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[u/mdw/catacomb] / symm / rc2.c
1 /* -*-c-*-
2 *
3 * The RC2 block cipher
4 *
5 * (c) 2000 Straylight/Edgeware
6 */
7
8 /*----- Licensing notice --------------------------------------------------*
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.
16 *
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.
21 *
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
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 #include "rc2-tab.h"
40
41 /*----- Global variables --------------------------------------------------*/
42
43 const octet rc2_keysz[] = { KSZ_RANGE, RC2_KEYSZ, 1, 128, 1 };
44
45 /*----- Important tables --------------------------------------------------*/
46
47 static const octet pi[256] = RC2_PI;
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:"
283 "\n\tkey = ");
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:"
300 "\n\tkey = ");
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 {
321 test_run(argc, argv, defs, SRCDIR"/t/rc2");
322 return (0);
323 }
324
325 #endif
326
327 /*----- That's all, folks -------------------------------------------------*/
Catacomb cryptographic library (downstream of http://git.distorted.org.uk/~mdw/catacomb/)