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

   1 /* -*-c-*-
   2  *
   3  * $Id: desx.c,v 1.2 2004/04/02 01:03:49 mdw Exp $
   4  *
   5  * Implementation of DESX
   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 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: desx.c,v $
  33  * Revision 1.2  2004/04/02 01:03:49  mdw
  34  * Miscellaneous constification.
  35  *
  36  * Revision 1.1  2001/04/03 19:36:50  mdw
  37  * New block cipher DESX added.
  38  *
  39  */
  40
  41 /*----- Header files ------------------------------------------------------*/
  42
  43 #include <assert.h>
  44 #include <stdio.h>
  45 #include <stdlib.h>
  46 #include <string.h>
  47
  48 #include <mLib/bits.h>
  49
  50 #include "blkc.h"
  51 #include "des-base.h"
  52 #include "des.h"
  53 #include "desx.h"
  54 #include "desx-tab.h"
  55 #include "gcipher.h"
  56
  57 /*----- Tables ------------------------------------------------------------*/
  58
  59 static const octet s[256] = DESX_S;
  60
  61 /*----- Global variables --------------------------------------------------*/
  62
  63 const octet desx_keysz[] = { KSZ_SET, 7, 8, 15, 16, 23, 24, 0 };
  64
  65 /*----- Main code ---------------------------------------------------------*/
  66
  67 /* --- @desx_init@ --- *
  68  *
  69  * Arguments:   @desx_ctx *k@ = pointer to key block
  70  *              @const void *buf@ = pointer to key buffer
  71  *              @size_t sz@ = size of key material
  72  *
  73  * Returns:     ---
  74  *
  75  * Use:         Initializes a DESX key buffer.  The key buffer contains, in
  76  *              order, a single-DES key (either 7 or 8 bytes), an optional
  77  *              8-byte pre-whitening key, and an optional 8-byte
  78  *              port-whitening key.  If no whitening keys are specified, the
  79  *              algorithm becomes the same as single-DES.
  80  */
  81
  82 static void mangle(octet *b, const octet *p)
  83 {
  84   unsigned i;
  85
  86   for (i = 0; i < 8; i++)
  87     b[i] = *p++ ^ s[b[i] ^ b[(i + 1) & 7u]];
  88 }
  89
  90 void desx_init(desx_ctx *k, const void *buf, size_t sz)
  91 {
  92   const octet *p = buf, *kk = buf;
  93   size_t n;
  94
  95   KSZ_ASSERT(desx, sz);
  96
  97   n = sz % 8 == 7 ? 7 : 8;
  98   des_init(&k->k, p, n);
  99   p += n;
 100   sz -= n;
 101   if (!sz)
 102     k->prea = k->preb = k->posta = k->postb = 0;
 103   else {
 104     const octet *q = p;
 105     k->prea = LOAD32(q + 0);
 106     k->preb = LOAD32(q + 4);
 107     p += 8;
 108     sz -= 8;
 109     if (sz) {
 110       k->posta = LOAD32(p + 0);
 111       k->postb = LOAD32(p + 4);
 112     } else {
 113       octet b[16];
 114
 115       if (n == 7) {
 116
 117         /* --- Expand 7 bits to 8 bits --- *
 118          *
 119          * Cloned and hacked from @des_init@ to set parity.
 120          */
 121
 122         uint32 x, y, z;
 123         x = LOAD32(kk + 0);
 124         x = (x & 0xfe000000) | ((x & 0x01fffff0) >> 1);
 125         x = (x & 0xfffe0000) | ((x & 0x0001fff8) >> 1);
 126         x = (x & 0xfffffe00) | ((x & 0x000001fc) >> 1);
 127         z = x; z ^= z >> 4; z ^= z >> 2; z ^= z >> 1;
 128         x |= (z & 0x01010101) ^ 0x01010101;
 129
 130         y = LOAD32(kk + 3) << 1;
 131         y = (y & 0x000000fe) | ((y & 0x1fffff00) << 1);
 132         y = (y & 0x0000fefe) | ((y & 0x3fff0000) << 1);
 133         y = (y & 0x00fefefe) | ((y & 0x7f000000) << 1);
 134         z = y; z ^= z >> 4; z ^= z >> 2; z ^= z >> 1;
 135         y |= (z & 0x01010101) ^ 0x01010101;
 136
 137         kk = b + 8;
 138         STORE32(kk + 0, x); STORE32(kk + 4, y);
 139       }
 140
 141       memset(b, 0, 8);
 142       mangle(b, kk);
 143       mangle(b, q);
 144       k->posta = LOAD32(b + 0);
 145       k->postb = LOAD32(b + 4);
 146     }
 147   }
 148 }
 149
 150 /* --- @desx_eblk@, @desx_dblk@ --- *
 151  *
 152  * Arguments:   @const desx_ctx *k@ = pointer to key block
 153  *              @const uint32 s[2]@ = pointer to source block
 154  *              @uint32 d[2]@ = pointer to destination block
 155  *
 156  * Returns:     ---
 157  *
 158  * Use:         Low-level block encryption and decryption.
 159  */
 160
 161 void desx_eblk(const desx_ctx *k, const uint32 *s, uint32 *d)
 162 {
 163   uint32 x = s[0], y = s[1];
 164   x ^= k->prea; y ^= k->preb;
 165   DES_IP(x, y);
 166   DES_EBLK(k->k.k, x, y, x, y);
 167   DES_IPINV(x, y);
 168   x ^= k->posta; y ^= k->postb;
 169   d[0] = x, d[1] = y;
 170 }
 171
 172 void desx_dblk(const desx_ctx *k, const uint32 *s, uint32 *d)
 173 {
 174   uint32 x = s[0], y = s[1];
 175   x ^= k->posta; y ^= k->postb;
 176   DES_IP(x, y);
 177   DES_DBLK(k->k.k, x, y, x, y);
 178   DES_IPINV(x, y);
 179   x ^= k->prea; y ^= k->preb;
 180   d[0] = x, d[1] = y;
 181 }
 182
 183 BLKC_TEST(DESX, desx)
 184
 185 /*----- That's all, folks -------------------------------------------------*/