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