crypto/srp/srp_vfy.c

   1 /*
   2  * Copyright 2011-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #ifndef OPENSSL_NO_SRP
  11 # include "internal/cryptlib.h"
  12 # include <openssl/sha.h>
  13 # include <openssl/srp.h>
  14 # include <openssl/evp.h>
  15 # include <openssl/buffer.h>
  16 # include <openssl/rand.h>
  17 # include <openssl/txt_db.h>
  18
  19 # define SRP_RANDOM_SALT_LEN 20
  20 # define MAX_LEN 2500
  21
  22 static char b64table[] =
  23     "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz./";
  24
  25 /*
  26  * the following two conversion routines have been inspired by code from
  27  * Stanford
  28  */
  29
  30 /*
  31  * Convert a base64 string into raw byte array representation.
  32  */
  33 static int t_fromb64(unsigned char *a, const char *src)
  34 {
  35     char *loc;
  36     int i, j;
  37     int size;
  38
  39     while (*src && (*src == ' ' || *src == '\t' || *src == '\n'))
  40         ++src;
  41     size = strlen(src);
  42     i = 0;
  43     while (i < size) {
  44         loc = strchr(b64table, src[i]);
  45         if (loc == (char *)0)
  46             break;
  47         else
  48             a[i] = loc - b64table;
  49         ++i;
  50     }
  51     /* if nothing valid to process we have a zero length response */
  52     if (i == 0)
  53         return 0;
  54     size = i;
  55     i = size - 1;
  56     j = size;
  57     while (1) {
  58         a[j] = a[i];
  59         if (--i < 0)
  60             break;
  61         a[j] |= (a[i] & 3) << 6;
  62         --j;
  63         a[j] = (unsigned char)((a[i] & 0x3c) >> 2);
  64         if (--i < 0)
  65             break;
  66         a[j] |= (a[i] & 0xf) << 4;
  67         --j;
  68         a[j] = (unsigned char)((a[i] & 0x30) >> 4);
  69         if (--i < 0)
  70             break;
  71         a[j] |= (a[i] << 2);
  72
  73         a[--j] = 0;
  74         if (--i < 0)
  75             break;
  76     }
  77     while (a[j] == 0 && j <= size)
  78         ++j;
  79     i = 0;
  80     while (j <= size)
  81         a[i++] = a[j++];
  82     return i;
  83 }
  84
  85 /*
  86  * Convert a raw byte string into a null-terminated base64 ASCII string.
  87  */
  88 static char *t_tob64(char *dst, const unsigned char *src, int size)
  89 {
  90     int c, pos = size % 3;
  91     unsigned char b0 = 0, b1 = 0, b2 = 0, notleading = 0;
  92     char *olddst = dst;
  93
  94     switch (pos) {
  95     case 1:
  96         b2 = src[0];
  97         break;
  98     case 2:
  99         b1 = src[0];
 100         b2 = src[1];
 101         break;
 102     }
 103
 104     while (1) {
 105         c = (b0 & 0xfc) >> 2;
 106         if (notleading || c != 0) {
 107             *dst++ = b64table[c];
 108             notleading = 1;
 109         }
 110         c = ((b0 & 3) << 4) | ((b1 & 0xf0) >> 4);
 111         if (notleading || c != 0) {
 112             *dst++ = b64table[c];
 113             notleading = 1;
 114         }
 115         c = ((b1 & 0xf) << 2) | ((b2 & 0xc0) >> 6);
 116         if (notleading || c != 0) {
 117             *dst++ = b64table[c];
 118             notleading = 1;
 119         }
 120         c = b2 & 0x3f;
 121         if (notleading || c != 0) {
 122             *dst++ = b64table[c];
 123             notleading = 1;
 124         }
 125         if (pos >= size)
 126             break;
 127         else {
 128             b0 = src[pos++];
 129             b1 = src[pos++];
 130             b2 = src[pos++];
 131         }
 132     }
 133
 134     *dst++ = '\0';
 135     return olddst;
 136 }
 137
 138 void SRP_user_pwd_free(SRP_user_pwd *user_pwd)
 139 {
 140     if (user_pwd == NULL)
 141         return;
 142     BN_free(user_pwd->s);
 143     BN_clear_free(user_pwd->v);
 144     OPENSSL_free(user_pwd->id);
 145     OPENSSL_free(user_pwd->info);
 146     OPENSSL_free(user_pwd);
 147 }
 148
 149 static SRP_user_pwd *SRP_user_pwd_new(void)
 150 {
 151     SRP_user_pwd *ret = OPENSSL_malloc(sizeof(*ret));
 152     if (ret == NULL)
 153         return NULL;
 154     ret->N = NULL;
 155     ret->g = NULL;
 156     ret->s = NULL;
 157     ret->v = NULL;
 158     ret->id = NULL;
 159     ret->info = NULL;
 160     return ret;
 161 }
 162
 163 static void SRP_user_pwd_set_gN(SRP_user_pwd *vinfo, const BIGNUM *g,
 164                                 const BIGNUM *N)
 165 {
 166     vinfo->N = N;
 167     vinfo->g = g;
 168 }
 169
 170 static int SRP_user_pwd_set_ids(SRP_user_pwd *vinfo, const char *id,
 171                                 const char *info)
 172 {
 173     if (id != NULL && NULL == (vinfo->id = OPENSSL_strdup(id)))
 174         return 0;
 175     return (info == NULL || NULL != (vinfo->info = OPENSSL_strdup(info)));
 176 }
 177
 178 static int SRP_user_pwd_set_sv(SRP_user_pwd *vinfo, const char *s,
 179                                const char *v)
 180 {
 181     unsigned char tmp[MAX_LEN];
 182     int len;
 183
 184     if (strlen(s) > MAX_LEN || strlen(v) > MAX_LEN)
 185         return 0;
 186     len = t_fromb64(tmp, v);
 187     if (NULL == (vinfo->v = BN_bin2bn(tmp, len, NULL)))
 188         return 0;
 189     len = t_fromb64(tmp, s);
 190     return ((vinfo->s = BN_bin2bn(tmp, len, NULL)) != NULL);
 191 }
 192
 193 static int SRP_user_pwd_set_sv_BN(SRP_user_pwd *vinfo, BIGNUM *s, BIGNUM *v)
 194 {
 195     vinfo->v = v;
 196     vinfo->s = s;
 197     return (vinfo->s != NULL && vinfo->v != NULL);
 198 }
 199
 200 static SRP_user_pwd *srp_user_pwd_dup(SRP_user_pwd *src)
 201 {
 202     SRP_user_pwd *ret;
 203
 204     if (src == NULL)
 205         return NULL;
 206     if ((ret = SRP_user_pwd_new()) == NULL)
 207         return NULL;
 208
 209     SRP_user_pwd_set_gN(ret, src->g, src->N);
 210     if (!SRP_user_pwd_set_ids(ret, src->id, src->info)
 211         || !SRP_user_pwd_set_sv_BN(ret, BN_dup(src->s), BN_dup(src->v))) {
 212             SRP_user_pwd_free(ret);
 213             return NULL;
 214     }
 215     return ret;
 216 }
 217
 218 SRP_VBASE *SRP_VBASE_new(char *seed_key)
 219 {
 220     SRP_VBASE *vb = OPENSSL_malloc(sizeof(*vb));
 221
 222     if (vb == NULL)
 223         return NULL;
 224     if ((vb->users_pwd = sk_SRP_user_pwd_new_null()) == NULL
 225         || (vb->gN_cache = sk_SRP_gN_cache_new_null()) == NULL) {
 226         OPENSSL_free(vb);
 227         return NULL;
 228     }
 229     vb->default_g = NULL;
 230     vb->default_N = NULL;
 231     vb->seed_key = NULL;
 232     if ((seed_key != NULL) && (vb->seed_key = OPENSSL_strdup(seed_key)) == NULL) {
 233         sk_SRP_user_pwd_free(vb->users_pwd);
 234         sk_SRP_gN_cache_free(vb->gN_cache);
 235         OPENSSL_free(vb);
 236         return NULL;
 237     }
 238     return vb;
 239 }
 240
 241 void SRP_VBASE_free(SRP_VBASE *vb)
 242 {
 243     if (!vb)
 244         return;
 245     sk_SRP_user_pwd_pop_free(vb->users_pwd, SRP_user_pwd_free);
 246     sk_SRP_gN_cache_free(vb->gN_cache);
 247     OPENSSL_free(vb->seed_key);
 248     OPENSSL_free(vb);
 249 }
 250
 251 static SRP_gN_cache *SRP_gN_new_init(const char *ch)
 252 {
 253     unsigned char tmp[MAX_LEN];
 254     int len;
 255     SRP_gN_cache *newgN = OPENSSL_malloc(sizeof(*newgN));
 256
 257     if (newgN == NULL)
 258         return NULL;
 259
 260     if ((newgN->b64_bn = OPENSSL_strdup(ch)) == NULL)
 261         goto err;
 262
 263     len = t_fromb64(tmp, ch);
 264     if ((newgN->bn = BN_bin2bn(tmp, len, NULL)))
 265         return newgN;
 266
 267     OPENSSL_free(newgN->b64_bn);
 268  err:
 269     OPENSSL_free(newgN);
 270     return NULL;
 271 }
 272
 273 static void SRP_gN_free(SRP_gN_cache *gN_cache)
 274 {
 275     if (gN_cache == NULL)
 276         return;
 277     OPENSSL_free(gN_cache->b64_bn);
 278     BN_free(gN_cache->bn);
 279     OPENSSL_free(gN_cache);
 280 }
 281
 282 static SRP_gN *SRP_get_gN_by_id(const char *id, STACK_OF(SRP_gN) *gN_tab)
 283 {
 284     int i;
 285
 286     SRP_gN *gN;
 287     if (gN_tab != NULL)
 288         for (i = 0; i < sk_SRP_gN_num(gN_tab); i++) {
 289             gN = sk_SRP_gN_value(gN_tab, i);
 290             if (gN && (id == NULL || strcmp(gN->id, id) == 0))
 291                 return gN;
 292         }
 293
 294     return SRP_get_default_gN(id);
 295 }
 296
 297 static BIGNUM *SRP_gN_place_bn(STACK_OF(SRP_gN_cache) *gN_cache, char *ch)
 298 {
 299     int i;
 300     if (gN_cache == NULL)
 301         return NULL;
 302
 303     /* search if we have already one... */
 304     for (i = 0; i < sk_SRP_gN_cache_num(gN_cache); i++) {
 305         SRP_gN_cache *cache = sk_SRP_gN_cache_value(gN_cache, i);
 306         if (strcmp(cache->b64_bn, ch) == 0)
 307             return cache->bn;
 308     }
 309     {                           /* it is the first time that we find it */
 310         SRP_gN_cache *newgN = SRP_gN_new_init(ch);
 311         if (newgN) {
 312             if (sk_SRP_gN_cache_insert(gN_cache, newgN, 0) > 0)
 313                 return newgN->bn;
 314             SRP_gN_free(newgN);
 315         }
 316     }
 317     return NULL;
 318 }
 319
 320 /*
 321  * this function parses verifier file. Format is:
 322  * string(index):base64(N):base64(g):0
 323  * string(username):base64(v):base64(salt):int(index)
 324  */
 325
 326 int SRP_VBASE_init(SRP_VBASE *vb, char *verifier_file)
 327 {
 328     int error_code;
 329     STACK_OF(SRP_gN) *SRP_gN_tab = sk_SRP_gN_new_null();
 330     char *last_index = NULL;
 331     int i;
 332     char **pp;
 333
 334     SRP_gN *gN = NULL;
 335     SRP_user_pwd *user_pwd = NULL;
 336
 337     TXT_DB *tmpdb = NULL;
 338     BIO *in = BIO_new(BIO_s_file());
 339
 340     error_code = SRP_ERR_OPEN_FILE;
 341
 342     if (in == NULL || BIO_read_filename(in, verifier_file) <= 0)
 343         goto err;
 344
 345     error_code = SRP_ERR_VBASE_INCOMPLETE_FILE;
 346
 347     if ((tmpdb = TXT_DB_read(in, DB_NUMBER)) == NULL)
 348         goto err;
 349
 350     error_code = SRP_ERR_MEMORY;
 351
 352     if (vb->seed_key) {
 353         last_index = SRP_get_default_gN(NULL)->id;
 354     }
 355     for (i = 0; i < sk_OPENSSL_PSTRING_num(tmpdb->data); i++) {
 356         pp = sk_OPENSSL_PSTRING_value(tmpdb->data, i);
 357         if (pp[DB_srptype][0] == DB_SRP_INDEX) {
 358             /*
 359              * we add this couple in the internal Stack
 360              */
 361
 362             if ((gN = OPENSSL_malloc(sizeof(*gN))) == NULL)
 363                 goto err;
 364
 365             if ((gN->id = OPENSSL_strdup(pp[DB_srpid])) == NULL
 366                 || (gN->N = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpverifier]))
 367                         == NULL
 368                 || (gN->g = SRP_gN_place_bn(vb->gN_cache, pp[DB_srpsalt]))
 369                         == NULL
 370                 || sk_SRP_gN_insert(SRP_gN_tab, gN, 0) == 0)
 371                 goto err;
 372
 373             gN = NULL;
 374
 375             if (vb->seed_key != NULL) {
 376                 last_index = pp[DB_srpid];
 377             }
 378         } else if (pp[DB_srptype][0] == DB_SRP_VALID) {
 379             /* it is a user .... */
 380             const SRP_gN *lgN;
 381
 382             if ((lgN = SRP_get_gN_by_id(pp[DB_srpgN], SRP_gN_tab)) != NULL) {
 383                 error_code = SRP_ERR_MEMORY;
 384                 if ((user_pwd = SRP_user_pwd_new()) == NULL)
 385                     goto err;
 386
 387                 SRP_user_pwd_set_gN(user_pwd, lgN->g, lgN->N);
 388                 if (!SRP_user_pwd_set_ids
 389                     (user_pwd, pp[DB_srpid], pp[DB_srpinfo]))
 390                     goto err;
 391
 392                 error_code = SRP_ERR_VBASE_BN_LIB;
 393                 if (!SRP_user_pwd_set_sv
 394                     (user_pwd, pp[DB_srpsalt], pp[DB_srpverifier]))
 395                     goto err;
 396
 397                 if (sk_SRP_user_pwd_insert(vb->users_pwd, user_pwd, 0) == 0)
 398                     goto err;
 399                 user_pwd = NULL; /* abandon responsibility */
 400             }
 401         }
 402     }
 403
 404     if (last_index != NULL) {
 405         /* this means that we want to simulate a default user */
 406
 407         if (((gN = SRP_get_gN_by_id(last_index, SRP_gN_tab)) == NULL)) {
 408             error_code = SRP_ERR_VBASE_BN_LIB;
 409             goto err;
 410         }
 411         vb->default_g = gN->g;
 412         vb->default_N = gN->N;
 413         gN = NULL;
 414     }
 415     error_code = SRP_NO_ERROR;
 416
 417  err:
 418     /*
 419      * there may be still some leaks to fix, if this fails, the application
 420      * terminates most likely
 421      */
 422
 423     if (gN != NULL) {
 424         OPENSSL_free(gN->id);
 425         OPENSSL_free(gN);
 426     }
 427
 428     SRP_user_pwd_free(user_pwd);
 429
 430     TXT_DB_free(tmpdb);
 431     BIO_free_all(in);
 432
 433     sk_SRP_gN_free(SRP_gN_tab);
 434
 435     return error_code;
 436
 437 }
 438
 439 static SRP_user_pwd *find_user(SRP_VBASE *vb, char *username)
 440 {
 441     int i;
 442     SRP_user_pwd *user;
 443
 444     if (vb == NULL)
 445         return NULL;
 446
 447     for (i = 0; i < sk_SRP_user_pwd_num(vb->users_pwd); i++) {
 448         user = sk_SRP_user_pwd_value(vb->users_pwd, i);
 449         if (strcmp(user->id, username) == 0)
 450             return user;
 451     }
 452
 453     return NULL;
 454 }
 455
 456  #if OPENSSL_API_COMPAT < 0x10100000L
 457 /*
 458  * DEPRECATED: use SRP_VBASE_get1_by_user instead.
 459  * This method ignores the configured seed and fails for an unknown user.
 460  * Ownership of the returned pointer is not released to the caller.
 461  * In other words, caller must not free the result.
 462  */
 463 SRP_user_pwd *SRP_VBASE_get_by_user(SRP_VBASE *vb, char *username)
 464 {
 465     return find_user(vb, username);
 466 }
 467 #endif
 468
 469 /*
 470  * Ownership of the returned pointer is released to the caller.
 471  * In other words, caller must free the result once done.
 472  */
 473 SRP_user_pwd *SRP_VBASE_get1_by_user(SRP_VBASE *vb, char *username)
 474 {
 475     SRP_user_pwd *user;
 476     unsigned char digv[SHA_DIGEST_LENGTH];
 477     unsigned char digs[SHA_DIGEST_LENGTH];
 478     EVP_MD_CTX *ctxt = NULL;
 479
 480     if (vb == NULL)
 481         return NULL;
 482
 483     if ((user = find_user(vb, username)) != NULL)
 484         return srp_user_pwd_dup(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_bytes(digv, SHA_DIGEST_LENGTH) <= 0)
 501         goto err;
 502     ctxt = EVP_MD_CTX_new();
 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_free(ctxt);
 508     ctxt = NULL;
 509     if (SRP_user_pwd_set_sv_BN(user,
 510                                BN_bin2bn(digs, SHA_DIGEST_LENGTH, NULL),
 511                                BN_bin2bn(digv, SHA_DIGEST_LENGTH, NULL)))
 512         return user;
 513
 514  err:
 515     EVP_MD_CTX_free(ctxt);
 516     SRP_user_pwd_free(user);
 517     return NULL;
 518 }
 519
 520 /*
 521  * create a verifier (*salt,*verifier,g and N are in base64)
 522  */
 523 char *SRP_create_verifier(const char *user, const char *pass, char **salt,
 524                           char **verifier, const char *N, const char *g)
 525 {
 526     int len;
 527     char *result = NULL, *vf = NULL;
 528     BIGNUM *N_bn = NULL, *g_bn = NULL, *s = NULL, *v = NULL;
 529     unsigned char tmp[MAX_LEN];
 530     unsigned char tmp2[MAX_LEN];
 531     char *defgNid = NULL;
 532     int vfsize = 0;
 533
 534     if ((user == NULL) ||
 535         (pass == NULL) || (salt == NULL) || (verifier == NULL))
 536         goto err;
 537
 538     if (N) {
 539         if ((len = t_fromb64(tmp, N)) == 0)
 540             goto err;
 541         N_bn = BN_bin2bn(tmp, len, NULL);
 542         if ((len = t_fromb64(tmp, g)) == 0)
 543             goto err;
 544         g_bn = BN_bin2bn(tmp, len, NULL);
 545         defgNid = "*";
 546     } else {
 547         SRP_gN *gN = SRP_get_gN_by_id(g, NULL);
 548         if (gN == NULL)
 549             goto err;
 550         N_bn = gN->N;
 551         g_bn = gN->g;
 552         defgNid = gN->id;
 553     }
 554
 555     if (*salt == NULL) {
 556         if (RAND_bytes(tmp2, SRP_RANDOM_SALT_LEN) <= 0)
 557             goto err;
 558
 559         s = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
 560     } else {
 561         if ((len = t_fromb64(tmp2, *salt)) == 0)
 562             goto err;
 563         s = BN_bin2bn(tmp2, len, NULL);
 564     }
 565
 566     if (!SRP_create_verifier_BN(user, pass, &s, &v, N_bn, g_bn))
 567         goto err;
 568
 569     BN_bn2bin(v, tmp);
 570     vfsize = BN_num_bytes(v) * 2;
 571     if (((vf = OPENSSL_malloc(vfsize)) == NULL))
 572         goto err;
 573     t_tob64(vf, tmp, BN_num_bytes(v));
 574
 575     if (*salt == NULL) {
 576         char *tmp_salt;
 577
 578         if ((tmp_salt = OPENSSL_malloc(SRP_RANDOM_SALT_LEN * 2)) == NULL) {
 579             goto err;
 580         }
 581         t_tob64(tmp_salt, tmp2, SRP_RANDOM_SALT_LEN);
 582         *salt = tmp_salt;
 583     }
 584
 585     *verifier = vf;
 586     vf = NULL;
 587     result = defgNid;
 588
 589  err:
 590     if (N) {
 591         BN_free(N_bn);
 592         BN_free(g_bn);
 593     }
 594     OPENSSL_clear_free(vf, vfsize);
 595     BN_clear_free(s);
 596     BN_clear_free(v);
 597     return result;
 598 }
 599
 600 /*
 601  * create a verifier (*salt,*verifier,g and N are BIGNUMs). If *salt != NULL
 602  * then the provided salt will be used. On successful exit *verifier will point
 603  * to a newly allocated BIGNUM containing the verifier and (if a salt was not
 604  * provided) *salt will be populated with a newly allocated BIGNUM containing a
 605  * random salt.
 606  * The caller is responsible for freeing the allocated *salt and *verifier
 607  * BIGNUMS.
 608  */
 609 int SRP_create_verifier_BN(const char *user, const char *pass, BIGNUM **salt,
 610                            BIGNUM **verifier, const BIGNUM *N,
 611                            const BIGNUM *g)
 612 {
 613     int result = 0;
 614     BIGNUM *x = NULL;
 615     BN_CTX *bn_ctx = BN_CTX_new();
 616     unsigned char tmp2[MAX_LEN];
 617     BIGNUM *salttmp = NULL;
 618
 619     if ((user == NULL) ||
 620         (pass == NULL) ||
 621         (salt == NULL) ||
 622         (verifier == NULL) || (N == NULL) || (g == NULL) || (bn_ctx == NULL))
 623         goto err;
 624
 625     if (*salt == NULL) {
 626         if (RAND_bytes(tmp2, SRP_RANDOM_SALT_LEN) <= 0)
 627             goto err;
 628
 629         salttmp = BN_bin2bn(tmp2, SRP_RANDOM_SALT_LEN, NULL);
 630     } else {
 631         salttmp = *salt;
 632     }
 633
 634     x = SRP_Calc_x(salttmp, user, pass);
 635
 636     *verifier = BN_new();
 637     if (*verifier == NULL)
 638         goto err;
 639
 640     if (!BN_mod_exp(*verifier, g, x, N, bn_ctx)) {
 641         BN_clear_free(*verifier);
 642         goto err;
 643     }
 644
 645     result = 1;
 646     *salt = salttmp;
 647
 648  err:
 649     if (salt != NULL && *salt != salttmp)
 650         BN_clear_free(salttmp);
 651     BN_clear_free(x);
 652     BN_CTX_free(bn_ctx);
 653     return result;
 654 }
 655
 656 #endif