git.distorted.org.uk Git - u/mdw/catacomb/blob - serpent.c

   1 /* -*-c-*-
   2  *
   3  * $Id: serpent.c,v 1.2 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * The Serpent block cipher
   6  *
   7  * (c) 2000 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Header files ------------------------------------------------------*/
  31
  32 #include <assert.h>
  33 #include <stdio.h>
  34
  35 #include <mLib/bits.h>
  36
  37 #include "blkc.h"
  38 #include "gcipher.h"
  39 #include "serpent.h"
  40 #include "serpent-sbox.h"
  41
  42 /*----- Global variables --------------------------------------------------*/
  43
  44 const octet serpent_keysz[] = { KSZ_RANGE, SERPENT_KEYSZ, 0, 32, 1 };
  45
  46 /*----- Main code ---------------------------------------------------------*/
  47
  48 /* --- @serpent_init@ --- *
  49  *
  50  * Arguments:   @serpent_ctx *k@ = pointer to context block to initialize
  51  *              @const void *buf@ = pointer to input buffer
  52  *              @size_t sz@ = size of input buffer
  53  *
  54  * Returns:     ---
  55  *
  56  * Use:         Initializes a Serpent context.  The key may be any length of
  57  *              up to 32 bytes (256 bits).
  58  */
  59
  60 void serpent_init(serpent_ctx *k, const void *buf, size_t sz)
  61 {
  62   uint32 a;
  63   unsigned b;
  64   const octet *p, *q;
  65   size_t i;
  66   uint32 pk[8 + 132];
  67
  68   KSZ_ASSERT(serpent, sz);
  69
  70   /* --- Read the key into the buffer --- */
  71
  72   if (sz > 32)
  73     sz = 32;
  74   i = 0; p = buf; q = p + sz;
  75   a = 0; b = 0;
  76   while (p < q) {
  77     a |= (uint32)*p++ << b;
  78     b += 8;
  79     if (b == 32) {
  80       pk[i++] = a;
  81       a = 0; b = 0;
  82     }
  83   }
  84
  85   /* --- Pad short keys --- */
  86
  87   if (i < 8) {
  88     a |= 0x01 << b;
  89     b += 8;
  90     pk[i++] = a;
  91     for (; i < 8; i++)
  92       pk[i] = 0;
  93   }
  94
  95   /* --- Expand the prekeys to fill the buffer --- */
  96
  97   for (i = 8; i < 8 + 132; i++) {
  98     uint32 x = (pk[i - 8] ^ pk[i - 5] ^ pk[i - 3] ^ pk[i - 1] ^
  99                 (i - 8) ^ 0x9e3779b9);
 100     k->k[i - 8] = pk[i] = ROL32(x, 11);
 101   }
 102
 103   /* --- Now substitute everything --- */
 104
 105   i = 0;
 106   goto midway;
 107   while (i < 132) {
 108 #define KSUB(r) do {                                                    \
 109     uint32 a, b, c, d;                                                  \
 110     a = k->k[i]; b = k->k[i + 1]; c = k->k[i + 2]; d = k->k[i + 3];     \
 111     S##r(a, b, c, d);                                                   \
 112     k->k[i] = a; k->k[i + 1] = b; k->k[i + 2] = c; k->k[i + 3] = d;     \
 113     i += 4;                                                             \
 114 } while (0)
 115     KSUB(2); KSUB(1); KSUB(0); KSUB(7);
 116     KSUB(6); KSUB(5); KSUB(4);
 117   midway:
 118     KSUB(3);
 119 #undef KSUB
 120   }
 121 }
 122
 123 /* --- @serpent_eblk@, @serpent_dblk@ --- *
 124  *
 125  * Arguments:   @const serpent_ctx *k@ = pointer to key context
 126  *              @const uint32 s[4]@ = pointer to source block
 127  *              @uint32 d[4]@ = pointer to destination block
 128  *
 129  * Returns:     ---
 130  *
 131  * Use:         Low-level block encryption.
 132  */
 133
 134 #define EROUND(a, b, c, d, r, k) do {                                   \
 135   a ^= *k++; b ^= *k++; c ^= *k++; d ^= *k++;                           \
 136   S##r(a, b, c, d);                                                     \
 137   a = ROL32(a, 13); c = ROL32(c,  3); b ^= a ^ c; d ^= c ^ (a << 3);    \
 138   b = ROL32(b,  1); d = ROL32(d,  7); a ^= b ^ d; c ^= d ^ (b << 7);    \
 139   a = ROL32(a,  5); c = ROL32(c, 22);                                   \
 140 } while (0)
 141
 142 #define DROUND(a, b, c, d, r, k) do {                                   \
 143   IS##r(a, b, c, d);                                                    \
 144   d ^= *--k; c ^= *--k; b ^= *--k; a ^= *--k;                           \
 145   a = ROR32(a,  5); c = ROR32(c, 22); a ^= b ^ d; c ^= d ^ (b << 7);    \
 146   b = ROR32(b,  1); d = ROR32(d,  7); b ^= a ^ c; d ^= c ^ (a << 3);    \
 147   a = ROR32(a, 13); c = ROR32(c,  3);                                   \
 148 } while (0)
 149
 150 void serpent_eblk(const serpent_ctx *k, const uint32 *s, uint32 *d)
 151 {
 152   uint32 aa = s[0], bb = s[1], cc = s[2], dd = s[3];
 153   const uint32 *kk = k->k;
 154
 155   EROUND(aa, bb, cc, dd, 0, kk); EROUND(aa, bb, cc, dd, 1, kk);
 156   EROUND(aa, bb, cc, dd, 2, kk); EROUND(aa, bb, cc, dd, 3, kk);
 157   EROUND(aa, bb, cc, dd, 4, kk); EROUND(aa, bb, cc, dd, 5, kk);
 158   EROUND(aa, bb, cc, dd, 6, kk); EROUND(aa, bb, cc, dd, 7, kk);
 159
 160   EROUND(aa, bb, cc, dd, 0, kk); EROUND(aa, bb, cc, dd, 1, kk);
 161   EROUND(aa, bb, cc, dd, 2, kk); EROUND(aa, bb, cc, dd, 3, kk);
 162   EROUND(aa, bb, cc, dd, 4, kk); EROUND(aa, bb, cc, dd, 5, kk);
 163   EROUND(aa, bb, cc, dd, 6, kk); EROUND(aa, bb, cc, dd, 7, kk);
 164
 165   EROUND(aa, bb, cc, dd, 0, kk); EROUND(aa, bb, cc, dd, 1, kk);
 166   EROUND(aa, bb, cc, dd, 2, kk); EROUND(aa, bb, cc, dd, 3, kk);
 167   EROUND(aa, bb, cc, dd, 4, kk); EROUND(aa, bb, cc, dd, 5, kk);
 168   EROUND(aa, bb, cc, dd, 6, kk); EROUND(aa, bb, cc, dd, 7, kk);
 169
 170   EROUND(aa, bb, cc, dd, 0, kk); EROUND(aa, bb, cc, dd, 1, kk);
 171   EROUND(aa, bb, cc, dd, 2, kk); EROUND(aa, bb, cc, dd, 3, kk);
 172   EROUND(aa, bb, cc, dd, 4, kk); EROUND(aa, bb, cc, dd, 5, kk);
 173   EROUND(aa, bb, cc, dd, 6, kk);
 174
 175   aa ^= *kk++; bb ^= *kk++; cc ^= *kk++; dd ^= *kk++;
 176   S7(aa, bb, cc, dd);
 177   aa ^= *kk++; bb ^= *kk++; cc ^= *kk++; dd ^= *kk++;
 178   d[0] = aa; d[1] = bb; d[2] = cc; d[3] = dd;
 179 }
 180
 181 void serpent_dblk(const serpent_ctx *k, const uint32 *s, uint32 *d)
 182 {
 183   uint32 aa = s[0], bb = s[1], cc = s[2], dd = s[3];
 184   const uint32 *kk = k->k + 132;
 185
 186   dd ^= *--kk; cc ^= *--kk; bb ^= *--kk; aa ^= *--kk;
 187
 188   DROUND(aa, bb, cc, dd, 7, kk); DROUND(aa, bb, cc, dd, 6, kk);
 189   DROUND(aa, bb, cc, dd, 5, kk); DROUND(aa, bb, cc, dd, 4, kk);
 190   DROUND(aa, bb, cc, dd, 3, kk); DROUND(aa, bb, cc, dd, 2, kk);
 191   DROUND(aa, bb, cc, dd, 1, kk); DROUND(aa, bb, cc, dd, 0, kk);
 192
 193   DROUND(aa, bb, cc, dd, 7, kk); DROUND(aa, bb, cc, dd, 6, kk);
 194   DROUND(aa, bb, cc, dd, 5, kk); DROUND(aa, bb, cc, dd, 4, kk);
 195   DROUND(aa, bb, cc, dd, 3, kk); DROUND(aa, bb, cc, dd, 2, kk);
 196   DROUND(aa, bb, cc, dd, 1, kk); DROUND(aa, bb, cc, dd, 0, kk);
 197
 198   DROUND(aa, bb, cc, dd, 7, kk); DROUND(aa, bb, cc, dd, 6, kk);
 199   DROUND(aa, bb, cc, dd, 5, kk); DROUND(aa, bb, cc, dd, 4, kk);
 200   DROUND(aa, bb, cc, dd, 3, kk); DROUND(aa, bb, cc, dd, 2, kk);
 201   DROUND(aa, bb, cc, dd, 1, kk); DROUND(aa, bb, cc, dd, 0, kk);
 202
 203   DROUND(aa, bb, cc, dd, 7, kk); DROUND(aa, bb, cc, dd, 6, kk);
 204   DROUND(aa, bb, cc, dd, 5, kk); DROUND(aa, bb, cc, dd, 4, kk);
 205   DROUND(aa, bb, cc, dd, 3, kk); DROUND(aa, bb, cc, dd, 2, kk);
 206   DROUND(aa, bb, cc, dd, 1, kk);
 207
 208   IS0(aa, bb, cc, dd);
 209   dd ^= *--kk; cc ^= *--kk; bb ^= *--kk; aa ^= *--kk;
 210   d[0] = aa; d[1] = bb; d[2] = cc; d[3] = dd;
 211 }
 212
 213 BLKC_TEST(SERPENT, serpent)
 214
 215 /*----- That's all, folks -------------------------------------------------*/