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

   1 /* -*-c-*-
   2  *
   3  * $Id$
   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 /*----- Header files ------------------------------------------------------*/
  31
  32 #include <assert.h>
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36
  37 #include <mLib/bits.h>
  38
  39 #include "blkc.h"
  40 #include "des-base.h"
  41 #include "des.h"
  42 #include "desx.h"
  43 #include "desx-tab.h"
  44 #include "gcipher.h"
  45
  46 /*----- Tables ------------------------------------------------------------*/
  47
  48 static const octet s[256] = DESX_S;
  49
  50 /*----- Global variables --------------------------------------------------*/
  51
  52 const octet desx_keysz[] = { KSZ_SET, 23, 7, 8, 15, 16, 24, 0 };
  53
  54 /*----- Main code ---------------------------------------------------------*/
  55
  56 /* --- @desx_init@ --- *
  57  *
  58  * Arguments:   @desx_ctx *k@ = pointer to key block
  59  *              @const void *buf@ = pointer to key buffer
  60  *              @size_t sz@ = size of key material
  61  *
  62  * Returns:     ---
  63  *
  64  * Use:         Initializes a DESX key buffer.  The key buffer contains, in
  65  *              order, a single-DES key (either 7 or 8 bytes), an optional
  66  *              8-byte pre-whitening key, and an optional 8-byte
  67  *              port-whitening key.  If no whitening keys are specified, the
  68  *              algorithm becomes the same as single-DES.
  69  */
  70
  71 static void mangle(octet *b, const octet *p)
  72 {
  73   unsigned i;
  74
  75   for (i = 0; i < 8; i++)
  76     b[i] = *p++ ^ s[b[i] ^ b[(i + 1) & 7u]];
  77 }
  78
  79 void desx_init(desx_ctx *k, const void *buf, size_t sz)
  80 {
  81   const octet *p = buf, *kk = buf;
  82   size_t n;
  83
  84   KSZ_ASSERT(desx, sz);
  85
  86   n = sz % 8 == 7 ? 7 : 8;
  87   des_init(&k->k, p, n);
  88   p += n;
  89   sz -= n;
  90   if (!sz)
  91     k->prea = k->preb = k->posta = k->postb = 0;
  92   else {
  93     const octet *q = p;
  94     k->prea = LOAD32(q + 0);
  95     k->preb = LOAD32(q + 4);
  96     p += 8;
  97     sz -= 8;
  98     if (sz) {
  99       k->posta = LOAD32(p + 0);
 100       k->postb = LOAD32(p + 4);
 101     } else {
 102       octet b[16];
 103       uint32 x, y;
 104
 105       des_expand(kk, n, &x, &y);
 106       STORE32(b + 8, x); STORE32(b + 12, y);
 107       memset(b, 0, 8);
 108       mangle(b, b + 8);
 109       mangle(b, q);
 110       k->posta = LOAD32(b + 0);
 111       k->postb = LOAD32(b + 4);
 112     }
 113   }
 114 }
 115
 116 /* --- @desx_eblk@, @desx_dblk@ --- *
 117  *
 118  * Arguments:   @const desx_ctx *k@ = pointer to key block
 119  *              @const uint32 s[2]@ = pointer to source block
 120  *              @uint32 d[2]@ = pointer to destination block
 121  *
 122  * Returns:     ---
 123  *
 124  * Use:         Low-level block encryption and decryption.
 125  */
 126
 127 void desx_eblk(const desx_ctx *k, const uint32 *s, uint32 *d)
 128 {
 129   uint32 x = s[0], y = s[1];
 130   x ^= k->prea; y ^= k->preb;
 131   DES_IP(x, y);
 132   DES_EBLK(k->k.k, x, y, x, y);
 133   DES_IPINV(x, y);
 134   x ^= k->posta; y ^= k->postb;
 135   d[0] = x, d[1] = y;
 136 }
 137
 138 void desx_dblk(const desx_ctx *k, const uint32 *s, uint32 *d)
 139 {
 140   uint32 x = s[0], y = s[1];
 141   x ^= k->posta; y ^= k->postb;
 142   DES_IP(x, y);
 143   DES_DBLK(k->k.k, x, y, x, y);
 144   DES_IPINV(x, y);
 145   x ^= k->prea; y ^= k->preb;
 146   d[0] = x, d[1] = y;
 147 }
 148
 149 BLKC_TEST(DESX, desx)
 150
 151 /*----- That's all, folks -------------------------------------------------*/