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 #ifdef G_OS_UNIX
  34 #include <fcntl.h>
  35 #include <unistd.h>
  36 #endif
  37
  38 #include "common/passcrypt.h"
  39 #include "common/utils.h"
  40 #include "account.h"
  41 #include "alertpanel.h"
  42 #include "inputdialog.h"
  43 #include "password.h"
  44 #include "prefs_common.h"
  45
  46 #ifndef PASSWORD_CRYPTO_OLD
  47 static gchar *_master_password = NULL;
  48
  49 static const gchar *master_password()
  50 {
  51         gchar *input;
  52         gboolean end = FALSE;
  53
  54         if (!prefs_common_get_prefs()->use_master_password) {
  55                 return PASSCRYPT_KEY;
  56         }
  57
  58         if (_master_password != NULL) {
  59                 debug_print("Master password is in memory, offering it.\n");
  60                 return _master_password;
  61         }
  62
  63         while (!end) {
  64                 input = input_dialog_with_invisible(_("Input master password"),
  65                                 _("Input master password"), NULL);
  66
  67                 if (input == NULL) {
  68                         debug_print("Cancel pressed at master password dialog.\n");
  69                         break;
  70                 }
  71
  72                 if (master_password_is_correct(input)) {
  73                         debug_print("Entered master password seems to be correct, remembering it.\n");
  74                         _master_password = input;
  75                         end = TRUE;
  76                 } else {
  77                         alertpanel_error(_("Incorrect master password."));
  78                 }
  79         }
  80
  81         return _master_password;
  82 }
  83
  84 const gboolean master_password_is_set()
  85 {
  86         if (prefs_common_get_prefs()->master_password_hash == NULL
  87                         || strlen(prefs_common_get_prefs()->master_password_hash) == 0)
  88                 return FALSE;
  89
  90         return TRUE;
  91 }
  92
  93 const gboolean master_password_is_correct(const gchar *input)
  94 {
  95         gchar *hash;
  96         gchar *stored_hash = prefs_common_get_prefs()->master_password_hash;
  97         const GChecksumType hashtype = G_CHECKSUM_SHA512;
  98         const gssize hashlen = g_checksum_type_get_length(hashtype);
  99         gssize stored_len;
 100
 101         g_return_val_if_fail(input != NULL, FALSE);
 102
 103         if (stored_hash == NULL)
 104                 return FALSE;
 105
 106         stored_len = strlen(stored_hash);
 107         g_return_val_if_fail(stored_len == 2*hashlen, FALSE);
 108
 109         hash = g_compute_checksum_for_string(hashtype, input, -1);
 110
 111         if (!strncasecmp(hash, stored_hash, stored_len)) {
 112                 g_free(hash);
 113                 return TRUE;
 114         }
 115         g_free(hash);
 116
 117         return FALSE;
 118 }
 119
 120 void master_password_forget()
 121 {
 122         /* If master password is currently in memory (entered by user),
 123          * get rid of it. User will have to enter the new one again. */
 124         if (_master_password != NULL) {
 125                 memset(_master_password, 0, strlen(_master_password));
 126                 g_free(_master_password);
 127         }
 128         _master_password = NULL;
 129 }
 130
 131 void master_password_change(const gchar *newp)
 132 {
 133         gchar *pwd, *newpwd;
 134         const gchar *oldp;
 135         GList *cur;
 136         PrefsAccount *acc;
 137
 138         /* Make sure the user has to enter the master password before
 139          * being able to change it. */
 140         master_password_forget();
 141
 142         oldp = master_password();
 143         g_return_if_fail(oldp != NULL);
 144
 145         /* Update master password hash in prefs */
 146         if (prefs_common_get_prefs()->master_password_hash != NULL)
 147                 g_free(prefs_common_get_prefs()->master_password_hash);
 148
 149         if (newp != NULL) {
 150                 debug_print("Storing hash of new master password\n");
 151                 prefs_common_get_prefs()->master_password_hash =
 152                         g_compute_checksum_for_string(G_CHECKSUM_SHA512, newp, -1);
 153         } else {
 154                 debug_print("Setting master_password_hash to NULL\n");
 155                 prefs_common_get_prefs()->master_password_hash = NULL;
 156         }
 157
 158         /* Now go over all accounts, reencrypting their passwords using
 159          * the new master password. */
 160
 161         if (oldp == NULL)
 162                 oldp = PASSCRYPT_KEY;
 163         if (newp == NULL)
 164                 newp = PASSCRYPT_KEY;
 165
 166         debug_print("Reencrypting all account passwords...\n");
 167         for (cur = account_get_list(); cur != NULL; cur = cur->next) {
 168                 acc = (PrefsAccount *)cur->data;
 169                 debug_print("account %s\n", acc->account_name);
 170
 171                 /* Password for receiving */
 172                 if (acc->passwd != NULL && strlen(acc->passwd) > 0) {
 173                         pwd = password_decrypt(acc->passwd, oldp);
 174                         if (pwd == NULL) {
 175                                 debug_print("failed to decrypt recv password with old master password\n");
 176                         } else {
 177                                 newpwd = password_encrypt(pwd, newp);
 178                                 memset(pwd, 0, strlen(pwd));
 179                                 g_free(pwd);
 180                                 if (newpwd == NULL) {
 181                                         debug_print("failed to encrypt recv password with new master password\n");
 182                                 } else {
 183                                         g_free(acc->passwd);
 184                                         acc->passwd = newpwd;
 185                                 }
 186                         }
 187                 }
 188
 189                 /* Password for sending */
 190                 if (acc->smtp_passwd != NULL && strlen(acc->smtp_passwd) > 0) {
 191                         pwd = password_decrypt(acc->smtp_passwd, oldp);
 192                         if (pwd == NULL) {
 193                                 debug_print("failed to decrypt smtp password with old master password\n");
 194                         } else {
 195                                 newpwd = password_encrypt(pwd, newp);
 196                                 memset(pwd, 0, strlen(pwd));
 197                                 g_free(pwd);
 198                                 if (newpwd == NULL) {
 199                                         debug_print("failed to encrypt smtp password with new master password\n");
 200                                 } else {
 201                                         g_free(acc->smtp_passwd);
 202                                         acc->smtp_passwd = newpwd;
 203                                 }
 204                         }
 205                 }
 206         }
 207
 208         master_password_forget();
 209 }
 210 #endif
 211
 212 gchar *password_encrypt_old(const gchar *password)
 213 {
 214         if (!password || strlen(password) == 0) {
 215                 return NULL;
 216         }
 217
 218         gchar *encrypted = g_strdup(password);
 219         gchar *encoded, *result;
 220         gsize len = strlen(password);
 221
 222         passcrypt_encrypt(encrypted, len);
 223         encoded = g_base64_encode(encrypted, len);
 224         g_free(encrypted);
 225         result = g_strconcat("!", encoded, NULL);
 226         g_free(encoded);
 227
 228         return result;
 229 }
 230
 231 gchar *password_decrypt_old(const gchar *password)
 232 {
 233         if (!password || strlen(password) == 0) {
 234                 return NULL;
 235         }
 236
 237         if (*password != '!' || strlen(password) < 2) {
 238                 return NULL;
 239         }
 240
 241         gsize len;
 242         gchar *decrypted = g_base64_decode(password + 1, &len);
 243
 244         passcrypt_decrypt(decrypted, len);
 245         return decrypted;
 246 }
 247
 248 #ifdef PASSWORD_CRYPTO_GNUTLS
 249 #define BUFSIZE 128
 250
 251 gchar *password_encrypt_gnutls(const gchar *password,
 252                 const gchar *encryption_password)
 253 {
 254         /* Another, slightly inferior combination is AES-128-CBC + SHA-256.
 255          * Any block cipher in CBC mode with keysize N and a hash algo with
 256          * digest length 2*N would do. */
 257         gnutls_cipher_algorithm_t algo = GNUTLS_CIPHER_AES_256_CBC;
 258         gnutls_digest_algorithm_t digest = GNUTLS_DIG_SHA512;
 259         gnutls_cipher_hd_t handle;
 260         gnutls_datum_t key, iv;
 261         int ivlen, keylen, digestlen, blocklen, ret, i;
 262         unsigned char hashbuf[BUFSIZE], *buf, *encbuf, *base, *output;
 263 #ifdef G_OS_UNIX
 264         int rnd;
 265 #endif
 266
 267         g_return_val_if_fail(password != NULL, NULL);
 268         g_return_val_if_fail(encryption_password != NULL, NULL);
 269
 270         ivlen = gnutls_cipher_get_iv_size(algo);
 271         keylen = gnutls_cipher_get_key_size(algo);
 272         blocklen = gnutls_cipher_get_block_size(algo);
 273         digestlen = gnutls_hash_get_len(digest);
 274
 275         /* Prepare key for cipher - first half of hash of passkey XORed with
 276          * the second. */
 277         memset(&hashbuf, 0, BUFSIZE);
 278         if ((ret = gnutls_hash_fast(digest, encryption_password,
 279                                         strlen(encryption_password), &hashbuf)) < 0) {
 280                 debug_print("Hashing passkey failed: %s\n", gnutls_strerror(ret));
 281                 return NULL;
 282         }
 283         for (i = 0; i < digestlen/2; i++) {
 284                 hashbuf[i] = hashbuf[i] ^ hashbuf[i+digestlen/2];
 285         }
 286
 287         key.data = malloc(keylen);
 288         memcpy(key.data, &hashbuf, keylen);
 289         key.size = keylen;
 290
 291 #ifdef G_OS_UNIX
 292         /* Prepare our source of random data. */
 293         rnd = open("/dev/urandom", O_RDONLY);
 294         if (rnd == -1) {
 295                 perror("fopen on /dev/urandom");
 296                 g_free(key.data);
 297                 g_free(iv.data);
 298                 return NULL;
 299         }
 300 #endif
 301
 302         /* Prepare random IV for cipher */
 303         iv.data = malloc(ivlen);
 304         iv.size = ivlen;
 305 #ifdef G_OS_UNIX
 306         ret = read(rnd, iv.data, ivlen);
 307         if (ret != ivlen) {
 308                 perror("read into iv");
 309                 g_free(key.data);
 310                 g_free(iv.data);
 311                 close(rnd);
 312                 return NULL;
 313         }
 314 #endif
 315
 316         /* Initialize the encryption */
 317         ret = gnutls_cipher_init(&handle, algo, &key, &iv);
 318         if (ret < 0) {
 319                 g_free(key.data);
 320                 g_free(iv.data);
 321 #ifdef G_OS_UNIX
 322                 close(rnd);
 323 #endif
 324                 return NULL;
 325         }
 326
 327         /* Fill buf with one block of random data, our password, pad the
 328          * rest with zero bytes. */
 329         buf = malloc(BUFSIZE + blocklen);
 330         memset(buf, 0, BUFSIZE);
 331 #ifdef G_OS_UNIX
 332         ret = read(rnd, buf, blocklen);
 333         if (ret != blocklen) {
 334                 perror("read into buffer");
 335                 g_free(buf);
 336                 g_free(key.data);
 337                 g_free(iv.data);
 338                 close(rnd);
 339                 gnutls_cipher_deinit(handle);
 340                 return NULL;
 341         }
 342
 343         /* We don't need any more random data. */
 344         close(rnd);
 345 #endif
 346
 347         memcpy(buf + blocklen, password, strlen(password));
 348
 349         /* Encrypt into encbuf */
 350         encbuf = malloc(BUFSIZE + blocklen);
 351         memset(encbuf, 0, BUFSIZE + blocklen);
 352         ret = gnutls_cipher_encrypt2(handle, buf, BUFSIZE + blocklen,
 353                         encbuf, BUFSIZE + blocklen);
 354         if (ret < 0) {
 355                 g_free(key.data);
 356                 g_free(iv.data);
 357                 g_free(buf);
 358                 g_free(encbuf);
 359                 gnutls_cipher_deinit(handle);
 360                 return NULL;
 361         }
 362
 363         /* Cleanup */
 364         gnutls_cipher_deinit(handle);
 365         g_free(key.data);
 366         g_free(iv.data);
 367         g_free(buf);
 368
 369         /* And finally prepare the resulting string:
 370          * "{algorithm}base64encodedciphertext" */
 371         base = g_base64_encode(encbuf, BUFSIZE);
 372         g_free(encbuf);
 373         output = g_strdup_printf("{%s}%s", gnutls_cipher_get_name(algo), base);
 374         g_free(base);
 375
 376         return output;
 377 }
 378
 379 gchar *password_decrypt_gnutls(const gchar *password,
 380                 const gchar *decryption_password)
 381 {
 382         gchar **tokens, *tmp;
 383         gnutls_cipher_algorithm_t algo;
 384         gnutls_digest_algorithm_t digest = GNUTLS_DIG_UNKNOWN;
 385         gnutls_cipher_hd_t handle;
 386         gnutls_datum_t key, iv;
 387         int ivlen, keylen, digestlen, blocklen, ret, i;
 388         gsize len;
 389         unsigned char hashbuf[BUFSIZE], *buf;
 390 #ifdef G_OS_UNIX
 391         int rnd;
 392 #endif
 393
 394         g_return_val_if_fail(password != NULL, NULL);
 395         g_return_val_if_fail(decryption_password != NULL, NULL);
 396
 397         tokens = g_strsplit_set(password, "{}", 3);
 398
 399         /* Parse the string, retrieving algorithm and encrypted data.
 400          * We expect "{algorithm}base64encodedciphertext". */
 401         if (strlen(tokens[0]) != 0 ||
 402                         (algo = gnutls_cipher_get_id(tokens[1])) == GNUTLS_CIPHER_UNKNOWN ||
 403                         strlen(tokens[2]) == 0)
 404                 return NULL;
 405
 406         /* Our hash algo needs to have digest length twice as long as our
 407          * cipher algo's key length. */
 408         if (algo == GNUTLS_CIPHER_AES_256_CBC) {
 409                 debug_print("Using AES-256-CBC + SHA-512 for decryption\n");
 410                 digest = GNUTLS_DIG_SHA512;
 411         } else if (algo == GNUTLS_CIPHER_AES_128_CBC) {
 412                 debug_print("Using AES-128-CBC + SHA-256 for decryption\n");
 413                 digest = GNUTLS_DIG_SHA256;
 414         }
 415         if (digest == GNUTLS_DIG_UNKNOWN) {
 416                 debug_print("Password is encrypted with unsupported cipher, giving up.\n");
 417                 g_strfreev(tokens);
 418                 return NULL;
 419         }
 420
 421         ivlen = gnutls_cipher_get_iv_size(algo);
 422         keylen = gnutls_cipher_get_key_size(algo);
 423         blocklen = gnutls_cipher_get_block_size(algo);
 424         digestlen = gnutls_hash_get_len(digest);
 425
 426         /* Prepare key for cipher - first half of hash of passkey XORed with
 427          * the second. AES-256 has key length 32 and length of SHA-512 hash
 428          * is exactly twice that, 64. */
 429         memset(&hashbuf, 0, BUFSIZE);
 430         if ((ret = gnutls_hash_fast(digest, decryption_password,
 431                                         strlen(decryption_password), &hashbuf)) < 0) {
 432                 debug_print("Hashing passkey failed: %s\n", gnutls_strerror(ret));
 433                 g_strfreev(tokens);
 434                 return NULL;
 435         }
 436         for (i = 0; i < digestlen/2; i++) {
 437                 hashbuf[i] = hashbuf[i] ^ hashbuf[i+digestlen/2];
 438         }
 439
 440         key.data = malloc(keylen);
 441         memcpy(key.data, &hashbuf, keylen);
 442         key.size = keylen;
 443
 444 #ifdef G_OS_UNIX
 445         /* Prepare our source of random data. */
 446         rnd = open("/dev/urandom", O_RDONLY);
 447         if (rnd == -1) {
 448                 perror("fopen on /dev/urandom");
 449                 g_free(key.data);
 450                 g_free(iv.data);
 451                 g_strfreev(tokens);
 452                 return NULL;
 453         }
 454 #endif
 455
 456         /* Prepare random IV for cipher */
 457         iv.data = malloc(ivlen);
 458         iv.size = ivlen;
 459 #ifdef G_OS_UNIX
 460         ret = read(rnd, iv.data, ivlen);
 461         if (ret != ivlen) {
 462                 perror("read into iv");
 463                 g_free(key.data);
 464                 g_free(iv.data);
 465                 g_strfreev(tokens);
 466                 close(rnd);
 467                 return NULL;
 468         }
 469
 470         /* We don't need any more random data. */
 471         close(rnd);
 472 #endif
 473
 474         /* Prepare encrypted password string for decryption. */
 475         tmp = g_base64_decode(tokens[2], &len);
 476         g_strfreev(tokens);
 477
 478         /* Initialize the decryption */
 479         ret = gnutls_cipher_init(&handle, algo, &key, &iv);
 480         if (ret < 0) {
 481                 debug_print("Cipher init failed: %s\n", gnutls_strerror(ret));
 482                 g_free(key.data);
 483                 g_free(iv.data);
 484                 return NULL;
 485         }
 486
 487         buf = malloc(BUFSIZE + blocklen);
 488         memset(buf, 0, BUFSIZE + blocklen);
 489         ret = gnutls_cipher_decrypt2(handle, tmp, len,
 490                         buf, BUFSIZE + blocklen);
 491         if (ret < 0) {
 492                 debug_print("Decryption failed: %s\n", gnutls_strerror(ret));
 493                 g_free(key.data);
 494                 g_free(iv.data);
 495                 g_free(buf);
 496                 gnutls_cipher_deinit(handle);
 497                 return NULL;
 498         }
 499
 500         /* Cleanup */
 501         gnutls_cipher_deinit(handle);
 502         g_free(key.data);
 503         g_free(iv.data);
 504
 505         tmp = g_strndup(buf + blocklen, MIN(strlen(buf + blocklen), BUFSIZE));
 506         g_free(buf);
 507         return tmp;
 508 }
 509
 510 #undef BUFSIZE
 511
 512 #endif
 513
 514 gchar *password_encrypt(const gchar *password,
 515                 const gchar *encryption_password)
 516 {
 517         if (password == NULL || strlen(password) == 0) {
 518                 return NULL;
 519         }
 520
 521 #ifndef PASSWORD_CRYPTO_OLD
 522         if (encryption_password == NULL)
 523                 encryption_password = master_password();
 524
 525         return password_encrypt_real(password, encryption_password);
 526 #endif
 527
 528         return password_encrypt_old(password);
 529 }
 530
 531 gchar *password_decrypt(const gchar *password,
 532                 const gchar *decryption_password)
 533 {
 534         if (password == NULL || strlen(password) == 0) {
 535                 return NULL;
 536         }
 537
 538         /* First, check if the password was possibly decrypted using old,
 539          * obsolete method */
 540         if (*password == '!') {
 541                 debug_print("Trying to decrypt password using the old method...\n");
 542                 return password_decrypt_old(password);
 543         }
 544
 545         /* Try available crypto backend */
 546 #ifndef PASSWORD_CRYPTO_OLD
 547         if (decryption_password == NULL)
 548                 decryption_password = master_password();
 549
 550         if (*password == '{') {
 551                 debug_print("Trying to decrypt password...\n");
 552                 return password_decrypt_real(password, decryption_password);
 553         }
 554 #endif
 555
 556         /* Fallback, in case the configuration is really old and
 557          * stored password in plaintext */
 558         debug_print("Assuming password was stored plaintext, returning it unchanged\n");
 559         return g_strdup(password);
 560 }