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

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