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1 | /* -*-c-*- |
2 | * |
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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" |
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39 | #include "rc2-tab.h" |
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40 | |
41 | /*----- Global variables --------------------------------------------------*/ |
42 | |
43 | const octet rc2_keysz[] = { KSZ_RANGE, RC2_KEYSZ, 1, 128, 1 }; |
44 | |
45 | /*----- Important tables --------------------------------------------------*/ |
46 | |
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47 | static const octet pi[256] = RC2_PI; |
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48 | |
49 | /*----- Main code ---------------------------------------------------------*/ |
50 | |
51 | /* --- @rc2_braindamage@ --- * |
52 | * |
53 | * Arguments: @rc2_ctx *k@ = pointer to context to initialize |
54 | * @const void *buf@ = pointer to key material |
55 | * @size_t sz@ = size of key material in bytes |
56 | * @unsigned eb@ = desired effective key size, in bits |
57 | * |
58 | * Returns: --- |
59 | * |
60 | * Use: Initializes an RC2 expanded key, and braindamages it to the |
61 | * requested effective key size. This is here for compatibility |
62 | * reasons. You should be using @rc2_init@ in normal code, |
63 | * which doesn't actually apply braindamage. |
64 | */ |
65 | |
66 | void rc2_braindamage(rc2_ctx *k, const void *buf, size_t sz, unsigned eb) |
67 | { |
68 | unsigned t8; |
69 | uint16 tm; |
70 | unsigned i; |
71 | uint16 *kk; |
72 | octet l[128]; |
73 | |
74 | KSZ_ASSERT(rc2, sz); |
75 | |
76 | /* --- Compute the braindamage parameters --- */ |
77 | |
78 | t8 = (eb + 7) / 8; |
79 | tm = 0xff & ((1 << (8 + eb - 8 * t8)) - 1); |
80 | |
81 | /* --- Copy and expand the initial key --- */ |
82 | |
83 | if (sz > sizeof(l)) |
84 | sz = sizeof(l); |
85 | memcpy(l, buf, sz); |
86 | |
87 | for (i = sz; i < sizeof(l); i++) |
88 | l[i] = pi[U8(l[i - 1] + l[i - sz])]; |
89 | |
90 | /* --- Braindamage the key --- */ |
91 | |
92 | i = sizeof(l) - t8; |
93 | l[i] = pi[l[i] & tm]; |
94 | while (i) { |
95 | i--; |
96 | l[i] = pi[U8(l[i + 1] ^ l[i + t8])]; |
97 | } |
98 | |
99 | /* --- Write it to the key block --- */ |
100 | |
101 | kk = k->k; |
102 | for (i = 0; i < sizeof(l); i += 2) |
103 | *kk++ = LOAD16_L(l + i); |
104 | BURN(l); |
105 | } |
106 | |
107 | /* --- @rc2_init@ --- * |
108 | * |
109 | * Arguments: @rc2_ctx *k@ = pointer to context to initialize |
110 | * @const void *buf@ = pointer to key material |
111 | * @size_t sz@ = size of key material in bytes |
112 | * |
113 | * Returns: --- |
114 | * |
115 | * Use: Initializes an RC2 expanded key. The effective key size is |
116 | * set to be equal to the real key size, in bits. |
117 | */ |
118 | |
119 | void rc2_init(rc2_ctx *k, const void *buf, size_t sz) |
120 | { |
121 | rc2_braindamage(k, buf, sz, sz * 8); |
122 | } |
123 | |
124 | /*----- Encryption and decryption -----------------------------------------*/ |
125 | |
126 | #define MIX(a, b, c, d, r, kk) do { \ |
127 | a += *kk++ + (d & c) + (~d & b); \ |
128 | a = ROL16(a, r); \ |
129 | } while (0) |
130 | |
131 | #define MASH(a, d, k) do { \ |
132 | a += k[d & 63]; \ |
133 | } while (0) |
134 | |
135 | #define UNMIX(a, b, c, d, r, kk) do { \ |
136 | a = ROR16(a, r); \ |
137 | a -= *--kk + (d & c) + (~d & b); \ |
138 | } while (0) |
139 | |
140 | #define UNMASH(a, d, k) do { \ |
141 | a -= k[d & 63]; \ |
142 | } while (0) |
143 | |
144 | /* --- @rc2_eblk@, @rc2_dblk@ --- * |
145 | * |
146 | * Arguments: @const rc2_ctx *k@ = pointer to RC2 context |
147 | * @const uint32 s[2]@ = pointer to source block |
148 | * @const uint32 d[2]@ = pointer to destination block |
149 | * |
150 | * Returns: --- |
151 | * |
152 | * Use: Low-level block encryption and decryption. |
153 | */ |
154 | |
155 | void rc2_eblk(const rc2_ctx *k, const uint32 *s, uint32 *dst) |
156 | { |
157 | uint16 a = U16(s[0] >> 0), b = U16(s[0] >> 16); |
158 | uint16 c = U16(s[1] >> 0), d = U16(s[1] >> 16); |
159 | const uint16 *kk = k->k; |
160 | |
161 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
162 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
163 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
164 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
165 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
166 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
167 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
168 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
169 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
170 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
171 | MASH(a, d, k->k); MASH(b, a, k->k); |
172 | MASH(c, b, k->k); MASH(d, c, k->k); |
173 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
174 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
175 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
176 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
177 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
178 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
179 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
180 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
181 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
182 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
183 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
184 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
185 | MASH(a, d, k->k); MASH(b, a, k->k); |
186 | MASH(c, b, k->k); MASH(d, c, k->k); |
187 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
188 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
189 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
190 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
191 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
192 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
193 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
194 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
195 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
196 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
197 | |
198 | dst[0] = a | (b << 16); dst[1] = c | (d << 16); |
199 | } |
200 | |
201 | void rc2_dblk(const rc2_ctx *k, const uint32 *s, uint32 *dst) |
202 | { |
203 | uint16 a = U16(s[0] >> 0), b = U16(s[0] >> 16); |
204 | uint16 c = U16(s[1] >> 0), d = U16(s[1] >> 16); |
205 | const uint16 *kk = k->k + 64; |
206 | |
207 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
208 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
209 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
210 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
211 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
212 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
213 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
214 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
215 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
216 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
217 | UNMASH(d, c, k->k); UNMASH(c, b, k->k); |
218 | UNMASH(b, a, k->k); UNMASH(a, d, k->k); |
219 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
220 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
221 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
222 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
223 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
224 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
225 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
226 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
227 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
228 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
229 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
230 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
231 | UNMASH(d, c, k->k); UNMASH(c, b, k->k); |
232 | UNMASH(b, a, k->k); UNMASH(a, d, k->k); |
233 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
234 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
235 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
236 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
237 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
238 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
239 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
240 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
241 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
242 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
243 | |
244 | dst[0] = a | (b << 16); dst[1] = c | (d << 16); |
245 | } |
246 | |
247 | /*----- Custom test rig ---------------------------------------------------* |
248 | * |
249 | * I need to test the braindamage feature. |
250 | */ |
251 | |
252 | #ifdef TEST_RIG |
253 | |
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); |
280 | if (memcmp(b.buf, v[3].buf, RC2_BLKSZ)) { |
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); |
297 | if (memcmp(b.buf, v[2].buf, RC2_BLKSZ)) { |
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 -------------------------------------------------*/ |