serpent.c 15.2 KB
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/* serpent.h
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 *
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 * The serpent block cipher.
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 *
 * For more details on this algorithm, see the Serpent website at
 * http://www.cl.cam.ac.uk/~rja14/serpent.html
 */

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/* nettle, low-level cryptographics library
 *
 * Copyright (C) 1998, 2000, 2001, Ross Anderson, Eli Biham, Lars
 *                                 Knudsen, Rafael R. Sevilla, Niels Mller
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 *
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 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
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 *
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 * This program 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
 * General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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 */

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/* I've modified this code a bit so that it interoperates with lsh
 * properly. 2000-9-5, Rafael R. Sevilla <dido@pacific.net.ph>
 */

/* NOTE: The copyright notice for the original version of this code
 * said "All rights reserved. This code is freely distributed for AES
 * selection process. No other use is allowed." However, the authors
 * later decided to GPL the code. /nisse */

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#if HAVE_CONFIG_H
# include "config.h"
#endif

#include <assert.h>
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#include "serpent.h"
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#include "serpent_sboxes.h"
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#include "macros.h"

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void
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serpent_set_key(struct serpent_ctx *ctx,
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                unsigned key_size, const uint8_t *key)
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{
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  unsigned i, j;
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  uint32_t w[132], k[132];
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  assert(key_size >= SERPENT_MIN_KEY_SIZE);
  assert(key_size <= SERPENT_MAX_KEY_SIZE);
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  for (i = key_size, j = 0;
       (i >= 4);
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       i-=4, j++)
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    {
      assert(j<8);
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      /* Read the key in the reverse direction. Why? */
      w[j] = READ_UINT32(key + i - 4);
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    }

    if (j < 8)
    {
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      /* Pad key, "aabbccddeeff" -> 0xccddeeff, 0x01aabb" */
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      uint32_t partial = 0x01;
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      while (i)
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	partial = (partial << 8 ) | *key++;
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      w[j++] = partial;

      while (j < 8)
	w[j++] = 0;
    }  
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  for(i=8; i<16; i++)
    w[i]=ROL(w[i-8]^w[i-5]^w[i-3]^w[i-1]^PHI^(i-8),11);
  for(i=0; i<8; i++)
    w[i]=w[i+8];
  for(i=8; i<132; i++)
    w[i]=ROL(w[i-8]^w[i-5]^w[i-3]^w[i-1]^PHI^i,11);

  RND03(w[  0], w[  1], w[  2], w[  3], k[  0], k[  1], k[  2], k[  3]);
  RND02(w[  4], w[  5], w[  6], w[  7], k[  4], k[  5], k[  6], k[  7]);
  RND01(w[  8], w[  9], w[ 10], w[ 11], k[  8], k[  9], k[ 10], k[ 11]);
  RND00(w[ 12], w[ 13], w[ 14], w[ 15], k[ 12], k[ 13], k[ 14], k[ 15]);
  RND31(w[ 16], w[ 17], w[ 18], w[ 19], k[ 16], k[ 17], k[ 18], k[ 19]);
  RND30(w[ 20], w[ 21], w[ 22], w[ 23], k[ 20], k[ 21], k[ 22], k[ 23]);
  RND29(w[ 24], w[ 25], w[ 26], w[ 27], k[ 24], k[ 25], k[ 26], k[ 27]);
  RND28(w[ 28], w[ 29], w[ 30], w[ 31], k[ 28], k[ 29], k[ 30], k[ 31]);
  RND27(w[ 32], w[ 33], w[ 34], w[ 35], k[ 32], k[ 33], k[ 34], k[ 35]);
  RND26(w[ 36], w[ 37], w[ 38], w[ 39], k[ 36], k[ 37], k[ 38], k[ 39]);
  RND25(w[ 40], w[ 41], w[ 42], w[ 43], k[ 40], k[ 41], k[ 42], k[ 43]);
  RND24(w[ 44], w[ 45], w[ 46], w[ 47], k[ 44], k[ 45], k[ 46], k[ 47]);
  RND23(w[ 48], w[ 49], w[ 50], w[ 51], k[ 48], k[ 49], k[ 50], k[ 51]);
  RND22(w[ 52], w[ 53], w[ 54], w[ 55], k[ 52], k[ 53], k[ 54], k[ 55]);
  RND21(w[ 56], w[ 57], w[ 58], w[ 59], k[ 56], k[ 57], k[ 58], k[ 59]);
  RND20(w[ 60], w[ 61], w[ 62], w[ 63], k[ 60], k[ 61], k[ 62], k[ 63]);
  RND19(w[ 64], w[ 65], w[ 66], w[ 67], k[ 64], k[ 65], k[ 66], k[ 67]);
  RND18(w[ 68], w[ 69], w[ 70], w[ 71], k[ 68], k[ 69], k[ 70], k[ 71]);
  RND17(w[ 72], w[ 73], w[ 74], w[ 75], k[ 72], k[ 73], k[ 74], k[ 75]);
  RND16(w[ 76], w[ 77], w[ 78], w[ 79], k[ 76], k[ 77], k[ 78], k[ 79]);
  RND15(w[ 80], w[ 81], w[ 82], w[ 83], k[ 80], k[ 81], k[ 82], k[ 83]);
  RND14(w[ 84], w[ 85], w[ 86], w[ 87], k[ 84], k[ 85], k[ 86], k[ 87]);
  RND13(w[ 88], w[ 89], w[ 90], w[ 91], k[ 88], k[ 89], k[ 90], k[ 91]);
  RND12(w[ 92], w[ 93], w[ 94], w[ 95], k[ 92], k[ 93], k[ 94], k[ 95]);
  RND11(w[ 96], w[ 97], w[ 98], w[ 99], k[ 96], k[ 97], k[ 98], k[ 99]);
  RND10(w[100], w[101], w[102], w[103], k[100], k[101], k[102], k[103]);
  RND09(w[104], w[105], w[106], w[107], k[104], k[105], k[106], k[107]);
  RND08(w[108], w[109], w[110], w[111], k[108], k[109], k[110], k[111]);
  RND07(w[112], w[113], w[114], w[115], k[112], k[113], k[114], k[115]);
  RND06(w[116], w[117], w[118], w[119], k[116], k[117], k[118], k[119]);
  RND05(w[120], w[121], w[122], w[123], k[120], k[121], k[122], k[123]);
  RND04(w[124], w[125], w[126], w[127], k[124], k[125], k[126], k[127]);
  RND03(w[128], w[129], w[130], w[131], k[128], k[129], k[130], k[131]);

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  for(i=0; i<=32; i++)
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    for(j=0; j<4; j++)
      ctx->keys[i][j] = k[4*i+j];
}

void
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serpent_encrypt(struct serpent_ctx *ctx,
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                unsigned length, uint8_t *dst,
                const uint8_t *plain)
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{
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  register uint32_t x0, x1, x2, x3;
  register uint32_t y0, y1, y2, y3;

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  FOR_BLOCKS(length, dst, plain, SERPENT_BLOCK_SIZE)
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    {
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      /* Why the reverse order? */
      x0=READ_UINT32(plain + 12);
      x1=READ_UINT32(plain + 8);
      x2=READ_UINT32(plain + 4);
      x3=READ_UINT32(plain);
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      /* Start to encrypt the plaintext x */
      keying(x0, x1, x2, x3, ctx->keys[ 0]);
      RND00(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[ 1]);
      RND01(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[ 2]);
      RND02(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[ 3]);
      RND03(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[ 4]);
      RND04(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[ 5]);
      RND05(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[ 6]);
      RND06(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[ 7]);
      RND07(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[ 8]);
      RND08(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[ 9]);
      RND09(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[10]);
      RND10(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[11]);
      RND11(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[12]);
      RND12(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[13]);
      RND13(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[14]);
      RND14(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[15]);
      RND15(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[16]);
      RND16(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[17]);
      RND17(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[18]);
      RND18(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[19]);
      RND19(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[20]);
      RND20(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[21]);
      RND21(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[22]);
      RND22(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[23]);
      RND23(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[24]);
      RND24(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[25]);
      RND25(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[26]);
      RND26(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[27]);
      RND27(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[28]);
      RND28(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[29]);
      RND29(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[30]);
      RND30(x0, x1, x2, x3, y0, y1, y2, y3);
      transform(y0, y1, y2, y3, x0, x1, x2, x3);
      keying(x0, x1, x2, x3, ctx->keys[31]);
      RND31(x0, x1, x2, x3, y0, y1, y2, y3);
      x0 = y0; x1 = y1; x2 = y2; x3 = y3;
      keying(x0, x1, x2, x3, ctx->keys[32]);
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      /* The ciphertext is now in x */
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      /* Why the reverse order? */
      WRITE_UINT32(dst, x3);
      WRITE_UINT32(dst+4, x2);
      WRITE_UINT32(dst+8, x1);
      WRITE_UINT32(dst+12, x0);
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    }
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}

void
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serpent_decrypt(struct serpent_ctx *ctx,
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                unsigned length, uint8_t *dst,
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                const uint8_t *cipher)
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{
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  register uint32_t x0, x1, x2, x3;
  register uint32_t y0, y1, y2, y3;
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  FOR_BLOCKS(length, dst, cipher, SERPENT_BLOCK_SIZE)
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    {
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      /* Why the reverse order? */
      x0 = READ_UINT32(cipher + 12);
      x1 = READ_UINT32(cipher + 8);
      x2 = READ_UINT32(cipher + 4);
      x3 = READ_UINT32(cipher);
      
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      /* Start to decrypt the ciphertext x */
      keying(x0, x1, x2, x3, ctx->keys[32]);
      InvRND31(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[31]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND30(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[30]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND29(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[29]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND28(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[28]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND27(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[27]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND26(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[26]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND25(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[25]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND24(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[24]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND23(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[23]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND22(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[22]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND21(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[21]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND20(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[20]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND19(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[19]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND18(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[18]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND17(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[17]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND16(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[16]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND15(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[15]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND14(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[14]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND13(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[13]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND12(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[12]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND11(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[11]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND10(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[10]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND09(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[ 9]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND08(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[ 8]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND07(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[ 7]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND06(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[ 6]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND05(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[ 5]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND04(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[ 4]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND03(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[ 3]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND02(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[ 2]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND01(x0, x1, x2, x3, y0, y1, y2, y3);
      keying(y0, y1, y2, y3, ctx->keys[ 1]);
      inv_transform(y0, y1, y2, y3, x0, x1, x2, x3);
      InvRND00(x0, x1, x2, x3, y0, y1, y2, y3);
      x0 = y0; x1 = y1; x2 = y2; x3 = y3;
      keying(x0, x1, x2, x3, ctx->keys[ 0]);
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      /* The plaintext is now in x */
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      /* Why the reverse order? */
      WRITE_UINT32(dst, x3);
      WRITE_UINT32(dst+4, x2);
      WRITE_UINT32(dst+8, x1);
      WRITE_UINT32(dst+12, x0);
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    }
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}