3 * $Id: skipjack.c,v 1.4 2004/04/02 01:03:49 mdw Exp $
5 * The Skipjack block cipher
7 * (c) 2000 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
32 * $Log: skipjack.c,v $
33 * Revision 1.4 2004/04/02 01:03:49 mdw
34 * Miscellaneous constification.
36 * Revision 1.3 2000/08/01 00:28:34 mdw
37 * Performance improvement: read keys in as 32-bit words and deal them out
40 * Revision 1.2 2000/07/15 20:48:45 mdw
41 * Remove some useless tests in the G function.
43 * Revision 1.1 2000/07/15 15:39:33 mdw
44 * The NSA's Skipjack block cipher.
48 /*----- Header files ------------------------------------------------------*/
50 #include <mLib/bits.h>
55 #include "skipjack-tab.h"
57 /*----- Global variables --------------------------------------------------*/
59 const octet skipjack_keysz[] = { KSZ_SET, 10, 0 };
61 /*----- The Skipjack S-box ------------------------------------------------*/
63 static const octet f[256] = SKIPJACK_S;
65 /*----- Main code ---------------------------------------------------------*/
67 /* --- @skipjack_init@ --- *
69 * Arguments: @skipjack_ctx *k@ = pointer to key block
70 * @const void *buf@ = pointer to key buffer
71 * @size_t sz@ = size of key material
75 * Use: Initializes a Skipjack key buffer. The key buffer must be
76 * exactly 10 bytes long.
79 void skipjack_init(skipjack_ctx *k, const void *buf, size_t sz)
83 KSZ_ASSERT(skipjack, sz);
85 k->kb = LOAD32(b + 4);
87 k->kc = U32((crud << 16) | (k->ka >> 16));
88 k->kd = U32((k->ka << 16) | (k->kb >> 16));
89 k->ke = U32((k->kb << 16) | crud);
93 /* --- @skipjack_eblk@, @skipjack_dblk@ --- *
95 * Arguments: @const skipjack_ctx *k@ = pointer to key block
96 * @const uint32 s[2]@ = pointer to source block
97 * @uint32 d[2]@ = pointer to skipjacktination block
101 * Use: Low-level block encryption and decryption.
104 #define G(x, k) do { \
105 octet _x = U8(x >> 8), _y = U8(x); \
106 _x ^= f[_y ^ U8(k >> 24)]; \
107 _y ^= f[_x ^ U8(k >> 16)]; \
108 _x ^= f[_y ^ U8(k >> 8)]; \
109 _y ^= f[_x ^ U8(k >> 0)]; \
110 x = (_x << 8) | _y; \
113 #define RULE_A(w, x, y, z, n, k) do { \
114 G(w, k); z ^= w ^ n++; \
117 #define RULE_B(w, x, y, z, n, k) do { \
118 x ^= w ^ n++; G(w, k); \
121 void skipjack_eblk(const skipjack_ctx *k, const uint32 *s, uint32 *d)
124 uint16 w = U16(s[0] >> 16), x = U16(s[0]);
125 uint16 y = U16(s[1] >> 16), z = U16(s[1]);
126 uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd, ke = k->ke;
128 RULE_A(w, x, y, z, n, ka); RULE_A(z, w, x, y, n, kb);
129 RULE_A(y, z, w, x, n, kc); RULE_A(x, y, z, w, n, kd);
130 RULE_A(w, x, y, z, n, ke); RULE_A(z, w, x, y, n, ka);
131 RULE_A(y, z, w, x, n, kb); RULE_A(x, y, z, w, n, kc);
132 RULE_B(w, x, y, z, n, kd); RULE_B(z, w, x, y, n, ke);
133 RULE_B(y, z, w, x, n, ka); RULE_B(x, y, z, w, n, kb);
134 RULE_B(w, x, y, z, n, kc); RULE_B(z, w, x, y, n, kd);
135 RULE_B(y, z, w, x, n, ke); RULE_B(x, y, z, w, n, ka);
136 RULE_A(w, x, y, z, n, kb); RULE_A(z, w, x, y, n, kc);
137 RULE_A(y, z, w, x, n, kd); RULE_A(x, y, z, w, n, ke);
138 RULE_A(w, x, y, z, n, ka); RULE_A(z, w, x, y, n, kb);
139 RULE_A(y, z, w, x, n, kc); RULE_A(x, y, z, w, n, kd);
140 RULE_B(w, x, y, z, n, ke); RULE_B(z, w, x, y, n, ka);
141 RULE_B(y, z, w, x, n, kb); RULE_B(x, y, z, w, n, kc);
142 RULE_B(w, x, y, z, n, kd); RULE_B(z, w, x, y, n, ke);
143 RULE_B(y, z, w, x, n, ka); RULE_B(x, y, z, w, n, kb);
145 d[0] = ((uint32)w << 16) | (uint32)x;
146 d[1] = ((uint32)y << 16) | (uint32)z;
149 #define G_INV(x, k) do { \
150 octet _x = U8(x >> 8), _y = U8(x); \
151 _y ^= f[_x ^ U8(k >> 0)]; \
152 _x ^= f[_y ^ U8(k >> 8)]; \
153 _y ^= f[_x ^ U8(k >> 16)]; \
154 _x ^= f[_y ^ U8(k >> 24)]; \
155 x = (_x << 8) | _y; \
158 #define RULE_A_INV(w, x, y, z, n, i) do { \
159 w ^= x ^ --n; G_INV(x, i); \
162 #define RULE_B_INV(w, x, y, z, n, i) do { \
163 G_INV(x, i); y ^= x ^ --n; \
166 void skipjack_dblk(const skipjack_ctx *k, const uint32 *s, uint32 *d)
169 uint16 w = U16(s[0] >> 16), x = U16(s[0]);
170 uint16 y = U16(s[1] >> 16), z = U16(s[1]);
171 uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd, ke = k->ke;
173 RULE_B_INV(w, x, y, z, n, kb); RULE_B_INV(x, y, z, w, n, ka);
174 RULE_B_INV(y, z, w, x, n, ke); RULE_B_INV(z, w, x, y, n, kd);
175 RULE_B_INV(w, x, y, z, n, kc); RULE_B_INV(x, y, z, w, n, kb);
176 RULE_B_INV(y, z, w, x, n, ka); RULE_B_INV(z, w, x, y, n, ke);
177 RULE_A_INV(w, x, y, z, n, kd); RULE_A_INV(x, y, z, w, n, kc);
178 RULE_A_INV(y, z, w, x, n, kb); RULE_A_INV(z, w, x, y, n, ka);
179 RULE_A_INV(w, x, y, z, n, ke); RULE_A_INV(x, y, z, w, n, kd);
180 RULE_A_INV(y, z, w, x, n, kc); RULE_A_INV(z, w, x, y, n, kb);
181 RULE_B_INV(w, x, y, z, n, ka); RULE_B_INV(x, y, z, w, n, ke);
182 RULE_B_INV(y, z, w, x, n, kd); RULE_B_INV(z, w, x, y, n, kc);
183 RULE_B_INV(w, x, y, z, n, kb); RULE_B_INV(x, y, z, w, n, ka);
184 RULE_B_INV(y, z, w, x, n, ke); RULE_B_INV(z, w, x, y, n, kd);
185 RULE_A_INV(w, x, y, z, n, kc); RULE_A_INV(x, y, z, w, n, kb);
186 RULE_A_INV(y, z, w, x, n, ka); RULE_A_INV(z, w, x, y, n, ke);
187 RULE_A_INV(w, x, y, z, n, kd); RULE_A_INV(x, y, z, w, n, kc);
188 RULE_A_INV(y, z, w, x, n, kb); RULE_A_INV(z, w, x, y, n, ka);
190 d[0] = ((uint32)w << 16) | (uint32)x;
191 d[1] = ((uint32)y << 16) | (uint32)z;
194 BLKC_TEST(SKIPJACK, skipjack)
196 /*----- That's all, folks -------------------------------------------------*/