src/password.c

   1 /*
   2  * Claws Mail -- a GTK+ based, lightweight, and fast e-mail client
   3  * Copyright (C) 2016 The Claws Mail Team
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  17  *
  18  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 #include "config.h"
  22 #include "claws-features.h"
  23 #endif
  24
  25 #ifdef PASSWORD_CRYPTO_GNUTLS
  26 # include <gnutls/gnutls.h>
  27 # include <gnutls/crypto.h>
  28 #endif
  29
  30 #include <glib.h>
  31 #include <glib/gi18n.h>
  32
  33 #if defined G_OS_UNIX
  34 #include <fcntl.h>
  35 #include <unistd.h>
  36 #elif defined G_OS_WIN32
  37 #include <windows.h>
  38 #include <wincrypt.h>
  39 #endif
  40
  41 #include "common/passcrypt.h"
  42 #include "common/plugin.h"
  43 #include "common/pkcs5_pbkdf2.h"
  44 #include "common/timing.h"
  45 #include "common/utils.h"
  46 #include "account.h"
  47 #include "alertpanel.h"
  48 #include "inputdialog.h"
  49 #include "password.h"
  50 #include "passwordstore.h"
  51 #include "prefs_common.h"
  52
  53 #ifndef PASSWORD_CRYPTO_OLD
  54 static gchar *_master_passphrase = NULL;
  55
  56 /* Length of stored key derivation, before base64. */
  57 #define KD_LENGTH 64
  58
  59 /* Length of randomly generated and saved salt, used for key derivation.
  60  * Also before base64. */
  61 #define KD_SALT_LENGTH 64
  62
  63 static void _generate_salt()
  64 {
  65         guchar salt[KD_SALT_LENGTH];
  66
  67         if (prefs_common_get_prefs()->master_passphrase_salt != NULL) {
  68                 g_free(prefs_common_get_prefs()->master_passphrase_salt);
  69         }
  70
  71         if (!get_random_bytes(salt, KD_SALT_LENGTH)) {
  72                 debug_print("Could not get random bytes for kd salt.\n");
  73                 return;
  74         }
  75
  76         prefs_common_get_prefs()->master_passphrase_salt =
  77                 g_base64_encode(salt, KD_SALT_LENGTH);
  78 }
  79
  80 #undef KD_SALT_LENGTH
  81
  82 static guchar *_make_key_deriv(const gchar *passphrase, guint rounds,
  83                 guint length)
  84 {
  85         guchar *kd, *salt;
  86         gchar *saltpref = prefs_common_get_prefs()->master_passphrase_salt;
  87         gsize saltlen;
  88         gint ret;
  89
  90         /* Grab our salt, generating and saving a new random one if needed. */
  91         if (saltpref == NULL || strlen(saltpref) == 0) {
  92                 _generate_salt();
  93                 saltpref = prefs_common_get_prefs()->master_passphrase_salt;
  94         }
  95         salt = g_base64_decode(saltpref, &saltlen);
  96         kd = g_malloc0(length);
  97
  98         START_TIMING("PBKDF2");
  99         ret = pkcs5_pbkdf2(passphrase, strlen(passphrase), salt, saltlen,
 100                         kd, length, rounds);
 101         END_TIMING();
 102
 103         g_free(salt);
 104
 105         if (ret == 0) {
 106                 return kd;
 107         }
 108
 109         g_free(kd);
 110         return NULL;
 111 }
 112
 113 const gchar *master_passphrase()
 114 {
 115         gchar *input;
 116         gboolean end = FALSE;
 117
 118         if (!prefs_common_get_prefs()->use_master_passphrase) {
 119                 return PASSCRYPT_KEY;
 120         }
 121
 122         if (_master_passphrase != NULL) {
 123                 debug_print("Master passphrase is in memory, offering it.\n");
 124                 return _master_passphrase;
 125         }
 126
 127         while (!end) {
 128                 input = input_dialog_with_invisible(_("Input master passphrase"),
 129                                 _("Input master passphrase"), NULL);
 130
 131                 if (input == NULL) {
 132                         debug_print("Cancel pressed at master passphrase dialog.\n");
 133                         break;
 134                 }
 135
 136                 if (master_passphrase_is_correct(input)) {
 137                         debug_print("Entered master passphrase seems to be correct, remembering it.\n");
 138                         _master_passphrase = input;
 139                         end = TRUE;
 140                 } else {
 141                         alertpanel_error(_("Incorrect master passphrase."));
 142                 }
 143         }
 144
 145         return _master_passphrase;
 146 }
 147
 148 gboolean master_passphrase_is_set()
 149 {
 150         if (prefs_common_get_prefs()->master_passphrase == NULL
 151                         || strlen(prefs_common_get_prefs()->master_passphrase) == 0)
 152                 return FALSE;
 153
 154         return TRUE;
 155 }
 156
 157 gboolean master_passphrase_is_correct(const gchar *input)
 158 {
 159         guchar *kd, *input_kd;
 160         gchar **tokens;
 161         gchar *stored_kd = prefs_common_get_prefs()->master_passphrase;
 162         gsize kd_len;
 163         guint rounds = 0;
 164         gint ret;
 165
 166         g_return_val_if_fail(stored_kd != NULL && strlen(stored_kd) > 0, FALSE);
 167         g_return_val_if_fail(input != NULL, FALSE);
 168
 169         if (stored_kd == NULL)
 170                 return FALSE;
 171
 172         tokens = g_strsplit_set(stored_kd, "{}", 3);
 173         if (tokens[0] == NULL ||
 174                         strlen(tokens[0]) != 0 || /* nothing before { */
 175                         tokens[1] == NULL ||
 176                         strncmp(tokens[1], "PBKDF2-HMAC-SHA1,", 17) || /* correct tag */
 177                         strlen(tokens[1]) <= 17 || /* something after , */
 178                         (rounds = atoi(tokens[1] + 17)) <= 0 || /* valid rounds # */
 179                         tokens[2] == NULL ||
 180                         strlen(tokens[2]) == 0) { /* string continues after } */
 181                 debug_print("Mangled master_passphrase format in config, can not use it.\n");
 182                 g_strfreev(tokens);
 183                 return FALSE;
 184         }
 185
 186         stored_kd = tokens[2];
 187         kd = g_base64_decode(stored_kd, &kd_len); /* should be 64 */
 188         g_strfreev(tokens);
 189
 190         if (kd_len != KD_LENGTH) {
 191                 debug_print("master_passphrase is %"G_GSIZE_FORMAT" bytes long, should be %d.\n",
 192                                 kd_len, KD_LENGTH);
 193                 g_free(kd);
 194                 return FALSE;
 195         }
 196
 197         input_kd = _make_key_deriv(input, rounds, KD_LENGTH);
 198         ret = memcmp(kd, input_kd, kd_len);
 199
 200         g_free(input_kd);
 201         g_free(kd);
 202
 203         if (ret == 0)
 204                 return TRUE;
 205
 206         return FALSE;
 207 }
 208
 209 gboolean master_passphrase_is_entered()
 210 {
 211         return (_master_passphrase == NULL) ? FALSE : TRUE;
 212 }
 213
 214 void master_passphrase_forget()
 215 {
 216         /* If master passphrase is currently in memory (entered by user),
 217          * get rid of it. User will have to enter the new one again. */
 218         if (_master_passphrase != NULL) {
 219                 memset(_master_passphrase, 0, strlen(_master_passphrase));
 220                 g_free(_master_passphrase);
 221                 _master_passphrase = NULL;
 222         }
 223 }
 224
 225 void master_passphrase_change(const gchar *oldp, const gchar *newp)
 226 {
 227         guchar *kd;
 228         gchar *base64_kd;
 229         guint rounds = prefs_common_get_prefs()->master_passphrase_pbkdf2_rounds;
 230
 231         g_return_if_fail(rounds > 0);
 232
 233         if (oldp == NULL) {
 234                 /* If oldp is NULL, make sure the user has to enter the
 235                  * current master passphrase before being able to change it. */
 236                 master_passphrase_forget();
 237                 oldp = master_passphrase();
 238         }
 239         g_return_if_fail(oldp != NULL);
 240
 241         /* Update master passphrase hash in prefs */
 242         if (prefs_common_get_prefs()->master_passphrase != NULL)
 243                 g_free(prefs_common_get_prefs()->master_passphrase);
 244
 245         if (newp != NULL) {
 246                 debug_print("Storing key derivation of new master passphrase\n");
 247                 kd = _make_key_deriv(newp, rounds, KD_LENGTH);
 248                 base64_kd = g_base64_encode(kd, 64);
 249                 prefs_common_get_prefs()->master_passphrase =
 250                         g_strdup_printf("{PBKDF2-HMAC-SHA1,%d}%s", rounds, base64_kd);
 251                 g_free(kd);
 252                 g_free(base64_kd);
 253         } else {
 254                 debug_print("Setting master_passphrase to NULL\n");
 255                 prefs_common_get_prefs()->master_passphrase = NULL;
 256         }
 257
 258         /* Now go over all accounts, reencrypting their passwords using
 259          * the new master passphrase. */
 260
 261         if (oldp == NULL)
 262                 oldp = PASSCRYPT_KEY;
 263         if (newp == NULL)
 264                 newp = PASSCRYPT_KEY;
 265
 266         debug_print("Reencrypting all account passwords...\n");
 267         passwd_store_reencrypt_all(oldp, newp);
 268
 269         master_passphrase_forget();
 270 }
 271 #endif
 272
 273 gchar *password_encrypt_old(const gchar *password)
 274 {
 275         if (!password || strlen(password) == 0) {
 276                 return NULL;
 277         }
 278
 279         gchar *encrypted = g_strdup(password);
 280         gchar *encoded, *result;
 281         gsize len = strlen(password);
 282
 283         passcrypt_encrypt(encrypted, len);
 284         encoded = g_base64_encode(encrypted, len);
 285         g_free(encrypted);
 286         result = g_strconcat("!", encoded, NULL);
 287         g_free(encoded);
 288
 289         return result;
 290 }
 291
 292 gchar *password_decrypt_old(const gchar *password)
 293 {
 294         if (!password || strlen(password) == 0) {
 295                 return NULL;
 296         }
 297
 298         if (*password != '!' || strlen(password) < 2) {
 299                 return NULL;
 300         }
 301
 302         gsize len;
 303         gchar *decrypted = g_base64_decode(password + 1, &len);
 304
 305         passcrypt_decrypt(decrypted, len);
 306         return decrypted;
 307 }
 308
 309 #ifdef PASSWORD_CRYPTO_GNUTLS
 310 #define BUFSIZE 128
 311
 312 /* Since we can't count on having GnuTLS new enough to have
 313  * gnutls_cipher_get_iv_size(), we hardcode the IV length for now. */
 314 #define IVLEN 16
 315
 316 gchar *password_encrypt_gnutls(const gchar *password,
 317                 const gchar *encryption_passphrase)
 318 {
 319         gnutls_cipher_algorithm_t algo = GNUTLS_CIPHER_AES_256_CBC;
 320         gnutls_cipher_hd_t handle;
 321         gnutls_datum_t key, iv;
 322         int keylen, blocklen, ret, len, i;
 323         unsigned char *buf, *encbuf, *base, *output;
 324         guint rounds = prefs_common_get_prefs()->master_passphrase_pbkdf2_rounds;
 325
 326         g_return_val_if_fail(password != NULL, NULL);
 327         g_return_val_if_fail(encryption_passphrase != NULL, NULL);
 328
 329 /*      ivlen = gnutls_cipher_get_iv_size(algo);*/
 330         keylen = gnutls_cipher_get_key_size(algo);
 331         blocklen = gnutls_cipher_get_block_size(algo);
 332 /*      digestlen = gnutls_hash_get_len(digest); */
 333
 334         /* Take the passphrase and compute a key derivation of suitable
 335          * length to be used as encryption key for our block cipher. */
 336         key.data = _make_key_deriv(encryption_passphrase, rounds, keylen);
 337         key.size = keylen;
 338
 339         /* Prepare random IV for cipher */
 340         iv.data = malloc(IVLEN);
 341         iv.size = IVLEN;
 342         if (!get_random_bytes(iv.data, IVLEN)) {
 343                 g_free(key.data);
 344                 g_free(iv.data);
 345                 return NULL;
 346         }
 347
 348         /* Initialize the encryption */
 349         ret = gnutls_cipher_init(&handle, algo, &key, &iv);
 350         if (ret < 0) {
 351                 g_free(key.data);
 352                 g_free(iv.data);
 353                 return NULL;
 354         }
 355
 356         /* Find out how big buffer (in multiples of BUFSIZE)
 357          * we need to store the password. */
 358         i = 1;
 359         len = strlen(password);
 360         while(len >= i * BUFSIZE)
 361                 i++;
 362         len = i * BUFSIZE;
 363
 364         /* Fill buf with one block of random data, our password, pad the
 365          * rest with zero bytes. */
 366         buf = malloc(len + blocklen);
 367         memset(buf, 0, len + blocklen);
 368         if (!get_random_bytes(buf, blocklen)) {
 369                 g_free(buf);
 370                 g_free(key.data);
 371                 g_free(iv.data);
 372                 gnutls_cipher_deinit(handle);
 373                 return NULL;
 374         }
 375
 376         memcpy(buf + blocklen, password, strlen(password));
 377
 378         /* Encrypt into encbuf */
 379         encbuf = malloc(len + blocklen);
 380         memset(encbuf, 0, len + blocklen);
 381         ret = gnutls_cipher_encrypt2(handle, buf, len + blocklen,
 382                         encbuf, len + blocklen);
 383         if (ret < 0) {
 384                 g_free(key.data);
 385                 g_free(iv.data);
 386                 g_free(buf);
 387                 g_free(encbuf);
 388                 gnutls_cipher_deinit(handle);
 389                 return NULL;
 390         }
 391
 392         /* Cleanup */
 393         gnutls_cipher_deinit(handle);
 394         g_free(key.data);
 395         g_free(iv.data);
 396         g_free(buf);
 397
 398         /* And finally prepare the resulting string:
 399          * "{algorithm,rounds}base64encodedciphertext" */
 400         base = g_base64_encode(encbuf, len + blocklen);
 401         g_free(encbuf);
 402         output = g_strdup_printf("{%s,%d}%s",
 403                         gnutls_cipher_get_name(algo), rounds, base);
 404         g_free(base);
 405
 406         return output;
 407 }
 408
 409 gchar *password_decrypt_gnutls(const gchar *password,
 410                 const gchar *decryption_passphrase)
 411 {
 412         gchar **tokens, *tmp;
 413         gnutls_cipher_algorithm_t algo;
 414         gnutls_cipher_hd_t handle;
 415         gnutls_datum_t key, iv;
 416         int keylen, blocklen, ret;
 417         gsize len;
 418         unsigned char *buf;
 419         guint rounds;
 420         size_t commapos;
 421         gboolean valid_utf8;
 422
 423         g_return_val_if_fail(password != NULL, NULL);
 424         g_return_val_if_fail(decryption_passphrase != NULL, NULL);
 425
 426         tokens = g_strsplit_set(password, "{}", 3);
 427
 428         /* Parse the string, retrieving algorithm and encrypted data.
 429          * We expect "{algorithm,rounds}base64encodedciphertext". */
 430         if (tokens[0] == NULL || strlen(tokens[0]) != 0 ||
 431                         tokens[1] == NULL || strlen(tokens[1]) == 0 ||
 432                         tokens[2] == NULL || strlen(tokens[2]) == 0) {
 433                 debug_print("Garbled password string.\n");
 434                 g_strfreev(tokens);
 435                 return NULL;
 436         }
 437
 438         commapos = strcspn(tokens[1], ",");
 439         if (commapos == strlen(tokens[1]) || commapos == 0) {
 440                 debug_print("Garbled algorithm substring.\n");
 441                 g_strfreev(tokens);
 442                 return NULL;
 443         }
 444
 445         buf = g_strndup(tokens[1], commapos);
 446         if ((algo = gnutls_cipher_get_id(buf)) == GNUTLS_CIPHER_UNKNOWN) {
 447                 debug_print("Password string has unknown algorithm: '%s'\n", buf);
 448                 g_free(buf);
 449                 g_strfreev(tokens);
 450                 return NULL;
 451         }
 452         g_free(buf);
 453
 454         if ((rounds = atoi(tokens[1] + commapos + 1)) <= 0) {
 455                 debug_print("Invalid number of rounds: %d\n", rounds);
 456                 g_strfreev(tokens);
 457                 return NULL;
 458         }
 459
 460 /*      ivlen = gnutls_cipher_get_iv_size(algo); */
 461         keylen = gnutls_cipher_get_key_size(algo);
 462         blocklen = gnutls_cipher_get_block_size(algo);
 463 /*      digestlen = gnutls_hash_get_len(digest); */
 464
 465         /* Take the passphrase and compute a key derivation of suitable
 466          * length to be used as encryption key for our block cipher. */
 467         key.data = _make_key_deriv(decryption_passphrase, rounds, keylen);
 468         key.size = keylen;
 469
 470         /* Prepare random IV for cipher */
 471         iv.data = malloc(IVLEN);
 472         iv.size = IVLEN;
 473         if (!get_random_bytes(iv.data, IVLEN)) {
 474                 g_free(key.data);
 475                 g_free(iv.data);
 476                 g_strfreev(tokens);
 477                 return NULL;
 478         }
 479
 480         /* Prepare encrypted password string for decryption. */
 481         tmp = g_base64_decode(tokens[2], &len);
 482         g_strfreev(tokens);
 483         if (tmp == NULL || len == 0) {
 484                 debug_print("Failed base64-decoding of stored password string\n");
 485                 g_free(key.data);
 486                 g_free(iv.data);
 487                 if (tmp != NULL)
 488                         g_free(tmp);
 489                 return NULL;
 490         }
 491         debug_print("Encrypted password string length: %"G_GSIZE_FORMAT"\n", len);
 492
 493         /* Initialize the decryption */
 494         ret = gnutls_cipher_init(&handle, algo, &key, &iv);
 495         if (ret < 0) {
 496                 debug_print("Cipher init failed: %s\n", gnutls_strerror(ret));
 497                 g_free(key.data);
 498                 g_free(iv.data);
 499                 g_free(tmp);
 500                 return NULL;
 501         }
 502
 503         /* Allocate the buffer to store decrypted plaintext in. */
 504         buf = malloc(len);
 505         memset(buf, 0, len);
 506
 507         /* Decrypt! */
 508         ret = gnutls_cipher_decrypt2(handle, tmp, len,
 509                         buf, len);
 510         g_free(tmp);
 511         if (ret < 0) {
 512                 debug_print("Decryption failed: %s\n", gnutls_strerror(ret));
 513                 g_free(key.data);
 514                 g_free(iv.data);
 515                 g_free(buf);
 516                 gnutls_cipher_deinit(handle);
 517                 return NULL;
 518         }
 519
 520         /* Cleanup */
 521         gnutls_cipher_deinit(handle);
 522         g_free(key.data);
 523         g_free(iv.data);
 524
 525         /* 'buf+blocklen' should now be pointing to the plaintext
 526          * password string.
 527          * (The first block contains random data from the IV.)
 528          *
 529          * At this point, it should be a valid UTF-8 string. Let's make sure. */
 530
 531         /* First, let's assume there's just garbage and play it safe
 532          * by looking for a first NULL byte within the decrypted range.
 533          * (We could really use g_strchr_len() here instead, but Glib
 534          * doesn't have that.) */
 535         if (!g_strstr_len(buf + blocklen, len - blocklen, "\0")) {
 536                 debug_print("Could not find a NULL byte in the decrypted password.\n");
 537                 valid_utf8 = FALSE;
 538         } else {
 539                 /* There is a NULL byte, we can rely on strlen() returning
 540                  * a sane value, so we don't read past the end of the allocated
 541                  * buffer. */
 542                 valid_utf8 = g_utf8_validate(buf + blocklen, strlen(buf + blocklen), NULL);
 543         }
 544
 545         if (!valid_utf8)
 546                 debug_print("Decrypted password is not a valid UTF-8 string!\n");
 547         cm_return_val_if_fail(valid_utf8, NULL);
 548
 549         tmp = g_strndup(buf + blocklen, strlen(buf + blocklen));
 550         memset(buf, 0, len);
 551         g_free(buf);
 552
 553         return tmp;
 554 }
 555
 556 #undef BUFSIZE
 557
 558 #endif
 559
 560 gchar *password_encrypt(const gchar *password,
 561                 const gchar *encryption_passphrase)
 562 {
 563         if (password == NULL || strlen(password) == 0) {
 564                 return NULL;
 565         }
 566
 567 #ifndef PASSWORD_CRYPTO_OLD
 568         if (encryption_passphrase == NULL)
 569                 encryption_passphrase = master_passphrase();
 570
 571         return password_encrypt_real(password, encryption_passphrase);
 572 #else
 573         return password_encrypt_old(password);
 574 #endif
 575 }
 576
 577 gchar *password_decrypt(const gchar *password,
 578                 const gchar *decryption_passphrase)
 579 {
 580         if (password == NULL || strlen(password) == 0) {
 581                 return NULL;
 582         }
 583
 584         /* First, check if the password was possibly decrypted using old,
 585          * obsolete method */
 586         if (*password == '!') {
 587                 debug_print("Trying to decrypt password using the old method...\n");
 588                 return password_decrypt_old(password);
 589         }
 590
 591         /* Try available crypto backend */
 592 #ifndef PASSWORD_CRYPTO_OLD
 593         if (decryption_passphrase == NULL)
 594                 decryption_passphrase = master_passphrase();
 595
 596         if (*password == '{') {
 597                 debug_print("Trying to decrypt password...\n");
 598                 return password_decrypt_real(password, decryption_passphrase);
 599         }
 600 #endif
 601
 602         /* Fallback, in case the configuration is really old and
 603          * stored password in plaintext */
 604         debug_print("Assuming password was stored plaintext, returning it unchanged\n");
 605         return g_strdup(password);
 606 }