *username)
 505 {
 506     int i;
 507     SRP_user_pwd *user;
 508
 509     if (vb == NULL)
 510         return NULL;
 511
 512     for (i = 0; i < sk_SRP_user_pwd_num(vb->users_pwd); i++) {
 513         user = sk_SRP_user_pwd_value(vb->users_pwd, i);
 514         if (strcmp(user->id, username) == 0)
 515             return user;
 516     }
 517
 518     return NULL;
 519 }
 520
 521 int SRP_VBASE_add0_user(SRP_VBASE *vb, SRP_user_pwd *user_pwd)
 522 {
 523     if (sk_SRP_user_pwd_push(vb->users_pwd, user_pwd) <= 0)
 524         return 0;
 525     return 1;
 526 }
 527
 528 # if !OPENSSL_API_1_1_0
 529 /*
 530  * DEPRECATED: use SRP_VBASE_get1_by_user instead.
 531  * This method ignores the configured seed and fails for an unknown user.
 532  * Ownership of the returned pointer is not released to the caller.
 533  * In other words, caller must not free the result.
 534  */
 535 SRP_user_pwd *SRP_VBASE_get_by_user(SRP_VBASE *vb, char *username)
 536 {
 537     return find_user(vb, username);
 538 }
 539 # endif
 540
 541 /*
 542  * Ownership of the returned pointer is released to the caller.
 543  * In other words, caller must free the result once done.
 544  */
 545 SRP_user_pwd *SRP_VBASE_get1_by_user(SRP_VBASE *vb, char *username)
 546 {
 547     SRP_user_pwd *user;
 548     unsigned char digv[SHA_DIGEST_LENGTH];
 549     unsigned char digs[SHA_DIGEST_LENGTH];
 550     EVP_MD_CTX *ctxt = NULL;
 551
 552     if (vb == NULL)
 553         return NULL;
 554
 555     if ((user = find_user(vb, username)) != NULL)
 556         return srp_user_pwd_dup(user);
 557
 558     if ((vb->seed_key == NULL) ||
 559         (vb->default_g == NULL) || (vb->default_N == NULL))
 560         return NULL;
 561
 562 /* if the user is unknown we set parameters as well if we have a seed_key */
 563
 564     if ((user = SRP_user_pwd_new()) == NULL)
 565         return NULL;
 566
 567     SRP_user_pwd_set_gN(user, vb->default_g, vb->default_N);
 568
 569     if (!SRP_user_pwd_set1_ids(user, username, NULL))
 570         goto err;
 571
 572     if (RAND_priv_bytes(digv, SHA_DIGEST_LENGTH) <= 0)
 573         goto err;
 574     ctxt = EVP_MD_CTX_new();
 575     if (ctxt == NULL
 576         || !EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL)
 577         || !EVP_DigestUpdate(ctxt, vb->seed_key, strlen(vb->seed_key))
 578         || !EVP_DigestUpdate(ctxt, username, strlen(username))
 579         || !EVP_DigestFinal_ex(ctxt, digs, NULL))
 580         goto err;
 581     EVP_MD_CTX_free(ctxt);
 582     ctxt = NULL;
 583     if (SRP_user_pwd_set0_sv(user,
 584                                BN_bin2bn(digs, SHA_DIGEST_LENGTH, NULL),
 585                                BN_bin2bn(digv, SHA_DIGEST_LENGTH, NULL)))
 586         return user;
 587
 588  err:
 589     EVP_MD_CTX_free(ctxt);
 590     SRP_user_pwd_free(user);
 591     return NULL;
 592 }
 593
 594 /*
 595  * create a verifier (*salt,*verifier,g and N are in base64)
 596  */
 597 char *SRP_create_verifier(const char *user, const char *pass, char **salt,
 598                           char **verifier, const char *N, const char *g)
 599 {
 600     int len;
 601     char *result = NULL, *vf = NULL;
 602     const BIGNUM *N_bn = NULL, *g_bn = NULL;
 603     BIGNUM *N_bn_alloc = NULL, *g_bn_alloc = NULL, *s = NULL, *v = NULL;
 604     unsigned char tmp[MAX_LEN];
 605     unsigned char tmp2[MAX_LEN];
 606     char *defgNid = NULL;
 607     int vfsize = 0;
 608
 609     if ((user == NULL) ||
 610         (pass == NULL) || (salt == NULL) || (verifier == NULL))
 611         goto err;
 612
 613     if (N) {
 614         if ((len = t_fromb64(tmp, sizeof(tmp), N)) <= 0)
 615             goto err;
 616         N_bn_alloc = BN_bin2bn(tmp, len, NULL);
 617         if (N_bn_alloc == NULL)
 618             goto err;
 619         N_bn = N_bn_alloc;
 620         if ((len = t_fromb64(tmp, sizeof(tmp) ,g)) <= 0)
 621             goto err;
 622         g_bn_alloc = BN_bin2bn(tmp, len, NULL);
 623         if (g_bn_alloc == NULL)
 624             goto err;
 625         g_bn = g_bn_alloc;
 626         defgNid = "*";
 627     } else {
 628         SRP_gN *gN = SRP_get_default_gN(g);
 629         if (gN == NULL)
 630             goto err;
 631         N_bn = gN->N;
 632         g_bn = gN->g;
 633         defgNid = gN->id;
 634     }
 635
 636     if (*salt == NULL) {
 637         if (RAND_bytes(tmp2, SRP_RANDOM_SALT_LEN) <= 0)
 638             goto err;
 639
 640         s = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
 641     } else {
 642         if ((len = t_fromb64(tmp2, sizeof(tmp2), *salt)) <= 0)
 643             goto err;
 644         s = BN_bin2bn(tmp2, len, NULL);
 645     }
 646     if (s == NULL)
 647         goto err;
 648
 649     if (!SRP_create_verifier_BN(user, pass, &s, &v, N_bn, g_bn))
 650         goto err;
 651
 652     if (BN_bn2bin(v, tmp) < 0)
 653         goto err;
 654     vfsize = BN_num_bytes(v) * 2;
 655     if (((vf = OPENSSL_malloc(vfsize)) == NULL))
 656         goto err;
 657     if (!t_tob64(vf, tmp, BN_num_bytes(v)))
 658         goto err;
 659
 660     if (*salt == NULL) {
 661         char *tmp_salt;
 662
 663         if ((tmp_salt = OPENSSL_malloc(SRP_RANDOM_SALT_LEN * 2)) == NULL) {
 664             goto err;
 665         }
 666         if (!t_tob64(tmp_salt, tmp2, SRP_RANDOM_SALT_LEN)) {
 667             OPENSSL_free(tmp_salt);
 668             goto err;
 669         }
 670         *salt = tmp_salt;
 671     }
 672
 673     *verifier = vf;
 674     vf = NULL;
 675     result = defgNid;
 676
 677  err:
 678     BN_free(N_bn_alloc);
 679     BN_free(g_bn_alloc);
 680     OPENSSL_clear_free(vf, vfsize);
 681     BN_clear_free(s);
 682     BN_clear_free(v);
 683     return result;
 684 }
 685
 686 /*
 687  * create a verifier (*salt,*verifier,g and N are BIGNUMs). If *salt != NULL
 688  * then the provided salt will be used. On successful exit *verifier will point
 689  * to a newly allocated BIGNUM containing the verifier and (if a salt was not
 690  * provided) *salt will be populated with a newly allocated BIGNUM containing a
 691  * random salt.
 692  * The caller is responsible for freeing the allocated *salt and *verifier
 693  * BIGNUMS.
 694  */
 695 int SRP_create_verifier_BN(const char *user, const char *pass, BIGNUM **salt,
 696                            BIGNUM **verifier, const BIGNUM *N,
 697                            const BIGNUM *g)
 698 {
 699     int result = 0;
 700     BIGNUM *x = NULL;
 701     BN_CTX *bn_ctx = BN_CTX_new();
 702     unsigned char tmp2[MAX_LEN];
 703     BIGNUM *salttmp = NULL;
 704
 705     if ((user == NULL) ||
 706         (pass == NULL) ||
 707         (salt == NULL) ||
 708         (verifier == NULL) || (N == NULL) || (g == NULL) || (bn_ctx == NULL))
 709         goto err;
 710
 711     if (*salt == NULL) {
 712         if (RAND_bytes(tmp2, SRP_RANDOM_SALT_LEN) <= 0)
 713             goto err;
 714
 715         salttmp = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
 716         if (salttmp == NULL)
 717             goto err;
 718     } else {
 719         salttmp = *salt;
 720     }
 721
 722     x = SRP_Calc_x(salttmp, user, pass);
 723     if (x == NULL)
 724         goto err;
 725
 726     *verifier = BN_new();
 727     if (*verifier == NULL)
 728         goto err;
 729
 730     if (!BN_mod_exp(*verifier, g, x, N, bn_ctx)) {
 731         BN_clear_free(*verifier);
 732         goto err;
 733     }
 734
 735     result = 1;
 736     *salt = salttmp;
 737
 738  err:
 739     if (salt != NULL && *salt != salttmp)
 740         BN_clear_free(salttmp);
 741     BN_clear_free(x);
 742     BN_CTX_free(bn_ctx);
 743     return result;
 744 }
 745
 746 #endif