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

   1 /* -*-c-*-
   2  *
   3  * $Id: safer.c,v 1.2 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * The SAFER block cipher
   6  *
   7  * (c) 2001 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 "paranoia.h"
  40 #include "safer.h"
  41 #include "safer-tab.h"
  42
  43 /*----- Global variables --------------------------------------------------*/
  44
  45 const octet safer_keysz[] = { KSZ_SET, 8, 16, 0 };
  46
  47 /*----- Important tables --------------------------------------------------*/
  48
  49 static const octet s[265] = SAFER_S, si[256] = SAFER_SI;
  50
  51 /*----- Main code ---------------------------------------------------------*/
  52
  53 /* --- @safer_setup@ --- *
  54  *
  55  * Arguments:   @safer_ctx *k@ = pointer to context to initialize
  56  *              @unsigned r@ = number of rounds wanted
  57  *              @unsigned f@ = various other flags
  58  *              @const void *buf@ = pointer to key material
  59  *              @size_t sz@ = size of key material in bytes
  60  *
  61  * Returns:     ---
  62  *
  63  * Use:         Initializes an SAFER expanded key.  A default number of
  64  *              rounds is chosen, based on the key length.
  65  */
  66
  67 struct ksched {
  68   unsigned i;
  69   octet x[9];
  70 };
  71
  72 static void init(struct ksched *t, const octet *k)
  73 {
  74   memcpy(t->x, k, 8);
  75   t->i = 1;
  76 }
  77
  78 static void init_sk(struct ksched *t, const octet *k)
  79 {
  80   unsigned i;
  81   octet x;
  82   memcpy(t->x, k, 8);
  83   for (x = 0, i = 0; i < 8; x ^= k[i++])
  84     ;
  85   t->x[8] = x;
  86   t->i = 1;
  87 }
  88
  89 static void next(struct ksched *t, octet *k)
  90 {
  91   unsigned i;
  92   if (k) {
  93     memcpy(k, t->x, 8);
  94     if (t->i > 1) {
  95       for (i = 0; i < 8; i++)
  96         k[i] += s[s[U8(9*t->i + i + 1)]];
  97     }
  98   }
  99   for (i = 0; i < 8; i++)
 100     t->x[i] = ROL8(t->x[i], 3);
 101   t->i++;
 102 }
 103
 104 static void next_sk(struct ksched *t, octet *k)
 105 {
 106   unsigned i;
 107   i = (t->i - 1)%9;
 108   if (k) {
 109     if (i < 2)
 110       memcpy(k, t->x + i, 8);
 111     else {
 112       memcpy(k, t->x + i, 9 - i);
 113       memcpy(k + 9 - i, t->x, i - 1);
 114     }
 115     if (t->i > 1) {
 116       for (i = 0; i < 8; i++)
 117         k[i] += s[s[U8(9*t->i + i + 1)]];
 118     }
 119   }
 120   for (i = 0; i < 9; i++)
 121     t->x[i] = ROL8(t->x[i], 3);
 122   t->i++;
 123 }
 124
 125 void safer_setup(safer_ctx *k, unsigned r, unsigned f,
 126                  const void *buf, size_t sz)
 127 {
 128   struct ksched ka, kb;
 129   void (*in)(struct ksched *, const octet *);
 130   void (*nx)(struct ksched *, octet *);
 131   octet *kk;
 132
 133   assert(r <= SAFER_MAXROUNDS);
 134   KSZ_ASSERT(safer, sz);
 135
 136   if (f & SAFER_SK) {
 137     in = init_sk;
 138     nx = next_sk;
 139   } else {
 140     in = init;
 141     nx = next;
 142   }
 143
 144   in(&kb, buf);
 145   in(&ka, sz == 8 ? buf : (const octet *)buf + 8);
 146
 147   k->r = r;
 148   kk = k->k;
 149   while (r) {
 150     nx(&ka, kk); nx(&kb, 0); kk += 8;
 151     nx(&kb, kk); nx(&ka, 0); kk += 8;
 152     r--;
 153   }
 154   nx(&ka, kk); kk += 8;
 155 }
 156
 157 /* --- @safer_init@, @safersk_init@ --- *
 158  *
 159  * Arguments:   @safer_ctx *k@ = pointer to context to initialize
 160  *              @const void *buf@ = pointer to key material
 161  *              @size_t sz@ = size of key material in bytes
 162  *
 163  * Returns:     ---
 164  *
 165  * Use:         Initializes an SAFER expanded key.  A default number of
 166  *              rounds is chosen, based on the key length.
 167  */
 168
 169 void safer_init(safer_ctx *k, const void *buf, size_t sz)
 170 {
 171   safer_setup(k, sz == 8 ? 6 : 10, 0, buf, sz);
 172 }
 173
 174 void safersk_init(safer_ctx *k, const void *buf, size_t sz)
 175 {
 176   safer_setup(k, sz == 8 ? 8 : 10, SAFER_SK, buf, sz);
 177 }
 178
 179 /* --- @safer_eblk@, @safer_dblk@ --- *
 180  *
 181  * Arguments:   @const safer_ctx *k@ = pointer to SAFER context
 182  *              @const uint32 s[2]@ = pointer to source block
 183  *              @const uint32 d[2]@ = pointer to destination block
 184  *
 185  * Returns:     ---
 186  *
 187  * Use:         Low-level block encryption and decryption.
 188  */
 189
 190 #define UNPACK(src, a, b, c, d, e, f, g, h) do {                        \
 191   a = U8(src[0] >> 24); b = U8(src[0] >> 16);                           \
 192   c = U8(src[0] >>  8); d = U8(src[0] >>  0);                           \
 193   e = U8(src[1] >> 24); f = U8(src[1] >> 16);                           \
 194   g = U8(src[1] >>  8); h = U8(src[1] >>  0);                           \
 195 } while (0)
 196
 197 #define PACK(dst, a, b, c, d, e, f, g, h) do {                          \
 198   dst[0] = (U8(a) << 24) | (U8(b) << 16) | (U8(c) << 8) | U8(d);        \
 199   dst[1] = (U8(e) << 24) | (U8(f) << 16) | (U8(g) << 8) | U8(h);        \
 200 } while (0)
 201
 202 #define F(x, y) y += x, x += y
 203 #define G(x, y) x -= y, y -= x
 204
 205 #define PHT(a, b, c, d, e, f, g, h) do {                                \
 206   F(a, b); F(c, d); F(e, f); F(g, h);                                   \
 207   F(a, c); F(e, g); F(b, d); F(f, h);                                   \
 208   F(a, e); F(b, f); F(c, g); F(d, h);                                   \
 209 } while (0)
 210  #define IPHT(a, b, c, d, e, f, g, h) do {                              \
 211   G(a, e); G(b, f); G(c, g); G(d, h);                                   \
 212   G(a, c); G(e, g); G(b, d); G(f, h);                                   \
 213   G(a, b); G(c, d); G(e, f); G(g, h);                                   \
 214 } while (0)
 215
 216 #define KXA(k, a, b, c, d, e, f, g, h) do {                             \
 217   a ^= *k++; b += *k++; c += *k++; d ^= *k++;                           \
 218   e ^= *k++; f += *k++; g += *k++; h ^= *k++;                           \
 219 } while (0)
 220 #define SUB(a, b, c, d, e, f, g, h) do {                                \
 221   a = s[U8(a)]; b = si[U8(b)]; c = si[U8(c)]; d = s[U8(d)];             \
 222   e = s[U8(e)]; f = si[U8(f)]; g = si[U8(g)]; h = s[U8(h)];             \
 223 } while (0)
 224 #define KAX(k, a, b, c, d, e, f, g, h) do {                             \
 225   a += *k++; b ^= *k++; c ^= *k++; d += *k++;                           \
 226   e += *k++; f ^= *k++; g ^= *k++; h += *k++;                           \
 227 } while (0)
 228
 229 #define KXS(k, a, b, c, d, e, f, g, h) do {                             \
 230   h ^= *--k; g -= *--k; f -= *--k; e ^= *--k;                           \
 231   d ^= *--k; c -= *--k; b -= *--k; a ^= *--k;                           \
 232 } while (0)
 233 #define ISUB(a, b, c, d, e, f, g, h) do {                               \
 234   a = si[U8(a)]; b = s[U8(b)]; c = s[U8(c)]; d = si[U8(d)];             \
 235   e = si[U8(e)]; f = s[U8(f)]; g = s[U8(g)]; h = si[U8(h)];             \
 236 } while (0)
 237 #define KSX(k, a, b, c, d, e, f, g, h) do {                             \
 238   h -= *--k; g ^= *--k; f ^= *--k; e -= *--k;                           \
 239   d -= *--k; c ^= *--k; b ^= *--k; a -= *--k;                           \
 240 } while (0)
 241
 242 #define EROUND(k, a, b, c, d, e, f, g, h) do {                          \
 243   KXA(k, a, b, c, d, e, f, g, h);                                       \
 244   SUB(a, b, c, d, e, f, g, h);                                          \
 245   KAX(k, a, b, c, d, e, f, g, h);                                       \
 246   PHT(a, b, c, d, e, f, g, h);                                          \
 247 } while (0)
 248
 249 #define DROUND(k, a, b, c, d, e, f, g, h) do {                          \
 250   IPHT(a, b, c, d, e, f, g, h);                                         \
 251   KSX(k, a, b, c, d, e, f, g, h);                                       \
 252   ISUB(a, b, c, d, e, f, g, h);                                         \
 253   KXS(k, a, b, c, d, e, f, g, h);                                       \
 254 } while (0)
 255
 256
 257 void safer_eblk(const safer_ctx *k, const uint32 *src, uint32 *dst)
 258 {
 259   octet a, b, c, d, e, f, g, h;
 260   unsigned r = k->r;
 261   const octet *kk = k->k;
 262
 263   UNPACK(src, a, b, c, d, e, f, g, h);
 264   while (r >= 3) {
 265     EROUND(kk, a, b, c, d, e, f, g, h);
 266     EROUND(kk, a, e, b, f, c, g, d, h);
 267     EROUND(kk, a, c, e, g, b, d, f, h);
 268     r -= 3;
 269   }
 270   switch (r) {
 271     case 0:
 272       KXA(kk, a, b, c, d, e, f, g, h);
 273       PACK(dst, a, b, c, d, e, f, g ,h);
 274       break;
 275     case 1:
 276       EROUND(kk, a, b, c, d, e, f, g, h);
 277       KXA(kk, a, e, b, f, c, g, d, h);
 278       PACK(dst, a, e, b, f, c, g, d, h);
 279       break;
 280     case 2:
 281       EROUND(kk, a, b, c, d, e, f, g, h);
 282       EROUND(kk, a, e, b, f, c, g, d, h);
 283       KXA(kk, a, c, e, g, b, d, f, h);
 284       PACK(dst, a, c, e, g, b, d, f, h);
 285       break;
 286   }
 287 }
 288
 289 void safer_dblk(const safer_ctx *k, const uint32 *src, uint32 *dst)
 290 {
 291   octet a, b, c, d, e, f, g, h;
 292   unsigned r = k->r;
 293   const octet *kk = k->k + 16 * r + 8;
 294   switch (r%3) {
 295     default:
 296     case 0:
 297       UNPACK(src, a, b, c, d, e, f, g, h);
 298       KXS(kk, a, b, c, d, e, f, g, h);
 299       break;
 300     case 1:
 301       UNPACK(src, a, e, b, f, c, g, d, h);
 302       KXS(kk, a, e, b, f, c, g, d, h);
 303       r--;
 304       goto one_round;
 305     case 2:
 306       UNPACK(src, a, c, e, g, b, d, f, h);
 307       KXS(kk, a, c, e, g, b, d, f, h);
 308       r -= 2;
 309       DROUND(kk, a, e, b, f, c, g, d, h);
 310     one_round:
 311       DROUND(kk, a, b, c, d, e, f, g, h);
 312       break;
 313   }
 314   while (r) {
 315     DROUND(kk, a, c, e, g, b, d, f, h);
 316     DROUND(kk, a, e, b, f, c, g, d, h);
 317     DROUND(kk, a, b, c, d, e, f, g, h);
 318     r -= 3;
 319   }
 320   PACK(dst, a, b, c, d, e, f, g, h);
 321 }
 322
 323 BLKC_TEST(SAFER, safer)
 324
 325 /*----- That's all, folks -------------------------------------------------*/