git.distorted.org.uk Git - u/mdw/catacomb/blob - symm/cast128.c

   1 /* -*-c-*-
   2  *
   3  * The CAST-128 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 #include <stdlib.h>
  33 #include <string.h>
  34
  35 #include <mLib/bits.h>
  36
  37 #include "blkc.h"
  38 #include "cast-base.h"
  39 #include "cast128.h"
  40 #include "gcipher.h"
  41 #include "paranoia.h"
  42
  43 /*----- Global variables --------------------------------------------------*/
  44
  45 const octet cast128_keysz[] = { KSZ_RANGE, CAST128_KEYSZ, 0, 16, 1 };
  46
  47 /*----- Main code ---------------------------------------------------------*/
  48
  49 /* --- @cast128_init@ --- *
  50  *
  51  * Arguments:   @cast128_ctx *k@ = pointer to key block to fill in
  52  *              @const void *buf@ = pointer to buffer of key material
  53  *              @size_t sz@ = size of key material
  54  *
  55  * Returns:     ---
  56  *
  57  * Use:         Initializes a CAST-128 key buffer.  CAST-128 accepts
  58  *              128-bit keys or shorter.
  59  */
  60
  61 void cast128_init(cast128_ctx *k, const void *buf, size_t sz)
  62 {
  63   const octet *p = buf;
  64   uint32 kk[4];
  65   unsigned i;
  66   uint32 a, b, c, d,  aa, bb, cc, dd;
  67
  68   /* --- Fiddle with the key size a bit --- */
  69
  70   KSZ_ASSERT(cast128, sz);
  71
  72   if (sz > 10)
  73     k->r = 16;
  74   else
  75     k->r = 12;
  76
  77   /* --- Read the key into the array --- */
  78
  79   i = 0;
  80   b = 32; aa = 0;
  81   for (;;) {
  82     if (!sz)
  83       break;
  84     b -= 8;
  85     aa |= ((uint32)*p++ << b);
  86     sz--;
  87     if (b == 0) {
  88       kk[i++] = aa;
  89       if (i == 4)
  90         break;
  91       aa = 0;
  92       b = 32;
  93     }
  94   }
  95
  96   for (; i < 4; i++) {
  97     kk[i] = aa;
  98     aa = 0;
  99   }
 100
 101   /* --- Read the key words out --- */
 102
 103   a = kk[0]; b = kk[1]; c = kk[2]; d = kk[3];
 104
 105 #define X_0123 a
 106 #define X_4567 b
 107 #define X_89ab c
 108 #define X_cdef d
 109
 110 #define X_0 U8(X_0123 >> 24)
 111 #define X_1 U8(X_0123 >> 16)
 112 #define X_2 U8(X_0123 >>  8)
 113 #define X_3 U8(X_0123 >>  0)
 114 #define X_4 U8(X_4567 >> 24)
 115 #define X_5 U8(X_4567 >> 16)
 116 #define X_6 U8(X_4567 >>  8)
 117 #define X_7 U8(X_4567 >>  0)
 118 #define X_8 U8(X_89ab >> 24)
 119 #define X_9 U8(X_89ab >> 16)
 120 #define X_a U8(X_89ab >>  8)
 121 #define X_b U8(X_89ab >>  0)
 122 #define X_c U8(X_cdef >> 24)
 123 #define X_d U8(X_cdef >> 16)
 124 #define X_e U8(X_cdef >>  8)
 125 #define X_f U8(X_cdef >>  0)
 126
 127 #define Z_0123 aa
 128 #define Z_4567 bb
 129 #define Z_89ab cc
 130 #define Z_cdef dd
 131
 132 #define Z_0 U8(Z_0123 >> 24)
 133 #define Z_1 U8(Z_0123 >> 16)
 134 #define Z_2 U8(Z_0123 >>  8)
 135 #define Z_3 U8(Z_0123 >>  0)
 136 #define Z_4 U8(Z_4567 >> 24)
 137 #define Z_5 U8(Z_4567 >> 16)
 138 #define Z_6 U8(Z_4567 >>  8)
 139 #define Z_7 U8(Z_4567 >>  0)
 140 #define Z_8 U8(Z_89ab >> 24)
 141 #define Z_9 U8(Z_89ab >> 16)
 142 #define Z_a U8(Z_89ab >>  8)
 143 #define Z_b U8(Z_89ab >>  0)
 144 #define Z_c U8(Z_cdef >> 24)
 145 #define Z_d U8(Z_cdef >> 16)
 146 #define Z_e U8(Z_cdef >>  8)
 147 #define Z_f U8(Z_cdef >>  0)
 148
 149 #define SK(w, x, y, z)                                                  \
 150   cast_sk[0][w] ^ cast_sk[1][x] ^ cast_sk[2][y] ^ cast_sk[3][z]
 151
 152   i = 0;
 153   Z_0123 = X_0123 ^ SK(X_d, X_f, X_c, X_e) ^ cast_sk[2][X_8];
 154   Z_4567 = X_89ab ^ SK(Z_0, Z_2, Z_1, Z_3) ^ cast_sk[3][X_a];
 155   Z_89ab = X_cdef ^ SK(Z_7, Z_6, Z_5, Z_4) ^ cast_sk[0][X_9];
 156   Z_cdef = X_4567 ^ SK(Z_a, Z_9, Z_b, Z_8) ^ cast_sk[1][X_b];
 157   k->km[i++] = SK(Z_8, Z_9, Z_7, Z_6) ^ cast_sk[0][Z_2];
 158   k->km[i++] = SK(Z_a, Z_b, Z_5, Z_4) ^ cast_sk[1][Z_6];
 159   k->km[i++] = SK(Z_c, Z_d, Z_3, Z_2) ^ cast_sk[2][Z_9];
 160   k->km[i++] = SK(Z_e, Z_f, Z_1, Z_0) ^ cast_sk[3][Z_c];
 161   X_0123 = Z_89ab ^ SK(Z_5, Z_7, Z_4, Z_6) ^ cast_sk[2][Z_0];
 162   X_4567 = Z_0123 ^ SK(X_0, X_2, X_1, X_3) ^ cast_sk[3][Z_2];
 163   X_89ab = Z_4567 ^ SK(X_7, X_6, X_5, X_4) ^ cast_sk[0][Z_1];
 164   X_cdef = Z_cdef ^ SK(X_a, X_9, X_b, X_8) ^ cast_sk[1][Z_3];
 165   k->km[i++] = SK(X_3, X_2, X_c, X_d) ^ cast_sk[0][X_8];
 166   k->km[i++] = SK(X_1, X_0, X_e, X_f) ^ cast_sk[1][X_d];
 167   k->km[i++] = SK(X_7, X_6, X_8, X_9) ^ cast_sk[2][X_3];
 168   k->km[i++] = SK(X_5, X_4, X_a, X_b) ^ cast_sk[3][X_7];
 169   Z_0123 = X_0123 ^ SK(X_d, X_f, X_c, X_e) ^ cast_sk[2][X_8];
 170   Z_4567 = X_89ab ^ SK(Z_0, Z_2, Z_1, Z_3) ^ cast_sk[3][X_a];
 171   Z_89ab = X_cdef ^ SK(Z_7, Z_6, Z_5, Z_4) ^ cast_sk[0][X_9];
 172   Z_cdef = X_4567 ^ SK(Z_a, Z_9, Z_b, Z_8) ^ cast_sk[1][X_b];
 173   k->km[i++] = SK(Z_3, Z_2, Z_c, Z_d) ^ cast_sk[0][Z_9];
 174   k->km[i++] = SK(Z_1, Z_0, Z_e, Z_f) ^ cast_sk[1][Z_c];
 175   k->km[i++] = SK(Z_7, Z_6, Z_8, Z_9) ^ cast_sk[2][Z_2];
 176   k->km[i++] = SK(Z_5, Z_4, Z_a, Z_b) ^ cast_sk[3][Z_6];
 177   X_0123 = Z_89ab ^ SK(Z_5, Z_7, Z_4, Z_6) ^ cast_sk[2][Z_0];
 178   X_4567 = Z_0123 ^ SK(X_0, X_2, X_1, X_3) ^ cast_sk[3][Z_2];
 179   X_89ab = Z_4567 ^ SK(X_7, X_6, X_5, X_4) ^ cast_sk[0][Z_1];
 180   X_cdef = Z_cdef ^ SK(X_a, X_9, X_b, X_8) ^ cast_sk[1][Z_3];
 181   k->km[i++] = SK(X_8, X_9, X_7, X_6) ^ cast_sk[0][X_3];
 182   k->km[i++] = SK(X_a, X_b, X_5, X_4) ^ cast_sk[1][X_7];
 183   k->km[i++] = SK(X_c, X_d, X_3, X_2) ^ cast_sk[2][X_8];
 184   k->km[i++] = SK(X_e, X_f, X_1, X_0) ^ cast_sk[3][X_d];
 185
 186   i = 0;
 187   Z_0123 = X_0123 ^ SK(X_d, X_f, X_c, X_e) ^ cast_sk[2][X_8];
 188   Z_4567 = X_89ab ^ SK(Z_0, Z_2, Z_1, Z_3) ^ cast_sk[3][X_a];
 189   Z_89ab = X_cdef ^ SK(Z_7, Z_6, Z_5, Z_4) ^ cast_sk[0][X_9];
 190   Z_cdef = X_4567 ^ SK(Z_a, Z_9, Z_b, Z_8) ^ cast_sk[1][X_b];
 191   k->kr[i++] = (SK(Z_8, Z_9, Z_7, Z_6) ^ cast_sk[0][Z_2]) & 0x1f;
 192   k->kr[i++] = (SK(Z_a, Z_b, Z_5, Z_4) ^ cast_sk[1][Z_6]) & 0x1f;
 193   k->kr[i++] = (SK(Z_c, Z_d, Z_3, Z_2) ^ cast_sk[2][Z_9]) & 0x1f;
 194   k->kr[i++] = (SK(Z_e, Z_f, Z_1, Z_0) ^ cast_sk[3][Z_c]) & 0x1f;
 195   X_0123 = Z_89ab ^ SK(Z_5, Z_7, Z_4, Z_6) ^ cast_sk[2][Z_0];
 196   X_4567 = Z_0123 ^ SK(X_0, X_2, X_1, X_3) ^ cast_sk[3][Z_2];
 197   X_89ab = Z_4567 ^ SK(X_7, X_6, X_5, X_4) ^ cast_sk[0][Z_1];
 198   X_cdef = Z_cdef ^ SK(X_a, X_9, X_b, X_8) ^ cast_sk[1][Z_3];
 199   k->kr[i++] = (SK(X_3, X_2, X_c, X_d) ^ cast_sk[0][X_8]) & 0x1f;
 200   k->kr[i++] = (SK(X_1, X_0, X_e, X_f) ^ cast_sk[1][X_d]) & 0x1f;
 201   k->kr[i++] = (SK(X_7, X_6, X_8, X_9) ^ cast_sk[2][X_3]) & 0x1f;
 202   k->kr[i++] = (SK(X_5, X_4, X_a, X_b) ^ cast_sk[3][X_7]) & 0x1f;
 203   Z_0123 = X_0123 ^ SK(X_d, X_f, X_c, X_e) ^ cast_sk[2][X_8];
 204   Z_4567 = X_89ab ^ SK(Z_0, Z_2, Z_1, Z_3) ^ cast_sk[3][X_a];
 205   Z_89ab = X_cdef ^ SK(Z_7, Z_6, Z_5, Z_4) ^ cast_sk[0][X_9];
 206   Z_cdef = X_4567 ^ SK(Z_a, Z_9, Z_b, Z_8) ^ cast_sk[1][X_b];
 207   k->kr[i++] = (SK(Z_3, Z_2, Z_c, Z_d) ^ cast_sk[0][Z_9]) & 0x1f;
 208   k->kr[i++] = (SK(Z_1, Z_0, Z_e, Z_f) ^ cast_sk[1][Z_c]) & 0x1f;
 209   k->kr[i++] = (SK(Z_7, Z_6, Z_8, Z_9) ^ cast_sk[2][Z_2]) & 0x1f;
 210   k->kr[i++] = (SK(Z_5, Z_4, Z_a, Z_b) ^ cast_sk[3][Z_6]) & 0x1f;
 211   X_0123 = Z_89ab ^ SK(Z_5, Z_7, Z_4, Z_6) ^ cast_sk[2][Z_0];
 212   X_4567 = Z_0123 ^ SK(X_0, X_2, X_1, X_3) ^ cast_sk[3][Z_2];
 213   X_89ab = Z_4567 ^ SK(X_7, X_6, X_5, X_4) ^ cast_sk[0][Z_1];
 214   X_cdef = Z_cdef ^ SK(X_a, X_9, X_b, X_8) ^ cast_sk[1][Z_3];
 215   k->kr[i++] = (SK(X_8, X_9, X_7, X_6) ^ cast_sk[0][X_3]) & 0x1f;
 216   k->kr[i++] = (SK(X_a, X_b, X_5, X_4) ^ cast_sk[1][X_7]) & 0x1f;
 217   k->kr[i++] = (SK(X_c, X_d, X_3, X_2) ^ cast_sk[2][X_8]) & 0x1f;
 218   k->kr[i++] = (SK(X_e, X_f, X_1, X_0) ^ cast_sk[3][X_d]) & 0x1f;
 219
 220   BURN(kk);
 221 }
 222
 223 /* --- @cast128_eblk@, @cast128_dblk@ --- *
 224  *
 225  * Arguments:   @const cast128_ctx *k@ = pointer to key block
 226  *              @const uint32 s[2]@ = pointer to source block
 227  *              @uint32 d[2]@ = pointer to destination block
 228  *
 229  * Returns:     ---
 230  *
 231  * Use:         Low-level block encryption and decryption.
 232  */
 233
 234 void cast128_eblk(const cast128_ctx *k, const uint32 *s, uint32 *d)
 235 {
 236   uint32 a = s[0], b = s[1];
 237   const uint32 *km = k->km;
 238   const octet *kr = k->kr;
 239
 240   switch (k->r) {
 241     default:
 242       CAST_R1(*km++, *kr++, a, b);
 243       CAST_R2(*km++, *kr++, b, a);
 244       CAST_R3(*km++, *kr++, a, b);
 245       CAST_R1(*km++, *kr++, b, a);
 246       CAST_R2(*km++, *kr++, a, b);
 247       CAST_R3(*km++, *kr++, b, a);
 248       CAST_R1(*km++, *kr++, a, b);
 249       CAST_R2(*km++, *kr++, b, a);
 250       CAST_R3(*km++, *kr++, a, b);
 251       CAST_R1(*km++, *kr++, b, a);
 252       CAST_R2(*km++, *kr++, a, b);
 253       CAST_R3(*km++, *kr++, b, a);
 254       if (k->r == 12)
 255         break;
 256       CAST_R1(*km++, *kr++, a, b);
 257       CAST_R2(*km++, *kr++, b, a);
 258       CAST_R3(*km++, *kr++, a, b);
 259       CAST_R1(*km++, *kr++, b, a);
 260       break;
 261   }
 262
 263   d[0] = b; d[1] = a;
 264 }
 265
 266 void cast128_dblk(const cast128_ctx *k, const uint32 *s, uint32 *d)
 267 {
 268   uint32 a = s[0], b = s[1];
 269   const uint32 *km = k->km + k->r;
 270   const octet *kr = k->kr + k->r;
 271
 272   switch (k->r) {
 273     case 16:
 274     default:
 275       CAST_R1(*--km, *--kr, a, b);
 276       CAST_R3(*--km, *--kr, b, a);
 277       CAST_R2(*--km, *--kr, a, b);
 278       CAST_R1(*--km, *--kr, b, a);
 279     case 12:
 280       CAST_R3(*--km, *--kr, a, b);
 281       CAST_R2(*--km, *--kr, b, a);
 282       CAST_R1(*--km, *--kr, a, b);
 283       CAST_R3(*--km, *--kr, b, a);
 284       CAST_R2(*--km, *--kr, a, b);
 285       CAST_R1(*--km, *--kr, b, a);
 286       CAST_R3(*--km, *--kr, a, b);
 287       CAST_R2(*--km, *--kr, b, a);
 288       CAST_R1(*--km, *--kr, a, b);
 289       CAST_R3(*--km, *--kr, b, a);
 290       CAST_R2(*--km, *--kr, a, b);
 291       CAST_R1(*--km, *--kr, b, a);
 292       break;
 293   }
 294
 295   d[0] = b; d[1] = a;
 296 }
 297
 298 BLKC_TEST(CAST128, cast128)
 299
 300 /*----- That's all, folks -------------------------------------------------*/