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1 | /* -*-c-*- |
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2 | * |
3 | * The RC2 block cipher |
4 | * |
5 | * (c) 2000 Straylight/Edgeware |
6 | */ |
7 | |
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8 | /*----- Licensing notice --------------------------------------------------* |
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9 | * |
10 | * This file is part of Catacomb. |
11 | * |
12 | * Catacomb is free software; you can redistribute it and/or modify |
13 | * it under the terms of the GNU Library General Public License as |
14 | * published by the Free Software Foundation; either version 2 of the |
15 | * License, or (at your option) any later version. |
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16 | * |
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17 | * Catacomb is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
20 | * GNU Library General Public License for more details. |
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21 | * |
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22 | * You should have received a copy of the GNU Library General Public |
23 | * License along with Catacomb; if not, write to the Free |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
25 | * MA 02111-1307, USA. |
26 | */ |
27 | |
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28 | /*----- Header files ------------------------------------------------------*/ |
29 | |
30 | #include <assert.h> |
31 | #include <stdio.h> |
32 | |
33 | #include <mLib/bits.h> |
34 | |
35 | #include "blkc.h" |
36 | #include "gcipher.h" |
37 | #include "paranoia.h" |
38 | #include "rc2.h" |
39 | |
40 | /*----- Global variables --------------------------------------------------*/ |
41 | |
42 | const octet rc2_keysz[] = { KSZ_RANGE, RC2_KEYSZ, 1, 128, 1 }; |
43 | |
44 | /*----- Important tables --------------------------------------------------*/ |
45 | |
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46 | extern const octet rc2_pi[256]; |
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47 | |
48 | /*----- Main code ---------------------------------------------------------*/ |
49 | |
50 | /* --- @rc2_braindamage@ --- * |
51 | * |
52 | * Arguments: @rc2_ctx *k@ = pointer to context to initialize |
53 | * @const void *buf@ = pointer to key material |
54 | * @size_t sz@ = size of key material in bytes |
55 | * @unsigned eb@ = desired effective key size, in bits |
56 | * |
57 | * Returns: --- |
58 | * |
59 | * Use: Initializes an RC2 expanded key, and braindamages it to the |
60 | * requested effective key size. This is here for compatibility |
61 | * reasons. You should be using @rc2_init@ in normal code, |
62 | * which doesn't actually apply braindamage. |
63 | */ |
64 | |
65 | void rc2_braindamage(rc2_ctx *k, const void *buf, size_t sz, unsigned eb) |
66 | { |
67 | unsigned t8; |
68 | uint16 tm; |
69 | unsigned i; |
70 | uint16 *kk; |
71 | octet l[128]; |
72 | |
73 | KSZ_ASSERT(rc2, sz); |
74 | |
75 | /* --- Compute the braindamage parameters --- */ |
76 | |
77 | t8 = (eb + 7) / 8; |
78 | tm = 0xff & ((1 << (8 + eb - 8 * t8)) - 1); |
79 | |
80 | /* --- Copy and expand the initial key --- */ |
81 | |
82 | if (sz > sizeof(l)) |
83 | sz = sizeof(l); |
84 | memcpy(l, buf, sz); |
85 | |
86 | for (i = sz; i < sizeof(l); i++) |
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87 | l[i] = rc2_pi[U8(l[i - 1] + l[i - sz])]; |
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88 | |
89 | /* --- Braindamage the key --- */ |
90 | |
91 | i = sizeof(l) - t8; |
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92 | l[i] = rc2_pi[l[i] & tm]; |
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93 | while (i) { |
94 | i--; |
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95 | l[i] = rc2_pi[U8(l[i + 1] ^ l[i + t8])]; |
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96 | } |
97 | |
98 | /* --- Write it to the key block --- */ |
99 | |
100 | kk = k->k; |
101 | for (i = 0; i < sizeof(l); i += 2) |
102 | *kk++ = LOAD16_L(l + i); |
103 | BURN(l); |
104 | } |
105 | |
106 | /* --- @rc2_init@ --- * |
107 | * |
108 | * Arguments: @rc2_ctx *k@ = pointer to context to initialize |
109 | * @const void *buf@ = pointer to key material |
110 | * @size_t sz@ = size of key material in bytes |
111 | * |
112 | * Returns: --- |
113 | * |
114 | * Use: Initializes an RC2 expanded key. The effective key size is |
115 | * set to be equal to the real key size, in bits. |
116 | */ |
117 | |
118 | void rc2_init(rc2_ctx *k, const void *buf, size_t sz) |
119 | { |
120 | rc2_braindamage(k, buf, sz, sz * 8); |
121 | } |
122 | |
123 | /*----- Encryption and decryption -----------------------------------------*/ |
124 | |
125 | #define MIX(a, b, c, d, r, kk) do { \ |
126 | a += *kk++ + (d & c) + (~d & b); \ |
127 | a = ROL16(a, r); \ |
128 | } while (0) |
129 | |
130 | #define MASH(a, d, k) do { \ |
131 | a += k[d & 63]; \ |
132 | } while (0) |
133 | |
134 | #define UNMIX(a, b, c, d, r, kk) do { \ |
135 | a = ROR16(a, r); \ |
136 | a -= *--kk + (d & c) + (~d & b); \ |
137 | } while (0) |
138 | |
139 | #define UNMASH(a, d, k) do { \ |
140 | a -= k[d & 63]; \ |
141 | } while (0) |
142 | |
143 | /* --- @rc2_eblk@, @rc2_dblk@ --- * |
144 | * |
145 | * Arguments: @const rc2_ctx *k@ = pointer to RC2 context |
146 | * @const uint32 s[2]@ = pointer to source block |
147 | * @const uint32 d[2]@ = pointer to destination block |
148 | * |
149 | * Returns: --- |
150 | * |
151 | * Use: Low-level block encryption and decryption. |
152 | */ |
153 | |
154 | void rc2_eblk(const rc2_ctx *k, const uint32 *s, uint32 *dst) |
155 | { |
156 | uint16 a = U16(s[0] >> 0), b = U16(s[0] >> 16); |
157 | uint16 c = U16(s[1] >> 0), d = U16(s[1] >> 16); |
158 | const uint16 *kk = k->k; |
159 | |
160 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
161 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
162 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
163 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
164 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
165 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
166 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
167 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
168 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
169 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
170 | MASH(a, d, k->k); MASH(b, a, k->k); |
171 | MASH(c, b, k->k); MASH(d, c, k->k); |
172 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
173 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
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 | |
197 | dst[0] = a | (b << 16); dst[1] = c | (d << 16); |
198 | } |
199 | |
200 | void rc2_dblk(const rc2_ctx *k, const uint32 *s, uint32 *dst) |
201 | { |
202 | uint16 a = U16(s[0] >> 0), b = U16(s[0] >> 16); |
203 | uint16 c = U16(s[1] >> 0), d = U16(s[1] >> 16); |
204 | const uint16 *kk = k->k + 64; |
205 | |
206 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
207 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
208 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
209 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
210 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
211 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
212 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
213 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
214 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
215 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
216 | UNMASH(d, c, k->k); UNMASH(c, b, k->k); |
217 | UNMASH(b, a, k->k); UNMASH(a, d, k->k); |
218 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
219 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
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 | |
243 | dst[0] = a | (b << 16); dst[1] = c | (d << 16); |
244 | } |
245 | |
246 | /*----- Custom test rig ---------------------------------------------------* |
247 | * |
248 | * I need to test the braindamage feature. |
249 | */ |
250 | |
251 | #ifdef TEST_RIG |
252 | |
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253 | #include <mLib/macros.h> |
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254 | #include <mLib/quis.h> |
255 | #include <mLib/testrig.h> |
256 | |
257 | static int verify(dstr *v) |
258 | { |
259 | rc2_ctx k; |
260 | uint32 p[RC2_BLKSZ / 4]; |
261 | uint32 c[RC2_BLKSZ / 4]; |
262 | uint32 d[RC2_BLKSZ / 4]; |
263 | dstr b = DSTR_INIT; |
264 | unsigned bd = *(unsigned *)v[1].buf; |
265 | int ok = 1; |
266 | |
267 | /* --- Initialize the key buffer --- */ |
268 | |
269 | dstr_ensure(&b, RC2_BLKSZ); |
270 | b.len = RC2_BLKSZ; |
271 | rc2_braindamage(&k, v[0].buf, v[0].len, bd); |
272 | BLKC_LOAD(RC2, p, v[2].buf); |
273 | BLKC_LOAD(RC2, c, v[3].buf); |
274 | |
275 | /* --- Test encryption --- */ |
276 | |
277 | BLKC_MOVE(RC2, d, p); |
278 | rc2_eblk(&k, d, d); |
279 | BLKC_STORE(RC2, b.buf, d); |
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280 | if (MEMCMP(b.buf, !=, v[3].buf, RC2_BLKSZ)) { |
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281 | ok = 0; |
282 | printf("\nfail encryption:" |
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283 | "\n\tkey = "); |
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284 | type_hex.dump(&v[0], stdout); |
285 | printf("\n\tbraindamage= %u", bd); |
286 | printf("\n\tplaintext = "); type_hex.dump(&v[2], stdout); |
287 | printf("\n\texpected = "); type_hex.dump(&v[3], stdout); |
288 | printf("\n\tcalculated = "); type_hex.dump(&b, stdout); |
289 | putchar('\n'); |
290 | } |
291 | |
292 | /* --- Test decryption --- */ |
293 | |
294 | BLKC_MOVE(RC2, d, c); |
295 | rc2_dblk(&k, d, d); |
296 | BLKC_STORE(RC2, b.buf, d); |
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297 | if (MEMCMP(b.buf, !=, v[2].buf, RC2_BLKSZ)) { |
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298 | ok = 0; |
299 | printf("\nfail decryption:" |
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300 | "\n\tkey = "); |
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301 | type_hex.dump(&v[0], stdout); |
302 | printf("\n\tbraindamage= %u", bd); |
303 | printf("\n\tciphertext = "); type_hex.dump(&v[3], stdout); |
304 | printf("\n\texpected = "); type_hex.dump(&v[2], stdout); |
305 | printf("\n\tcalculated = "); type_hex.dump(&b, stdout); |
306 | putchar('\n'); |
307 | } |
308 | |
309 | /* --- Return --- */ |
310 | |
311 | return (ok); |
312 | } |
313 | |
314 | static test_chunk defs[] = { |
315 | { "rc2", verify, { &type_hex, &type_int, &type_hex, &type_hex, 0 } }, |
316 | { 0, 0, { 0 } } |
317 | }; |
318 | |
319 | int main(int argc, char *argv[]) |
320 | { |
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321 | test_run(argc, argv, defs, SRCDIR"/t/rc2"); |
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322 | return (0); |
323 | } |
324 | |
325 | #endif |
326 | |
327 | /*----- That's all, folks -------------------------------------------------*/ |