release/src/router/nettle/pbkdf2.c

   1 /* pbkdf2.c
   2  *
   3  * PKCS #5 password-based key derivation function PBKDF2, see RFC 2898.
   4  */
   5
   6 /* nettle, low-level cryptographics library
   7  *
   8  * Copyright (C) 2012 Simon Josefsson, Niels Möller
   9  *
  10  * The nettle library is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU Lesser General Public License as published by
  12  * the Free Software Foundation; either version 2.1 of the License, or (at your
  13  * option) any later version.
  14  *
  15  * The nettle library is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  17  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  18  * License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public License
  21  * along with the nettle library; see the file COPYING.LIB.  If not, write to
  22  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  23  * MA 02111-1301, USA.
  24  */
  25
  26 #if HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include <assert.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33
  34 #include "pbkdf2.h"
  35
  36 #include "macros.h"
  37 #include "memxor.h"
  38 #include "nettle-internal.h"
  39
  40 void
  41 pbkdf2 (void *mac_ctx,
  42         nettle_hash_update_func *update,
  43         nettle_hash_digest_func *digest,
  44         unsigned digest_size, unsigned iterations,
  45         unsigned salt_length, const uint8_t *salt,
  46         unsigned length, uint8_t *dst)
  47 {
  48   TMP_DECL(U, uint8_t, NETTLE_MAX_HASH_DIGEST_SIZE);
  49   TMP_DECL(T, uint8_t, NETTLE_MAX_HASH_DIGEST_SIZE);
  50
  51   unsigned i;
  52
  53   assert (iterations > 0);
  54
  55   if (length == 0)
  56     return;
  57
  58   TMP_ALLOC (U, digest_size);
  59   TMP_ALLOC (T, digest_size);
  60
  61   for (i = 1;;
  62        i++, dst += digest_size, length -= digest_size)
  63     {
  64       uint8_t tmp[4];
  65       uint8_t *prev;
  66       unsigned u;
  67
  68       WRITE_UINT32 (tmp, i);
  69
  70       update (mac_ctx, salt_length, salt);
  71       update (mac_ctx, sizeof(tmp), tmp);
  72       digest (mac_ctx, digest_size, T);
  73
  74       prev = T;
  75
  76       for (u = 1; u < iterations; u++, prev = U)
  77         {
  78           update (mac_ctx, digest_size, prev);
  79           digest (mac_ctx, digest_size, U);
  80
  81           memxor (T, U, digest_size);
  82         }
  83
  84       if (length <= digest_size)
  85         {
  86           memcpy (dst, T, length);
  87           return;
  88         }
  89       memcpy (dst, T, digest_size);
  90     }
  91 }