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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: skipjack.c,v 1.5 2004/04/08 01:36:15 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 | */ |
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29 | |
30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <mLib/bits.h> |
33 | |
34 | #include "blkc.h" |
35 | #include "gcipher.h" |
36 | #include "skipjack.h" |
37 | #include "skipjack-tab.h" |
38 | |
39 | /*----- Global variables --------------------------------------------------*/ |
40 | |
41 | const octet skipjack_keysz[] = { KSZ_SET, 10, 0 }; |
42 | |
43 | /*----- The Skipjack S-box ------------------------------------------------*/ |
44 | |
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45 | static const octet f[256] = SKIPJACK_S; |
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46 | |
47 | /*----- Main code ---------------------------------------------------------*/ |
48 | |
49 | /* --- @skipjack_init@ --- * |
50 | * |
51 | * Arguments: @skipjack_ctx *k@ = pointer to key block |
52 | * @const void *buf@ = pointer to key buffer |
53 | * @size_t sz@ = size of key material |
54 | * |
55 | * Returns: --- |
56 | * |
57 | * Use: Initializes a Skipjack key buffer. The key buffer must be |
58 | * exactly 10 bytes long. |
59 | */ |
60 | |
61 | void skipjack_init(skipjack_ctx *k, const void *buf, size_t sz) |
62 | { |
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63 | const octet *b = buf; |
64 | uint32 crud; |
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65 | KSZ_ASSERT(skipjack, sz); |
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66 | k->ka = LOAD32(b); |
67 | k->kb = LOAD32(b + 4); |
68 | crud = LOAD16(b + 8); |
69 | k->kc = U32((crud << 16) | (k->ka >> 16)); |
70 | k->kd = U32((k->ka << 16) | (k->kb >> 16)); |
71 | k->ke = U32((k->kb << 16) | crud); |
72 | crud = 0; |
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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 | |
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86 | #define G(x, k) do { \ |
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87 | octet _x = U8(x >> 8), _y = U8(x); \ |
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88 | _x ^= f[_y ^ U8(k >> 24)]; \ |
89 | _y ^= f[_x ^ U8(k >> 16)]; \ |
90 | _x ^= f[_y ^ U8(k >> 8)]; \ |
91 | _y ^= f[_x ^ U8(k >> 0)]; \ |
92 | x = (_x << 8) | _y; \ |
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93 | } while (0) |
94 | |
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95 | #define RULE_A(w, x, y, z, n, k) do { \ |
96 | G(w, k); z ^= w ^ n++; \ |
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97 | } while (0) |
98 | |
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99 | #define RULE_B(w, x, y, z, n, k) do { \ |
100 | x ^= w ^ n++; G(w, k); \ |
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101 | } while (0) |
102 | |
103 | void skipjack_eblk(const skipjack_ctx *k, const uint32 *s, uint32 *d) |
104 | { |
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105 | unsigned n = 1; |
106 | uint16 w = U16(s[0] >> 16), x = U16(s[0]); |
107 | uint16 y = U16(s[1] >> 16), z = U16(s[1]); |
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108 | uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd, ke = k->ke; |
109 | |
110 | RULE_A(w, x, y, z, n, ka); RULE_A(z, w, x, y, n, kb); |
111 | RULE_A(y, z, w, x, n, kc); RULE_A(x, y, z, w, n, kd); |
112 | RULE_A(w, x, y, z, n, ke); RULE_A(z, w, x, y, n, ka); |
113 | RULE_A(y, z, w, x, n, kb); RULE_A(x, y, z, w, n, kc); |
114 | RULE_B(w, x, y, z, n, kd); RULE_B(z, w, x, y, n, ke); |
115 | RULE_B(y, z, w, x, n, ka); RULE_B(x, y, z, w, n, kb); |
116 | RULE_B(w, x, y, z, n, kc); RULE_B(z, w, x, y, n, kd); |
117 | RULE_B(y, z, w, x, n, ke); RULE_B(x, y, z, w, n, ka); |
118 | RULE_A(w, x, y, z, n, kb); RULE_A(z, w, x, y, n, kc); |
119 | RULE_A(y, z, w, x, n, kd); RULE_A(x, y, z, w, n, ke); |
120 | RULE_A(w, x, y, z, n, ka); RULE_A(z, w, x, y, n, kb); |
121 | RULE_A(y, z, w, x, n, kc); RULE_A(x, y, z, w, n, kd); |
122 | RULE_B(w, x, y, z, n, ke); RULE_B(z, w, x, y, n, ka); |
123 | RULE_B(y, z, w, x, n, kb); RULE_B(x, y, z, w, n, kc); |
124 | RULE_B(w, x, y, z, n, kd); RULE_B(z, w, x, y, n, ke); |
125 | RULE_B(y, z, w, x, n, ka); RULE_B(x, y, z, w, n, kb); |
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126 | |
127 | d[0] = ((uint32)w << 16) | (uint32)x; |
128 | d[1] = ((uint32)y << 16) | (uint32)z; |
129 | } |
130 | |
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131 | #define G_INV(x, k) do { \ |
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132 | octet _x = U8(x >> 8), _y = U8(x); \ |
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133 | _y ^= f[_x ^ U8(k >> 0)]; \ |
134 | _x ^= f[_y ^ U8(k >> 8)]; \ |
135 | _y ^= f[_x ^ U8(k >> 16)]; \ |
136 | _x ^= f[_y ^ U8(k >> 24)]; \ |
137 | x = (_x << 8) | _y; \ |
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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 | { |
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150 | unsigned n = 33; |
151 | uint16 w = U16(s[0] >> 16), x = U16(s[0]); |
152 | uint16 y = U16(s[1] >> 16), z = U16(s[1]); |
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153 | uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd, ke = k->ke; |
154 | |
155 | RULE_B_INV(w, x, y, z, n, kb); RULE_B_INV(x, y, z, w, n, ka); |
156 | RULE_B_INV(y, z, w, x, n, ke); RULE_B_INV(z, w, x, y, n, kd); |
157 | RULE_B_INV(w, x, y, z, n, kc); RULE_B_INV(x, y, z, w, n, kb); |
158 | RULE_B_INV(y, z, w, x, n, ka); RULE_B_INV(z, w, x, y, n, ke); |
159 | RULE_A_INV(w, x, y, z, n, kd); RULE_A_INV(x, y, z, w, n, kc); |
160 | RULE_A_INV(y, z, w, x, n, kb); RULE_A_INV(z, w, x, y, n, ka); |
161 | RULE_A_INV(w, x, y, z, n, ke); RULE_A_INV(x, y, z, w, n, kd); |
162 | RULE_A_INV(y, z, w, x, n, kc); RULE_A_INV(z, w, x, y, n, kb); |
163 | RULE_B_INV(w, x, y, z, n, ka); RULE_B_INV(x, y, z, w, n, ke); |
164 | RULE_B_INV(y, z, w, x, n, kd); RULE_B_INV(z, w, x, y, n, kc); |
165 | RULE_B_INV(w, x, y, z, n, kb); RULE_B_INV(x, y, z, w, n, ka); |
166 | RULE_B_INV(y, z, w, x, n, ke); RULE_B_INV(z, w, x, y, n, kd); |
167 | RULE_A_INV(w, x, y, z, n, kc); RULE_A_INV(x, y, z, w, n, kb); |
168 | RULE_A_INV(y, z, w, x, n, ka); RULE_A_INV(z, w, x, y, n, ke); |
169 | RULE_A_INV(w, x, y, z, n, kd); RULE_A_INV(x, y, z, w, n, kc); |
170 | RULE_A_INV(y, z, w, x, n, kb); RULE_A_INV(z, w, x, y, n, ka); |
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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 -------------------------------------------------*/ |