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1 | /* -*-c-*- |
2 | * |
b817bfc6 |
3 | * $Id: twofish.c,v 1.5 2004/04/08 01:36:15 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 | |
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 }; |
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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) \ |
71 | ((qa[((x) >> 0) & 0xff] << 0) | \ |
72 | (qb[((x) >> 8) & 0xff] << 8) | \ |
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@ --- * |
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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 |
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99 | * @const twofish_fk *fk@ = family-key information |
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100 | * |
101 | * Returns: --- |
102 | * |
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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. |
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106 | */ |
107 | |
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108 | void twofish_initfk(twofish_ctx *k, const void *buf, size_t sz, |
109 | const twofish_fk *fk) |
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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]; |
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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]; |
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178 | qq++; |
179 | r++; |
180 | } |
181 | |
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 | } |
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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 | } |
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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 | { |
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275 | static const twofish_fk fk = { { 0 } }; |
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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 | |
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319 | /*----- Main encryption ---------------------------------------------------*/ |
320 | |
321 | /* --- Feistel function --- */ |
322 | |
323 | #define GG(k, t0, t1, x, y, kk) do { \ |
324 | t0 = (k->g[0][U8(x >> 0)] ^ \ |
325 | k->g[1][U8(x >> 8)] ^ \ |
326 | k->g[2][U8(x >> 16)] ^ \ |
327 | k->g[3][U8(x >> 24)]); \ |
328 | t1 = (k->g[1][U8(y >> 0)] ^ \ |
329 | k->g[2][U8(y >> 8)] ^ \ |
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 -------------------------------------------------*/ |