75e749160fab6c017784b4d0381fbd3b1885693e
3 * Implementation of the Twofish cipher
5 * (c) 2000 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Catacomb.
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.
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.
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,
28 /*----- Header files ------------------------------------------------------*/
32 #include <mLib/bits.h>
37 #include "twofish-tab.h"
40 /*----- Global variables --------------------------------------------------*/
42 const octet twofish_keysz
[] = { KSZ_RANGE
, TWOFISH_KEYSZ
, 0, 32, 1 };
44 /*----- Important tables --------------------------------------------------*/
46 static const octet q0
[256] = TWOFISH_Q0
, q1
[256] = TWOFISH_Q1
;
47 static const uint32 qmds
[4][256] = TWOFISH_QMDS
;
48 static const octet rslog
[] = TWOFISH_RSLOG
, rsexp
[] = TWOFISH_RSEXP
;
49 static const octet rs
[32] = TWOFISH_RS
;
51 /*----- Key initialization ------------------------------------------------*/
55 * Arguments: @uint32 x@ = input to the function
56 * @const uint32 *l@ = key values to mix in
57 * @unsigned k@ = number of key values there are
59 * Returns: The output of the function @h@.
61 * Use: Implements the Twofish function @h@.
64 static uint32
h(uint32 x
, const uint32
*l
, unsigned k
)
66 /* --- Apply a series of @q@ tables to an integer --- */
68 # define Q(x, qa, qb, qc, qd) \
69 ((qa[((x) >> 0) & 0xff] << 0) | \
70 (qb[((x) >> 8) & 0xff] << 8) | \
71 (qc[((x) >> 16) & 0xff] << 16) | \
72 (qd[((x) >> 24) & 0xff] << 24))
74 /* --- Grind through the tables --- */
77 case 4: x
= Q(x
, q1
, q0
, q0
, q1
) ^ l
[3];
78 case 3: x
= Q(x
, q1
, q1
, q0
, q0
) ^ l
[2];
79 case 2: x
= Q(x
, q0
, q1
, q0
, q1
) ^ l
[1];
80 x
= Q(x
, q0
, q0
, q1
, q1
) ^ l
[0];
86 /* --- Apply the MDS matrix --- */
88 return (qmds
[0][U8(x
>> 0)] ^ qmds
[1][U8(x
>> 8)] ^
89 qmds
[2][U8(x
>> 16)] ^ qmds
[3][U8(x
>> 24)]);
92 /* --- @twofish_initfk@ --- *
94 * Arguments: @twofish_ctx *k@ = pointer to key block to fill in
95 * @const void *buf@ = pointer to buffer of key material
96 * @size_t sz@ = size of key material
97 * @const twofish_fk *fk@ = family-key information
101 * Use: Does the underlying Twofish key initialization with family
102 * key. Pass in a family-key structure initialized to
103 * all-bits-zero for a standard key schedule.
106 void twofish_initfk(twofish_ctx
*k
, const void *buf
, size_t sz
,
107 const twofish_fk
*fk
)
111 uint32 mo
[KMAX
], me
[KMAX
];
114 /* --- Expand the key into the three word arrays --- */
122 /* --- Sort out the key size --- */
124 KSZ_ASSERT(twofish
, sz
);
132 assert(((void)"This can't happen (bad key size in twofish_init)", 0));
134 /* --- Extend the key if necessary --- */
140 memset(b
+ sz
, 0, ssz
- sz
);
144 /* --- Finally get the word count --- */
148 /* --- Extract words from the key --- *
150 * The @s@ table, constructed using the Reed-Solomon matrix, is cut into
151 * sequences of bytes, since this is actually more useful for computing
156 for (i
= 0; i
< sz
; i
++) {
161 /* --- Extract the easy subkeys --- */
163 me
[i
] = LOAD32_L(q
) ^ fk
->t0
[2 * i
];
164 mo
[i
] = LOAD32_L(q
+ 4) ^ fk
->t0
[2 * i
+ 1];
166 /* --- Now do the Reed-Solomon thing --- */
168 for (j
= 0; j
< 4; j
++) {
173 for (k
= 0; k
< 8; k
++) {
174 unsigned char x
= *qq
^ fk
->t1
[i
* 8 + k
];
175 if (x
) a
^= rsexp
[rslog
[x
] + *r
];
180 s
[j
][sz
- 1 - i
] = ss
[j
] = a
;
185 /* --- Clear away the temporary buffer --- */
191 /* --- Construct the expanded key --- */
194 uint32 p
= 0x01010101;
198 for (i
= 0; i
< 40; i
+= 2) {
201 b
= h(ip
+ p
, mo
, sz
);
205 k
->k
[i
+ 1] = ROL32(b
, 9);
209 for (i
= 0; i
< 8; i
++)
210 k
->k
[i
] ^= fk
->t23
[i
];
211 for (i
= 8; i
< 40; i
+= 2) {
212 k
->k
[i
] ^= fk
->t4
[0];
213 k
->k
[i
+ 1] ^= fk
->t4
[1];
217 /* --- Construct the S-box tables --- */
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
}
228 for (i
= 0; i
< 4; i
++) {
232 for (j
= 0; j
< 256; j
++) {
235 /* --- Push the byte through the q tables --- */
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];
245 /* --- Write it in the key schedule --- */
247 k
->g
[i
][j
] = qmds
[i
][x
];
252 /* --- Clear everything away --- */
259 /* --- @twofish_init@ --- *
261 * Arguments: @twofish_ctx *k@ = pointer to key block to fill in
262 * @const void *buf@ = pointer to buffer of key material
263 * @size_t sz@ = size of key material
267 * Use: Initializes a Twofish key buffer. Twofish accepts key sizes
268 * of up to 256 bits (32 bytes).
271 void twofish_init(twofish_ctx
*k
, const void *buf
, size_t sz
)
273 static const twofish_fk fk
= { { 0 } };
274 twofish_initfk(k
, buf
, sz
, &fk
);
277 /* --- @twofish_fkinit@ --- *
279 * Arguments: @twofish_fk *fk@ = pointer to family key block
280 * @const void *buf@ = pointer to buffer of key material
281 * @size_t sz@ = size of key material
285 * Use: Initializes a family-key buffer. This implementation allows
286 * family keys of any size acceptable to the Twofish algorithm.
289 void twofish_fkinit(twofish_fk
*fk
, const void *buf
, size_t sz
)
296 twofish_init(&k
, buf
, sz
);
298 for (i
= 0; i
< 4; i
++) pt
[i
] = (uint32
)-1;
299 twofish_eblk(&k
, pt
, fk
->t0
+ 4);
302 for (i
= 0; i
< sz
; i
++) { fk
->t0
[i
] = LOAD32_L(kk
); kk
+= 4; }
304 for (i
= 0; i
< 4; i
++) pt
[i
] = 0; twofish_eblk(&k
, pt
, ct
);
305 for (i
= 0; i
< 4; i
++) STORE32_L(fk
->t1
+ i
* 4, ct
[i
]);
306 pt
[0] = 1; twofish_eblk(&k
, pt
, ct
);
307 for (i
= 0; i
< 4; i
++) STORE32_L(fk
->t1
+ 4 + i
* 4, ct
[i
]);
309 pt
[0] = 2; twofish_eblk(&k
, pt
, fk
->t23
+ 0);
310 pt
[0] = 3; twofish_eblk(&k
, pt
, fk
->t23
+ 4);
311 pt
[0] = 4; twofish_eblk(&k
, pt
, ct
);
312 fk
->t4
[0] = ct
[0]; fk
->t4
[1] = ct
[1];
317 /*----- Main encryption ---------------------------------------------------*/
319 /* --- Feistel function --- */
321 #define GG(k, t0, t1, x, y, kk) do { \
322 t0 = (k->g[0][U8(x >> 0)] ^ \
323 k->g[1][U8(x >> 8)] ^ \
324 k->g[2][U8(x >> 16)] ^ \
325 k->g[3][U8(x >> 24)]); \
326 t1 = (k->g[1][U8(y >> 0)] ^ \
327 k->g[2][U8(y >> 8)] ^ \
328 k->g[3][U8(y >> 16)] ^ \
329 k->g[0][U8(y >> 24)]); \
336 /* --- Round operations --- */
338 #define EROUND(k, w, x, y, z, kk) do { \
340 GG(k, _t0, _t1, w, x, kk); \
342 y ^= _t0; y = ROR32(y, 1); \
343 z = ROL32(z, 1); z ^= _t1; \
346 #define DROUND(k, w, x, y, z, kk) do { \
349 GG(k, _t0, _t1, w, x, kk); \
350 y = ROL32(y, 1); y ^= _t0; \
351 z ^= _t1; z = ROR32(z, 1); \
354 /* --- Complete encryption functions --- */
356 #define EBLK(k, a, b, c, d, w, x, y, z) do { \
357 const uint32 *_kk = k->k + 8; \
358 uint32 _a = a, _b = b, _c = c, _d = d; \
359 _a ^= k->k[0]; _b ^= k->k[1]; _c ^= k->k[2]; _d ^= k->k[3]; \
360 EROUND(k, _a, _b, _c, _d, _kk); \
361 EROUND(k, _c, _d, _a, _b, _kk); \
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 _c ^= k->k[4]; _d ^= k->k[5]; _a ^= k->k[6]; _b ^= k->k[7]; \
377 w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \
380 #define DBLK(k, a, b, c, d, w, x, y, z) do { \
381 const uint32 *_kk = k->k + 40; \
382 uint32 _a = a, _b = b, _c = c, _d = d; \
383 _a ^= k->k[4]; _b ^= k->k[5]; _c ^= k->k[6]; _d ^= k->k[7]; \
384 DROUND(k, _a, _b, _c, _d, _kk); \
385 DROUND(k, _c, _d, _a, _b, _kk); \
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 _c ^= k->k[0]; _d ^= k->k[1]; _a ^= k->k[2]; _b ^= k->k[3]; \
401 w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \
404 /* --- @twofish_eblk@, @twofish_dblk@ --- *
406 * Arguments: @const twofish_ctx *k@ = pointer to key block
407 * @const uint32 s[4]@ = pointer to source block
408 * @uint32 d[4]@ = pointer to destination block
412 * Use: Low-level block encryption and decryption.
415 void twofish_eblk(const twofish_ctx
*k
, const uint32
*s
, uint32
*d
)
417 EBLK(k
, s
[0], s
[1], s
[2], s
[3], d
[0], d
[1], d
[2], d
[3]);
420 void twofish_dblk(const twofish_ctx
*k
, const uint32
*s
, uint32
*d
)
422 DBLK(k
, s
[0], s
[1], s
[2], s
[3], d
[0], d
[1], d
[2], d
[3]);
425 BLKC_TEST(TWOFISH
, twofish
)
427 /*----- That's all, folks -------------------------------------------------*/