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