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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: twofish.c,v 1.4 2004/04/02 01:03:49 mdw Exp $ |
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4 | * |
5 | * Implementation of the Twofish 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: twofish.c,v $ |
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33 | * Revision 1.4 2004/04/02 01:03:49 mdw |
34 | * Miscellaneous constification. |
35 | * |
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36 | * Revision 1.3 2002/01/13 13:37:59 mdw |
37 | * Add support for Twofish family keys. |
38 | * |
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39 | * Revision 1.2 2000/06/22 18:58:00 mdw |
40 | * Twofish can handle keys with any byte-aligned size. |
41 | * |
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42 | * Revision 1.1 2000/06/17 12:10:17 mdw |
43 | * New cipher. |
44 | * |
45 | */ |
46 | |
47 | /*----- Header files ------------------------------------------------------*/ |
48 | |
49 | #include <assert.h> |
50 | |
51 | #include <mLib/bits.h> |
52 | |
53 | #include "blkc.h" |
54 | #include "gcipher.h" |
55 | #include "twofish.h" |
56 | #include "twofish-tab.h" |
57 | #include "paranoia.h" |
58 | |
59 | /*----- Global variables --------------------------------------------------*/ |
60 | |
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61 | const octet twofish_keysz[] = { KSZ_RANGE, TWOFISH_KEYSZ, 0, 32, 1 }; |
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62 | |
63 | /*----- Important tables --------------------------------------------------*/ |
64 | |
65 | static const octet q0[256] = TWOFISH_Q0, q1[256] = TWOFISH_Q1; |
66 | static const uint32 qmds[4][256] = TWOFISH_QMDS; |
67 | static const octet rslog[] = TWOFISH_RSLOG, rsexp[] = TWOFISH_RSEXP; |
68 | static const octet rs[32] = TWOFISH_RS; |
69 | |
70 | /*----- Key initialization ------------------------------------------------*/ |
71 | |
72 | /* --- @h@ --- * |
73 | * |
74 | * Arguments: @uint32 x@ = input to the function |
75 | * @const uint32 *l@ = key values to mix in |
76 | * @unsigned k@ = number of key values there are |
77 | * |
78 | * Returns: The output of the function @h@. |
79 | * |
80 | * Use: Implements the Twofish function @h@. |
81 | */ |
82 | |
83 | static uint32 h(uint32 x, const uint32 *l, unsigned k) |
84 | { |
85 | /* --- Apply a series of @q@ tables to an integer --- */ |
86 | |
87 | # define Q(x, qa, qb, qc, qd) \ |
88 | ((qa[((x) >> 0) & 0xff] << 0) | \ |
89 | (qb[((x) >> 8) & 0xff] << 8) | \ |
90 | (qc[((x) >> 16) & 0xff] << 16) | \ |
91 | (qd[((x) >> 24) & 0xff] << 24)) |
92 | |
93 | /* --- Grind through the tables --- */ |
94 | |
95 | switch (k) { |
96 | case 4: x = Q(x, q1, q0, q0, q1) ^ l[3]; |
97 | case 3: x = Q(x, q1, q1, q0, q0) ^ l[2]; |
98 | case 2: x = Q(x, q0, q1, q0, q1) ^ l[1]; |
99 | x = Q(x, q0, q0, q1, q1) ^ l[0]; |
100 | break; |
101 | } |
102 | |
103 | #undef Q |
104 | |
105 | /* --- Apply the MDS matrix --- */ |
106 | |
107 | return (qmds[0][U8(x >> 0)] ^ qmds[1][U8(x >> 8)] ^ |
108 | qmds[2][U8(x >> 16)] ^ qmds[3][U8(x >> 24)]); |
109 | } |
110 | |
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111 | /* --- @twofish_initfk@ --- * |
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112 | * |
113 | * Arguments: @twofish_ctx *k@ = pointer to key block to fill in |
114 | * @const void *buf@ = pointer to buffer of key material |
115 | * @size_t sz@ = size of key material |
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116 | * @const twofish_fk *fk@ = family-key information |
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117 | * |
118 | * Returns: --- |
119 | * |
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120 | * Use: Does the underlying Twofish key initialization with family |
121 | * key. Pass in a family-key structure initialized to |
122 | * all-bits-zero for a standard key schedule. |
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123 | */ |
124 | |
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125 | void twofish_initfk(twofish_ctx *k, const void *buf, size_t sz, |
126 | const twofish_fk *fk) |
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127 | { |
128 | # define KMAX 4 |
129 | |
130 | uint32 mo[KMAX], me[KMAX]; |
131 | octet s[4][KMAX]; |
132 | |
133 | /* --- Expand the key into the three word arrays --- */ |
134 | |
135 | { |
136 | size_t ssz; |
137 | const octet *p, *q; |
138 | octet b[32]; |
139 | int i; |
140 | |
141 | /* --- Sort out the key size --- */ |
142 | |
143 | KSZ_ASSERT(twofish, sz); |
144 | if (sz <= 16) |
145 | ssz = 16; |
146 | else if (sz <= 24) |
147 | ssz = 24; |
148 | else if (sz <= 32) |
149 | ssz = 32; |
150 | else |
151 | assert(((void)"This can't happen (bad key size in twofish_init)", 0)); |
152 | |
153 | /* --- Extend the key if necessary --- */ |
154 | |
155 | if (sz == ssz) |
156 | p = buf; |
157 | else { |
158 | memcpy(b, buf, sz); |
159 | memset(b + sz, 0, ssz - sz); |
160 | p = b; |
161 | } |
162 | |
163 | /* --- Finally get the word count --- */ |
164 | |
165 | sz = ssz / 8; |
166 | |
167 | /* --- Extract words from the key --- * |
168 | * |
169 | * The @s@ table, constructed using the Reed-Solomon matrix, is cut into |
170 | * sequences of bytes, since this is actually more useful for computing |
171 | * the S-boxes. |
172 | */ |
173 | |
174 | q = p; |
175 | for (i = 0; i < sz; i++) { |
176 | octet ss[4]; |
177 | const octet *r = rs; |
178 | int j; |
179 | |
180 | /* --- Extract the easy subkeys --- */ |
181 | |
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182 | me[i] = LOAD32_L(q) ^ fk->t0[2 * i]; |
183 | mo[i] = LOAD32_L(q + 4) ^ fk->t0[2 * i + 1]; |
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184 | |
185 | /* --- Now do the Reed-Solomon thing --- */ |
186 | |
187 | for (j = 0; j < 4; j++) { |
188 | const octet *qq = q; |
189 | unsigned a = 0; |
190 | int k; |
191 | |
192 | for (k = 0; k < 8; k++) { |
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193 | unsigned char x = *qq ^ fk->t1[i * 8 + k]; |
194 | if (x) a ^= rsexp[rslog[x] + *r]; |
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195 | qq++; |
196 | r++; |
197 | } |
198 | |
199 | s[j][sz - 1 - i] = ss[j] = a; |
200 | } |
201 | q += 8; |
202 | } |
203 | |
204 | /* --- Clear away the temporary buffer --- */ |
205 | |
206 | if (p == b) |
207 | BURN(b); |
208 | } |
209 | |
210 | /* --- Construct the expanded key --- */ |
211 | |
212 | { |
213 | uint32 p = 0x01010101; |
214 | uint32 ip = 0; |
215 | int i; |
216 | |
217 | for (i = 0; i < 40; i += 2) { |
218 | uint32 a, b; |
219 | a = h(ip, me, sz); |
220 | b = h(ip + p, mo, sz); |
221 | b = ROL32(b, 8); |
222 | a += b; b += a; |
223 | k->k[i] = U32(a); |
224 | k->k[i + 1] = ROL32(b, 9); |
225 | ip += 2 * p; |
226 | } |
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227 | |
228 | for (i = 0; i < 8; i++) |
229 | k->k[i] ^= fk->t23[i]; |
230 | for (i = 8; i < 40; i += 2) { |
231 | k->k[i] ^= fk->t4[0]; |
232 | k->k[i + 1] ^= fk->t4[1]; |
233 | } |
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234 | } |
235 | |
236 | /* --- Construct the S-box tables --- */ |
237 | |
238 | { |
239 | unsigned i; |
240 | static const octet *q[4][KMAX + 1] = { |
241 | { q1, q0, q0, q1, q1 }, |
242 | { q0, q0, q1, q1, q0 }, |
243 | { q1, q1, q0, q0, q0 }, |
244 | { q0, q1, q1, q0, q1 } |
245 | }; |
246 | |
247 | for (i = 0; i < 4; i++) { |
248 | unsigned j; |
249 | uint32 x; |
250 | |
251 | for (j = 0; j < 256; j++) { |
252 | x = j; |
253 | |
254 | /* --- Push the byte through the q tables --- */ |
255 | |
256 | switch (sz) { |
257 | case 4: x = q[i][4][x] ^ s[i][3]; |
258 | case 3: x = q[i][3][x] ^ s[i][2]; |
259 | case 2: x = q[i][2][x] ^ s[i][1]; |
260 | x = q[i][1][x] ^ s[i][0]; |
261 | break; |
262 | } |
263 | |
264 | /* --- Write it in the key schedule --- */ |
265 | |
266 | k->g[i][j] = qmds[i][x]; |
267 | } |
268 | } |
269 | } |
270 | |
271 | /* --- Clear everything away --- */ |
272 | |
273 | BURN(me); |
274 | BURN(mo); |
275 | BURN(s); |
276 | } |
277 | |
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278 | /* --- @twofish_init@ --- * |
279 | * |
280 | * Arguments: @twofish_ctx *k@ = pointer to key block to fill in |
281 | * @const void *buf@ = pointer to buffer of key material |
282 | * @size_t sz@ = size of key material |
283 | * |
284 | * Returns: --- |
285 | * |
286 | * Use: Initializes a Twofish key buffer. Twofish accepts key sizes |
287 | * of up to 256 bits (32 bytes). |
288 | */ |
289 | |
290 | void twofish_init(twofish_ctx *k, const void *buf, size_t sz) |
291 | { |
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292 | static const twofish_fk fk = { { 0 } }; |
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293 | twofish_initfk(k, buf, sz, &fk); |
294 | } |
295 | |
296 | /* --- @twofish_fkinit@ --- * |
297 | * |
298 | * Arguments: @twofish_fk *fk@ = pointer to family key block |
299 | * @const void *buf@ = pointer to buffer of key material |
300 | * @size_t sz@ = size of key material |
301 | * |
302 | * Returns: --- |
303 | * |
304 | * Use: Initializes a family-key buffer. This implementation allows |
305 | * family keys of any size acceptable to the Twofish algorithm. |
306 | */ |
307 | |
308 | void twofish_fkinit(twofish_fk *fk, const void *buf, size_t sz) |
309 | { |
310 | twofish_ctx k; |
311 | uint32 pt[4], ct[4]; |
312 | const octet *kk; |
313 | unsigned i; |
314 | |
315 | twofish_init(&k, buf, sz); |
316 | |
317 | for (i = 0; i < 4; i++) pt[i] = (uint32)-1; |
318 | twofish_eblk(&k, pt, fk->t0 + 4); |
319 | |
320 | kk = buf; sz /= 4; |
321 | for (i = 0; i < sz; i++) { fk->t0[i] = LOAD32_L(kk); kk += 4; } |
322 | |
323 | for (i = 0; i < 4; i++) pt[i] = 0; twofish_eblk(&k, pt, ct); |
324 | for (i = 0; i < 4; i++) STORE32_L(fk->t1 + i * 4, ct[i]); |
325 | pt[0] = 1; twofish_eblk(&k, pt, ct); |
326 | for (i = 0; i < 4; i++) STORE32_L(fk->t1 + 4 + i * 4, ct[i]); |
327 | |
328 | pt[0] = 2; twofish_eblk(&k, pt, fk->t23 + 0); |
329 | pt[0] = 3; twofish_eblk(&k, pt, fk->t23 + 4); |
330 | pt[0] = 4; twofish_eblk(&k, pt, ct); |
331 | fk->t4[0] = ct[0]; fk->t4[1] = ct[1]; |
332 | |
333 | BURN(k); |
334 | } |
335 | |
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336 | /*----- Main encryption ---------------------------------------------------*/ |
337 | |
338 | /* --- Feistel function --- */ |
339 | |
340 | #define GG(k, t0, t1, x, y, kk) do { \ |
341 | t0 = (k->g[0][U8(x >> 0)] ^ \ |
342 | k->g[1][U8(x >> 8)] ^ \ |
343 | k->g[2][U8(x >> 16)] ^ \ |
344 | k->g[3][U8(x >> 24)]); \ |
345 | t1 = (k->g[1][U8(y >> 0)] ^ \ |
346 | k->g[2][U8(y >> 8)] ^ \ |
347 | k->g[3][U8(y >> 16)] ^ \ |
348 | k->g[0][U8(y >> 24)]); \ |
349 | t0 += t1; \ |
350 | t1 += t0; \ |
351 | t0 += kk[0]; \ |
352 | t1 += kk[1]; \ |
353 | } while (0) |
354 | |
355 | /* --- Round operations --- */ |
356 | |
357 | #define EROUND(k, w, x, y, z, kk) do { \ |
358 | uint32 _t0, _t1; \ |
359 | GG(k, _t0, _t1, w, x, kk); \ |
360 | kk += 2; \ |
361 | y ^= _t0; y = ROR32(y, 1); \ |
362 | z = ROL32(z, 1); z ^= _t1; \ |
363 | } while (0) |
364 | |
365 | #define DROUND(k, w, x, y, z, kk) do { \ |
366 | uint32 _t0, _t1; \ |
367 | kk -= 2; \ |
368 | GG(k, _t0, _t1, w, x, kk); \ |
369 | y = ROL32(y, 1); y ^= _t0; \ |
370 | z ^= _t1; z = ROR32(z, 1); \ |
371 | } while (0) |
372 | |
373 | /* --- Complete encryption functions --- */ |
374 | |
375 | #define EBLK(k, a, b, c, d, w, x, y, z) do { \ |
376 | const uint32 *_kk = k->k + 8; \ |
377 | uint32 _a = a, _b = b, _c = c, _d = d; \ |
378 | _a ^= k->k[0]; _b ^= k->k[1]; _c ^= k->k[2]; _d ^= k->k[3]; \ |
379 | EROUND(k, _a, _b, _c, _d, _kk); \ |
380 | EROUND(k, _c, _d, _a, _b, _kk); \ |
381 | EROUND(k, _a, _b, _c, _d, _kk); \ |
382 | EROUND(k, _c, _d, _a, _b, _kk); \ |
383 | EROUND(k, _a, _b, _c, _d, _kk); \ |
384 | EROUND(k, _c, _d, _a, _b, _kk); \ |
385 | EROUND(k, _a, _b, _c, _d, _kk); \ |
386 | EROUND(k, _c, _d, _a, _b, _kk); \ |
387 | EROUND(k, _a, _b, _c, _d, _kk); \ |
388 | EROUND(k, _c, _d, _a, _b, _kk); \ |
389 | EROUND(k, _a, _b, _c, _d, _kk); \ |
390 | EROUND(k, _c, _d, _a, _b, _kk); \ |
391 | EROUND(k, _a, _b, _c, _d, _kk); \ |
392 | EROUND(k, _c, _d, _a, _b, _kk); \ |
393 | EROUND(k, _a, _b, _c, _d, _kk); \ |
394 | EROUND(k, _c, _d, _a, _b, _kk); \ |
395 | _c ^= k->k[4]; _d ^= k->k[5]; _a ^= k->k[6]; _b ^= k->k[7]; \ |
396 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ |
397 | } while (0) |
398 | |
399 | #define DBLK(k, a, b, c, d, w, x, y, z) do { \ |
400 | const uint32 *_kk = k->k + 40; \ |
401 | uint32 _a = a, _b = b, _c = c, _d = d; \ |
402 | _a ^= k->k[4]; _b ^= k->k[5]; _c ^= k->k[6]; _d ^= k->k[7]; \ |
403 | DROUND(k, _a, _b, _c, _d, _kk); \ |
404 | DROUND(k, _c, _d, _a, _b, _kk); \ |
405 | DROUND(k, _a, _b, _c, _d, _kk); \ |
406 | DROUND(k, _c, _d, _a, _b, _kk); \ |
407 | DROUND(k, _a, _b, _c, _d, _kk); \ |
408 | DROUND(k, _c, _d, _a, _b, _kk); \ |
409 | DROUND(k, _a, _b, _c, _d, _kk); \ |
410 | DROUND(k, _c, _d, _a, _b, _kk); \ |
411 | DROUND(k, _a, _b, _c, _d, _kk); \ |
412 | DROUND(k, _c, _d, _a, _b, _kk); \ |
413 | DROUND(k, _a, _b, _c, _d, _kk); \ |
414 | DROUND(k, _c, _d, _a, _b, _kk); \ |
415 | DROUND(k, _a, _b, _c, _d, _kk); \ |
416 | DROUND(k, _c, _d, _a, _b, _kk); \ |
417 | DROUND(k, _a, _b, _c, _d, _kk); \ |
418 | DROUND(k, _c, _d, _a, _b, _kk); \ |
419 | _c ^= k->k[0]; _d ^= k->k[1]; _a ^= k->k[2]; _b ^= k->k[3]; \ |
420 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ |
421 | } while (0) |
422 | |
423 | /* --- @twofish_eblk@, @twofish_dblk@ --- * |
424 | * |
425 | * Arguments: @const twofish_ctx *k@ = pointer to key block |
426 | * @const uint32 s[4]@ = pointer to source block |
427 | * @uint32 d[4]@ = pointer to destination block |
428 | * |
429 | * Returns: --- |
430 | * |
431 | * Use: Low-level block encryption and decryption. |
432 | */ |
433 | |
434 | void twofish_eblk(const twofish_ctx *k, const uint32 *s, uint32 *d) |
435 | { |
436 | EBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); |
437 | } |
438 | |
439 | void twofish_dblk(const twofish_ctx *k, const uint32 *s, uint32 *d) |
440 | { |
441 | DBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); |
442 | } |
443 | |
444 | BLKC_TEST(TWOFISH, twofish) |
445 | |
446 | /*----- That's all, folks -------------------------------------------------*/ |