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8dd8c294 | 1 | /* -*-c-*- |
8dd8c294 | 2 | * |
3 | * Implementation of the Twofish cipher | |
4 | * | |
5 | * (c) 2000 Straylight/Edgeware | |
6 | */ | |
7 | ||
45c0fd36 | 8 | /*----- Licensing notice --------------------------------------------------* |
8dd8c294 | 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. | |
45c0fd36 | 16 | * |
8dd8c294 | 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. | |
45c0fd36 | 21 | * |
8dd8c294 | 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 | ||
8dd8c294 | 28 | /*----- Header files ------------------------------------------------------*/ |
29 | ||
30 | #include <assert.h> | |
31 | ||
32 | #include <mLib/bits.h> | |
33 | ||
34 | #include "blkc.h" | |
35 | #include "gcipher.h" | |
36 | #include "twofish.h" | |
8dd8c294 | 37 | #include "paranoia.h" |
38 | ||
39 | /*----- Global variables --------------------------------------------------*/ | |
40 | ||
405497f7 | 41 | const octet twofish_keysz[] = { KSZ_RANGE, TWOFISH_KEYSZ, 0, 32, 1 }; |
8dd8c294 | 42 | |
43 | /*----- Important tables --------------------------------------------------*/ | |
44 | ||
e5b61a8d MW |
45 | extern const octet twofish_q0[256], twofish_q1[256]; |
46 | extern const uint32 twofish_qmds[4][256]; | |
47 | extern const octet twofish_rslog[], twofish_rsexp[]; | |
48 | extern const octet twofish_rs[32]; | |
49 | ||
50 | #define Q0 twofish_q0 | |
51 | #define Q1 twofish_q1 | |
52 | #define QMDS twofish_qmds | |
53 | #define RSLOG twofish_rslog | |
54 | #define RSEXP twofish_rsexp | |
55 | #define RS twofish_rs | |
8dd8c294 | 56 | |
57 | /*----- Key initialization ------------------------------------------------*/ | |
58 | ||
59 | /* --- @h@ --- * | |
60 | * | |
61 | * Arguments: @uint32 x@ = input to the function | |
62 | * @const uint32 *l@ = key values to mix in | |
63 | * @unsigned k@ = number of key values there are | |
64 | * | |
65 | * Returns: The output of the function @h@. | |
66 | * | |
67 | * Use: Implements the Twofish function @h@. | |
68 | */ | |
69 | ||
70 | static uint32 h(uint32 x, const uint32 *l, unsigned k) | |
71 | { | |
72 | /* --- Apply a series of @q@ tables to an integer --- */ | |
73 | ||
74 | # define Q(x, qa, qb, qc, qd) \ | |
e5b61a8d MW |
75 | ((qa[((x) >> 0) & 0xff] << 0) | \ |
76 | (qb[((x) >> 8) & 0xff] << 8) | \ | |
8dd8c294 | 77 | (qc[((x) >> 16) & 0xff] << 16) | \ |
78 | (qd[((x) >> 24) & 0xff] << 24)) | |
79 | ||
80 | /* --- Grind through the tables --- */ | |
81 | ||
82 | switch (k) { | |
e5b61a8d MW |
83 | case 4: x = Q(x, Q1, Q0, Q0, Q1) ^ l[3]; |
84 | case 3: x = Q(x, Q1, Q1, Q0, Q0) ^ l[2]; | |
85 | case 2: x = Q(x, Q0, Q1, Q0, Q1) ^ l[1]; | |
86 | x = Q(x, Q0, Q0, Q1, Q1) ^ l[0]; | |
8dd8c294 | 87 | break; |
88 | } | |
89 | ||
90 | #undef Q | |
91 | ||
92 | /* --- Apply the MDS matrix --- */ | |
93 | ||
e5b61a8d MW |
94 | return (QMDS[0][U8(x >> 0)] ^ QMDS[1][U8(x >> 8)] ^ |
95 | QMDS[2][U8(x >> 16)] ^ QMDS[3][U8(x >> 24)]); | |
8dd8c294 | 96 | } |
97 | ||
574d8527 | 98 | /* --- @twofish_initfk@ --- * |
8dd8c294 | 99 | * |
100 | * Arguments: @twofish_ctx *k@ = pointer to key block to fill in | |
101 | * @const void *buf@ = pointer to buffer of key material | |
102 | * @size_t sz@ = size of key material | |
574d8527 | 103 | * @const twofish_fk *fk@ = family-key information |
8dd8c294 | 104 | * |
105 | * Returns: --- | |
106 | * | |
574d8527 | 107 | * Use: Does the underlying Twofish key initialization with family |
108 | * key. Pass in a family-key structure initialized to | |
109 | * all-bits-zero for a standard key schedule. | |
8dd8c294 | 110 | */ |
111 | ||
574d8527 | 112 | void twofish_initfk(twofish_ctx *k, const void *buf, size_t sz, |
113 | const twofish_fk *fk) | |
8dd8c294 | 114 | { |
115 | # define KMAX 4 | |
116 | ||
117 | uint32 mo[KMAX], me[KMAX]; | |
118 | octet s[4][KMAX]; | |
119 | ||
120 | /* --- Expand the key into the three word arrays --- */ | |
121 | ||
122 | { | |
123 | size_t ssz; | |
124 | const octet *p, *q; | |
125 | octet b[32]; | |
126 | int i; | |
127 | ||
128 | /* --- Sort out the key size --- */ | |
129 | ||
130 | KSZ_ASSERT(twofish, sz); | |
131 | if (sz <= 16) | |
132 | ssz = 16; | |
133 | else if (sz <= 24) | |
134 | ssz = 24; | |
135 | else if (sz <= 32) | |
136 | ssz = 32; | |
137 | else | |
138 | assert(((void)"This can't happen (bad key size in twofish_init)", 0)); | |
139 | ||
140 | /* --- Extend the key if necessary --- */ | |
141 | ||
142 | if (sz == ssz) | |
143 | p = buf; | |
144 | else { | |
145 | memcpy(b, buf, sz); | |
146 | memset(b + sz, 0, ssz - sz); | |
147 | p = b; | |
148 | } | |
149 | ||
150 | /* --- Finally get the word count --- */ | |
151 | ||
152 | sz = ssz / 8; | |
153 | ||
154 | /* --- Extract words from the key --- * | |
155 | * | |
156 | * The @s@ table, constructed using the Reed-Solomon matrix, is cut into | |
157 | * sequences of bytes, since this is actually more useful for computing | |
158 | * the S-boxes. | |
159 | */ | |
160 | ||
161 | q = p; | |
162 | for (i = 0; i < sz; i++) { | |
163 | octet ss[4]; | |
e5b61a8d | 164 | const octet *r = RS; |
8dd8c294 | 165 | int j; |
166 | ||
167 | /* --- Extract the easy subkeys --- */ | |
168 | ||
574d8527 | 169 | me[i] = LOAD32_L(q) ^ fk->t0[2 * i]; |
170 | mo[i] = LOAD32_L(q + 4) ^ fk->t0[2 * i + 1]; | |
8dd8c294 | 171 | |
172 | /* --- Now do the Reed-Solomon thing --- */ | |
173 | ||
174 | for (j = 0; j < 4; j++) { | |
175 | const octet *qq = q; | |
176 | unsigned a = 0; | |
177 | int k; | |
178 | ||
179 | for (k = 0; k < 8; k++) { | |
574d8527 | 180 | unsigned char x = *qq ^ fk->t1[i * 8 + k]; |
e5b61a8d | 181 | if (x) a ^= RSEXP[RSLOG[x] + *r]; |
8dd8c294 | 182 | qq++; |
183 | r++; | |
184 | } | |
45c0fd36 | 185 | |
8dd8c294 | 186 | s[j][sz - 1 - i] = ss[j] = a; |
187 | } | |
188 | q += 8; | |
189 | } | |
190 | ||
191 | /* --- Clear away the temporary buffer --- */ | |
192 | ||
193 | if (p == b) | |
194 | BURN(b); | |
195 | } | |
196 | ||
197 | /* --- Construct the expanded key --- */ | |
198 | ||
199 | { | |
200 | uint32 p = 0x01010101; | |
201 | uint32 ip = 0; | |
202 | int i; | |
203 | ||
204 | for (i = 0; i < 40; i += 2) { | |
205 | uint32 a, b; | |
206 | a = h(ip, me, sz); | |
207 | b = h(ip + p, mo, sz); | |
208 | b = ROL32(b, 8); | |
209 | a += b; b += a; | |
210 | k->k[i] = U32(a); | |
211 | k->k[i + 1] = ROL32(b, 9); | |
212 | ip += 2 * p; | |
213 | } | |
574d8527 | 214 | |
215 | for (i = 0; i < 8; i++) | |
216 | k->k[i] ^= fk->t23[i]; | |
217 | for (i = 8; i < 40; i += 2) { | |
218 | k->k[i] ^= fk->t4[0]; | |
219 | k->k[i + 1] ^= fk->t4[1]; | |
220 | } | |
8dd8c294 | 221 | } |
222 | ||
223 | /* --- Construct the S-box tables --- */ | |
224 | ||
225 | { | |
226 | unsigned i; | |
227 | static const octet *q[4][KMAX + 1] = { | |
e5b61a8d MW |
228 | { Q1, Q0, Q0, Q1, Q1 }, |
229 | { Q0, Q0, Q1, Q1, Q0 }, | |
230 | { Q1, Q1, Q0, Q0, Q0 }, | |
231 | { Q0, Q1, Q1, Q0, Q1 } | |
8dd8c294 | 232 | }; |
233 | ||
234 | for (i = 0; i < 4; i++) { | |
235 | unsigned j; | |
236 | uint32 x; | |
237 | ||
238 | for (j = 0; j < 256; j++) { | |
239 | x = j; | |
240 | ||
241 | /* --- Push the byte through the q tables --- */ | |
242 | ||
243 | switch (sz) { | |
244 | case 4: x = q[i][4][x] ^ s[i][3]; | |
245 | case 3: x = q[i][3][x] ^ s[i][2]; | |
246 | case 2: x = q[i][2][x] ^ s[i][1]; | |
247 | x = q[i][1][x] ^ s[i][0]; | |
248 | break; | |
249 | } | |
250 | ||
251 | /* --- Write it in the key schedule --- */ | |
252 | ||
e5b61a8d | 253 | k->g[i][j] = QMDS[i][x]; |
8dd8c294 | 254 | } |
255 | } | |
256 | } | |
257 | ||
258 | /* --- Clear everything away --- */ | |
259 | ||
260 | BURN(me); | |
261 | BURN(mo); | |
262 | BURN(s); | |
263 | } | |
264 | ||
574d8527 | 265 | /* --- @twofish_init@ --- * |
266 | * | |
267 | * Arguments: @twofish_ctx *k@ = pointer to key block to fill in | |
268 | * @const void *buf@ = pointer to buffer of key material | |
269 | * @size_t sz@ = size of key material | |
270 | * | |
271 | * Returns: --- | |
272 | * | |
273 | * Use: Initializes a Twofish key buffer. Twofish accepts key sizes | |
274 | * of up to 256 bits (32 bytes). | |
275 | */ | |
276 | ||
277 | void twofish_init(twofish_ctx *k, const void *buf, size_t sz) | |
278 | { | |
4e66da02 | 279 | static const twofish_fk fk = { { 0 } }; |
574d8527 | 280 | twofish_initfk(k, buf, sz, &fk); |
281 | } | |
282 | ||
283 | /* --- @twofish_fkinit@ --- * | |
284 | * | |
285 | * Arguments: @twofish_fk *fk@ = pointer to family key block | |
286 | * @const void *buf@ = pointer to buffer of key material | |
287 | * @size_t sz@ = size of key material | |
288 | * | |
289 | * Returns: --- | |
290 | * | |
291 | * Use: Initializes a family-key buffer. This implementation allows | |
292 | * family keys of any size acceptable to the Twofish algorithm. | |
293 | */ | |
294 | ||
295 | void twofish_fkinit(twofish_fk *fk, const void *buf, size_t sz) | |
296 | { | |
297 | twofish_ctx k; | |
298 | uint32 pt[4], ct[4]; | |
299 | const octet *kk; | |
300 | unsigned i; | |
301 | ||
302 | twofish_init(&k, buf, sz); | |
303 | ||
304 | for (i = 0; i < 4; i++) pt[i] = (uint32)-1; | |
305 | twofish_eblk(&k, pt, fk->t0 + 4); | |
306 | ||
307 | kk = buf; sz /= 4; | |
308 | for (i = 0; i < sz; i++) { fk->t0[i] = LOAD32_L(kk); kk += 4; } | |
309 | ||
310 | for (i = 0; i < 4; i++) pt[i] = 0; twofish_eblk(&k, pt, ct); | |
311 | for (i = 0; i < 4; i++) STORE32_L(fk->t1 + i * 4, ct[i]); | |
312 | pt[0] = 1; twofish_eblk(&k, pt, ct); | |
313 | for (i = 0; i < 4; i++) STORE32_L(fk->t1 + 4 + i * 4, ct[i]); | |
314 | ||
315 | pt[0] = 2; twofish_eblk(&k, pt, fk->t23 + 0); | |
316 | pt[0] = 3; twofish_eblk(&k, pt, fk->t23 + 4); | |
317 | pt[0] = 4; twofish_eblk(&k, pt, ct); | |
318 | fk->t4[0] = ct[0]; fk->t4[1] = ct[1]; | |
319 | ||
320 | BURN(k); | |
321 | } | |
322 | ||
8dd8c294 | 323 | /*----- Main encryption ---------------------------------------------------*/ |
324 | ||
325 | /* --- Feistel function --- */ | |
326 | ||
327 | #define GG(k, t0, t1, x, y, kk) do { \ | |
45c0fd36 MW |
328 | t0 = (k->g[0][U8(x >> 0)] ^ \ |
329 | k->g[1][U8(x >> 8)] ^ \ | |
8dd8c294 | 330 | k->g[2][U8(x >> 16)] ^ \ |
331 | k->g[3][U8(x >> 24)]); \ | |
45c0fd36 MW |
332 | t1 = (k->g[1][U8(y >> 0)] ^ \ |
333 | k->g[2][U8(y >> 8)] ^ \ | |
8dd8c294 | 334 | k->g[3][U8(y >> 16)] ^ \ |
335 | k->g[0][U8(y >> 24)]); \ | |
336 | t0 += t1; \ | |
337 | t1 += t0; \ | |
338 | t0 += kk[0]; \ | |
339 | t1 += kk[1]; \ | |
340 | } while (0) | |
341 | ||
342 | /* --- Round operations --- */ | |
343 | ||
344 | #define EROUND(k, w, x, y, z, kk) do { \ | |
345 | uint32 _t0, _t1; \ | |
346 | GG(k, _t0, _t1, w, x, kk); \ | |
347 | kk += 2; \ | |
348 | y ^= _t0; y = ROR32(y, 1); \ | |
349 | z = ROL32(z, 1); z ^= _t1; \ | |
350 | } while (0) | |
351 | ||
352 | #define DROUND(k, w, x, y, z, kk) do { \ | |
353 | uint32 _t0, _t1; \ | |
354 | kk -= 2; \ | |
355 | GG(k, _t0, _t1, w, x, kk); \ | |
356 | y = ROL32(y, 1); y ^= _t0; \ | |
357 | z ^= _t1; z = ROR32(z, 1); \ | |
358 | } while (0) | |
359 | ||
360 | /* --- Complete encryption functions --- */ | |
361 | ||
362 | #define EBLK(k, a, b, c, d, w, x, y, z) do { \ | |
363 | const uint32 *_kk = k->k + 8; \ | |
364 | uint32 _a = a, _b = b, _c = c, _d = d; \ | |
365 | _a ^= k->k[0]; _b ^= k->k[1]; _c ^= k->k[2]; _d ^= k->k[3]; \ | |
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 | 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 | _c ^= k->k[4]; _d ^= k->k[5]; _a ^= k->k[6]; _b ^= k->k[7]; \ | |
383 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ | |
384 | } while (0) | |
385 | ||
386 | #define DBLK(k, a, b, c, d, w, x, y, z) do { \ | |
387 | const uint32 *_kk = k->k + 40; \ | |
388 | uint32 _a = a, _b = b, _c = c, _d = d; \ | |
389 | _a ^= k->k[4]; _b ^= k->k[5]; _c ^= k->k[6]; _d ^= k->k[7]; \ | |
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 | 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 | _c ^= k->k[0]; _d ^= k->k[1]; _a ^= k->k[2]; _b ^= k->k[3]; \ | |
407 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ | |
408 | } while (0) | |
409 | ||
410 | /* --- @twofish_eblk@, @twofish_dblk@ --- * | |
411 | * | |
412 | * Arguments: @const twofish_ctx *k@ = pointer to key block | |
413 | * @const uint32 s[4]@ = pointer to source block | |
414 | * @uint32 d[4]@ = pointer to destination block | |
415 | * | |
416 | * Returns: --- | |
417 | * | |
418 | * Use: Low-level block encryption and decryption. | |
419 | */ | |
420 | ||
421 | void twofish_eblk(const twofish_ctx *k, const uint32 *s, uint32 *d) | |
422 | { | |
423 | EBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); | |
424 | } | |
425 | ||
426 | void twofish_dblk(const twofish_ctx *k, const uint32 *s, uint32 *d) | |
427 | { | |
428 | DBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); | |
429 | } | |
430 | ||
431 | BLKC_TEST(TWOFISH, twofish) | |
432 | ||
433 | /*----- That's all, folks -------------------------------------------------*/ |