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

   1 /* -*-c-*-
   2  *
   3  * $Id: square.c,v 1.3 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * The Square 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
  35 #include <mLib/bits.h>
  36
  37 #include "blkc.h"
  38 #include "gcipher.h"
  39 #include "paranoia.h"
  40 #include "square.h"
  41 #include "square-tab.h"
  42
  43 /*----- Global variables --------------------------------------------------*/
  44
  45 const octet square_keysz[] = { KSZ_RANGE, SQUARE_KEYSZ, 4, 16, 4 };
  46
  47 /*----- Constant tables ---------------------------------------------------*/
  48
  49 static const octet S[256] = SQUARE_S, SI[256] = SQUARE_SI;
  50 static const uint32 T[4][256] = SQUARE_T, TI[4][256] = SQUARE_TI;
  51 static const uint32 U[4][256] = SQUARE_U;
  52 static const octet rcon[] = SQUARE_RCON;
  53
  54 /*----- Main code ---------------------------------------------------------*/
  55
  56 /* --- @square_init@ --- *
  57  *
  58  * Arguments:   @square_ctx *k@ = pointer to context to initialize
  59  *              @const void *buf@ = pointer to buffer of key material
  60  *              @size_t sz@ = size of the key material
  61  *
  62  * Returns:     ---
  63  *
  64  * Use:         Initializes a Square context with a particular key.  Square
  65  *              keys must be a multiple of 32 bits long, and may be at most
  66  *              128 bits.
  67  */
  68
  69 void square_init(square_ctx *k, const void *buf, size_t sz)
  70 {
  71   unsigned nk, nr, nw;
  72   unsigned i, j, jj;
  73   const octet *p;
  74   uint32 ww;
  75   uint32 kk[SQUARE_KWORDS];
  76
  77   /* --- Sort out the key size --- */
  78
  79   KSZ_ASSERT(square, sz);
  80   nk = sz / 4;
  81
  82   /* --- Fetch the first key words out --- */
  83
  84   p = buf;
  85   for (i = 0; i < nk; i++) {
  86     kk[i] = LOAD32_L(p);
  87     p += 4;
  88   }
  89   nr = 8;
  90
  91   /* --- Expand this material to fill the rest of the table --- */
  92
  93   nw = (nr + 1) * 4;
  94   ww = kk[i - 1];
  95   p = rcon;
  96   for (; i < nw; i++) {
  97     uint32 w = kk[i - nk];
  98     if (i % nk == 0) {
  99       ww = ROR32(ww, 8);
 100       w ^= ww ^ *p++;
 101     } else
 102       w ^= ww;
 103     kk[i] = ww = w;
 104   }
 105
 106   /* --- Make the encryption and decryption keys --- */
 107
 108   for (i = 0; i < nr * 4; i++) {
 109     uint32 w = kk[i];
 110     k->w[i] = (U[0][U8(w >>  0)] ^ U[1][U8(w >>  8)] ^
 111                U[2][U8(w >> 16)] ^ U[3][U8(w >> 24)]);
 112   }
 113   for (; i < nw; i++)
 114     k->w[i] = kk[i];
 115
 116   jj = nw;
 117   for (i = 0; i < nr * 4; i += 4) {
 118     jj -= 4;
 119     for (j = 0; j < 4; j++)
 120       k->wi[i + j] = kk[jj + j];
 121   }
 122   for (j = 0; j < 4; j++)
 123     k->wi[i + j] = k->w[j];
 124
 125   BURN(kk);
 126 }
 127
 128 /* --- @square_eblk@, @square_dblk@ --- *
 129  *
 130  * Arguments:   @const square_ctx *k@ = pointer to Square context
 131  *              @const uint32 s[4]@ = pointer to source block
 132  *              @uint32 d[4]@ = pointer to destination block
 133  *
 134  * Returns:     ---
 135  *
 136  * Use:         Low-level block encryption and decryption.
 137  */
 138
 139 #define SUB(s, sh, a, b, c, d)                                          \
 140   (s[U8((a) >> sh)] <<  0 | s[U8((b) >> sh)] <<  8 |                    \
 141    s[U8((c) >> sh)] << 16 | s[U8((d) >> sh)] << 24)
 142
 143 #define MIX(t, sh, a, b, c, d)                                          \
 144   (t[0][U8((a) >> sh)] ^ t[1][U8((b) >> sh)] ^                          \
 145    t[2][U8((c) >> sh)] ^ t[3][U8((d) >> sh)])
 146
 147 #define DO(what, t, aa, bb, cc, dd, a, b, c, d, w) do {                 \
 148   aa = what(t,  0, a, b, c, d) ^ *w++;                                  \
 149   bb = what(t,  8, a, b, c, d) ^ *w++;                                  \
 150   cc = what(t, 16, a, b, c, d) ^ *w++;                                  \
 151   dd = what(t, 24, a, b, c, d) ^ *w++;                                  \
 152 } while (0)
 153
 154 void square_eblk(const square_ctx *k, const uint32 *s, uint32 *dst)
 155 {
 156   uint32 a = s[0], b = s[1], c = s[2], d = s[3];
 157   uint32 aa, bb, cc, dd;
 158   const uint32 *w = k->w;
 159
 160   a ^= *w++; b ^= *w++; c ^= *w++; d ^= *w++;
 161
 162   DO(MIX, T, aa, bb, cc, dd, a, b, c, d, w);
 163   DO(MIX, T, a, b, c, d, aa, bb, cc, dd, w);
 164   DO(MIX, T, aa, bb, cc, dd, a, b, c, d, w);
 165   DO(MIX, T, a, b, c, d, aa, bb, cc, dd, w);
 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(SUB, S, a, b, c, d, aa, bb, cc, dd, w);
 170
 171   dst[0] = a; dst[1] = b; dst[2] = c; dst[3] = d;
 172 }
 173
 174 void square_dblk(const square_ctx *k, const uint32 *s, uint32 *dst)
 175 {
 176   uint32 a = s[0], b = s[1], c = s[2], d = s[3];
 177   uint32 aa, bb, cc, dd;
 178   const uint32 *w = k->wi;
 179
 180   a ^= *w++; b ^= *w++; c ^= *w++; d ^= *w++;
 181
 182   DO(MIX, TI, aa, bb, cc, dd, a, b, c, d, w);
 183   DO(MIX, TI, a, b, c, d, aa, bb, cc, dd, w);
 184   DO(MIX, TI, aa, bb, cc, dd, a, b, c, d, w);
 185   DO(MIX, TI, a, b, c, d, aa, bb, cc, dd, w);
 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(SUB, SI, a, b, c, d, aa, bb, cc, dd, w);
 190
 191   dst[0] = a; dst[1] = b; dst[2] = c; dst[3] = d;
 192 }
 193
 194 BLKC_TEST(SQUARE, square)
 195
 196 /*----- That's all, folks -------------------------------------------------*/