aes-set-decrypt-key.c 5.68 KB
Newer Older
Niels Möller's avatar
Niels Möller committed
1 2 3 4 5 6 7
/* aes-set-decrypt-key.c
 *
 * Inverse key setup for the aes/rijndael block cipher.
 */

/* nettle, low-level cryptographics library
 *
Niels Möller's avatar
Niels Möller committed
8
 * Copyright (C) 2000, 2001, 2002 Rafael R. Sevilla, Niels Möller
Niels Möller's avatar
Niels Möller committed
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
 *  
 * The nettle library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 * 
 * The nettle library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with the nettle library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/* Originally written by Rafael R. Sevilla <dido@pacific.net.ph> */

28 29 30 31
#if HAVE_CONFIG_H
# include "config.h"
#endif

Niels Möller's avatar
Niels Möller committed
32 33
#include "aes-internal.h"

34
#include "macros.h"
Niels Möller's avatar
Niels Möller committed
35

36 37
/* NOTE: We don't include rotated versions of the table. */
static const uint32_t mtable[0x100] =
Niels Möller's avatar
Niels Möller committed
38
{
39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102
  0x00000000,0x0b0d090e,0x161a121c,0x1d171b12,
  0x2c342438,0x27392d36,0x3a2e3624,0x31233f2a,
  0x58684870,0x5365417e,0x4e725a6c,0x457f5362,
  0x745c6c48,0x7f516546,0x62467e54,0x694b775a,
  0xb0d090e0,0xbbdd99ee,0xa6ca82fc,0xadc78bf2,
  0x9ce4b4d8,0x97e9bdd6,0x8afea6c4,0x81f3afca,
  0xe8b8d890,0xe3b5d19e,0xfea2ca8c,0xf5afc382,
  0xc48cfca8,0xcf81f5a6,0xd296eeb4,0xd99be7ba,
  0x7bbb3bdb,0x70b632d5,0x6da129c7,0x66ac20c9,
  0x578f1fe3,0x5c8216ed,0x41950dff,0x4a9804f1,
  0x23d373ab,0x28de7aa5,0x35c961b7,0x3ec468b9,
  0x0fe75793,0x04ea5e9d,0x19fd458f,0x12f04c81,
  0xcb6bab3b,0xc066a235,0xdd71b927,0xd67cb029,
  0xe75f8f03,0xec52860d,0xf1459d1f,0xfa489411,
  0x9303e34b,0x980eea45,0x8519f157,0x8e14f859,
  0xbf37c773,0xb43ace7d,0xa92dd56f,0xa220dc61,
  0xf66d76ad,0xfd607fa3,0xe07764b1,0xeb7a6dbf,
  0xda595295,0xd1545b9b,0xcc434089,0xc74e4987,
  0xae053edd,0xa50837d3,0xb81f2cc1,0xb31225cf,
  0x82311ae5,0x893c13eb,0x942b08f9,0x9f2601f7,
  0x46bde64d,0x4db0ef43,0x50a7f451,0x5baafd5f,
  0x6a89c275,0x6184cb7b,0x7c93d069,0x779ed967,
  0x1ed5ae3d,0x15d8a733,0x08cfbc21,0x03c2b52f,
  0x32e18a05,0x39ec830b,0x24fb9819,0x2ff69117,
  0x8dd64d76,0x86db4478,0x9bcc5f6a,0x90c15664,
  0xa1e2694e,0xaaef6040,0xb7f87b52,0xbcf5725c,
  0xd5be0506,0xdeb30c08,0xc3a4171a,0xc8a91e14,
  0xf98a213e,0xf2872830,0xef903322,0xe49d3a2c,
  0x3d06dd96,0x360bd498,0x2b1ccf8a,0x2011c684,
  0x1132f9ae,0x1a3ff0a0,0x0728ebb2,0x0c25e2bc,
  0x656e95e6,0x6e639ce8,0x737487fa,0x78798ef4,
  0x495ab1de,0x4257b8d0,0x5f40a3c2,0x544daacc,
  0xf7daec41,0xfcd7e54f,0xe1c0fe5d,0xeacdf753,
  0xdbeec879,0xd0e3c177,0xcdf4da65,0xc6f9d36b,
  0xafb2a431,0xa4bfad3f,0xb9a8b62d,0xb2a5bf23,
  0x83868009,0x888b8907,0x959c9215,0x9e919b1b,
  0x470a7ca1,0x4c0775af,0x51106ebd,0x5a1d67b3,
  0x6b3e5899,0x60335197,0x7d244a85,0x7629438b,
  0x1f6234d1,0x146f3ddf,0x097826cd,0x02752fc3,
  0x335610e9,0x385b19e7,0x254c02f5,0x2e410bfb,
  0x8c61d79a,0x876cde94,0x9a7bc586,0x9176cc88,
  0xa055f3a2,0xab58faac,0xb64fe1be,0xbd42e8b0,
  0xd4099fea,0xdf0496e4,0xc2138df6,0xc91e84f8,
  0xf83dbbd2,0xf330b2dc,0xee27a9ce,0xe52aa0c0,
  0x3cb1477a,0x37bc4e74,0x2aab5566,0x21a65c68,
  0x10856342,0x1b886a4c,0x069f715e,0x0d927850,
  0x64d90f0a,0x6fd40604,0x72c31d16,0x79ce1418,
  0x48ed2b32,0x43e0223c,0x5ef7392e,0x55fa3020,
  0x01b79aec,0x0aba93e2,0x17ad88f0,0x1ca081fe,
  0x2d83bed4,0x268eb7da,0x3b99acc8,0x3094a5c6,
  0x59dfd29c,0x52d2db92,0x4fc5c080,0x44c8c98e,
  0x75ebf6a4,0x7ee6ffaa,0x63f1e4b8,0x68fcedb6,
  0xb1670a0c,0xba6a0302,0xa77d1810,0xac70111e,
  0x9d532e34,0x965e273a,0x8b493c28,0x80443526,
  0xe90f427c,0xe2024b72,0xff155060,0xf418596e,
  0xc53b6644,0xce366f4a,0xd3217458,0xd82c7d56,
  0x7a0ca137,0x7101a839,0x6c16b32b,0x671bba25,
  0x5638850f,0x5d358c01,0x40229713,0x4b2f9e1d,
  0x2264e947,0x2969e049,0x347efb5b,0x3f73f255,
  0x0e50cd7f,0x055dc471,0x184adf63,0x1347d66d,
  0xcadc31d7,0xc1d138d9,0xdcc623cb,0xd7cb2ac5,
  0xe6e815ef,0xede51ce1,0xf0f207f3,0xfbff0efd,
  0x92b479a7,0x99b970a9,0x84ae6bbb,0x8fa362b5,
  0xbe805d9f,0xb58d5491,0xa89a4f83,0xa397468d,
Niels Möller's avatar
Niels Möller committed
103 104
};

105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120
#define MIX_COLUMN(T, key) do { \
    uint32_t _k, _nk, _t;	\
    _k = (key);			\
    _nk = T[_k & 0xff];		\
    _k >>= 8;			\
    _t = T[_k & 0xff];		\
    _nk ^= ROTL32(8, _t);	\
    _k >>= 8;			\
    _t = T[_k & 0xff];		\
    _nk ^= ROTL32(16, _t);	\
    _k >>= 8;			\
    _t = T[_k & 0xff];		\
    _nk ^= ROTL32(24, _t);	\
    (key) = _nk;		\
  } while(0)
  
Niels Möller's avatar
Niels Möller committed
121 122 123 124

#define SWAP(a, b) \
do { uint32_t t_swap = (a); (a) = (b); (b) = t_swap; } while(0)

125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157
void
aes_invert_key(struct aes_ctx *dst,
	       const struct aes_ctx *src)
{
  unsigned nrounds;
  unsigned i;

  nrounds = src->nrounds;

  /* Reverse the order of subkeys, in groups of 4. */
  /* FIXME: Instead of reordering the subkeys, change the access order
     of aes_decrypt, since it's a separate function anyway? */
  if (src == dst)
    {
      unsigned j, k;

      for (i = 0, j = nrounds * 4;
	   i < j;
	   i += 4, j -= 4)
	for (k = 0; k<4; k++)
	  SWAP(dst->keys[i+k], dst->keys[j+k]);
    }
  else
    {
      unsigned k;

      dst->nrounds = nrounds;
      for (i = 0; i <= nrounds * 4; i += 4)
	for (k = 0; k < 4; k++)
	  dst->keys[i+k] = src->keys[nrounds * 4 - i + k];
    }

  /* Transform all subkeys but the first and last. */
158 159
  for (i = 4; i < 4 * nrounds; i++)
    MIX_COLUMN (mtable, dst->keys[i]);
160 161
}

Niels Möller's avatar
Niels Möller committed
162 163 164 165 166 167 168
void
aes_set_decrypt_key(struct aes_ctx *ctx,
		    unsigned keysize, const uint8_t *key)
{
  /* We first create subkeys for encryption,
   * then modify the subkeys for decryption. */
  aes_set_encrypt_key(ctx, keysize, key);
169
  aes_invert_key(ctx, ctx);
Niels Möller's avatar
Niels Möller committed
170 171
}