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

   1 /* -*-c-*-
   2  *
   3  * The Skipjack 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 <mLib/bits.h>
  31
  32 #include "blkc.h"
  33 #include "gcipher.h"
  34 #include "skipjack.h"
  35
  36 /*----- Global variables --------------------------------------------------*/
  37
  38 const octet skipjack_keysz[] = { KSZ_SET, 10, 0 };
  39
  40 /*----- The Skipjack S-box ------------------------------------------------*/
  41
  42 extern const octet skipjack_s[256];
  43
  44 /*----- Main code ---------------------------------------------------------*/
  45
  46 /* --- @skipjack_init@ --- *
  47  *
  48  * Arguments:   @skipjack_ctx *k@ = pointer to key block
  49  *              @const void *buf@ = pointer to key buffer
  50  *              @size_t sz@ = size of key material
  51  *
  52  * Returns:     ---
  53  *
  54  * Use:         Initializes a Skipjack key buffer.  The key buffer must be
  55  *              exactly 10 bytes long.
  56  */
  57
  58 void skipjack_init(skipjack_ctx *k, const void *buf, size_t sz)
  59 {
  60   const octet *b = buf;
  61   uint32 crud;
  62   KSZ_ASSERT(skipjack, sz);
  63   k->ka = LOAD32(b);
  64   k->kb = LOAD32(b + 4);
  65   crud = LOAD16(b + 8);
  66   k->kc = U32((crud << 16) | (k->ka >> 16));
  67   k->kd = U32((k->ka << 16) | (k->kb >> 16));
  68   k->ke = U32((k->kb << 16) | crud);
  69   crud = 0;
  70 }
  71
  72 /* --- @skipjack_eblk@, @skipjack_dblk@ --- *
  73  *
  74  * Arguments:   @const skipjack_ctx *k@ = pointer to key block
  75  *              @const uint32 s[2]@ = pointer to source block
  76  *              @uint32 d[2]@ = pointer to skipjacktination block
  77  *
  78  * Returns:     ---
  79  *
  80  * Use:         Low-level block encryption and decryption.
  81  */
  82
  83 #define G(x, k) do {                                                    \
  84   octet _x = U8(x >> 8), _y = U8(x);                                    \
  85   _x ^= skipjack_s[_y ^ U8(k >> 24)];                                   \
  86   _y ^= skipjack_s[_x ^ U8(k >> 16)];                                   \
  87   _x ^= skipjack_s[_y ^ U8(k >>  8)];                                   \
  88   _y ^= skipjack_s[_x ^ U8(k >>  0)];                                   \
  89   x = (_x << 8) | _y;                                                   \
  90 } while (0)
  91
  92 #define RULE_A(w, x, y, z, n, k) do {                                   \
  93   G(w, k); z ^= w ^ n++;                                                \
  94 } while (0)
  95
  96 #define RULE_B(w, x, y, z, n, k) do {                                   \
  97   x ^= w ^ n++; G(w, k);                                                \
  98 } while (0)
  99
 100 void skipjack_eblk(const skipjack_ctx *k, const uint32 *s, uint32 *d)
 101 {
 102   unsigned n = 1;
 103   uint16 w = U16(s[0] >> 16), x = U16(s[0]);
 104   uint16 y = U16(s[1] >> 16), z = U16(s[1]);
 105   uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd, ke = k->ke;
 106
 107   RULE_A(w, x, y, z, n, ka); RULE_A(z, w, x, y, n, kb);
 108   RULE_A(y, z, w, x, n, kc); RULE_A(x, y, z, w, n, kd);
 109   RULE_A(w, x, y, z, n, ke); RULE_A(z, w, x, y, n, ka);
 110   RULE_A(y, z, w, x, n, kb); RULE_A(x, y, z, w, n, kc);
 111   RULE_B(w, x, y, z, n, kd); RULE_B(z, w, x, y, n, ke);
 112   RULE_B(y, z, w, x, n, ka); RULE_B(x, y, z, w, n, kb);
 113   RULE_B(w, x, y, z, n, kc); RULE_B(z, w, x, y, n, kd);
 114   RULE_B(y, z, w, x, n, ke); RULE_B(x, y, z, w, n, ka);
 115   RULE_A(w, x, y, z, n, kb); RULE_A(z, w, x, y, n, kc);
 116   RULE_A(y, z, w, x, n, kd); RULE_A(x, y, z, w, n, ke);
 117   RULE_A(w, x, y, z, n, ka); RULE_A(z, w, x, y, n, kb);
 118   RULE_A(y, z, w, x, n, kc); RULE_A(x, y, z, w, n, kd);
 119   RULE_B(w, x, y, z, n, ke); RULE_B(z, w, x, y, n, ka);
 120   RULE_B(y, z, w, x, n, kb); RULE_B(x, y, z, w, n, kc);
 121   RULE_B(w, x, y, z, n, kd); RULE_B(z, w, x, y, n, ke);
 122   RULE_B(y, z, w, x, n, ka); RULE_B(x, y, z, w, n, kb);
 123
 124   d[0] = ((uint32)w << 16) | (uint32)x;
 125   d[1] = ((uint32)y << 16) | (uint32)z;
 126 }
 127
 128 #define G_INV(x, k) do {                                                \
 129   octet _x = U8(x >> 8), _y = U8(x);                                    \
 130   _y ^= skipjack_s[_x ^ U8(k >>  0)];                                   \
 131   _x ^= skipjack_s[_y ^ U8(k >>  8)];                                   \
 132   _y ^= skipjack_s[_x ^ U8(k >> 16)];                                   \
 133   _x ^= skipjack_s[_y ^ U8(k >> 24)];                                   \
 134   x = (_x << 8) | _y;                                                   \
 135 } while (0)
 136
 137 #define RULE_A_INV(w, x, y, z, n, i) do {                               \
 138   w ^= x ^ --n; G_INV(x, i);                                            \
 139 } while (0)
 140
 141 #define RULE_B_INV(w, x, y, z, n, i) do {                               \
 142   G_INV(x, i); y ^= x ^ --n;                                            \
 143 } while (0)
 144
 145 void skipjack_dblk(const skipjack_ctx *k, const uint32 *s, uint32 *d)
 146 {
 147   unsigned n = 33;
 148   uint16 w = U16(s[0] >> 16), x = U16(s[0]);
 149   uint16 y = U16(s[1] >> 16), z = U16(s[1]);
 150   uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd, ke = k->ke;
 151
 152   RULE_B_INV(w, x, y, z, n, kb); RULE_B_INV(x, y, z, w, n, ka);
 153   RULE_B_INV(y, z, w, x, n, ke); RULE_B_INV(z, w, x, y, n, kd);
 154   RULE_B_INV(w, x, y, z, n, kc); RULE_B_INV(x, y, z, w, n, kb);
 155   RULE_B_INV(y, z, w, x, n, ka); RULE_B_INV(z, w, x, y, n, ke);
 156   RULE_A_INV(w, x, y, z, n, kd); RULE_A_INV(x, y, z, w, n, kc);
 157   RULE_A_INV(y, z, w, x, n, kb); RULE_A_INV(z, w, x, y, n, ka);
 158   RULE_A_INV(w, x, y, z, n, ke); RULE_A_INV(x, y, z, w, n, kd);
 159   RULE_A_INV(y, z, w, x, n, kc); RULE_A_INV(z, w, x, y, n, kb);
 160   RULE_B_INV(w, x, y, z, n, ka); RULE_B_INV(x, y, z, w, n, ke);
 161   RULE_B_INV(y, z, w, x, n, kd); RULE_B_INV(z, w, x, y, n, kc);
 162   RULE_B_INV(w, x, y, z, n, kb); RULE_B_INV(x, y, z, w, n, ka);
 163   RULE_B_INV(y, z, w, x, n, ke); RULE_B_INV(z, w, x, y, n, kd);
 164   RULE_A_INV(w, x, y, z, n, kc); RULE_A_INV(x, y, z, w, n, kb);
 165   RULE_A_INV(y, z, w, x, n, ka); RULE_A_INV(z, w, x, y, n, ke);
 166   RULE_A_INV(w, x, y, z, n, kd); RULE_A_INV(x, y, z, w, n, kc);
 167   RULE_A_INV(y, z, w, x, n, kb); RULE_A_INV(z, w, x, y, n, ka);
 168
 169   d[0] = ((uint32)w << 16) | (uint32)x;
 170   d[1] = ((uint32)y << 16) | (uint32)z;
 171 }
 172
 173 BLKC_TEST(SKIPJACK, skipjack)
 174
 175 /*----- That's all, folks -------------------------------------------------*/