3 * $Id: twofish.c,v 1.5 2004/04/08 01:36:15 mdw Exp $
5 * Implementation of the Twofish cipher
7 * (c) 2000 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
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.
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.
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,
30 /*----- Header files ------------------------------------------------------*/
34 #include <mLib/bits.h>
39 #include "twofish-tab.h"
42 /*----- Global variables --------------------------------------------------*/
44 const octet twofish_keysz
[] = { KSZ_RANGE
, TWOFISH_KEYSZ
, 0, 32, 1 };
46 /*----- Important tables --------------------------------------------------*/
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
;
53 /*----- Key initialization ------------------------------------------------*/
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
61 * Returns: The output of the function @h@.
63 * Use: Implements the Twofish function @h@.
66 static uint32
h(uint32 x
, const uint32
*l
, unsigned k
)
68 /* --- Apply a series of @q@ tables to an integer --- */
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))
76 /* --- Grind through the tables --- */
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];
88 /* --- Apply the MDS matrix --- */
90 return (qmds
[0][U8(x
>> 0)] ^ qmds
[1][U8(x
>> 8)] ^
91 qmds
[2][U8(x
>> 16)] ^ qmds
[3][U8(x
>> 24)]);
94 /* --- @twofish_initfk@ --- *
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
99 * @const twofish_fk *fk@ = family-key information
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.
108 void twofish_initfk(twofish_ctx
*k
, const void *buf
, size_t sz
,
109 const twofish_fk
*fk
)
113 uint32 mo
[KMAX
], me
[KMAX
];
116 /* --- Expand the key into the three word arrays --- */
124 /* --- Sort out the key size --- */
126 KSZ_ASSERT(twofish
, sz
);
134 assert(((void)"This can't happen (bad key size in twofish_init)", 0));
136 /* --- Extend the key if necessary --- */
142 memset(b
+ sz
, 0, ssz
- sz
);
146 /* --- Finally get the word count --- */
150 /* --- Extract words from the key --- *
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
158 for (i
= 0; i
< sz
; i
++) {
163 /* --- Extract the easy subkeys --- */
165 me
[i
] = LOAD32_L(q
) ^ fk
->t0
[2 * i
];
166 mo
[i
] = LOAD32_L(q
+ 4) ^ fk
->t0
[2 * i
+ 1];
168 /* --- Now do the Reed-Solomon thing --- */
170 for (j
= 0; j
< 4; j
++) {
175 for (k
= 0; k
< 8; k
++) {
176 unsigned char x
= *qq
^ fk
->t1
[i
* 8 + k
];
177 if (x
) a
^= rsexp
[rslog
[x
] + *r
];
182 s
[j
][sz
- 1 - i
] = ss
[j
] = a
;
187 /* --- Clear away the temporary buffer --- */
193 /* --- Construct the expanded key --- */
196 uint32 p
= 0x01010101;
200 for (i
= 0; i
< 40; i
+= 2) {
203 b
= h(ip
+ p
, mo
, sz
);
207 k
->k
[i
+ 1] = ROL32(b
, 9);
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];
219 /* --- Construct the S-box tables --- */
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
}
230 for (i
= 0; i
< 4; i
++) {
234 for (j
= 0; j
< 256; j
++) {
237 /* --- Push the byte through the q tables --- */
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];
247 /* --- Write it in the key schedule --- */
249 k
->g
[i
][j
] = qmds
[i
][x
];
254 /* --- Clear everything away --- */
261 /* --- @twofish_init@ --- *
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
269 * Use: Initializes a Twofish key buffer. Twofish accepts key sizes
270 * of up to 256 bits (32 bytes).
273 void twofish_init(twofish_ctx
*k
, const void *buf
, size_t sz
)
275 static const twofish_fk fk
= { { 0 } };
276 twofish_initfk(k
, buf
, sz
, &fk
);
279 /* --- @twofish_fkinit@ --- *
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
287 * Use: Initializes a family-key buffer. This implementation allows
288 * family keys of any size acceptable to the Twofish algorithm.
291 void twofish_fkinit(twofish_fk
*fk
, const void *buf
, size_t sz
)
298 twofish_init(&k
, buf
, sz
);
300 for (i
= 0; i
< 4; i
++) pt
[i
] = (uint32
)-1;
301 twofish_eblk(&k
, pt
, fk
->t0
+ 4);
304 for (i
= 0; i
< sz
; i
++) { fk
->t0
[i
] = LOAD32_L(kk
); kk
+= 4; }
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
]);
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];
319 /*----- Main encryption ---------------------------------------------------*/
321 /* --- Feistel function --- */
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)]); \
338 /* --- Round operations --- */
340 #define EROUND(k, w, x, y, z, kk) do { \
342 GG(k, _t0, _t1, w, x, kk); \
344 y ^= _t0; y = ROR32(y, 1); \
345 z = ROL32(z, 1); z ^= _t1; \
348 #define DROUND(k, w, x, y, z, kk) do { \
351 GG(k, _t0, _t1, w, x, kk); \
352 y = ROL32(y, 1); y ^= _t0; \
353 z ^= _t1; z = ROR32(z, 1); \
356 /* --- Complete encryption functions --- */
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); \
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); \
406 /* --- @twofish_eblk@, @twofish_dblk@ --- *
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
414 * Use: Low-level block encryption and decryption.
417 void twofish_eblk(const twofish_ctx
*k
, const uint32
*s
, uint32
*d
)
419 EBLK(k
, s
[0], s
[1], s
[2], s
[3], d
[0], d
[1], d
[2], d
[3]);
422 void twofish_dblk(const twofish_ctx
*k
, const uint32
*s
, uint32
*d
)
424 DBLK(k
, s
[0], s
[1], s
[2], s
[3], d
[0], d
[1], d
[2], d
[3]);
427 BLKC_TEST(TWOFISH
, twofish
)
429 /*----- That's all, folks -------------------------------------------------*/