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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: serpent.c,v 1.2 2004/04/08 01:36:15 mdw Exp $ |
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4 | * |
5 | * The Serpent 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 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <assert.h> |
33 | #include <stdio.h> |
34 | |
35 | #include <mLib/bits.h> |
36 | |
37 | #include "blkc.h" |
38 | #include "gcipher.h" |
39 | #include "serpent.h" |
40 | #include "serpent-sbox.h" |
41 | |
42 | /*----- Global variables --------------------------------------------------*/ |
43 | |
44 | const octet serpent_keysz[] = { KSZ_RANGE, SERPENT_KEYSZ, 0, 32, 1 }; |
45 | |
46 | /*----- Main code ---------------------------------------------------------*/ |
47 | |
48 | /* --- @serpent_init@ --- * |
49 | * |
50 | * Arguments: @serpent_ctx *k@ = pointer to context block to initialize |
51 | * @const void *buf@ = pointer to input buffer |
52 | * @size_t sz@ = size of input buffer |
53 | * |
54 | * Returns: --- |
55 | * |
56 | * Use: Initializes a Serpent context. The key may be any length of |
57 | * up to 32 bytes (256 bits). |
58 | */ |
59 | |
60 | void serpent_init(serpent_ctx *k, const void *buf, size_t sz) |
61 | { |
62 | uint32 a; |
63 | unsigned b; |
64 | const octet *p, *q; |
65 | size_t i; |
66 | uint32 pk[8 + 132]; |
67 | |
68 | KSZ_ASSERT(serpent, sz); |
69 | |
70 | /* --- Read the key into the buffer --- */ |
71 | |
72 | if (sz > 32) |
73 | sz = 32; |
74 | i = 0; p = buf; q = p + sz; |
75 | a = 0; b = 0; |
76 | while (p < q) { |
77 | a |= (uint32)*p++ << b; |
78 | b += 8; |
79 | if (b == 32) { |
80 | pk[i++] = a; |
81 | a = 0; b = 0; |
82 | } |
83 | } |
84 | |
85 | /* --- Pad short keys --- */ |
86 | |
87 | if (i < 8) { |
88 | a |= 0x01 << b; |
89 | b += 8; |
90 | pk[i++] = a; |
91 | for (; i < 8; i++) |
92 | pk[i] = 0; |
93 | } |
94 | |
95 | /* --- Expand the prekeys to fill the buffer --- */ |
96 | |
97 | for (i = 8; i < 8 + 132; i++) { |
98 | uint32 x = (pk[i - 8] ^ pk[i - 5] ^ pk[i - 3] ^ pk[i - 1] ^ |
99 | (i - 8) ^ 0x9e3779b9); |
100 | k->k[i - 8] = pk[i] = ROL32(x, 11); |
101 | } |
102 | |
103 | /* --- Now substitute everything --- */ |
104 | |
105 | i = 0; |
106 | goto midway; |
107 | while (i < 132) { |
108 | #define KSUB(r) do { \ |
109 | uint32 a, b, c, d; \ |
110 | a = k->k[i]; b = k->k[i + 1]; c = k->k[i + 2]; d = k->k[i + 3]; \ |
111 | S##r(a, b, c, d); \ |
112 | k->k[i] = a; k->k[i + 1] = b; k->k[i + 2] = c; k->k[i + 3] = d; \ |
113 | i += 4; \ |
114 | } while (0) |
115 | KSUB(2); KSUB(1); KSUB(0); KSUB(7); |
116 | KSUB(6); KSUB(5); KSUB(4); |
117 | midway: |
118 | KSUB(3); |
119 | #undef KSUB |
120 | } |
121 | } |
122 | |
123 | /* --- @serpent_eblk@, @serpent_dblk@ --- * |
124 | * |
125 | * Arguments: @const serpent_ctx *k@ = pointer to key context |
126 | * @const uint32 s[4]@ = pointer to source block |
127 | * @uint32 d[4]@ = pointer to destination block |
128 | * |
129 | * Returns: --- |
130 | * |
131 | * Use: Low-level block encryption. |
132 | */ |
133 | |
134 | #define EROUND(a, b, c, d, r, k) do { \ |
135 | a ^= *k++; b ^= *k++; c ^= *k++; d ^= *k++; \ |
136 | S##r(a, b, c, d); \ |
137 | a = ROL32(a, 13); c = ROL32(c, 3); b ^= a ^ c; d ^= c ^ (a << 3); \ |
138 | b = ROL32(b, 1); d = ROL32(d, 7); a ^= b ^ d; c ^= d ^ (b << 7); \ |
139 | a = ROL32(a, 5); c = ROL32(c, 22); \ |
140 | } while (0) |
141 | |
142 | #define DROUND(a, b, c, d, r, k) do { \ |
143 | IS##r(a, b, c, d); \ |
144 | d ^= *--k; c ^= *--k; b ^= *--k; a ^= *--k; \ |
145 | a = ROR32(a, 5); c = ROR32(c, 22); a ^= b ^ d; c ^= d ^ (b << 7); \ |
146 | b = ROR32(b, 1); d = ROR32(d, 7); b ^= a ^ c; d ^= c ^ (a << 3); \ |
147 | a = ROR32(a, 13); c = ROR32(c, 3); \ |
148 | } while (0) |
149 | |
150 | void serpent_eblk(const serpent_ctx *k, const uint32 *s, uint32 *d) |
151 | { |
152 | uint32 aa = s[0], bb = s[1], cc = s[2], dd = s[3]; |
153 | const uint32 *kk = k->k; |
154 | |
155 | EROUND(aa, bb, cc, dd, 0, kk); EROUND(aa, bb, cc, dd, 1, kk); |
156 | EROUND(aa, bb, cc, dd, 2, kk); EROUND(aa, bb, cc, dd, 3, kk); |
157 | EROUND(aa, bb, cc, dd, 4, kk); EROUND(aa, bb, cc, dd, 5, kk); |
158 | EROUND(aa, bb, cc, dd, 6, kk); EROUND(aa, bb, cc, dd, 7, kk); |
159 | |
160 | EROUND(aa, bb, cc, dd, 0, kk); EROUND(aa, bb, cc, dd, 1, kk); |
161 | EROUND(aa, bb, cc, dd, 2, kk); EROUND(aa, bb, cc, dd, 3, kk); |
162 | EROUND(aa, bb, cc, dd, 4, kk); EROUND(aa, bb, cc, dd, 5, kk); |
163 | EROUND(aa, bb, cc, dd, 6, kk); EROUND(aa, bb, cc, dd, 7, kk); |
164 | |
165 | EROUND(aa, bb, cc, dd, 0, kk); EROUND(aa, bb, cc, dd, 1, kk); |
166 | EROUND(aa, bb, cc, dd, 2, kk); EROUND(aa, bb, cc, dd, 3, kk); |
167 | EROUND(aa, bb, cc, dd, 4, kk); EROUND(aa, bb, cc, dd, 5, kk); |
168 | EROUND(aa, bb, cc, dd, 6, kk); EROUND(aa, bb, cc, dd, 7, kk); |
169 | |
170 | EROUND(aa, bb, cc, dd, 0, kk); EROUND(aa, bb, cc, dd, 1, kk); |
171 | EROUND(aa, bb, cc, dd, 2, kk); EROUND(aa, bb, cc, dd, 3, kk); |
172 | EROUND(aa, bb, cc, dd, 4, kk); EROUND(aa, bb, cc, dd, 5, kk); |
173 | EROUND(aa, bb, cc, dd, 6, kk); |
174 | |
175 | aa ^= *kk++; bb ^= *kk++; cc ^= *kk++; dd ^= *kk++; |
176 | S7(aa, bb, cc, dd); |
177 | aa ^= *kk++; bb ^= *kk++; cc ^= *kk++; dd ^= *kk++; |
178 | d[0] = aa; d[1] = bb; d[2] = cc; d[3] = dd; |
179 | } |
180 | |
181 | void serpent_dblk(const serpent_ctx *k, const uint32 *s, uint32 *d) |
182 | { |
183 | uint32 aa = s[0], bb = s[1], cc = s[2], dd = s[3]; |
184 | const uint32 *kk = k->k + 132; |
185 | |
186 | dd ^= *--kk; cc ^= *--kk; bb ^= *--kk; aa ^= *--kk; |
187 | |
188 | DROUND(aa, bb, cc, dd, 7, kk); DROUND(aa, bb, cc, dd, 6, kk); |
189 | DROUND(aa, bb, cc, dd, 5, kk); DROUND(aa, bb, cc, dd, 4, kk); |
190 | DROUND(aa, bb, cc, dd, 3, kk); DROUND(aa, bb, cc, dd, 2, kk); |
191 | DROUND(aa, bb, cc, dd, 1, kk); DROUND(aa, bb, cc, dd, 0, kk); |
192 | |
193 | DROUND(aa, bb, cc, dd, 7, kk); DROUND(aa, bb, cc, dd, 6, kk); |
194 | DROUND(aa, bb, cc, dd, 5, kk); DROUND(aa, bb, cc, dd, 4, kk); |
195 | DROUND(aa, bb, cc, dd, 3, kk); DROUND(aa, bb, cc, dd, 2, kk); |
196 | DROUND(aa, bb, cc, dd, 1, kk); DROUND(aa, bb, cc, dd, 0, kk); |
197 | |
198 | DROUND(aa, bb, cc, dd, 7, kk); DROUND(aa, bb, cc, dd, 6, kk); |
199 | DROUND(aa, bb, cc, dd, 5, kk); DROUND(aa, bb, cc, dd, 4, kk); |
200 | DROUND(aa, bb, cc, dd, 3, kk); DROUND(aa, bb, cc, dd, 2, kk); |
201 | DROUND(aa, bb, cc, dd, 1, kk); DROUND(aa, bb, cc, dd, 0, kk); |
202 | |
203 | DROUND(aa, bb, cc, dd, 7, kk); DROUND(aa, bb, cc, dd, 6, kk); |
204 | DROUND(aa, bb, cc, dd, 5, kk); DROUND(aa, bb, cc, dd, 4, kk); |
205 | DROUND(aa, bb, cc, dd, 3, kk); DROUND(aa, bb, cc, dd, 2, kk); |
206 | DROUND(aa, bb, cc, dd, 1, kk); |
207 | |
208 | IS0(aa, bb, cc, dd); |
209 | dd ^= *--kk; cc ^= *--kk; bb ^= *--kk; aa ^= *--kk; |
210 | d[0] = aa; d[1] = bb; d[2] = cc; d[3] = dd; |
211 | } |
212 | |
213 | BLKC_TEST(SERPENT, serpent) |
214 | |
215 | /*----- That's all, folks -------------------------------------------------*/ |