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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: rc2.c,v 1.2 2001/04/29 17:39:52 mdw Exp $ |
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4 | * |
5 | * The RC2 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: rc2.c,v $ |
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33 | * Revision 1.2 2001/04/29 17:39:52 mdw |
34 | * Moved big horrible table to a separate header. |
35 | * |
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36 | * Revision 1.1 2000/06/17 11:54:34 mdw |
37 | * New cipher. |
38 | * |
39 | */ |
40 | |
41 | /*----- Header files ------------------------------------------------------*/ |
42 | |
43 | #include <assert.h> |
44 | #include <stdio.h> |
45 | |
46 | #include <mLib/bits.h> |
47 | |
48 | #include "blkc.h" |
49 | #include "gcipher.h" |
50 | #include "paranoia.h" |
51 | #include "rc2.h" |
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52 | #include "rc2-tab.h" |
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53 | |
54 | /*----- Global variables --------------------------------------------------*/ |
55 | |
56 | const octet rc2_keysz[] = { KSZ_RANGE, RC2_KEYSZ, 1, 128, 1 }; |
57 | |
58 | /*----- Important tables --------------------------------------------------*/ |
59 | |
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60 | static const octet pi[256] = RC2_PI; |
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61 | |
62 | /*----- Main code ---------------------------------------------------------*/ |
63 | |
64 | /* --- @rc2_braindamage@ --- * |
65 | * |
66 | * Arguments: @rc2_ctx *k@ = pointer to context to initialize |
67 | * @const void *buf@ = pointer to key material |
68 | * @size_t sz@ = size of key material in bytes |
69 | * @unsigned eb@ = desired effective key size, in bits |
70 | * |
71 | * Returns: --- |
72 | * |
73 | * Use: Initializes an RC2 expanded key, and braindamages it to the |
74 | * requested effective key size. This is here for compatibility |
75 | * reasons. You should be using @rc2_init@ in normal code, |
76 | * which doesn't actually apply braindamage. |
77 | */ |
78 | |
79 | void rc2_braindamage(rc2_ctx *k, const void *buf, size_t sz, unsigned eb) |
80 | { |
81 | unsigned t8; |
82 | uint16 tm; |
83 | unsigned i; |
84 | uint16 *kk; |
85 | octet l[128]; |
86 | |
87 | KSZ_ASSERT(rc2, sz); |
88 | |
89 | /* --- Compute the braindamage parameters --- */ |
90 | |
91 | t8 = (eb + 7) / 8; |
92 | tm = 0xff & ((1 << (8 + eb - 8 * t8)) - 1); |
93 | |
94 | /* --- Copy and expand the initial key --- */ |
95 | |
96 | if (sz > sizeof(l)) |
97 | sz = sizeof(l); |
98 | memcpy(l, buf, sz); |
99 | |
100 | for (i = sz; i < sizeof(l); i++) |
101 | l[i] = pi[U8(l[i - 1] + l[i - sz])]; |
102 | |
103 | /* --- Braindamage the key --- */ |
104 | |
105 | i = sizeof(l) - t8; |
106 | l[i] = pi[l[i] & tm]; |
107 | while (i) { |
108 | i--; |
109 | l[i] = pi[U8(l[i + 1] ^ l[i + t8])]; |
110 | } |
111 | |
112 | /* --- Write it to the key block --- */ |
113 | |
114 | kk = k->k; |
115 | for (i = 0; i < sizeof(l); i += 2) |
116 | *kk++ = LOAD16_L(l + i); |
117 | BURN(l); |
118 | } |
119 | |
120 | /* --- @rc2_init@ --- * |
121 | * |
122 | * Arguments: @rc2_ctx *k@ = pointer to context to initialize |
123 | * @const void *buf@ = pointer to key material |
124 | * @size_t sz@ = size of key material in bytes |
125 | * |
126 | * Returns: --- |
127 | * |
128 | * Use: Initializes an RC2 expanded key. The effective key size is |
129 | * set to be equal to the real key size, in bits. |
130 | */ |
131 | |
132 | void rc2_init(rc2_ctx *k, const void *buf, size_t sz) |
133 | { |
134 | rc2_braindamage(k, buf, sz, sz * 8); |
135 | } |
136 | |
137 | /*----- Encryption and decryption -----------------------------------------*/ |
138 | |
139 | #define MIX(a, b, c, d, r, kk) do { \ |
140 | a += *kk++ + (d & c) + (~d & b); \ |
141 | a = ROL16(a, r); \ |
142 | } while (0) |
143 | |
144 | #define MASH(a, d, k) do { \ |
145 | a += k[d & 63]; \ |
146 | } while (0) |
147 | |
148 | #define UNMIX(a, b, c, d, r, kk) do { \ |
149 | a = ROR16(a, r); \ |
150 | a -= *--kk + (d & c) + (~d & b); \ |
151 | } while (0) |
152 | |
153 | #define UNMASH(a, d, k) do { \ |
154 | a -= k[d & 63]; \ |
155 | } while (0) |
156 | |
157 | /* --- @rc2_eblk@, @rc2_dblk@ --- * |
158 | * |
159 | * Arguments: @const rc2_ctx *k@ = pointer to RC2 context |
160 | * @const uint32 s[2]@ = pointer to source block |
161 | * @const uint32 d[2]@ = pointer to destination block |
162 | * |
163 | * Returns: --- |
164 | * |
165 | * Use: Low-level block encryption and decryption. |
166 | */ |
167 | |
168 | void rc2_eblk(const rc2_ctx *k, const uint32 *s, uint32 *dst) |
169 | { |
170 | uint16 a = U16(s[0] >> 0), b = U16(s[0] >> 16); |
171 | uint16 c = U16(s[1] >> 0), d = U16(s[1] >> 16); |
172 | const uint16 *kk = k->k; |
173 | |
174 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
175 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
176 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
177 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
178 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
179 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
180 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
181 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
182 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
183 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
184 | MASH(a, d, k->k); MASH(b, a, k->k); |
185 | MASH(c, b, k->k); MASH(d, c, k->k); |
186 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
187 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
188 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
189 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
190 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
191 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
192 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
193 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
194 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
195 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
196 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
197 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
198 | MASH(a, d, k->k); MASH(b, a, k->k); |
199 | MASH(c, b, k->k); MASH(d, c, k->k); |
200 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
201 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
202 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
203 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
204 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
205 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
206 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
207 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
208 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
209 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
210 | |
211 | dst[0] = a | (b << 16); dst[1] = c | (d << 16); |
212 | } |
213 | |
214 | void rc2_dblk(const rc2_ctx *k, const uint32 *s, uint32 *dst) |
215 | { |
216 | uint16 a = U16(s[0] >> 0), b = U16(s[0] >> 16); |
217 | uint16 c = U16(s[1] >> 0), d = U16(s[1] >> 16); |
218 | const uint16 *kk = k->k + 64; |
219 | |
220 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
221 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
222 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
223 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
224 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
225 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
226 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
227 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
228 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
229 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
230 | UNMASH(d, c, k->k); UNMASH(c, b, k->k); |
231 | UNMASH(b, a, k->k); UNMASH(a, d, k->k); |
232 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
233 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
234 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
235 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
236 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
237 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
238 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
239 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
240 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
241 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
242 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
243 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
244 | UNMASH(d, c, k->k); UNMASH(c, b, k->k); |
245 | UNMASH(b, a, k->k); UNMASH(a, d, k->k); |
246 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
247 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
248 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
249 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
250 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
251 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
252 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
253 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
254 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
255 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
256 | |
257 | dst[0] = a | (b << 16); dst[1] = c | (d << 16); |
258 | } |
259 | |
260 | /*----- Custom test rig ---------------------------------------------------* |
261 | * |
262 | * I need to test the braindamage feature. |
263 | */ |
264 | |
265 | #ifdef TEST_RIG |
266 | |
267 | #include <mLib/quis.h> |
268 | #include <mLib/testrig.h> |
269 | |
270 | static int verify(dstr *v) |
271 | { |
272 | rc2_ctx k; |
273 | uint32 p[RC2_BLKSZ / 4]; |
274 | uint32 c[RC2_BLKSZ / 4]; |
275 | uint32 d[RC2_BLKSZ / 4]; |
276 | dstr b = DSTR_INIT; |
277 | unsigned bd = *(unsigned *)v[1].buf; |
278 | int ok = 1; |
279 | |
280 | /* --- Initialize the key buffer --- */ |
281 | |
282 | dstr_ensure(&b, RC2_BLKSZ); |
283 | b.len = RC2_BLKSZ; |
284 | rc2_braindamage(&k, v[0].buf, v[0].len, bd); |
285 | BLKC_LOAD(RC2, p, v[2].buf); |
286 | BLKC_LOAD(RC2, c, v[3].buf); |
287 | |
288 | /* --- Test encryption --- */ |
289 | |
290 | BLKC_MOVE(RC2, d, p); |
291 | rc2_eblk(&k, d, d); |
292 | BLKC_STORE(RC2, b.buf, d); |
293 | if (memcmp(b.buf, v[3].buf, RC2_BLKSZ)) { |
294 | ok = 0; |
295 | printf("\nfail encryption:" |
296 | "\n\tkey = "); |
297 | type_hex.dump(&v[0], stdout); |
298 | printf("\n\tbraindamage= %u", bd); |
299 | printf("\n\tplaintext = "); type_hex.dump(&v[2], stdout); |
300 | printf("\n\texpected = "); type_hex.dump(&v[3], stdout); |
301 | printf("\n\tcalculated = "); type_hex.dump(&b, stdout); |
302 | putchar('\n'); |
303 | } |
304 | |
305 | /* --- Test decryption --- */ |
306 | |
307 | BLKC_MOVE(RC2, d, c); |
308 | rc2_dblk(&k, d, d); |
309 | BLKC_STORE(RC2, b.buf, d); |
310 | if (memcmp(b.buf, v[2].buf, RC2_BLKSZ)) { |
311 | ok = 0; |
312 | printf("\nfail decryption:" |
313 | "\n\tkey = "); |
314 | type_hex.dump(&v[0], stdout); |
315 | printf("\n\tbraindamage= %u", bd); |
316 | printf("\n\tciphertext = "); type_hex.dump(&v[3], stdout); |
317 | printf("\n\texpected = "); type_hex.dump(&v[2], stdout); |
318 | printf("\n\tcalculated = "); type_hex.dump(&b, stdout); |
319 | putchar('\n'); |
320 | } |
321 | |
322 | /* --- Return --- */ |
323 | |
324 | return (ok); |
325 | } |
326 | |
327 | static test_chunk defs[] = { |
328 | { "rc2", verify, { &type_hex, &type_int, &type_hex, &type_hex, 0 } }, |
329 | { 0, 0, { 0 } } |
330 | }; |
331 | |
332 | int main(int argc, char *argv[]) |
333 | { |
334 | test_run(argc, argv, defs, SRCDIR"/tests/rc2"); |
335 | return (0); |
336 | } |
337 | |
338 | #endif |
339 | |
340 | /*----- That's all, folks -------------------------------------------------*/ |