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8dd8c294 | 1 | /* -*-c-*- |
2 | * | |
b817bfc6 | 3 | * $Id: twofish.c,v 1.5 2004/04/08 01:36:15 mdw Exp $ |
8dd8c294 | 4 | * |
5 | * Implementation of the Twofish cipher | |
6 | * | |
7 | * (c) 2000 Straylight/Edgeware | |
8 | */ | |
9 | ||
45c0fd36 | 10 | /*----- Licensing notice --------------------------------------------------* |
8dd8c294 | 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. | |
45c0fd36 | 18 | * |
8dd8c294 | 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. | |
45c0fd36 | 23 | * |
8dd8c294 | 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 | ||
8dd8c294 | 30 | /*----- Header files ------------------------------------------------------*/ |
31 | ||
32 | #include <assert.h> | |
33 | ||
34 | #include <mLib/bits.h> | |
35 | ||
36 | #include "blkc.h" | |
37 | #include "gcipher.h" | |
38 | #include "twofish.h" | |
39 | #include "twofish-tab.h" | |
40 | #include "paranoia.h" | |
41 | ||
42 | /*----- Global variables --------------------------------------------------*/ | |
43 | ||
405497f7 | 44 | const octet twofish_keysz[] = { KSZ_RANGE, TWOFISH_KEYSZ, 0, 32, 1 }; |
8dd8c294 | 45 | |
46 | /*----- Important tables --------------------------------------------------*/ | |
47 | ||
48 | static const octet q0[256] = TWOFISH_Q0, q1[256] = TWOFISH_Q1; | |
49 | static const uint32 qmds[4][256] = TWOFISH_QMDS; | |
50 | static const octet rslog[] = TWOFISH_RSLOG, rsexp[] = TWOFISH_RSEXP; | |
51 | static const octet rs[32] = TWOFISH_RS; | |
52 | ||
53 | /*----- Key initialization ------------------------------------------------*/ | |
54 | ||
55 | /* --- @h@ --- * | |
56 | * | |
57 | * Arguments: @uint32 x@ = input to the function | |
58 | * @const uint32 *l@ = key values to mix in | |
59 | * @unsigned k@ = number of key values there are | |
60 | * | |
61 | * Returns: The output of the function @h@. | |
62 | * | |
63 | * Use: Implements the Twofish function @h@. | |
64 | */ | |
65 | ||
66 | static uint32 h(uint32 x, const uint32 *l, unsigned k) | |
67 | { | |
68 | /* --- Apply a series of @q@ tables to an integer --- */ | |
69 | ||
70 | # define Q(x, qa, qb, qc, qd) \ | |
45c0fd36 MW |
71 | ((qa[((x) >> 0) & 0xff] << 0) | \ |
72 | (qb[((x) >> 8) & 0xff] << 8) | \ | |
8dd8c294 | 73 | (qc[((x) >> 16) & 0xff] << 16) | \ |
74 | (qd[((x) >> 24) & 0xff] << 24)) | |
75 | ||
76 | /* --- Grind through the tables --- */ | |
77 | ||
78 | switch (k) { | |
79 | case 4: x = Q(x, q1, q0, q0, q1) ^ l[3]; | |
80 | case 3: x = Q(x, q1, q1, q0, q0) ^ l[2]; | |
81 | case 2: x = Q(x, q0, q1, q0, q1) ^ l[1]; | |
82 | x = Q(x, q0, q0, q1, q1) ^ l[0]; | |
83 | break; | |
84 | } | |
85 | ||
86 | #undef Q | |
87 | ||
88 | /* --- Apply the MDS matrix --- */ | |
89 | ||
90 | return (qmds[0][U8(x >> 0)] ^ qmds[1][U8(x >> 8)] ^ | |
91 | qmds[2][U8(x >> 16)] ^ qmds[3][U8(x >> 24)]); | |
92 | } | |
93 | ||
574d8527 | 94 | /* --- @twofish_initfk@ --- * |
8dd8c294 | 95 | * |
96 | * Arguments: @twofish_ctx *k@ = pointer to key block to fill in | |
97 | * @const void *buf@ = pointer to buffer of key material | |
98 | * @size_t sz@ = size of key material | |
574d8527 | 99 | * @const twofish_fk *fk@ = family-key information |
8dd8c294 | 100 | * |
101 | * Returns: --- | |
102 | * | |
574d8527 | 103 | * Use: Does the underlying Twofish key initialization with family |
104 | * key. Pass in a family-key structure initialized to | |
105 | * all-bits-zero for a standard key schedule. | |
8dd8c294 | 106 | */ |
107 | ||
574d8527 | 108 | void twofish_initfk(twofish_ctx *k, const void *buf, size_t sz, |
109 | const twofish_fk *fk) | |
8dd8c294 | 110 | { |
111 | # define KMAX 4 | |
112 | ||
113 | uint32 mo[KMAX], me[KMAX]; | |
114 | octet s[4][KMAX]; | |
115 | ||
116 | /* --- Expand the key into the three word arrays --- */ | |
117 | ||
118 | { | |
119 | size_t ssz; | |
120 | const octet *p, *q; | |
121 | octet b[32]; | |
122 | int i; | |
123 | ||
124 | /* --- Sort out the key size --- */ | |
125 | ||
126 | KSZ_ASSERT(twofish, sz); | |
127 | if (sz <= 16) | |
128 | ssz = 16; | |
129 | else if (sz <= 24) | |
130 | ssz = 24; | |
131 | else if (sz <= 32) | |
132 | ssz = 32; | |
133 | else | |
134 | assert(((void)"This can't happen (bad key size in twofish_init)", 0)); | |
135 | ||
136 | /* --- Extend the key if necessary --- */ | |
137 | ||
138 | if (sz == ssz) | |
139 | p = buf; | |
140 | else { | |
141 | memcpy(b, buf, sz); | |
142 | memset(b + sz, 0, ssz - sz); | |
143 | p = b; | |
144 | } | |
145 | ||
146 | /* --- Finally get the word count --- */ | |
147 | ||
148 | sz = ssz / 8; | |
149 | ||
150 | /* --- Extract words from the key --- * | |
151 | * | |
152 | * The @s@ table, constructed using the Reed-Solomon matrix, is cut into | |
153 | * sequences of bytes, since this is actually more useful for computing | |
154 | * the S-boxes. | |
155 | */ | |
156 | ||
157 | q = p; | |
158 | for (i = 0; i < sz; i++) { | |
159 | octet ss[4]; | |
160 | const octet *r = rs; | |
161 | int j; | |
162 | ||
163 | /* --- Extract the easy subkeys --- */ | |
164 | ||
574d8527 | 165 | me[i] = LOAD32_L(q) ^ fk->t0[2 * i]; |
166 | mo[i] = LOAD32_L(q + 4) ^ fk->t0[2 * i + 1]; | |
8dd8c294 | 167 | |
168 | /* --- Now do the Reed-Solomon thing --- */ | |
169 | ||
170 | for (j = 0; j < 4; j++) { | |
171 | const octet *qq = q; | |
172 | unsigned a = 0; | |
173 | int k; | |
174 | ||
175 | for (k = 0; k < 8; k++) { | |
574d8527 | 176 | unsigned char x = *qq ^ fk->t1[i * 8 + k]; |
177 | if (x) a ^= rsexp[rslog[x] + *r]; | |
8dd8c294 | 178 | qq++; |
179 | r++; | |
180 | } | |
45c0fd36 | 181 | |
8dd8c294 | 182 | s[j][sz - 1 - i] = ss[j] = a; |
183 | } | |
184 | q += 8; | |
185 | } | |
186 | ||
187 | /* --- Clear away the temporary buffer --- */ | |
188 | ||
189 | if (p == b) | |
190 | BURN(b); | |
191 | } | |
192 | ||
193 | /* --- Construct the expanded key --- */ | |
194 | ||
195 | { | |
196 | uint32 p = 0x01010101; | |
197 | uint32 ip = 0; | |
198 | int i; | |
199 | ||
200 | for (i = 0; i < 40; i += 2) { | |
201 | uint32 a, b; | |
202 | a = h(ip, me, sz); | |
203 | b = h(ip + p, mo, sz); | |
204 | b = ROL32(b, 8); | |
205 | a += b; b += a; | |
206 | k->k[i] = U32(a); | |
207 | k->k[i + 1] = ROL32(b, 9); | |
208 | ip += 2 * p; | |
209 | } | |
574d8527 | 210 | |
211 | for (i = 0; i < 8; i++) | |
212 | k->k[i] ^= fk->t23[i]; | |
213 | for (i = 8; i < 40; i += 2) { | |
214 | k->k[i] ^= fk->t4[0]; | |
215 | k->k[i + 1] ^= fk->t4[1]; | |
216 | } | |
8dd8c294 | 217 | } |
218 | ||
219 | /* --- Construct the S-box tables --- */ | |
220 | ||
221 | { | |
222 | unsigned i; | |
223 | static const octet *q[4][KMAX + 1] = { | |
224 | { q1, q0, q0, q1, q1 }, | |
225 | { q0, q0, q1, q1, q0 }, | |
226 | { q1, q1, q0, q0, q0 }, | |
227 | { q0, q1, q1, q0, q1 } | |
228 | }; | |
229 | ||
230 | for (i = 0; i < 4; i++) { | |
231 | unsigned j; | |
232 | uint32 x; | |
233 | ||
234 | for (j = 0; j < 256; j++) { | |
235 | x = j; | |
236 | ||
237 | /* --- Push the byte through the q tables --- */ | |
238 | ||
239 | switch (sz) { | |
240 | case 4: x = q[i][4][x] ^ s[i][3]; | |
241 | case 3: x = q[i][3][x] ^ s[i][2]; | |
242 | case 2: x = q[i][2][x] ^ s[i][1]; | |
243 | x = q[i][1][x] ^ s[i][0]; | |
244 | break; | |
245 | } | |
246 | ||
247 | /* --- Write it in the key schedule --- */ | |
248 | ||
249 | k->g[i][j] = qmds[i][x]; | |
250 | } | |
251 | } | |
252 | } | |
253 | ||
254 | /* --- Clear everything away --- */ | |
255 | ||
256 | BURN(me); | |
257 | BURN(mo); | |
258 | BURN(s); | |
259 | } | |
260 | ||
574d8527 | 261 | /* --- @twofish_init@ --- * |
262 | * | |
263 | * Arguments: @twofish_ctx *k@ = pointer to key block to fill in | |
264 | * @const void *buf@ = pointer to buffer of key material | |
265 | * @size_t sz@ = size of key material | |
266 | * | |
267 | * Returns: --- | |
268 | * | |
269 | * Use: Initializes a Twofish key buffer. Twofish accepts key sizes | |
270 | * of up to 256 bits (32 bytes). | |
271 | */ | |
272 | ||
273 | void twofish_init(twofish_ctx *k, const void *buf, size_t sz) | |
274 | { | |
4e66da02 | 275 | static const twofish_fk fk = { { 0 } }; |
574d8527 | 276 | twofish_initfk(k, buf, sz, &fk); |
277 | } | |
278 | ||
279 | /* --- @twofish_fkinit@ --- * | |
280 | * | |
281 | * Arguments: @twofish_fk *fk@ = pointer to family key block | |
282 | * @const void *buf@ = pointer to buffer of key material | |
283 | * @size_t sz@ = size of key material | |
284 | * | |
285 | * Returns: --- | |
286 | * | |
287 | * Use: Initializes a family-key buffer. This implementation allows | |
288 | * family keys of any size acceptable to the Twofish algorithm. | |
289 | */ | |
290 | ||
291 | void twofish_fkinit(twofish_fk *fk, const void *buf, size_t sz) | |
292 | { | |
293 | twofish_ctx k; | |
294 | uint32 pt[4], ct[4]; | |
295 | const octet *kk; | |
296 | unsigned i; | |
297 | ||
298 | twofish_init(&k, buf, sz); | |
299 | ||
300 | for (i = 0; i < 4; i++) pt[i] = (uint32)-1; | |
301 | twofish_eblk(&k, pt, fk->t0 + 4); | |
302 | ||
303 | kk = buf; sz /= 4; | |
304 | for (i = 0; i < sz; i++) { fk->t0[i] = LOAD32_L(kk); kk += 4; } | |
305 | ||
306 | for (i = 0; i < 4; i++) pt[i] = 0; twofish_eblk(&k, pt, ct); | |
307 | for (i = 0; i < 4; i++) STORE32_L(fk->t1 + i * 4, ct[i]); | |
308 | pt[0] = 1; twofish_eblk(&k, pt, ct); | |
309 | for (i = 0; i < 4; i++) STORE32_L(fk->t1 + 4 + i * 4, ct[i]); | |
310 | ||
311 | pt[0] = 2; twofish_eblk(&k, pt, fk->t23 + 0); | |
312 | pt[0] = 3; twofish_eblk(&k, pt, fk->t23 + 4); | |
313 | pt[0] = 4; twofish_eblk(&k, pt, ct); | |
314 | fk->t4[0] = ct[0]; fk->t4[1] = ct[1]; | |
315 | ||
316 | BURN(k); | |
317 | } | |
318 | ||
8dd8c294 | 319 | /*----- Main encryption ---------------------------------------------------*/ |
320 | ||
321 | /* --- Feistel function --- */ | |
322 | ||
323 | #define GG(k, t0, t1, x, y, kk) do { \ | |
45c0fd36 MW |
324 | t0 = (k->g[0][U8(x >> 0)] ^ \ |
325 | k->g[1][U8(x >> 8)] ^ \ | |
8dd8c294 | 326 | k->g[2][U8(x >> 16)] ^ \ |
327 | k->g[3][U8(x >> 24)]); \ | |
45c0fd36 MW |
328 | t1 = (k->g[1][U8(y >> 0)] ^ \ |
329 | k->g[2][U8(y >> 8)] ^ \ | |
8dd8c294 | 330 | k->g[3][U8(y >> 16)] ^ \ |
331 | k->g[0][U8(y >> 24)]); \ | |
332 | t0 += t1; \ | |
333 | t1 += t0; \ | |
334 | t0 += kk[0]; \ | |
335 | t1 += kk[1]; \ | |
336 | } while (0) | |
337 | ||
338 | /* --- Round operations --- */ | |
339 | ||
340 | #define EROUND(k, w, x, y, z, kk) do { \ | |
341 | uint32 _t0, _t1; \ | |
342 | GG(k, _t0, _t1, w, x, kk); \ | |
343 | kk += 2; \ | |
344 | y ^= _t0; y = ROR32(y, 1); \ | |
345 | z = ROL32(z, 1); z ^= _t1; \ | |
346 | } while (0) | |
347 | ||
348 | #define DROUND(k, w, x, y, z, kk) do { \ | |
349 | uint32 _t0, _t1; \ | |
350 | kk -= 2; \ | |
351 | GG(k, _t0, _t1, w, x, kk); \ | |
352 | y = ROL32(y, 1); y ^= _t0; \ | |
353 | z ^= _t1; z = ROR32(z, 1); \ | |
354 | } while (0) | |
355 | ||
356 | /* --- Complete encryption functions --- */ | |
357 | ||
358 | #define EBLK(k, a, b, c, d, w, x, y, z) do { \ | |
359 | const uint32 *_kk = k->k + 8; \ | |
360 | uint32 _a = a, _b = b, _c = c, _d = d; \ | |
361 | _a ^= k->k[0]; _b ^= k->k[1]; _c ^= k->k[2]; _d ^= k->k[3]; \ | |
362 | EROUND(k, _a, _b, _c, _d, _kk); \ | |
363 | EROUND(k, _c, _d, _a, _b, _kk); \ | |
364 | EROUND(k, _a, _b, _c, _d, _kk); \ | |
365 | EROUND(k, _c, _d, _a, _b, _kk); \ | |
366 | EROUND(k, _a, _b, _c, _d, _kk); \ | |
367 | EROUND(k, _c, _d, _a, _b, _kk); \ | |
368 | EROUND(k, _a, _b, _c, _d, _kk); \ | |
369 | EROUND(k, _c, _d, _a, _b, _kk); \ | |
370 | EROUND(k, _a, _b, _c, _d, _kk); \ | |
371 | EROUND(k, _c, _d, _a, _b, _kk); \ | |
372 | EROUND(k, _a, _b, _c, _d, _kk); \ | |
373 | EROUND(k, _c, _d, _a, _b, _kk); \ | |
374 | EROUND(k, _a, _b, _c, _d, _kk); \ | |
375 | EROUND(k, _c, _d, _a, _b, _kk); \ | |
376 | EROUND(k, _a, _b, _c, _d, _kk); \ | |
377 | EROUND(k, _c, _d, _a, _b, _kk); \ | |
378 | _c ^= k->k[4]; _d ^= k->k[5]; _a ^= k->k[6]; _b ^= k->k[7]; \ | |
379 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ | |
380 | } while (0) | |
381 | ||
382 | #define DBLK(k, a, b, c, d, w, x, y, z) do { \ | |
383 | const uint32 *_kk = k->k + 40; \ | |
384 | uint32 _a = a, _b = b, _c = c, _d = d; \ | |
385 | _a ^= k->k[4]; _b ^= k->k[5]; _c ^= k->k[6]; _d ^= k->k[7]; \ | |
386 | DROUND(k, _a, _b, _c, _d, _kk); \ | |
387 | DROUND(k, _c, _d, _a, _b, _kk); \ | |
388 | DROUND(k, _a, _b, _c, _d, _kk); \ | |
389 | DROUND(k, _c, _d, _a, _b, _kk); \ | |
390 | DROUND(k, _a, _b, _c, _d, _kk); \ | |
391 | DROUND(k, _c, _d, _a, _b, _kk); \ | |
392 | DROUND(k, _a, _b, _c, _d, _kk); \ | |
393 | DROUND(k, _c, _d, _a, _b, _kk); \ | |
394 | DROUND(k, _a, _b, _c, _d, _kk); \ | |
395 | DROUND(k, _c, _d, _a, _b, _kk); \ | |
396 | DROUND(k, _a, _b, _c, _d, _kk); \ | |
397 | DROUND(k, _c, _d, _a, _b, _kk); \ | |
398 | DROUND(k, _a, _b, _c, _d, _kk); \ | |
399 | DROUND(k, _c, _d, _a, _b, _kk); \ | |
400 | DROUND(k, _a, _b, _c, _d, _kk); \ | |
401 | DROUND(k, _c, _d, _a, _b, _kk); \ | |
402 | _c ^= k->k[0]; _d ^= k->k[1]; _a ^= k->k[2]; _b ^= k->k[3]; \ | |
403 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ | |
404 | } while (0) | |
405 | ||
406 | /* --- @twofish_eblk@, @twofish_dblk@ --- * | |
407 | * | |
408 | * Arguments: @const twofish_ctx *k@ = pointer to key block | |
409 | * @const uint32 s[4]@ = pointer to source block | |
410 | * @uint32 d[4]@ = pointer to destination block | |
411 | * | |
412 | * Returns: --- | |
413 | * | |
414 | * Use: Low-level block encryption and decryption. | |
415 | */ | |
416 | ||
417 | void twofish_eblk(const twofish_ctx *k, const uint32 *s, uint32 *d) | |
418 | { | |
419 | EBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); | |
420 | } | |
421 | ||
422 | void twofish_dblk(const twofish_ctx *k, const uint32 *s, uint32 *d) | |
423 | { | |
424 | DBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); | |
425 | } | |
426 | ||
427 | BLKC_TEST(TWOFISH, twofish) | |
428 | ||
429 | /*----- That's all, folks -------------------------------------------------*/ |