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

   1 /* -*-c-*-
   2  *
   3  * The Square 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 #include <mLib/macros.h>
  35
  36 #include "blkc.h"
  37 #include "gcipher.h"
  38 #include "paranoia.h"
  39 #include "square.h"
  40
  41 /*----- Global variables --------------------------------------------------*/
  42
  43 const octet square_keysz[] = { KSZ_RANGE, SQUARE_KEYSZ, 4, 16, 4 };
  44
  45 /*----- Constant tables ---------------------------------------------------*/
  46
  47 extern const octet square_s[256], square_si[256];
  48 extern const uint32 square_t[4][256], square_ti[4][256];
  49 extern const uint32 square_u[4][256];
  50 extern const octet square_rcon[32];
  51
  52 #define S square_s
  53 #define SI square_si
  54 #define T square_t
  55 #define TI square_ti
  56 #define U square_u
  57 #define RCON square_rcon
  58
  59 /*----- Main code ---------------------------------------------------------*/
  60
  61 /* --- @square_init@ --- *
  62  *
  63  * Arguments:   @square_ctx *k@ = pointer to context to initialize
  64  *              @const void *buf@ = pointer to buffer of key material
  65  *              @size_t sz@ = size of the key material
  66  *
  67  * Returns:     ---
  68  *
  69  * Use:         Initializes a Square context with a particular key.  Square
  70  *              keys must be a multiple of 32 bits long, and may be at most
  71  *              128 bits.
  72  */
  73
  74 void square_init(square_ctx *k, const void *buf, size_t sz)
  75 {
  76   unsigned nk, nr, nw;
  77   unsigned i, j, jj;
  78   const octet *p;
  79   uint32 ww;
  80   uint32 kk[SQUARE_KWORDS];
  81
  82   /* --- Sort out the key size --- */
  83
  84   KSZ_ASSERT(square, sz);
  85   nk = sz / 4;
  86
  87   /* --- Fetch the first key words out --- */
  88
  89   p = buf;
  90   for (i = 0; i < nk; i++) {
  91     kk[i] = LOAD32_L(p);
  92     p += 4;
  93   }
  94   nr = 8;
  95
  96   /* --- GCC complains about an out-of-bounds subscript here --- *
  97    *
  98    * This is impossible.  Thanks to @KSZ_ASSERT@, we know that @4 <= sz <=
  99    * 16@ and hence @1 <= i <= nk <= 4@; but @SQUARE_KWORDS == 36@.
 100    */
 101
 102   ww = MUFFLE_WARNINGS_EXPR(GCC_WARNING("-Warray-bounds"), kk[i - 1]);
 103
 104   /* --- Expand this material to fill the rest of the table --- */
 105
 106   nw = (nr + 1) * 4;
 107   p = RCON;
 108   for (; i < nw; i++) {
 109     uint32 w = kk[i - nk];
 110     if (i % nk == 0) {
 111       ww = ROR32(ww, 8);
 112       w ^= ww ^ *p++;
 113     } else
 114       w ^= ww;
 115     kk[i] = ww = w;
 116   }
 117
 118   /* --- Make the encryption and decryption keys --- */
 119
 120   for (i = 0; i < nr * 4; i++) {
 121     uint32 w = kk[i];
 122     k->w[i] = (U[0][U8(w >>  0)] ^ U[1][U8(w >>  8)] ^
 123                U[2][U8(w >> 16)] ^ U[3][U8(w >> 24)]);
 124   }
 125   for (; i < nw; i++)
 126     k->w[i] = kk[i];
 127
 128   jj = nw;
 129   for (i = 0; i < nr * 4; i += 4) {
 130     jj -= 4;
 131     for (j = 0; j < 4; j++)
 132       k->wi[i + j] = kk[jj + j];
 133   }
 134   for (j = 0; j < 4; j++)
 135     k->wi[i + j] = k->w[j];
 136
 137   BURN(kk);
 138 }
 139
 140 /* --- @square_eblk@, @square_dblk@ --- *
 141  *
 142  * Arguments:   @const square_ctx *k@ = pointer to Square context
 143  *              @const uint32 s[4]@ = pointer to source block
 144  *              @uint32 d[4]@ = pointer to destination block
 145  *
 146  * Returns:     ---
 147  *
 148  * Use:         Low-level block encryption and decryption.
 149  */
 150
 151 #define SUB(s, sh, a, b, c, d)                                          \
 152   (s[U8((a) >> sh)] <<  0 | s[U8((b) >> sh)] <<  8 |                    \
 153    s[U8((c) >> sh)] << 16 | s[U8((d) >> sh)] << 24)
 154
 155 #define MIX(t, sh, a, b, c, d)                                          \
 156   (t[0][U8((a) >> sh)] ^ t[1][U8((b) >> sh)] ^                          \
 157    t[2][U8((c) >> sh)] ^ t[3][U8((d) >> sh)])
 158
 159 #define DO(what, t, aa, bb, cc, dd, a, b, c, d, w) do {                 \
 160   aa = what(t,  0, a, b, c, d) ^ *w++;                                  \
 161   bb = what(t,  8, a, b, c, d) ^ *w++;                                  \
 162   cc = what(t, 16, a, b, c, d) ^ *w++;                                  \
 163   dd = what(t, 24, a, b, c, d) ^ *w++;                                  \
 164 } while (0)
 165
 166 void square_eblk(const square_ctx *k, const uint32 *s, uint32 *dst)
 167 {
 168   uint32 a = s[0], b = s[1], c = s[2], d = s[3];
 169   uint32 aa, bb, cc, dd;
 170   const uint32 *w = k->w;
 171
 172   a ^= *w++; b ^= *w++; c ^= *w++; d ^= *w++;
 173
 174   DO(MIX, T, aa, bb, cc, dd, a, b, c, d, w);
 175   DO(MIX, T, a, b, c, d, aa, bb, cc, dd, w);
 176   DO(MIX, T, aa, bb, cc, dd, a, b, c, d, w);
 177   DO(MIX, T, a, b, c, d, aa, bb, cc, dd, w);
 178   DO(MIX, T, aa, bb, cc, dd, a, b, c, d, w);
 179   DO(MIX, T, a, b, c, d, aa, bb, cc, dd, w);
 180   DO(MIX, T, aa, bb, cc, dd, a, b, c, d, w);
 181   DO(SUB, S, a, b, c, d, aa, bb, cc, dd, w);
 182
 183   dst[0] = a; dst[1] = b; dst[2] = c; dst[3] = d;
 184 }
 185
 186 void square_dblk(const square_ctx *k, const uint32 *s, uint32 *dst)
 187 {
 188   uint32 a = s[0], b = s[1], c = s[2], d = s[3];
 189   uint32 aa, bb, cc, dd;
 190   const uint32 *w = k->wi;
 191
 192   a ^= *w++; b ^= *w++; c ^= *w++; d ^= *w++;
 193
 194   DO(MIX, TI, aa, bb, cc, dd, a, b, c, d, w);
 195   DO(MIX, TI, a, b, c, d, aa, bb, cc, dd, w);
 196   DO(MIX, TI, aa, bb, cc, dd, a, b, c, d, w);
 197   DO(MIX, TI, a, b, c, d, aa, bb, cc, dd, w);
 198   DO(MIX, TI, aa, bb, cc, dd, a, b, c, d, w);
 199   DO(MIX, TI, a, b, c, d, aa, bb, cc, dd, w);
 200   DO(MIX, TI, aa, bb, cc, dd, a, b, c, d, w);
 201   DO(SUB, SI, a, b, c, d, aa, bb, cc, dd, w);
 202
 203   dst[0] = a; dst[1] = b; dst[2] = c; dst[3] = d;
 204 }
 205
 206 BLKC_TEST(SQUARE, square)
 207
 208 /*----- That's all, folks -------------------------------------------------*/