git.distorted.org.uk Git - u/mdw/catacomb/blob - cast256.c

   1 /* -*-c-*-
   2  *
   3  * $Id: cast256.c,v 1.2 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * The CAST-256 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 #include <stdlib.h>
  35 #include <string.h>
  36
  37 #include <mLib/bits.h>
  38
  39 #include "blkc.h"
  40 #include "cast-base.h"
  41 #include "cast256.h"
  42 #include "gcipher.h"
  43 #include "paranoia.h"
  44
  45 /*----- Global variables --------------------------------------------------*/
  46
  47 const octet cast256_keysz[] = { KSZ_RANGE, CAST256_KEYSZ, 0, 32, 1 };
  48
  49 /*----- Main code ---------------------------------------------------------*/
  50
  51 /* --- @cast256_init@ --- *
  52  *
  53  * Arguments:   @cast128_ctx *k@ = pointer to key block to fill in
  54  *              @const void *buf@ = pointer to buffer of key material
  55  *              @size_t sz@ = size of key material
  56  *
  57  * Returns:     ---
  58  *
  59  * Use:         Initializes a CAST-256 key buffer.  CAST-256 accepts
  60  *              256-bit keys or shorter.
  61  */
  62
  63 void cast256_init(cast256_ctx *k, const void *buf, size_t sz)
  64 {
  65   const octet *p = buf;
  66   uint32 kk[8];
  67   uint32 *km;
  68   octet *kr;
  69   unsigned i, j;
  70   uint32 a, b, c, d, e, f, g, h;
  71   uint32 m;
  72   unsigned r;
  73
  74   /* --- Fiddle with the key size --- */
  75
  76   KSZ_ASSERT(cast256, sz);
  77
  78   /* --- Read the key into the array --- */
  79
  80   i = 0;
  81   b = 32; a = 0;
  82   for (;;) {
  83     if (!sz)
  84       break;
  85     b -= 8;
  86     a |= ((uint32)*p++ << b);
  87     sz--;
  88     if (b == 0) {
  89       kk[i++] = a;
  90       if (i == 8)
  91         break;
  92       a = 0;
  93       b = 32;
  94     }
  95   }
  96
  97   for (; i < 8; i++) {
  98     kk[i] = a;
  99     a = 0;
 100   }
 101
 102   /* --- Read the key words out --- */
 103
 104   a = kk[0]; b = kk[1]; c = kk[2]; d = kk[3];
 105   e = kk[4]; f = kk[5]; g = kk[6]; h = kk[7];
 106
 107 #define ROOT2 0x5a827999
 108 #define ROOT3 0x6ed9eba1
 109
 110   m = ROOT2;
 111   r = 19;
 112
 113   km = k->km;
 114   kr = k->kr;
 115   for (i = 0; i < 12; i++) {
 116     for (j = 0; j < 2; j++) {
 117       CAST_R1(m, r, g, h); m += ROOT3; r = (r + 17) & 0x1f;
 118       CAST_R2(m, r, f, g); m += ROOT3; r = (r + 17) & 0x1f;
 119       CAST_R3(m, r, e, f); m += ROOT3; r = (r + 17) & 0x1f;
 120       CAST_R1(m, r, d, e); m += ROOT3; r = (r + 17) & 0x1f;
 121       CAST_R2(m, r, c, d); m += ROOT3; r = (r + 17) & 0x1f;
 122       CAST_R3(m, r, b, c); m += ROOT3; r = (r + 17) & 0x1f;
 123       CAST_R1(m, r, a, b); m += ROOT3; r = (r + 17) & 0x1f;
 124       CAST_R2(m, r, h, a); m += ROOT3; r = (r + 17) & 0x1f;
 125     }
 126     km[0] = h; km[1] = f; km[2] = d; km[3] = b;
 127     kr[0] = a & 0x1f; kr[1] = c & 0x1f; kr[2] = e & 0x1f; kr[3] = g & 0x1f;
 128     km += 4; kr += 4;
 129   }
 130 }
 131
 132 /* --- @cast256_eblk@, @cast256_dblk@ --- *
 133  *
 134  * Arguments:   @const cast256_ctx *k@ = pointer to key block
 135  *              @const uint32 s[2]@ = pointer to source block
 136  *              @uint32 d[2]@ = pointer to destination block
 137  *
 138  * Returns:     ---
 139  *
 140  * Use:         Low-level block encryption and decryption.
 141  */
 142
 143 #define Q0(k, r, a, b, c, d) do {                                       \
 144   CAST_R1(k[0], r[0], c, d);                                            \
 145   CAST_R2(k[1], r[1], b, c);                                            \
 146   CAST_R3(k[2], r[2], a, b);                                            \
 147   CAST_R1(k[3], r[3], d, a);                                            \
 148 } while (0)
 149
 150 #define Q1(k, r, a, b, c, d) do {                                       \
 151   CAST_R1(k[3], r[3], d, a);                                            \
 152   CAST_R3(k[2], r[2], a, b);                                            \
 153   CAST_R2(k[1], r[1], b, c);                                            \
 154   CAST_R1(k[0], r[0], c, d);                                            \
 155 } while (0)
 156
 157 void cast256_eblk(const cast256_ctx *k, const uint32 *s, uint32 *d)
 158 {
 159   uint32 aa = s[0], bb = s[1], cc = s[2], dd = s[3];
 160   const uint32 *km = k->km;
 161   const octet *kr = k->kr;
 162
 163   Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 164   Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 165   Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 166   Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 167   Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 168   Q0(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 169
 170   Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 171   Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 172   Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 173   Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 174   Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 175   Q1(km, kr, aa, bb, cc, dd); km += 4; kr += 4;
 176
 177   d[0] = aa; d[1] = bb; d[2] = cc; d[3] = dd;
 178 }
 179
 180 void cast256_dblk(const cast256_ctx *k, const uint32 *s, uint32 *d)
 181 {
 182   uint32 aa = s[0], bb = s[1], cc = s[2], dd = s[3];
 183   const uint32 *km = k->km + 48;
 184   const octet *kr = k->kr + 48;
 185
 186   km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
 187   km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
 188   km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
 189   km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
 190   km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
 191   km -= 4; kr -= 4; Q0(km, kr, aa, bb, cc, dd);
 192
 193   km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
 194   km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
 195   km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
 196   km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
 197   km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
 198   km -= 4; kr -= 4; Q1(km, kr, aa, bb, cc, dd);
 199
 200   d[0] = aa; d[1] = bb; d[2] = cc; d[3] = dd;
 201 }
 202
 203 BLKC_TEST(CAST256, cast256)
 204
 205 /*----- That's all, folks -------------------------------------------------*/