3 * $Id: rijndael-mktab.c,v 1.2 2000/06/18 23:12:15 mdw Exp $
5 * Build precomputed tables for the Rijndael block 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 --------------------------------------------------*
32 * $Log: rijndael-mktab.c,v $
33 * Revision 1.2 2000/06/18 23:12:15 mdw
34 * Change typesetting of Galois Field names.
36 * Revision 1.1 2000/06/17 11:56:07 mdw
41 /*----- Header files ------------------------------------------------------*/
47 #include <mLib/bits.h>
49 /*----- Magic variables ---------------------------------------------------*/
51 static octet s
[256], si
[256];
52 static uint32 t
[4][256], ti
[4][256];
53 static uint32 u
[4][256];
56 /*----- Main code ---------------------------------------------------------*/
60 * Arguments: @unsigned x, y@ = polynomials over %$\gf{2^8}$%
61 * @unsigned m@ = modulus
63 * Returns: The product of two polynomials.
65 * Use: Computes a product of polynomials, quite slowly.
68 static unsigned mul(unsigned x
, unsigned y
, unsigned m
)
73 for (i
= 0; i
< 8; i
++) {
89 * This is built from inversion in the multiplicative group of
90 * %$\gf{2^8}[x]/(p(x))$%, where %$p(x) = x^8 + x^4 + x^3 + x + 1$%, followed
91 * by an affine transformation treating inputs as vectors over %$\gf{2}$%.
92 * The result is a horrible function.
94 * The inversion is done slightly sneakily, by building log and antilog
95 * tables. Let %$a$% be an element of the finite field. If the inverse of
96 * %$a$% is %$a^{-1}$%, then %$\log a a^{-1} = 0$%. Hence
97 * %$\log a = -\log a^{-1}$%. This saves fiddling about with Euclidean
103 static void sbox(void)
105 octet log
[256], alog
[256];
110 /* --- Find a suitable generator, and build log tables --- */
113 for (g
= 2; g
< 256; g
++) {
115 for (i
= 0; i
< 256; i
++) {
118 x
= mul(x
, g
, S_MOD
);
119 if (x
== 1 && i
!= 254)
125 fprintf(stderr
, "couldn't find generator\n");
129 /* --- Now grind through and do the affine transform --- *
131 * The matrix multiply is an AND and a parity op. The add is an XOR.
134 for (i
= 0; i
< 256; i
++) {
137 unsigned v
= i ? alog
[255 - log
[i
]] : 0;
139 assert(i
== 0 || mul(i
, v
, S_MOD
) == 1);
142 for (j
= 0; j
< 8; j
++) {
148 x
= (x
<< 1) | (r
& 1);
159 * Construct the t tables for doing the round function efficiently.
162 static void tbox(void)
166 for (i
= 0; i
< 256; i
++) {
170 /* --- Build a forwards t-box entry --- */
173 b
= a
<< 1; if (b
& 0x100) b
^= S_MOD
;
175 w
= (b
<< 0) | (a
<< 8) | (a
<< 16) | (c
<< 24);
177 t
[1][i
] = ROL32(w
, 8);
178 t
[2][i
] = ROL32(w
, 16);
179 t
[3][i
] = ROL32(w
, 24);
181 /* --- Build a backwards t-box entry --- */
183 a
= mul(si
[i
], 0x0e, S_MOD
);
184 b
= mul(si
[i
], 0x09, S_MOD
);
185 c
= mul(si
[i
], 0x0d, S_MOD
);
186 d
= mul(si
[i
], 0x0b, S_MOD
);
187 w
= (a
<< 0) | (b
<< 8) | (c
<< 16) | (d
<< 24);
189 ti
[1][i
] = ROL32(w
, 8);
190 ti
[2][i
] = ROL32(w
, 16);
191 ti
[3][i
] = ROL32(w
, 24);
197 * Construct the tables for performing the decryption key schedule.
200 static void ubox(void)
204 for (i
= 0; i
< 256; i
++) {
207 a
= mul(i
, 0x0e, S_MOD
);
208 b
= mul(i
, 0x09, S_MOD
);
209 c
= mul(i
, 0x0d, S_MOD
);
210 d
= mul(i
, 0x0b, S_MOD
);
211 w
= (a
<< 0) | (b
<< 8) | (c
<< 16) | (d
<< 24);
213 u
[1][i
] = ROL32(w
, 8);
214 u
[2][i
] = ROL32(w
, 16);
215 u
[3][i
] = ROL32(w
, 24);
219 /* --- Round constants --- */
226 for (i
= 0; i
< sizeof(rc
); i
++) {
243 * Rijndael tables [generated]\n\
246 #ifndef CATACOMB_RIJNDAEL_TAB_H\n\
247 #define CATACOMB_RIJNDAEL_TAB_H\n\
250 /* --- Write out the S-box --- */
254 /* --- The byte substitution and its inverse --- */\n\
256 #define RIJNDAEL_S { \\\n\
258 for (i
= 0; i
< 256; i
++) {
259 printf("0x%02x", s
[i
]);
261 fputs(" \\\n}\n\n", stdout
);
263 fputs(", \\\n ", stdout
);
269 #define RIJNDAEL_SI { \\\n\
271 for (i
= 0; i
< 256; i
++) {
272 printf("0x%02x", si
[i
]);
274 fputs(" \\\n}\n\n", stdout
);
276 fputs(", \\\n ", stdout
);
281 /* --- Write out the big t tables --- */
285 /* --- The big round tables --- */\n\
287 #define RIJNDAEL_T { \\\n\
289 for (j
= 0; j
< 4; j
++) {
290 for (i
= 0; i
< 256; i
++) {
291 printf("0x%08x", t
[j
][i
]);
294 fputs(" } \\\n}\n\n", stdout
);
299 } else if (i
% 4 == 3)
300 fputs(", \\\n ", stdout
);
307 #define RIJNDAEL_TI { \\\n\
309 for (j
= 0; j
< 4; j
++) {
310 for (i
= 0; i
< 256; i
++) {
311 printf("0x%08x", ti
[j
][i
]);
314 fputs(" } \\\n}\n\n", stdout
);
319 } else if (i
% 4 == 3)
320 fputs(", \\\n ", stdout
);
326 /* --- Write out the big u tables --- */
330 /* --- The decryption key schedule tables --- */\n\
332 #define RIJNDAEL_U { \\\n\
334 for (j
= 0; j
< 4; j
++) {
335 for (i
= 0; i
< 256; i
++) {
336 printf("0x%08x", u
[j
][i
]);
339 fputs(" } \\\n}\n\n", stdout
);
344 } else if (i
% 4 == 3)
345 fputs(", \\\n ", stdout
);
351 /* --- Round constants --- */
355 /* --- The round constants --- */\n\
357 #define RIJNDAEL_RCON { \\\n\
359 for (i
= 0; i
< sizeof(rc
); i
++) {
360 printf("0x%02x", rc
[i
]);
361 if (i
== sizeof(rc
) - 1)
362 fputs(" \\\n}\n\n", stdout
);
364 fputs(", \\\n ", stdout
);
373 if (fclose(stdout
)) {
374 fprintf(stderr
, "error writing data\n");
381 /*----- That's all, folks -------------------------------------------------*/