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 static 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 const 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 const 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 %ld 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;
 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         /* Fill buf with one block of random data, our password, pad the
 357          * rest with zero bytes. */
 358         buf = malloc(BUFSIZE + blocklen);
 359         memset(buf, 0, BUFSIZE);
 360         if (!get_random_bytes(buf, blocklen)) {
 361                 g_free(buf);
 362                 g_free(key.data);
 363                 g_free(iv.data);
 364                 gnutls_cipher_deinit(handle);
 365                 return NULL;
 366         }
 367
 368         memcpy(buf + blocklen, password, strlen(password));
 369
 370         /* Encrypt into encbuf */
 371         encbuf = malloc(BUFSIZE + blocklen);
 372         memset(encbuf, 0, BUFSIZE + blocklen);
 373         ret = gnutls_cipher_encrypt2(handle, buf, BUFSIZE + blocklen,
 374                         encbuf, BUFSIZE + blocklen);
 375         if (ret < 0) {
 376                 g_free(key.data);
 377                 g_free(iv.data);
 378                 g_free(buf);
 379                 g_free(encbuf);
 380                 gnutls_cipher_deinit(handle);
 381                 return NULL;
 382         }
 383
 384         /* Cleanup */
 385         gnutls_cipher_deinit(handle);
 386         g_free(key.data);
 387         g_free(iv.data);
 388         g_free(buf);
 389
 390         /* And finally prepare the resulting string:
 391          * "{algorithm,rounds}base64encodedciphertext" */
 392         base = g_base64_encode(encbuf, BUFSIZE);
 393         g_free(encbuf);
 394         output = g_strdup_printf("{%s,%d}%s",
 395                         gnutls_cipher_get_name(algo), rounds, base);
 396         g_free(base);
 397
 398         return output;
 399 }
 400
 401 gchar *password_decrypt_gnutls(const gchar *password,
 402                 const gchar *decryption_passphrase)
 403 {
 404         gchar **tokens, *tmp;
 405         gnutls_cipher_algorithm_t algo;
 406         gnutls_cipher_hd_t handle;
 407         gnutls_datum_t key, iv;
 408         int keylen, blocklen, ret;
 409         gsize len;
 410         unsigned char *buf;
 411         guint rounds;
 412         size_t commapos;
 413
 414         g_return_val_if_fail(password != NULL, NULL);
 415         g_return_val_if_fail(decryption_passphrase != NULL, NULL);
 416
 417         tokens = g_strsplit_set(password, "{}", 3);
 418
 419         /* Parse the string, retrieving algorithm and encrypted data.
 420          * We expect "{algorithm,rounds}base64encodedciphertext". */
 421         if (tokens[0] == NULL || strlen(tokens[0]) != 0 ||
 422                         tokens[1] == NULL || strlen(tokens[1]) == 0 ||
 423                         tokens[2] == NULL || strlen(tokens[2]) == 0) {
 424                 debug_print("Garbled password string.\n");
 425                 g_strfreev(tokens);
 426                 return NULL;
 427         }
 428
 429         commapos = strcspn(tokens[1], ",");
 430         if (commapos == strlen(tokens[1]) || commapos == 0) {
 431                 debug_print("Garbled algorithm substring.\n");
 432                 g_strfreev(tokens);
 433                 return NULL;
 434         }
 435
 436         buf = g_strndup(tokens[1], commapos);
 437         if ((algo = gnutls_cipher_get_id(buf)) == GNUTLS_CIPHER_UNKNOWN) {
 438                 debug_print("Password string has unknown algorithm: '%s'\n", buf);
 439                 g_free(buf);
 440                 g_strfreev(tokens);
 441                 return NULL;
 442         }
 443         g_free(buf);
 444
 445         if ((rounds = atoi(tokens[1] + commapos + 1)) <= 0) {
 446                 debug_print("Invalid number of rounds: %d\n", rounds);
 447                 g_strfreev(tokens);
 448                 return NULL;
 449         }
 450
 451 /*      ivlen = gnutls_cipher_get_iv_size(algo); */
 452         keylen = gnutls_cipher_get_key_size(algo);
 453         blocklen = gnutls_cipher_get_block_size(algo);
 454 /*      digestlen = gnutls_hash_get_len(digest); */
 455
 456         /* Take the passphrase and compute a key derivation of suitable
 457          * length to be used as encryption key for our block cipher. */
 458         key.data = _make_key_deriv(decryption_passphrase, rounds, keylen);
 459         key.size = keylen;
 460
 461         /* Prepare random IV for cipher */
 462         iv.data = malloc(IVLEN);
 463         iv.size = IVLEN;
 464         if (!get_random_bytes(iv.data, IVLEN)) {
 465                 g_free(key.data);
 466                 g_free(iv.data);
 467                 g_strfreev(tokens);
 468                 return NULL;
 469         }
 470
 471         /* Prepare encrypted password string for decryption. */
 472         tmp = g_base64_decode(tokens[2], &len);
 473         g_strfreev(tokens);
 474
 475         /* Initialize the decryption */
 476         ret = gnutls_cipher_init(&handle, algo, &key, &iv);
 477         if (ret < 0) {
 478                 debug_print("Cipher init failed: %s\n", gnutls_strerror(ret));
 479                 g_free(key.data);
 480                 g_free(iv.data);
 481                 return NULL;
 482         }
 483
 484         buf = malloc(BUFSIZE + blocklen);
 485         memset(buf, 0, BUFSIZE + blocklen);
 486         ret = gnutls_cipher_decrypt2(handle, tmp, len,
 487                         buf, BUFSIZE + blocklen);
 488         if (ret < 0) {
 489                 debug_print("Decryption failed: %s\n", gnutls_strerror(ret));
 490                 g_free(key.data);
 491                 g_free(iv.data);
 492                 g_free(buf);
 493                 gnutls_cipher_deinit(handle);
 494                 return NULL;
 495         }
 496
 497         /* Cleanup */
 498         gnutls_cipher_deinit(handle);
 499         g_free(key.data);
 500         g_free(iv.data);
 501
 502         tmp = g_strndup(buf + blocklen, MIN(strlen(buf + blocklen), BUFSIZE));
 503         g_free(buf);
 504         return tmp;
 505 }
 506
 507 #undef BUFSIZE
 508
 509 #endif
 510
 511 gchar *password_encrypt(const gchar *password,
 512                 const gchar *encryption_passphrase)
 513 {
 514         if (password == NULL || strlen(password) == 0) {
 515                 return NULL;
 516         }
 517
 518 #ifndef PASSWORD_CRYPTO_OLD
 519         if (encryption_passphrase == NULL)
 520                 encryption_passphrase = master_passphrase();
 521
 522         return password_encrypt_real(password, encryption_passphrase);
 523 #else
 524         return password_encrypt_old(password);
 525 #endif
 526 }
 527
 528 gchar *password_decrypt(const gchar *password,
 529                 const gchar *decryption_passphrase)
 530 {
 531         if (password == NULL || strlen(password) == 0) {
 532                 return NULL;
 533         }
 534
 535         /* First, check if the password was possibly decrypted using old,
 536          * obsolete method */
 537         if (*password == '!') {
 538                 debug_print("Trying to decrypt password using the old method...\n");
 539                 return password_decrypt_old(password);
 540         }
 541
 542         /* Try available crypto backend */
 543 #ifndef PASSWORD_CRYPTO_OLD
 544         if (decryption_passphrase == NULL)
 545                 decryption_passphrase = master_passphrase();
 546
 547         if (*password == '{') {
 548                 debug_print("Trying to decrypt password...\n");
 549                 return password_decrypt_real(password, decryption_passphrase);
 550         }
 551 #endif
 552
 553         /* Fallback, in case the configuration is really old and
 554          * stored password in plaintext */
 555         debug_print("Assuming password was stored plaintext, returning it unchanged\n");
 556         return g_strdup(password);
 557 }