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

   1 /* -*-c-*-
   2  *
   3  * $Id: skipjack.c,v 1.1 2000/07/15 15:39:33 mdw Exp $
   4  *
   5  * The Skipjack 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 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: skipjack.c,v $
  33  * Revision 1.1  2000/07/15 15:39:33  mdw
  34  * The NSA's Skipjack block cipher.
  35  *
  36  */
  37
  38 /*----- Header files ------------------------------------------------------*/
  39
  40 #include <mLib/bits.h>
  41
  42 #include "blkc.h"
  43 #include "gcipher.h"
  44 #include "skipjack.h"
  45 #include "skipjack-tab.h"
  46
  47 /*----- Global variables --------------------------------------------------*/
  48
  49 const octet skipjack_keysz[] = { KSZ_SET, 10, 0 };
  50
  51 /*----- The Skipjack S-box ------------------------------------------------*/
  52
  53 static octet f[256] = SKIPJACK_S;
  54
  55 /*----- Main code ---------------------------------------------------------*/
  56
  57 /* --- @skipjack_init@ --- *
  58  *
  59  * Arguments:   @skipjack_ctx *k@ = pointer to key block
  60  *              @const void *buf@ = pointer to key buffer
  61  *              @size_t sz@ = size of key material
  62  *
  63  * Returns:     ---
  64  *
  65  * Use:         Initializes a Skipjack key buffer.  The key buffer must be
  66  *              exactly 10 bytes long.
  67  */
  68
  69 void skipjack_init(skipjack_ctx *k, const void *buf, size_t sz)
  70 {
  71   KSZ_ASSERT(skipjack, sz);
  72   memcpy(k->k, buf, sz);
  73 }
  74
  75 /* --- @skipjack_eblk@, @skipjack_dblk@ --- *
  76  *
  77  * Arguments:   @const skipjack_ctx *k@ = pointer to key block
  78  *              @const uint32 s[2]@ = pointer to source block
  79  *              @uint32 d[2]@ = pointer to skipjacktination block
  80  *
  81  * Returns:     ---
  82  *
  83  * Use:         Low-level block encryption and decryption.
  84  */
  85
  86 #define G(x, i) do {                                                    \
  87   octet _x = U8(x >> 8), _y = U8(x);                                    \
  88   _x ^= f[_y ^ k->k[i++]]; if (i >= 10) i = 0;                          \
  89   _y ^= f[_x ^ k->k[i++]]; if (i >= 10) i = 0;                          \
  90   _x ^= f[_y ^ k->k[i++]]; if (i >= 10) i = 0;                          \
  91   _y ^= f[_x ^ k->k[i++]]; if (i >= 10) i = 0;                          \
  92   x = U16((_x << 8) | _y);                                              \
  93 } while (0)
  94
  95 #define RULE_A(w, x, y, z, n, i) do {                                   \
  96   G(w, i); z ^= w ^ n++;                                                \
  97 } while (0)
  98
  99 #define RULE_B(w, x, y, z, n, i) do {                                   \
 100   x ^= w ^ n++; G(w, i);                                                \
 101 } while (0)
 102
 103 void skipjack_eblk(const skipjack_ctx *k, const uint32 *s, uint32 *d)
 104 {
 105   unsigned i = 0;
 106   unsigned n = 1;
 107   uint16 w = U16(s[0] >> 16), x = U16(s[0]);
 108   uint16 y = U16(s[1] >> 16), z = U16(s[1]);
 109
 110   RULE_A(w, x, y, z, n, i); RULE_A(z, w, x, y, n, i);
 111   RULE_A(y, z, w, x, n, i); RULE_A(x, y, z, w, n, i);
 112   RULE_A(w, x, y, z, n, i); RULE_A(z, w, x, y, n, i);
 113   RULE_A(y, z, w, x, n, i); RULE_A(x, y, z, w, n, i);
 114   RULE_B(w, x, y, z, n, i); RULE_B(z, w, x, y, n, i);
 115   RULE_B(y, z, w, x, n, i); RULE_B(x, y, z, w, n, i);
 116   RULE_B(w, x, y, z, n, i); RULE_B(z, w, x, y, n, i);
 117   RULE_B(y, z, w, x, n, i); RULE_B(x, y, z, w, n, i);
 118   RULE_A(w, x, y, z, n, i); RULE_A(z, w, x, y, n, i);
 119   RULE_A(y, z, w, x, n, i); RULE_A(x, y, z, w, n, i);
 120   RULE_A(w, x, y, z, n, i); RULE_A(z, w, x, y, n, i);
 121   RULE_A(y, z, w, x, n, i); RULE_A(x, y, z, w, n, i);
 122   RULE_B(w, x, y, z, n, i); RULE_B(z, w, x, y, n, i);
 123   RULE_B(y, z, w, x, n, i); RULE_B(x, y, z, w, n, i);
 124   RULE_B(w, x, y, z, n, i); RULE_B(z, w, x, y, n, i);
 125   RULE_B(y, z, w, x, n, i); RULE_B(x, y, z, w, n, i);
 126
 127   d[0] = ((uint32)w << 16) | (uint32)x;
 128   d[1] = ((uint32)y << 16) | (uint32)z;
 129 }
 130
 131 #define G_INV(x, i) do {                                                \
 132   octet _x = U8(x >> 8), _y = U8(x);                                    \
 133   _y ^= f[_x ^ k->k[--i]]; if (i == 0) i = 10;                          \
 134   _x ^= f[_y ^ k->k[--i]]; if (i == 0) i = 10;                          \
 135   _y ^= f[_x ^ k->k[--i]]; if (i == 0) i = 10;                          \
 136   _x ^= f[_y ^ k->k[--i]]; if (i == 0) i = 10;                          \
 137   x = U16((_x << 8) | _y);                                              \
 138 } while (0)
 139
 140 #define RULE_A_INV(w, x, y, z, n, i) do {                               \
 141   w ^= x ^ --n; G_INV(x, i);                                            \
 142 } while (0)
 143
 144 #define RULE_B_INV(w, x, y, z, n, i) do {                               \
 145   G_INV(x, i); y ^= x ^ --n;                                            \
 146 } while (0)
 147
 148 void skipjack_dblk(const skipjack_ctx *k, const uint32 *s, uint32 *d)
 149 {
 150   unsigned i = 8;
 151   unsigned n = 33;
 152   uint16 w = U16(s[0] >> 16), x = U16(s[0]);
 153   uint16 y = U16(s[1] >> 16), z = U16(s[1]);
 154
 155   RULE_B_INV(w, x, y, z, n, i); RULE_B_INV(x, y, z, w, n, i);
 156   RULE_B_INV(y, z, w, x, n, i); RULE_B_INV(z, w, x, y, n, i);
 157   RULE_B_INV(w, x, y, z, n, i); RULE_B_INV(x, y, z, w, n, i);
 158   RULE_B_INV(y, z, w, x, n, i); RULE_B_INV(z, w, x, y, n, i);
 159   RULE_A_INV(w, x, y, z, n, i); RULE_A_INV(x, y, z, w, n, i);
 160   RULE_A_INV(y, z, w, x, n, i); RULE_A_INV(z, w, x, y, n, i);
 161   RULE_A_INV(w, x, y, z, n, i); RULE_A_INV(x, y, z, w, n, i);
 162   RULE_A_INV(y, z, w, x, n, i); RULE_A_INV(z, w, x, y, n, i);
 163   RULE_B_INV(w, x, y, z, n, i); RULE_B_INV(x, y, z, w, n, i);
 164   RULE_B_INV(y, z, w, x, n, i); RULE_B_INV(z, w, x, y, n, i);
 165   RULE_B_INV(w, x, y, z, n, i); RULE_B_INV(x, y, z, w, n, i);
 166   RULE_B_INV(y, z, w, x, n, i); RULE_B_INV(z, w, x, y, n, i);
 167   RULE_A_INV(w, x, y, z, n, i); RULE_A_INV(x, y, z, w, n, i);
 168   RULE_A_INV(y, z, w, x, n, i); RULE_A_INV(z, w, x, y, n, i);
 169   RULE_A_INV(w, x, y, z, n, i); RULE_A_INV(x, y, z, w, n, i);
 170   RULE_A_INV(y, z, w, x, n, i); RULE_A_INV(z, w, x, y, n, i);
 171
 172   d[0] = ((uint32)w << 16) | (uint32)x;
 173   d[1] = ((uint32)y << 16) | (uint32)z;
 174 }
 175
 176 BLKC_TEST(SKIPJACK, skipjack)
 177
 178 /*----- That's all, folks -------------------------------------------------*/