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

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