lib/crypto_backend/pbkdf2_generic.c

   1 /*
   2  * Implementation of Password-Based Cryptography as per PKCS#5
   3  * Copyright (C) 2002,2003 Simon Josefsson
   4  * Copyright (C) 2004 Free Software Foundation
   5  *
   6  * cryptsetup related changes
   7  * Copyright (C) 2012, Red Hat, Inc. All rights reserved.
   8  * Copyright (C) 2012-2014, Milan Broz
   9  *
  10  * This file is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Lesser General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2.1 of the License, or (at your option) any later version.
  14  *
  15  * This file is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public
  21  * License along with this file; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  *
  24  */
  25
  26 #include <errno.h>
  27 #include <alloca.h>
  28 #include "crypto_backend.h"
  29
  30 static int hash_buf(const char *src, size_t src_len,
  31                     char *dst, size_t dst_len,
  32                     const char *hash_name)
  33 {
  34         struct crypt_hash *hd = NULL;
  35         int r;
  36
  37         if (crypt_hash_init(&hd, hash_name))
  38                 return -EINVAL;
  39
  40         r = crypt_hash_write(hd, src, src_len);
  41
  42         if (!r)
  43                 r = crypt_hash_final(hd, dst, dst_len);
  44
  45         crypt_hash_destroy(hd);
  46         return r;
  47 }
  48
  49 /*
  50  * 5.2 PBKDF2
  51  *
  52  *  PBKDF2 applies a pseudorandom function (see Appendix B.1 for an
  53  *  example) to derive keys. The length of the derived key is essentially
  54  *  unbounded. (However, the maximum effective search space for the
  55  *  derived key may be limited by the structure of the underlying
  56  *  pseudorandom function. See Appendix B.1 for further discussion.)
  57  *  PBKDF2 is recommended for new applications.
  58  *
  59  *  PBKDF2 (P, S, c, dkLen)
  60  *
  61  *  Options:        PRF        underlying pseudorandom function (hLen
  62  *                             denotes the length in octets of the
  63  *                             pseudorandom function output)
  64  *
  65  *  Input:          P          password, an octet string (ASCII or UTF-8)
  66  *                  S          salt, an octet string
  67  *                  c          iteration count, a positive integer
  68  *                  dkLen      intended length in octets of the derived
  69  *                             key, a positive integer, at most
  70  *                             (2^32 - 1) * hLen
  71  *
  72  *  Output:         DK         derived key, a dkLen-octet string
  73  */
  74
  75 /*
  76  * if hash_block_size is not zero, the HMAC key is pre-hashed
  77  * inside this function.
  78  * This prevents situation when crypto backend doesn't support
  79  * long HMAC keys or it tries hash long key in every iteration
  80  * (because of crypt_final() cannot do simple key reset.
  81  */
  82
  83 #define MAX_PRF_BLOCK_LEN 80
  84
  85 int pkcs5_pbkdf2(const char *hash,
  86                         const char *P, size_t Plen,
  87                         const char *S, size_t Slen,
  88                         unsigned int c, unsigned int dkLen,
  89                         char *DK, unsigned int hash_block_size)
  90 {
  91         struct crypt_hmac *hmac;
  92         char U[MAX_PRF_BLOCK_LEN];
  93         char T[MAX_PRF_BLOCK_LEN];
  94         char P_hash[MAX_PRF_BLOCK_LEN];
  95         int i, k, rc = -EINVAL;
  96         unsigned int u, hLen, l, r;
  97         size_t tmplen = Slen + 4;
  98         char *tmp;
  99
 100         tmp = alloca(tmplen);
 101         if (tmp == NULL)
 102                 return -ENOMEM;
 103
 104         hLen = crypt_hmac_size(hash);
 105         if (hLen == 0 || hLen > MAX_PRF_BLOCK_LEN)
 106                 return -EINVAL;
 107
 108         if (c == 0)
 109                 return -EINVAL;
 110
 111         if (dkLen == 0)
 112                 return -EINVAL;
 113
 114         /*
 115          *
 116          *  Steps:
 117          *
 118          *     1. If dkLen > (2^32 - 1) * hLen, output "derived key too long" and
 119          *        stop.
 120          */
 121
 122         if (dkLen > 4294967295U)
 123                 return -EINVAL;
 124
 125         /*
 126          *     2. Let l be the number of hLen-octet blocks in the derived key,
 127          *        rounding up, and let r be the number of octets in the last
 128          *        block:
 129          *
 130          *                  l = CEIL (dkLen / hLen) ,
 131          *                  r = dkLen - (l - 1) * hLen .
 132          *
 133          *        Here, CEIL (x) is the "ceiling" function, i.e. the smallest
 134          *        integer greater than, or equal to, x.
 135          */
 136
 137         l = dkLen / hLen;
 138         if (dkLen % hLen)
 139                 l++;
 140         r = dkLen - (l - 1) * hLen;
 141
 142         /*
 143          *     3. For each block of the derived key apply the function F defined
 144          *        below to the password P, the salt S, the iteration count c, and
 145          *        the block index to compute the block:
 146          *
 147          *                  T_1 = F (P, S, c, 1) ,
 148          *                  T_2 = F (P, S, c, 2) ,
 149          *                  ...
 150          *                  T_l = F (P, S, c, l) ,
 151          *
 152          *        where the function F is defined as the exclusive-or sum of the
 153          *        first c iterates of the underlying pseudorandom function PRF
 154          *        applied to the password P and the concatenation of the salt S
 155          *        and the block index i:
 156          *
 157          *                  F (P, S, c, i) = U_1 \xor U_2 \xor ... \xor U_c
 158          *
 159          *        where
 160          *
 161          *                  U_1 = PRF (P, S || INT (i)) ,
 162          *                  U_2 = PRF (P, U_1) ,
 163          *                  ...
 164          *                  U_c = PRF (P, U_{c-1}) .
 165          *
 166          *        Here, INT (i) is a four-octet encoding of the integer i, most
 167          *        significant octet first.
 168          *
 169          *     4. Concatenate the blocks and extract the first dkLen octets to
 170          *        produce a derived key DK:
 171          *
 172          *                  DK = T_1 || T_2 ||  ...  || T_l<0..r-1>
 173          *
 174          *     5. Output the derived key DK.
 175          *
 176          *  Note. The construction of the function F follows a "belt-and-
 177          *  suspenders" approach. The iterates U_i are computed recursively to
 178          *  remove a degree of parallelism from an opponent; they are exclusive-
 179          *  ored together to reduce concerns about the recursion degenerating
 180          *  into a small set of values.
 181          *
 182          */
 183
 184         /* If hash_block_size is provided, hash password in advance. */
 185         if (hash_block_size > 0 && Plen > hash_block_size) {
 186                 if (hash_buf(P, Plen, P_hash, hLen, hash))
 187                         return -EINVAL;
 188
 189                 if (crypt_hmac_init(&hmac, hash, P_hash, hLen))
 190                         return -EINVAL;
 191                 crypt_backend_memzero(P_hash, sizeof(P_hash));
 192         } else {
 193                 if (crypt_hmac_init(&hmac, hash, P, Plen))
 194                         return -EINVAL;
 195         }
 196
 197         for (i = 1; (unsigned int) i <= l; i++) {
 198                 memset(T, 0, hLen);
 199
 200                 for (u = 1; u <= c ; u++) {
 201                         if (u == 1) {
 202                                 memcpy(tmp, S, Slen);
 203                                 tmp[Slen + 0] = (i & 0xff000000) >> 24;
 204                                 tmp[Slen + 1] = (i & 0x00ff0000) >> 16;
 205                                 tmp[Slen + 2] = (i & 0x0000ff00) >> 8;
 206                                 tmp[Slen + 3] = (i & 0x000000ff) >> 0;
 207
 208                                 if (crypt_hmac_write(hmac, tmp, tmplen))
 209                                         goto out;
 210                         } else {
 211                                 if (crypt_hmac_write(hmac, U, hLen))
 212                                         goto out;
 213                         }
 214
 215                         if (crypt_hmac_final(hmac, U, hLen))
 216                                 goto out;
 217
 218                         for (k = 0; (unsigned int) k < hLen; k++)
 219                                 T[k] ^= U[k];
 220                 }
 221
 222                 memcpy(DK + (i - 1) * hLen, T, (unsigned int) i == l ? r : hLen);
 223         }
 224         rc = 0;
 225 out:
 226         crypt_hmac_destroy(hmac);
 227         crypt_backend_memzero(U, sizeof(U));
 228         crypt_backend_memzero(T, sizeof(T));
 229         crypt_backend_memzero(tmp, tmplen);
 230
 231         return rc;
 232 }
 233
 234 #if 0
 235 #include <stdio.h>
 236
 237 struct test_vector {
 238         const char *hash;
 239         unsigned int hash_block_length;
 240         unsigned int iterations;
 241         const char *password;
 242         unsigned int password_length;
 243         const char *salt;
 244         unsigned int salt_length;
 245         const char *output;
 246         unsigned int output_length;
 247 };
 248
 249 struct test_vector test_vectors[] = {
 250         /* RFC 3962 */
 251         {
 252                 "sha1", 64, 1,
 253                 "password", 8,
 254                 "ATHENA.MIT.EDUraeburn", 21,
 255                 "\xcd\xed\xb5\x28\x1b\xb2\xf8\x01"
 256                 "\x56\x5a\x11\x22\xb2\x56\x35\x15"
 257                 "\x0a\xd1\xf7\xa0\x4b\xb9\xf3\xa3"
 258                 "\x33\xec\xc0\xe2\xe1\xf7\x08\x37", 32
 259         }, {
 260                 "sha1", 64, 2,
 261                 "password", 8,
 262                 "ATHENA.MIT.EDUraeburn", 21,
 263                 "\x01\xdb\xee\x7f\x4a\x9e\x24\x3e"
 264                 "\x98\x8b\x62\xc7\x3c\xda\x93\x5d"
 265                 "\xa0\x53\x78\xb9\x32\x44\xec\x8f"
 266                 "\x48\xa9\x9e\x61\xad\x79\x9d\x86", 32
 267         }, {
 268                 "sha1", 64, 1200,
 269                 "password", 8,
 270                 "ATHENA.MIT.EDUraeburn", 21,
 271                 "\x5c\x08\xeb\x61\xfd\xf7\x1e\x4e"
 272                 "\x4e\xc3\xcf\x6b\xa1\xf5\x51\x2b"
 273                 "\xa7\xe5\x2d\xdb\xc5\xe5\x14\x2f"
 274                 "\x70\x8a\x31\xe2\xe6\x2b\x1e\x13", 32
 275         }, {
 276                 "sha1", 64, 5,
 277                 "password", 8,
 278                 "\0224VxxV4\022", 8, // "\x1234567878563412
 279                 "\xd1\xda\xa7\x86\x15\xf2\x87\xe6"
 280                 "\xa1\xc8\xb1\x20\xd7\x06\x2a\x49"
 281                 "\x3f\x98\xd2\x03\xe6\xbe\x49\xa6"
 282                 "\xad\xf4\xfa\x57\x4b\x6e\x64\xee", 32
 283         }, {
 284                 "sha1", 64, 1200,
 285                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
 286                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX", 64,
 287                 "pass phrase equals block size", 29,
 288                 "\x13\x9c\x30\xc0\x96\x6b\xc3\x2b"
 289                 "\xa5\x5f\xdb\xf2\x12\x53\x0a\xc9"
 290                 "\xc5\xec\x59\xf1\xa4\x52\xf5\xcc"
 291                 "\x9a\xd9\x40\xfe\xa0\x59\x8e\xd1", 32
 292         }, {
 293                 "sha1", 64, 1200,
 294                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
 295                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX", 65,
 296                 "pass phrase exceeds block size", 30,
 297                 "\x9c\xca\xd6\xd4\x68\x77\x0c\xd5"
 298                 "\x1b\x10\xe6\xa6\x87\x21\xbe\x61"
 299                 "\x1a\x8b\x4d\x28\x26\x01\xdb\x3b"
 300                 "\x36\xbe\x92\x46\x91\x5e\xc8\x2a", 32
 301         }, {
 302                 "sha1", 64, 50,
 303                 "\360\235\204\236", 4, // g-clef ("\xf09d849e)
 304                 "EXAMPLE.COMpianist", 18,
 305                 "\x6b\x9c\xf2\x6d\x45\x45\x5a\x43"
 306                 "\xa5\xb8\xbb\x27\x6a\x40\x3b\x39"
 307                 "\xe7\xfe\x37\xa0\xc4\x1e\x02\xc2"
 308                 "\x81\xff\x30\x69\xe1\xe9\x4f\x52", 32
 309         }, {
 310         /* RFC-6070 */
 311                 "sha1", 64, 1,
 312                 "password", 8,
 313                 "salt", 4,
 314                 "\x0c\x60\xc8\x0f\x96\x1f\x0e\x71\xf3\xa9"
 315                 "\xb5\x24\xaf\x60\x12\x06\x2f\xe0\x37\xa6", 20
 316         }, {
 317                 "sha1", 64, 2,
 318                 "password", 8,
 319                 "salt", 4,
 320                 "\xea\x6c\x01\x4d\xc7\x2d\x6f\x8c\xcd\x1e"
 321                 "\xd9\x2a\xce\x1d\x41\xf0\xd8\xde\x89\x57", 20
 322         }, {
 323                 "sha1", 64, 4096,
 324                 "password", 8,
 325                 "salt", 4,
 326                 "\x4b\x00\x79\x01\xb7\x65\x48\x9a\xbe\xad"
 327                 "\x49\xd9\x26\xf7\x21\xd0\x65\xa4\x29\xc1", 20
 328         }, {
 329                 "sha1", 64, 16777216,
 330                 "password", 8,
 331                 "salt", 4,
 332                 "\xee\xfe\x3d\x61\xcd\x4d\xa4\xe4\xe9\x94"
 333                 "\x5b\x3d\x6b\xa2\x15\x8c\x26\x34\xe9\x84", 20
 334         }, {
 335                 "sha1", 64, 4096,
 336                 "passwordPASSWORDpassword", 24,
 337                 "saltSALTsaltSALTsaltSALTsaltSALTsalt", 36,
 338                 "\x3d\x2e\xec\x4f\xe4\x1c\x84\x9b\x80\xc8"
 339                 "\xd8\x36\x62\xc0\xe4\x4a\x8b\x29\x1a\x96"
 340                 "\x4c\xf2\xf0\x70\x38", 25
 341         }, {
 342                 "sha1", 64, 4096,
 343                 "pass\0word", 9,
 344                 "sa\0lt", 5,
 345                 "\x56\xfa\x6a\xa7\x55\x48\x09\x9d\xcc\x37"
 346                 "\xd7\xf0\x34\x25\xe0\xc3", 16
 347         }, {
 348         /* empty password test */
 349                 "sha1", 64, 2,
 350                 "", 0,
 351                 "salt", 4,
 352                 "\x13\x3a\x4c\xe8\x37\xb4\xd2\x52\x1e\xe2"
 353                 "\xbf\x03\xe1\x1c\x71\xca\x79\x4e\x07\x97", 20
 354         }, {
 355         /* Password exceeds block size test */
 356                 "sha256", 64, 1200,
 357                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
 358                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX", 65,
 359                 "pass phrase exceeds block size", 30,
 360                 "\x22\x34\x4b\xc4\xb6\xe3\x26\x75"
 361                 "\xa8\x09\x0f\x3e\xa8\x0b\xe0\x1d"
 362                 "\x5f\x95\x12\x6a\x2c\xdd\xc3\xfa"
 363                 "\xcc\x4a\x5e\x6d\xca\x04\xec\x58", 32
 364         }, {
 365                 "sha512", 128, 1200,
 366                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
 367                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
 368                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
 369                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX", 129,
 370                 "pass phrase exceeds block size", 30,
 371                 "\x0f\xb2\xed\x2c\x0e\x6e\xfb\x7d"
 372                 "\x7d\x8e\xdd\x58\x01\xb4\x59\x72"
 373                 "\x99\x92\x16\x30\x5e\xa4\x36\x8d"
 374                 "\x76\x14\x80\xf3\xe3\x7a\x22\xb9", 32
 375         }, {
 376                 "whirlpool", 64, 1200,
 377                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
 378                 "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX", 65,
 379                 "pass phrase exceeds block size", 30,
 380                 "\x9c\x1c\x74\xf5\x88\x26\xe7\x6a"
 381                 "\x53\x58\xf4\x0c\x39\xe7\x80\x89"
 382                 "\x07\xc0\x31\x19\x9a\x50\xa2\x48"
 383                 "\xf1\xd9\xfe\x78\x64\xe5\x84\x50", 32
 384         }
 385 };
 386
 387 static void printhex(const char *s, const char *buf, size_t len)
 388 {
 389         size_t i;
 390
 391         printf("%s: ", s);
 392         for (i = 0; i < len; i++)
 393                 printf("\\x%02x", (unsigned char)buf[i]);
 394         printf("\n");
 395         fflush(stdout);
 396 }
 397
 398 static int pkcs5_pbkdf2_test_vectors(void)
 399 {
 400         char result[64];
 401         unsigned int i, j;
 402         struct test_vector *vec;
 403
 404         for (i = 0; i < (sizeof(test_vectors) / sizeof(*test_vectors)); i++) {
 405                 vec = &test_vectors[i];
 406                 for (j = 1; j <= vec->output_length; j++) {
 407                         if (pkcs5_pbkdf2(vec->hash,
 408                             vec->password, vec->password_length,
 409                             vec->salt, vec->salt_length,
 410                             vec->iterations,
 411                             j, result, vec->hash_block_length)) {
 412                                 printf("pbkdf2 failed, vector %d\n", i);
 413                                 return -EINVAL;
 414                         }
 415                         if (memcmp(result, vec->output, j) != 0) {
 416                                 printf("vector %u\n", i);
 417                                 printhex(" got", result, j);
 418                                 printhex("want", vec->output, j);
 419                                 return -EINVAL;
 420                         }
 421                         memset(result, 0, sizeof(result));
 422                 }
 423         }
 424         return 0;
 425 }
 426 #endif