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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: rc5.c,v 1.3 2004/04/08 01:36:15 mdw Exp $ |
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4 | * |
5 | * The RC5-32/12 block cipher |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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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. |
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18 | * |
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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. |
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23 | * |
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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 <stdlib.h> |
34 | #include <string.h> |
35 | |
36 | #include <mLib/alloc.h> |
37 | #include <mLib/bits.h> |
38 | |
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39 | #include "arena.h" |
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40 | #include "blkc.h" |
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41 | #include "gcipher.h" |
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42 | #include "rc5.h" |
43 | |
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44 | /*----- Global variables --------------------------------------------------*/ |
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45 | |
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46 | const octet rc5_keysz[] = { KSZ_RANGE, RC5_KEYSZ, 1, 255, 1 }; |
47 | |
48 | /*----- Internal magical constants ----------------------------------------*/ |
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49 | |
50 | #define T ((RC5_ROUNDS + 1) * 2) |
51 | #define P 0xb7e15163 |
52 | #define Q 0x9e3779b9 |
53 | |
54 | /*----- Main code ---------------------------------------------------------*/ |
55 | |
56 | /* --- @rc5_init@ --- * |
57 | * |
58 | * Arguments: @rc5_ctx *k@ = pointer to a key block |
59 | * @const void *sbuf@ = pointer to key material |
60 | * @size_t sz@ = size of the key material |
61 | * |
62 | * Returns: --- |
63 | * |
64 | * Use: Initializes an RC5 key block. |
65 | */ |
66 | |
67 | void rc5_init(rc5_ctx *k, const void *sbuf, size_t sz) |
68 | { |
69 | uint32 *l; |
70 | size_t w; |
71 | |
72 | /* --- Set up the @L@ table --- * |
73 | * |
74 | * This is slightly unfortunately defined. |
75 | */ |
76 | |
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77 | KSZ_ASSERT(rc5, sz); |
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78 | |
79 | { |
80 | int i; |
81 | const octet *p = sbuf; |
82 | |
83 | /* --- Create the buffer --- */ |
84 | |
85 | w = (sz + 3) / 4; |
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86 | l = XS_ALLOC(w * sizeof(uint32)); |
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87 | |
88 | /* --- Extract the key material --- */ |
89 | |
90 | for (i = 0; sz > 3; i++) { |
91 | l[i] = LOAD32_L(p); |
92 | p += 4; |
93 | sz -= 4; |
94 | } |
95 | |
96 | /* --- Fix up the tail end --- */ |
97 | |
98 | if (sz) { |
99 | uint32 x = U8(*p++); |
100 | if (sz > 1) x |= (U8(*p++) << 8); |
101 | if (sz > 2) x |= (U8(*p++) << 16); |
102 | l[i] = x; |
103 | } |
104 | } |
105 | |
106 | /* --- Initialize the @S@ table --- */ |
107 | |
108 | { |
109 | int i; |
110 | |
111 | k->s[0] = P; |
112 | for (i = 1; i < T; i++) |
113 | k->s[i] = k->s[i - 1] + Q; |
114 | } |
115 | |
116 | /* --- Mix in the key --- */ |
117 | |
118 | { |
119 | int m = 3 * (w > T ? w : T); |
120 | int i, j, c; |
121 | uint32 a, b; |
122 | |
123 | for (c = i = j = a = b = 0; c < m; c++) { |
124 | uint32 x; |
125 | |
126 | x = k->s[i] + a + b; |
127 | k->s[i] = a = ROL32(x, 3); |
128 | i++; if (i >= T) i = 0; |
129 | |
130 | x = l[j] + a + b; |
131 | l[j] = b = ROL32(x, a + b); |
132 | j++; if (j >= w) j = 0; |
133 | } |
134 | } |
135 | |
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136 | memset(l, 0, w * sizeof(uint32)); |
137 | XS_FREE(l); |
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138 | } |
139 | |
140 | /* --- @EROUND@, @DROUND@ --- */ |
141 | |
142 | #define EROUND(x, y, k) do { \ |
143 | uint32 _x; \ |
144 | _x = x ^ y; x = ROL32(_x, y) + k[0]; \ |
145 | _x = y ^ x; y = ROL32(_x, x) + k[1]; \ |
146 | k += 2; \ |
147 | } while (0) |
148 | |
149 | #define DROUND(x, y, k) do { \ |
150 | uint32 _x; \ |
151 | k -= 2; \ |
152 | _x = y - k[1]; y = ROR32(_x, x) ^ x; \ |
153 | _x = x - k[0]; x = ROR32(_x, y) ^ y; \ |
154 | } while (0) |
155 | |
156 | /* --- @EBLK@, @DBLK@ --- */ |
157 | |
158 | #define EBLK(a, b, c, d, k) do { \ |
159 | uint32 _l, _r; \ |
160 | const uint32 *_k = (k)->s; \ |
161 | \ |
162 | _l = (a) + _k[0]; \ |
163 | _r = (b) + _k[1]; \ |
164 | _k += 2; \ |
165 | \ |
166 | EROUND(_l, _r, _k); \ |
167 | EROUND(_l, _r, _k); \ |
168 | EROUND(_l, _r, _k); \ |
169 | EROUND(_l, _r, _k); \ |
170 | EROUND(_l, _r, _k); \ |
171 | EROUND(_l, _r, _k); \ |
172 | EROUND(_l, _r, _k); \ |
173 | EROUND(_l, _r, _k); \ |
174 | EROUND(_l, _r, _k); \ |
175 | EROUND(_l, _r, _k); \ |
176 | EROUND(_l, _r, _k); \ |
177 | EROUND(_l, _r, _k); \ |
178 | (c) = _l; \ |
179 | (d) = _r; \ |
180 | } while (0) |
181 | |
182 | #define DBLK(a, b, c, d, k) do { \ |
183 | uint32 _l, _r; \ |
184 | const uint32 *_k = (k)->s + T; \ |
185 | \ |
186 | _l = (a); \ |
187 | _r = (b); \ |
188 | \ |
189 | DROUND(_l, _r, _k); \ |
190 | DROUND(_l, _r, _k); \ |
191 | DROUND(_l, _r, _k); \ |
192 | DROUND(_l, _r, _k); \ |
193 | DROUND(_l, _r, _k); \ |
194 | DROUND(_l, _r, _k); \ |
195 | DROUND(_l, _r, _k); \ |
196 | DROUND(_l, _r, _k); \ |
197 | DROUND(_l, _r, _k); \ |
198 | DROUND(_l, _r, _k); \ |
199 | DROUND(_l, _r, _k); \ |
200 | DROUND(_l, _r, _k); \ |
201 | \ |
202 | _k -= 2; \ |
203 | (d) = _r - _k[1]; \ |
204 | (c) = _l - _k[0]; \ |
205 | } while (0) |
206 | |
207 | /* --- @rc5_eblk@, @rc5_dblk@ --- * |
208 | * |
209 | * Arguments: @const rc5_ctx *k@ = pointer to RC5 context block |
210 | * @const uint32 s[2]@ = pointer to source block |
211 | * @uint32 *d[2]@ = pointer to destination block |
212 | * |
213 | * Returns: --- |
214 | * |
215 | * Use: Low level block encryption and decryption. |
216 | */ |
217 | |
218 | void rc5_eblk(const rc5_ctx *k, const uint32 *s, uint32 *d) |
219 | { |
220 | EBLK(s[0], s[1], d[0], d[1], k); |
221 | } |
222 | |
223 | void rc5_dblk(const rc5_ctx *k, const uint32 *s, uint32 *d) |
224 | { |
225 | DBLK(s[0], s[1], d[0], d[1], k); |
226 | } |
227 | |
228 | /* --- Test rig --- */ |
229 | |
230 | BLKC_TEST(RC5, rc5) |
231 | |
232 | /*----- That's all, folks -------------------------------------------------*/ |