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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: skipjack.c,v 1.3 2000/08/01 00:28:34 mdw Exp $ |
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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 $ |
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33 | * Revision 1.3 2000/08/01 00:28:34 mdw |
34 | * Performance improvement: read keys in as 32-bit words and deal them out |
35 | * byte-by-byte. |
36 | * |
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37 | * Revision 1.2 2000/07/15 20:48:45 mdw |
38 | * Remove some useless tests in the G function. |
39 | * |
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40 | * Revision 1.1 2000/07/15 15:39:33 mdw |
41 | * The NSA's Skipjack block cipher. |
42 | * |
43 | */ |
44 | |
45 | /*----- Header files ------------------------------------------------------*/ |
46 | |
47 | #include <mLib/bits.h> |
48 | |
49 | #include "blkc.h" |
50 | #include "gcipher.h" |
51 | #include "skipjack.h" |
52 | #include "skipjack-tab.h" |
53 | |
54 | /*----- Global variables --------------------------------------------------*/ |
55 | |
56 | const octet skipjack_keysz[] = { KSZ_SET, 10, 0 }; |
57 | |
58 | /*----- The Skipjack S-box ------------------------------------------------*/ |
59 | |
60 | static octet f[256] = SKIPJACK_S; |
61 | |
62 | /*----- Main code ---------------------------------------------------------*/ |
63 | |
64 | /* --- @skipjack_init@ --- * |
65 | * |
66 | * Arguments: @skipjack_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 Skipjack key buffer. The key buffer must be |
73 | * exactly 10 bytes long. |
74 | */ |
75 | |
76 | void skipjack_init(skipjack_ctx *k, const void *buf, size_t sz) |
77 | { |
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78 | const octet *b = buf; |
79 | uint32 crud; |
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80 | KSZ_ASSERT(skipjack, sz); |
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81 | k->ka = LOAD32(b); |
82 | k->kb = LOAD32(b + 4); |
83 | crud = LOAD16(b + 8); |
84 | k->kc = U32((crud << 16) | (k->ka >> 16)); |
85 | k->kd = U32((k->ka << 16) | (k->kb >> 16)); |
86 | k->ke = U32((k->kb << 16) | crud); |
87 | crud = 0; |
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88 | } |
89 | |
90 | /* --- @skipjack_eblk@, @skipjack_dblk@ --- * |
91 | * |
92 | * Arguments: @const skipjack_ctx *k@ = pointer to key block |
93 | * @const uint32 s[2]@ = pointer to source block |
94 | * @uint32 d[2]@ = pointer to skipjacktination block |
95 | * |
96 | * Returns: --- |
97 | * |
98 | * Use: Low-level block encryption and decryption. |
99 | */ |
100 | |
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101 | #define G(x, k) do { \ |
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102 | octet _x = U8(x >> 8), _y = U8(x); \ |
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103 | _x ^= f[_y ^ U8(k >> 24)]; \ |
104 | _y ^= f[_x ^ U8(k >> 16)]; \ |
105 | _x ^= f[_y ^ U8(k >> 8)]; \ |
106 | _y ^= f[_x ^ U8(k >> 0)]; \ |
107 | x = (_x << 8) | _y; \ |
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108 | } while (0) |
109 | |
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110 | #define RULE_A(w, x, y, z, n, k) do { \ |
111 | G(w, k); z ^= w ^ n++; \ |
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112 | } while (0) |
113 | |
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114 | #define RULE_B(w, x, y, z, n, k) do { \ |
115 | x ^= w ^ n++; G(w, k); \ |
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116 | } while (0) |
117 | |
118 | void skipjack_eblk(const skipjack_ctx *k, const uint32 *s, uint32 *d) |
119 | { |
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120 | unsigned n = 1; |
121 | uint16 w = U16(s[0] >> 16), x = U16(s[0]); |
122 | uint16 y = U16(s[1] >> 16), z = U16(s[1]); |
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123 | uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd, ke = k->ke; |
124 | |
125 | RULE_A(w, x, y, z, n, ka); RULE_A(z, w, x, y, n, kb); |
126 | RULE_A(y, z, w, x, n, kc); RULE_A(x, y, z, w, n, kd); |
127 | RULE_A(w, x, y, z, n, ke); RULE_A(z, w, x, y, n, ka); |
128 | RULE_A(y, z, w, x, n, kb); RULE_A(x, y, z, w, n, kc); |
129 | RULE_B(w, x, y, z, n, kd); RULE_B(z, w, x, y, n, ke); |
130 | RULE_B(y, z, w, x, n, ka); RULE_B(x, y, z, w, n, kb); |
131 | RULE_B(w, x, y, z, n, kc); RULE_B(z, w, x, y, n, kd); |
132 | RULE_B(y, z, w, x, n, ke); RULE_B(x, y, z, w, n, ka); |
133 | RULE_A(w, x, y, z, n, kb); RULE_A(z, w, x, y, n, kc); |
134 | RULE_A(y, z, w, x, n, kd); RULE_A(x, y, z, w, n, ke); |
135 | RULE_A(w, x, y, z, n, ka); RULE_A(z, w, x, y, n, kb); |
136 | RULE_A(y, z, w, x, n, kc); RULE_A(x, y, z, w, n, kd); |
137 | RULE_B(w, x, y, z, n, ke); RULE_B(z, w, x, y, n, ka); |
138 | RULE_B(y, z, w, x, n, kb); RULE_B(x, y, z, w, n, kc); |
139 | RULE_B(w, x, y, z, n, kd); RULE_B(z, w, x, y, n, ke); |
140 | RULE_B(y, z, w, x, n, ka); RULE_B(x, y, z, w, n, kb); |
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141 | |
142 | d[0] = ((uint32)w << 16) | (uint32)x; |
143 | d[1] = ((uint32)y << 16) | (uint32)z; |
144 | } |
145 | |
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146 | #define G_INV(x, k) do { \ |
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147 | octet _x = U8(x >> 8), _y = U8(x); \ |
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148 | _y ^= f[_x ^ U8(k >> 0)]; \ |
149 | _x ^= f[_y ^ U8(k >> 8)]; \ |
150 | _y ^= f[_x ^ U8(k >> 16)]; \ |
151 | _x ^= f[_y ^ U8(k >> 24)]; \ |
152 | x = (_x << 8) | _y; \ |
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153 | } while (0) |
154 | |
155 | #define RULE_A_INV(w, x, y, z, n, i) do { \ |
156 | w ^= x ^ --n; G_INV(x, i); \ |
157 | } while (0) |
158 | |
159 | #define RULE_B_INV(w, x, y, z, n, i) do { \ |
160 | G_INV(x, i); y ^= x ^ --n; \ |
161 | } while (0) |
162 | |
163 | void skipjack_dblk(const skipjack_ctx *k, const uint32 *s, uint32 *d) |
164 | { |
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165 | unsigned n = 33; |
166 | uint16 w = U16(s[0] >> 16), x = U16(s[0]); |
167 | uint16 y = U16(s[1] >> 16), z = U16(s[1]); |
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168 | uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd, ke = k->ke; |
169 | |
170 | RULE_B_INV(w, x, y, z, n, kb); RULE_B_INV(x, y, z, w, n, ka); |
171 | RULE_B_INV(y, z, w, x, n, ke); RULE_B_INV(z, w, x, y, n, kd); |
172 | RULE_B_INV(w, x, y, z, n, kc); RULE_B_INV(x, y, z, w, n, kb); |
173 | RULE_B_INV(y, z, w, x, n, ka); RULE_B_INV(z, w, x, y, n, ke); |
174 | RULE_A_INV(w, x, y, z, n, kd); RULE_A_INV(x, y, z, w, n, kc); |
175 | RULE_A_INV(y, z, w, x, n, kb); RULE_A_INV(z, w, x, y, n, ka); |
176 | RULE_A_INV(w, x, y, z, n, ke); RULE_A_INV(x, y, z, w, n, kd); |
177 | RULE_A_INV(y, z, w, x, n, kc); RULE_A_INV(z, w, x, y, n, kb); |
178 | RULE_B_INV(w, x, y, z, n, ka); RULE_B_INV(x, y, z, w, n, ke); |
179 | RULE_B_INV(y, z, w, x, n, kd); RULE_B_INV(z, w, x, y, n, kc); |
180 | RULE_B_INV(w, x, y, z, n, kb); RULE_B_INV(x, y, z, w, n, ka); |
181 | RULE_B_INV(y, z, w, x, n, ke); RULE_B_INV(z, w, x, y, n, kd); |
182 | RULE_A_INV(w, x, y, z, n, kc); RULE_A_INV(x, y, z, w, n, kb); |
183 | RULE_A_INV(y, z, w, x, n, ka); RULE_A_INV(z, w, x, y, n, ke); |
184 | RULE_A_INV(w, x, y, z, n, kd); RULE_A_INV(x, y, z, w, n, kc); |
185 | RULE_A_INV(y, z, w, x, n, kb); RULE_A_INV(z, w, x, y, n, ka); |
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186 | |
187 | d[0] = ((uint32)w << 16) | (uint32)x; |
188 | d[1] = ((uint32)y << 16) | (uint32)z; |
189 | } |
190 | |
191 | BLKC_TEST(SKIPJACK, skipjack) |
192 | |
193 | /*----- That's all, folks -------------------------------------------------*/ |