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>
39 /*----- Global variables --------------------------------------------------*/
41 const octet twofish_keysz
[] = { KSZ_RANGE
, TWOFISH_KEYSZ
, 0, 32, 1 };
43 /*----- Important tables --------------------------------------------------*/
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];
52 #define QMDS twofish_qmds
53 #define RSLOG twofish_rslog
54 #define RSEXP twofish_rsexp
57 /*----- Key initialization ------------------------------------------------*/
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
65 * Returns: The output of the function @h@.
67 * Use: Implements the Twofish function @h@.
70 static uint32
h(uint32 x
, const uint32
*l
, unsigned k
)
72 /* --- Apply a series of @q@ tables to an integer --- */
74 # define Q(x, qa, qb, qc, qd) \
75 ((qa[((x) >> 0) & 0xff] << 0) | \
76 (qb[((x) >> 8) & 0xff] << 8) | \
77 (qc[((x) >> 16) & 0xff] << 16) | \
78 (qd[((x) >> 24) & 0xff] << 24))
80 /* --- Grind through the tables --- */
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];
92 /* --- Apply the MDS matrix --- */
94 return (QMDS
[0][U8(x
>> 0)] ^ QMDS
[1][U8(x
>> 8)] ^
95 QMDS
[2][U8(x
>> 16)] ^ QMDS
[3][U8(x
>> 24)]);
98 /* --- @twofish_initfk@ --- *
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
103 * @const twofish_fk *fk@ = family-key information
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.
112 void twofish_initfk(twofish_ctx
*k
, const void *buf
, size_t sz
,
113 const twofish_fk
*fk
)
117 uint32 mo
[KMAX
], me
[KMAX
];
120 /* --- Expand the key into the three word arrays --- */
128 /* --- Sort out the key size --- */
130 KSZ_ASSERT(twofish
, sz
);
138 assert(((void)"This can't happen (bad key size in twofish_init)", 0));
140 /* --- Extend the key if necessary --- */
146 memset(b
+ sz
, 0, ssz
- sz
);
150 /* --- Finally get the word count --- */
154 /* --- Extract words from the key --- *
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
162 for (i
= 0; i
< sz
; i
++) {
167 /* --- Extract the easy subkeys --- */
169 me
[i
] = LOAD32_L(q
) ^ fk
->t0
[2 * i
];
170 mo
[i
] = LOAD32_L(q
+ 4) ^ fk
->t0
[2 * i
+ 1];
172 /* --- Now do the Reed-Solomon thing --- */
174 for (j
= 0; j
< 4; j
++) {
179 for (k
= 0; k
< 8; k
++) {
180 unsigned char x
= *qq
^ fk
->t1
[i
* 8 + k
];
181 if (x
) a
^= RSEXP
[RSLOG
[x
] + *r
];
186 s
[j
][sz
- 1 - i
] = ss
[j
] = a
;
191 /* --- Clear away the temporary buffer --- */
197 /* --- Construct the expanded key --- */
200 uint32 p
= 0x01010101;
204 for (i
= 0; i
< 40; i
+= 2) {
207 b
= h(ip
+ p
, mo
, sz
);
211 k
->k
[i
+ 1] = ROL32(b
, 9);
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];
223 /* --- Construct the S-box tables --- */
227 static const octet
*q
[4][KMAX
+ 1] = {
228 { Q1
, Q0
, Q0
, Q1
, Q1
},
229 { Q0
, Q0
, Q1
, Q1
, Q0
},
230 { Q1
, Q1
, Q0
, Q0
, Q0
},
231 { Q0
, Q1
, Q1
, Q0
, Q1
}
234 for (i
= 0; i
< 4; i
++) {
238 for (j
= 0; j
< 256; j
++) {
241 /* --- Push the byte through the q tables --- */
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];
251 /* --- Write it in the key schedule --- */
253 k
->g
[i
][j
] = QMDS
[i
][x
];
258 /* --- Clear everything away --- */
265 /* --- @twofish_init@ --- *
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
273 * Use: Initializes a Twofish key buffer. Twofish accepts key sizes
274 * of up to 256 bits (32 bytes).
277 void twofish_init(twofish_ctx
*k
, const void *buf
, size_t sz
)
279 static const twofish_fk fk
= { { 0 } };
280 twofish_initfk(k
, buf
, sz
, &fk
);
283 /* --- @twofish_fkinit@ --- *
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
291 * Use: Initializes a family-key buffer. This implementation allows
292 * family keys of any size acceptable to the Twofish algorithm.
295 void twofish_fkinit(twofish_fk
*fk
, const void *buf
, size_t sz
)
302 twofish_init(&k
, buf
, sz
);
304 for (i
= 0; i
< 4; i
++) pt
[i
] = (uint32
)-1;
305 twofish_eblk(&k
, pt
, fk
->t0
+ 4);
308 for (i
= 0; i
< sz
; i
++) { fk
->t0
[i
] = LOAD32_L(kk
); kk
+= 4; }
310 for (i
= 0; i
< 4; i
++) pt
[i
] = 0;
311 twofish_eblk(&k
, pt
, ct
);
312 for (i
= 0; i
< 4; i
++) STORE32_L(fk
->t1
+ i
* 4, ct
[i
]);
313 pt
[0] = 1; twofish_eblk(&k
, pt
, ct
);
314 for (i
= 0; i
< 4; i
++) STORE32_L(fk
->t1
+ 4 + i
* 4, ct
[i
]);
316 pt
[0] = 2; twofish_eblk(&k
, pt
, fk
->t23
+ 0);
317 pt
[0] = 3; twofish_eblk(&k
, pt
, fk
->t23
+ 4);
318 pt
[0] = 4; twofish_eblk(&k
, pt
, ct
);
319 fk
->t4
[0] = ct
[0]; fk
->t4
[1] = ct
[1];
324 /*----- Main encryption ---------------------------------------------------*/
326 /* --- Feistel function --- */
328 #define GG(k, t0, t1, x, y, kk) do { \
329 t0 = (k->g[0][U8(x >> 0)] ^ \
330 k->g[1][U8(x >> 8)] ^ \
331 k->g[2][U8(x >> 16)] ^ \
332 k->g[3][U8(x >> 24)]); \
333 t1 = (k->g[1][U8(y >> 0)] ^ \
334 k->g[2][U8(y >> 8)] ^ \
335 k->g[3][U8(y >> 16)] ^ \
336 k->g[0][U8(y >> 24)]); \
343 /* --- Round operations --- */
345 #define EROUND(k, w, x, y, z, kk) do { \
347 GG(k, _t0, _t1, w, x, kk); \
349 y ^= _t0; y = ROR32(y, 1); \
350 z = ROL32(z, 1); z ^= _t1; \
353 #define DROUND(k, w, x, y, z, kk) do { \
356 GG(k, _t0, _t1, w, x, kk); \
357 y = ROL32(y, 1); y ^= _t0; \
358 z ^= _t1; z = ROR32(z, 1); \
361 /* --- Complete encryption functions --- */
363 #define EBLK(k, a, b, c, d, w, x, y, z) do { \
364 const uint32 *_kk = k->k + 8; \
365 uint32 _a = a, _b = b, _c = c, _d = d; \
366 _a ^= k->k[0]; _b ^= k->k[1]; _c ^= k->k[2]; _d ^= k->k[3]; \
367 EROUND(k, _a, _b, _c, _d, _kk); \
368 EROUND(k, _c, _d, _a, _b, _kk); \
369 EROUND(k, _a, _b, _c, _d, _kk); \
370 EROUND(k, _c, _d, _a, _b, _kk); \
371 EROUND(k, _a, _b, _c, _d, _kk); \
372 EROUND(k, _c, _d, _a, _b, _kk); \
373 EROUND(k, _a, _b, _c, _d, _kk); \
374 EROUND(k, _c, _d, _a, _b, _kk); \
375 EROUND(k, _a, _b, _c, _d, _kk); \
376 EROUND(k, _c, _d, _a, _b, _kk); \
377 EROUND(k, _a, _b, _c, _d, _kk); \
378 EROUND(k, _c, _d, _a, _b, _kk); \
379 EROUND(k, _a, _b, _c, _d, _kk); \
380 EROUND(k, _c, _d, _a, _b, _kk); \
381 EROUND(k, _a, _b, _c, _d, _kk); \
382 EROUND(k, _c, _d, _a, _b, _kk); \
383 _c ^= k->k[4]; _d ^= k->k[5]; _a ^= k->k[6]; _b ^= k->k[7]; \
384 w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \
387 #define DBLK(k, a, b, c, d, w, x, y, z) do { \
388 const uint32 *_kk = k->k + 40; \
389 uint32 _a = a, _b = b, _c = c, _d = d; \
390 _a ^= k->k[4]; _b ^= k->k[5]; _c ^= k->k[6]; _d ^= k->k[7]; \
391 DROUND(k, _a, _b, _c, _d, _kk); \
392 DROUND(k, _c, _d, _a, _b, _kk); \
393 DROUND(k, _a, _b, _c, _d, _kk); \
394 DROUND(k, _c, _d, _a, _b, _kk); \
395 DROUND(k, _a, _b, _c, _d, _kk); \
396 DROUND(k, _c, _d, _a, _b, _kk); \
397 DROUND(k, _a, _b, _c, _d, _kk); \
398 DROUND(k, _c, _d, _a, _b, _kk); \
399 DROUND(k, _a, _b, _c, _d, _kk); \
400 DROUND(k, _c, _d, _a, _b, _kk); \
401 DROUND(k, _a, _b, _c, _d, _kk); \
402 DROUND(k, _c, _d, _a, _b, _kk); \
403 DROUND(k, _a, _b, _c, _d, _kk); \
404 DROUND(k, _c, _d, _a, _b, _kk); \
405 DROUND(k, _a, _b, _c, _d, _kk); \
406 DROUND(k, _c, _d, _a, _b, _kk); \
407 _c ^= k->k[0]; _d ^= k->k[1]; _a ^= k->k[2]; _b ^= k->k[3]; \
408 w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \
411 /* --- @twofish_eblk@, @twofish_dblk@ --- *
413 * Arguments: @const twofish_ctx *k@ = pointer to key block
414 * @const uint32 s[4]@ = pointer to source block
415 * @uint32 d[4]@ = pointer to destination block
419 * Use: Low-level block encryption and decryption.
422 void twofish_eblk(const twofish_ctx
*k
, const uint32
*s
, uint32
*d
)
424 EBLK(k
, s
[0], s
[1], s
[2], s
[3], d
[0], d
[1], d
[2], d
[3]);
427 void twofish_dblk(const twofish_ctx
*k
, const uint32
*s
, uint32
*d
)
429 DBLK(k
, s
[0], s
[1], s
[2], s
[3], d
[0], d
[1], d
[2], d
[3]);
432 BLKC_TEST(TWOFISH
, twofish
)
434 /*----- That's all, folks -------------------------------------------------*/