8dd8c294 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: twofish.c,v 1.1 2000/06/17 12:10:17 mdw Exp $ |
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 $ |
33 | * Revision 1.1 2000/06/17 12:10:17 mdw |
34 | * New cipher. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include <assert.h> |
41 | |
42 | #include <mLib/bits.h> |
43 | |
44 | #include "blkc.h" |
45 | #include "gcipher.h" |
46 | #include "twofish.h" |
47 | #include "twofish-tab.h" |
48 | #include "paranoia.h" |
49 | |
50 | /*----- Global variables --------------------------------------------------*/ |
51 | |
52 | const octet twofish_keysz[] = { KSZ_RANGE, TWOFISH_KEYSZ, 4, 32, 4 }; |
53 | |
54 | /*----- Important tables --------------------------------------------------*/ |
55 | |
56 | static const octet q0[256] = TWOFISH_Q0, q1[256] = TWOFISH_Q1; |
57 | static const uint32 qmds[4][256] = TWOFISH_QMDS; |
58 | static const octet rslog[] = TWOFISH_RSLOG, rsexp[] = TWOFISH_RSEXP; |
59 | static const octet rs[32] = TWOFISH_RS; |
60 | |
61 | /*----- Key initialization ------------------------------------------------*/ |
62 | |
63 | /* --- @h@ --- * |
64 | * |
65 | * Arguments: @uint32 x@ = input to the function |
66 | * @const uint32 *l@ = key values to mix in |
67 | * @unsigned k@ = number of key values there are |
68 | * |
69 | * Returns: The output of the function @h@. |
70 | * |
71 | * Use: Implements the Twofish function @h@. |
72 | */ |
73 | |
74 | static uint32 h(uint32 x, const uint32 *l, unsigned k) |
75 | { |
76 | /* --- Apply a series of @q@ tables to an integer --- */ |
77 | |
78 | # define Q(x, qa, qb, qc, qd) \ |
79 | ((qa[((x) >> 0) & 0xff] << 0) | \ |
80 | (qb[((x) >> 8) & 0xff] << 8) | \ |
81 | (qc[((x) >> 16) & 0xff] << 16) | \ |
82 | (qd[((x) >> 24) & 0xff] << 24)) |
83 | |
84 | /* --- Grind through the tables --- */ |
85 | |
86 | switch (k) { |
87 | case 4: x = Q(x, q1, q0, q0, q1) ^ l[3]; |
88 | case 3: x = Q(x, q1, q1, q0, q0) ^ l[2]; |
89 | case 2: x = Q(x, q0, q1, q0, q1) ^ l[1]; |
90 | x = Q(x, q0, q0, q1, q1) ^ l[0]; |
91 | break; |
92 | } |
93 | |
94 | #undef Q |
95 | |
96 | /* --- Apply the MDS matrix --- */ |
97 | |
98 | return (qmds[0][U8(x >> 0)] ^ qmds[1][U8(x >> 8)] ^ |
99 | qmds[2][U8(x >> 16)] ^ qmds[3][U8(x >> 24)]); |
100 | } |
101 | |
102 | /* --- @twofish_init@ --- * |
103 | * |
104 | * Arguments: @twofish_ctx *k@ = pointer to key block to fill in |
105 | * @const void *buf@ = pointer to buffer of key material |
106 | * @size_t sz@ = size of key material |
107 | * |
108 | * Returns: --- |
109 | * |
110 | * Use: Initializes a Twofish key buffer. Twofish accepts key sizes |
111 | * of up to 256 bits (32 bytes). |
112 | */ |
113 | |
114 | void twofish_init(twofish_ctx *k, const void *buf, size_t sz) |
115 | { |
116 | # define KMAX 4 |
117 | |
118 | uint32 mo[KMAX], me[KMAX]; |
119 | octet s[4][KMAX]; |
120 | |
121 | /* --- Expand the key into the three word arrays --- */ |
122 | |
123 | { |
124 | size_t ssz; |
125 | const octet *p, *q; |
126 | octet b[32]; |
127 | int i; |
128 | |
129 | /* --- Sort out the key size --- */ |
130 | |
131 | KSZ_ASSERT(twofish, sz); |
132 | if (sz <= 16) |
133 | ssz = 16; |
134 | else if (sz <= 24) |
135 | ssz = 24; |
136 | else if (sz <= 32) |
137 | ssz = 32; |
138 | else |
139 | assert(((void)"This can't happen (bad key size in twofish_init)", 0)); |
140 | |
141 | /* --- Extend the key if necessary --- */ |
142 | |
143 | if (sz == ssz) |
144 | p = buf; |
145 | else { |
146 | memcpy(b, buf, sz); |
147 | memset(b + sz, 0, ssz - sz); |
148 | p = b; |
149 | } |
150 | |
151 | /* --- Finally get the word count --- */ |
152 | |
153 | sz = ssz / 8; |
154 | |
155 | /* --- Extract words from the key --- * |
156 | * |
157 | * The @s@ table, constructed using the Reed-Solomon matrix, is cut into |
158 | * sequences of bytes, since this is actually more useful for computing |
159 | * the S-boxes. |
160 | */ |
161 | |
162 | q = p; |
163 | for (i = 0; i < sz; i++) { |
164 | octet ss[4]; |
165 | const octet *r = rs; |
166 | int j; |
167 | |
168 | /* --- Extract the easy subkeys --- */ |
169 | |
170 | me[i] = LOAD32_L(q); |
171 | mo[i] = LOAD32_L(q + 4); |
172 | |
173 | /* --- Now do the Reed-Solomon thing --- */ |
174 | |
175 | for (j = 0; j < 4; j++) { |
176 | const octet *qq = q; |
177 | unsigned a = 0; |
178 | int k; |
179 | |
180 | for (k = 0; k < 8; k++) { |
181 | if (*qq) |
182 | a ^= rsexp[rslog[*qq] + *r]; |
183 | qq++; |
184 | r++; |
185 | } |
186 | |
187 | s[j][sz - 1 - i] = ss[j] = a; |
188 | } |
189 | q += 8; |
190 | } |
191 | |
192 | /* --- Clear away the temporary buffer --- */ |
193 | |
194 | if (p == b) |
195 | BURN(b); |
196 | } |
197 | |
198 | /* --- Construct the expanded key --- */ |
199 | |
200 | { |
201 | uint32 p = 0x01010101; |
202 | uint32 ip = 0; |
203 | int i; |
204 | |
205 | for (i = 0; i < 40; i += 2) { |
206 | uint32 a, b; |
207 | a = h(ip, me, sz); |
208 | b = h(ip + p, mo, sz); |
209 | b = ROL32(b, 8); |
210 | a += b; b += a; |
211 | k->k[i] = U32(a); |
212 | k->k[i + 1] = ROL32(b, 9); |
213 | ip += 2 * p; |
214 | } |
215 | } |
216 | |
217 | /* --- Construct the S-box tables --- */ |
218 | |
219 | { |
220 | unsigned i; |
221 | static const octet *q[4][KMAX + 1] = { |
222 | { q1, q0, q0, q1, q1 }, |
223 | { q0, q0, q1, q1, q0 }, |
224 | { q1, q1, q0, q0, q0 }, |
225 | { q0, q1, q1, q0, q1 } |
226 | }; |
227 | |
228 | for (i = 0; i < 4; i++) { |
229 | unsigned j; |
230 | uint32 x; |
231 | |
232 | for (j = 0; j < 256; j++) { |
233 | x = j; |
234 | |
235 | /* --- Push the byte through the q tables --- */ |
236 | |
237 | switch (sz) { |
238 | case 4: x = q[i][4][x] ^ s[i][3]; |
239 | case 3: x = q[i][3][x] ^ s[i][2]; |
240 | case 2: x = q[i][2][x] ^ s[i][1]; |
241 | x = q[i][1][x] ^ s[i][0]; |
242 | break; |
243 | } |
244 | |
245 | /* --- Write it in the key schedule --- */ |
246 | |
247 | k->g[i][j] = qmds[i][x]; |
248 | } |
249 | } |
250 | } |
251 | |
252 | /* --- Clear everything away --- */ |
253 | |
254 | BURN(me); |
255 | BURN(mo); |
256 | BURN(s); |
257 | } |
258 | |
259 | /*----- Main encryption ---------------------------------------------------*/ |
260 | |
261 | /* --- Feistel function --- */ |
262 | |
263 | #define GG(k, t0, t1, x, y, kk) do { \ |
264 | t0 = (k->g[0][U8(x >> 0)] ^ \ |
265 | k->g[1][U8(x >> 8)] ^ \ |
266 | k->g[2][U8(x >> 16)] ^ \ |
267 | k->g[3][U8(x >> 24)]); \ |
268 | t1 = (k->g[1][U8(y >> 0)] ^ \ |
269 | k->g[2][U8(y >> 8)] ^ \ |
270 | k->g[3][U8(y >> 16)] ^ \ |
271 | k->g[0][U8(y >> 24)]); \ |
272 | t0 += t1; \ |
273 | t1 += t0; \ |
274 | t0 += kk[0]; \ |
275 | t1 += kk[1]; \ |
276 | } while (0) |
277 | |
278 | /* --- Round operations --- */ |
279 | |
280 | #define EROUND(k, w, x, y, z, kk) do { \ |
281 | uint32 _t0, _t1; \ |
282 | GG(k, _t0, _t1, w, x, kk); \ |
283 | kk += 2; \ |
284 | y ^= _t0; y = ROR32(y, 1); \ |
285 | z = ROL32(z, 1); z ^= _t1; \ |
286 | } while (0) |
287 | |
288 | #define DROUND(k, w, x, y, z, kk) do { \ |
289 | uint32 _t0, _t1; \ |
290 | kk -= 2; \ |
291 | GG(k, _t0, _t1, w, x, kk); \ |
292 | y = ROL32(y, 1); y ^= _t0; \ |
293 | z ^= _t1; z = ROR32(z, 1); \ |
294 | } while (0) |
295 | |
296 | /* --- Complete encryption functions --- */ |
297 | |
298 | #define EBLK(k, a, b, c, d, w, x, y, z) do { \ |
299 | const uint32 *_kk = k->k + 8; \ |
300 | uint32 _a = a, _b = b, _c = c, _d = d; \ |
301 | _a ^= k->k[0]; _b ^= k->k[1]; _c ^= k->k[2]; _d ^= k->k[3]; \ |
302 | EROUND(k, _a, _b, _c, _d, _kk); \ |
303 | EROUND(k, _c, _d, _a, _b, _kk); \ |
304 | EROUND(k, _a, _b, _c, _d, _kk); \ |
305 | EROUND(k, _c, _d, _a, _b, _kk); \ |
306 | EROUND(k, _a, _b, _c, _d, _kk); \ |
307 | EROUND(k, _c, _d, _a, _b, _kk); \ |
308 | EROUND(k, _a, _b, _c, _d, _kk); \ |
309 | EROUND(k, _c, _d, _a, _b, _kk); \ |
310 | EROUND(k, _a, _b, _c, _d, _kk); \ |
311 | EROUND(k, _c, _d, _a, _b, _kk); \ |
312 | EROUND(k, _a, _b, _c, _d, _kk); \ |
313 | EROUND(k, _c, _d, _a, _b, _kk); \ |
314 | EROUND(k, _a, _b, _c, _d, _kk); \ |
315 | EROUND(k, _c, _d, _a, _b, _kk); \ |
316 | EROUND(k, _a, _b, _c, _d, _kk); \ |
317 | EROUND(k, _c, _d, _a, _b, _kk); \ |
318 | _c ^= k->k[4]; _d ^= k->k[5]; _a ^= k->k[6]; _b ^= k->k[7]; \ |
319 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ |
320 | } while (0) |
321 | |
322 | #define DBLK(k, a, b, c, d, w, x, y, z) do { \ |
323 | const uint32 *_kk = k->k + 40; \ |
324 | uint32 _a = a, _b = b, _c = c, _d = d; \ |
325 | _a ^= k->k[4]; _b ^= k->k[5]; _c ^= k->k[6]; _d ^= k->k[7]; \ |
326 | DROUND(k, _a, _b, _c, _d, _kk); \ |
327 | DROUND(k, _c, _d, _a, _b, _kk); \ |
328 | DROUND(k, _a, _b, _c, _d, _kk); \ |
329 | DROUND(k, _c, _d, _a, _b, _kk); \ |
330 | DROUND(k, _a, _b, _c, _d, _kk); \ |
331 | DROUND(k, _c, _d, _a, _b, _kk); \ |
332 | DROUND(k, _a, _b, _c, _d, _kk); \ |
333 | DROUND(k, _c, _d, _a, _b, _kk); \ |
334 | DROUND(k, _a, _b, _c, _d, _kk); \ |
335 | DROUND(k, _c, _d, _a, _b, _kk); \ |
336 | DROUND(k, _a, _b, _c, _d, _kk); \ |
337 | DROUND(k, _c, _d, _a, _b, _kk); \ |
338 | DROUND(k, _a, _b, _c, _d, _kk); \ |
339 | DROUND(k, _c, _d, _a, _b, _kk); \ |
340 | DROUND(k, _a, _b, _c, _d, _kk); \ |
341 | DROUND(k, _c, _d, _a, _b, _kk); \ |
342 | _c ^= k->k[0]; _d ^= k->k[1]; _a ^= k->k[2]; _b ^= k->k[3]; \ |
343 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ |
344 | } while (0) |
345 | |
346 | /* --- @twofish_eblk@, @twofish_dblk@ --- * |
347 | * |
348 | * Arguments: @const twofish_ctx *k@ = pointer to key block |
349 | * @const uint32 s[4]@ = pointer to source block |
350 | * @uint32 d[4]@ = pointer to destination block |
351 | * |
352 | * Returns: --- |
353 | * |
354 | * Use: Low-level block encryption and decryption. |
355 | */ |
356 | |
357 | void twofish_eblk(const twofish_ctx *k, const uint32 *s, uint32 *d) |
358 | { |
359 | EBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); |
360 | } |
361 | |
362 | void twofish_dblk(const twofish_ctx *k, const uint32 *s, uint32 *d) |
363 | { |
364 | DBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); |
365 | } |
366 | |
367 | BLKC_TEST(TWOFISH, twofish) |
368 | |
369 | /*----- That's all, folks -------------------------------------------------*/ |