3 * $Id: twofish.c,v 1.3 2002/01/13 13:37:59 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 /*----- Revision history --------------------------------------------------*
33 * Revision 1.3 2002/01/13 13:37:59 mdw
34 * Add support for Twofish family keys.
36 * Revision 1.2 2000/06/22 18:58:00 mdw
37 * Twofish can handle keys with any byte-aligned size.
39 * Revision 1.1 2000/06/17 12:10:17 mdw
44 /*----- Header files ------------------------------------------------------*/
48 #include <mLib/bits.h>
53 #include "twofish-tab.h"
56 /*----- Global variables --------------------------------------------------*/
58 const octet twofish_keysz
[] = { KSZ_RANGE
, TWOFISH_KEYSZ
, 0, 32, 1 };
60 /*----- Important tables --------------------------------------------------*/
62 static const octet q0
[256] = TWOFISH_Q0
, q1
[256] = TWOFISH_Q1
;
63 static const uint32 qmds
[4][256] = TWOFISH_QMDS
;
64 static const octet rslog
[] = TWOFISH_RSLOG
, rsexp
[] = TWOFISH_RSEXP
;
65 static const octet rs
[32] = TWOFISH_RS
;
67 /*----- Key initialization ------------------------------------------------*/
71 * Arguments: @uint32 x@ = input to the function
72 * @const uint32 *l@ = key values to mix in
73 * @unsigned k@ = number of key values there are
75 * Returns: The output of the function @h@.
77 * Use: Implements the Twofish function @h@.
80 static uint32
h(uint32 x
, const uint32
*l
, unsigned k
)
82 /* --- Apply a series of @q@ tables to an integer --- */
84 # define Q(x, qa, qb, qc, qd) \
85 ((qa[((x) >> 0) & 0xff] << 0) | \
86 (qb[((x) >> 8) & 0xff] << 8) | \
87 (qc[((x) >> 16) & 0xff] << 16) | \
88 (qd[((x) >> 24) & 0xff] << 24))
90 /* --- Grind through the tables --- */
93 case 4: x
= Q(x
, q1
, q0
, q0
, q1
) ^ l
[3];
94 case 3: x
= Q(x
, q1
, q1
, q0
, q0
) ^ l
[2];
95 case 2: x
= Q(x
, q0
, q1
, q0
, q1
) ^ l
[1];
96 x
= Q(x
, q0
, q0
, q1
, q1
) ^ l
[0];
102 /* --- Apply the MDS matrix --- */
104 return (qmds
[0][U8(x
>> 0)] ^ qmds
[1][U8(x
>> 8)] ^
105 qmds
[2][U8(x
>> 16)] ^ qmds
[3][U8(x
>> 24)]);
108 /* --- @twofish_initfk@ --- *
110 * Arguments: @twofish_ctx *k@ = pointer to key block to fill in
111 * @const void *buf@ = pointer to buffer of key material
112 * @size_t sz@ = size of key material
113 * @const twofish_fk *fk@ = family-key information
117 * Use: Does the underlying Twofish key initialization with family
118 * key. Pass in a family-key structure initialized to
119 * all-bits-zero for a standard key schedule.
122 void twofish_initfk(twofish_ctx
*k
, const void *buf
, size_t sz
,
123 const twofish_fk
*fk
)
127 uint32 mo
[KMAX
], me
[KMAX
];
130 /* --- Expand the key into the three word arrays --- */
138 /* --- Sort out the key size --- */
140 KSZ_ASSERT(twofish
, sz
);
148 assert(((void)"This can't happen (bad key size in twofish_init)", 0));
150 /* --- Extend the key if necessary --- */
156 memset(b
+ sz
, 0, ssz
- sz
);
160 /* --- Finally get the word count --- */
164 /* --- Extract words from the key --- *
166 * The @s@ table, constructed using the Reed-Solomon matrix, is cut into
167 * sequences of bytes, since this is actually more useful for computing
172 for (i
= 0; i
< sz
; i
++) {
177 /* --- Extract the easy subkeys --- */
179 me
[i
] = LOAD32_L(q
) ^ fk
->t0
[2 * i
];
180 mo
[i
] = LOAD32_L(q
+ 4) ^ fk
->t0
[2 * i
+ 1];
182 /* --- Now do the Reed-Solomon thing --- */
184 for (j
= 0; j
< 4; j
++) {
189 for (k
= 0; k
< 8; k
++) {
190 unsigned char x
= *qq
^ fk
->t1
[i
* 8 + k
];
191 if (x
) a
^= rsexp
[rslog
[x
] + *r
];
196 s
[j
][sz
- 1 - i
] = ss
[j
] = a
;
201 /* --- Clear away the temporary buffer --- */
207 /* --- Construct the expanded key --- */
210 uint32 p
= 0x01010101;
214 for (i
= 0; i
< 40; i
+= 2) {
217 b
= h(ip
+ p
, mo
, sz
);
221 k
->k
[i
+ 1] = ROL32(b
, 9);
225 for (i
= 0; i
< 8; i
++)
226 k
->k
[i
] ^= fk
->t23
[i
];
227 for (i
= 8; i
< 40; i
+= 2) {
228 k
->k
[i
] ^= fk
->t4
[0];
229 k
->k
[i
+ 1] ^= fk
->t4
[1];
233 /* --- Construct the S-box tables --- */
237 static const octet
*q
[4][KMAX
+ 1] = {
238 { q1
, q0
, q0
, q1
, q1
},
239 { q0
, q0
, q1
, q1
, q0
},
240 { q1
, q1
, q0
, q0
, q0
},
241 { q0
, q1
, q1
, q0
, q1
}
244 for (i
= 0; i
< 4; i
++) {
248 for (j
= 0; j
< 256; j
++) {
251 /* --- Push the byte through the q tables --- */
254 case 4: x
= q
[i
][4][x
] ^ s
[i
][3];
255 case 3: x
= q
[i
][3][x
] ^ s
[i
][2];
256 case 2: x
= q
[i
][2][x
] ^ s
[i
][1];
257 x
= q
[i
][1][x
] ^ s
[i
][0];
261 /* --- Write it in the key schedule --- */
263 k
->g
[i
][j
] = qmds
[i
][x
];
268 /* --- Clear everything away --- */
275 /* --- @twofish_init@ --- *
277 * Arguments: @twofish_ctx *k@ = pointer to key block to fill in
278 * @const void *buf@ = pointer to buffer of key material
279 * @size_t sz@ = size of key material
283 * Use: Initializes a Twofish key buffer. Twofish accepts key sizes
284 * of up to 256 bits (32 bytes).
287 void twofish_init(twofish_ctx
*k
, const void *buf
, size_t sz
)
289 static twofish_fk fk
= { { 0 } };
290 twofish_initfk(k
, buf
, sz
, &fk
);
293 /* --- @twofish_fkinit@ --- *
295 * Arguments: @twofish_fk *fk@ = pointer to family key block
296 * @const void *buf@ = pointer to buffer of key material
297 * @size_t sz@ = size of key material
301 * Use: Initializes a family-key buffer. This implementation allows
302 * family keys of any size acceptable to the Twofish algorithm.
305 void twofish_fkinit(twofish_fk
*fk
, const void *buf
, size_t sz
)
312 twofish_init(&k
, buf
, sz
);
314 for (i
= 0; i
< 4; i
++) pt
[i
] = (uint32
)-1;
315 twofish_eblk(&k
, pt
, fk
->t0
+ 4);
318 for (i
= 0; i
< sz
; i
++) { fk
->t0
[i
] = LOAD32_L(kk
); kk
+= 4; }
320 for (i
= 0; i
< 4; i
++) pt
[i
] = 0; twofish_eblk(&k
, pt
, ct
);
321 for (i
= 0; i
< 4; i
++) STORE32_L(fk
->t1
+ i
* 4, ct
[i
]);
322 pt
[0] = 1; twofish_eblk(&k
, pt
, ct
);
323 for (i
= 0; i
< 4; i
++) STORE32_L(fk
->t1
+ 4 + i
* 4, ct
[i
]);
325 pt
[0] = 2; twofish_eblk(&k
, pt
, fk
->t23
+ 0);
326 pt
[0] = 3; twofish_eblk(&k
, pt
, fk
->t23
+ 4);
327 pt
[0] = 4; twofish_eblk(&k
, pt
, ct
);
328 fk
->t4
[0] = ct
[0]; fk
->t4
[1] = ct
[1];
333 /*----- Main encryption ---------------------------------------------------*/
335 /* --- Feistel function --- */
337 #define GG(k, t0, t1, x, y, kk) do { \
338 t0 = (k->g[0][U8(x >> 0)] ^ \
339 k->g[1][U8(x >> 8)] ^ \
340 k->g[2][U8(x >> 16)] ^ \
341 k->g[3][U8(x >> 24)]); \
342 t1 = (k->g[1][U8(y >> 0)] ^ \
343 k->g[2][U8(y >> 8)] ^ \
344 k->g[3][U8(y >> 16)] ^ \
345 k->g[0][U8(y >> 24)]); \
352 /* --- Round operations --- */
354 #define EROUND(k, w, x, y, z, kk) do { \
356 GG(k, _t0, _t1, w, x, kk); \
358 y ^= _t0; y = ROR32(y, 1); \
359 z = ROL32(z, 1); z ^= _t1; \
362 #define DROUND(k, w, x, y, z, kk) do { \
365 GG(k, _t0, _t1, w, x, kk); \
366 y = ROL32(y, 1); y ^= _t0; \
367 z ^= _t1; z = ROR32(z, 1); \
370 /* --- Complete encryption functions --- */
372 #define EBLK(k, a, b, c, d, w, x, y, z) do { \
373 const uint32 *_kk = k->k + 8; \
374 uint32 _a = a, _b = b, _c = c, _d = d; \
375 _a ^= k->k[0]; _b ^= k->k[1]; _c ^= k->k[2]; _d ^= k->k[3]; \
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 EROUND(k, _a, _b, _c, _d, _kk); \
383 EROUND(k, _c, _d, _a, _b, _kk); \
384 EROUND(k, _a, _b, _c, _d, _kk); \
385 EROUND(k, _c, _d, _a, _b, _kk); \
386 EROUND(k, _a, _b, _c, _d, _kk); \
387 EROUND(k, _c, _d, _a, _b, _kk); \
388 EROUND(k, _a, _b, _c, _d, _kk); \
389 EROUND(k, _c, _d, _a, _b, _kk); \
390 EROUND(k, _a, _b, _c, _d, _kk); \
391 EROUND(k, _c, _d, _a, _b, _kk); \
392 _c ^= k->k[4]; _d ^= k->k[5]; _a ^= k->k[6]; _b ^= k->k[7]; \
393 w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \
396 #define DBLK(k, a, b, c, d, w, x, y, z) do { \
397 const uint32 *_kk = k->k + 40; \
398 uint32 _a = a, _b = b, _c = c, _d = d; \
399 _a ^= k->k[4]; _b ^= k->k[5]; _c ^= k->k[6]; _d ^= k->k[7]; \
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 DROUND(k, _a, _b, _c, _d, _kk); \
407 DROUND(k, _c, _d, _a, _b, _kk); \
408 DROUND(k, _a, _b, _c, _d, _kk); \
409 DROUND(k, _c, _d, _a, _b, _kk); \
410 DROUND(k, _a, _b, _c, _d, _kk); \
411 DROUND(k, _c, _d, _a, _b, _kk); \
412 DROUND(k, _a, _b, _c, _d, _kk); \
413 DROUND(k, _c, _d, _a, _b, _kk); \
414 DROUND(k, _a, _b, _c, _d, _kk); \
415 DROUND(k, _c, _d, _a, _b, _kk); \
416 _c ^= k->k[0]; _d ^= k->k[1]; _a ^= k->k[2]; _b ^= k->k[3]; \
417 w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \
420 /* --- @twofish_eblk@, @twofish_dblk@ --- *
422 * Arguments: @const twofish_ctx *k@ = pointer to key block
423 * @const uint32 s[4]@ = pointer to source block
424 * @uint32 d[4]@ = pointer to destination block
428 * Use: Low-level block encryption and decryption.
431 void twofish_eblk(const twofish_ctx
*k
, const uint32
*s
, uint32
*d
)
433 EBLK(k
, s
[0], s
[1], s
[2], s
[3], d
[0], d
[1], d
[2], d
[3]);
436 void twofish_dblk(const twofish_ctx
*k
, const uint32
*s
, uint32
*d
)
438 DBLK(k
, s
[0], s
[1], s
[2], s
[3], d
[0], d
[1], d
[2], d
[3]);
441 BLKC_TEST(TWOFISH
, twofish
)
443 /*----- That's all, folks -------------------------------------------------*/