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3a65506d | 1 | /* -*-c-*- |
2 | * | |
b817bfc6 | 3 | * $Id: rijndael-mktab.c,v 1.4 2004/04/08 01:36:15 mdw Exp $ |
3a65506d | 4 | * |
5 | * Build precomputed tables for the Rijndael block cipher | |
6 | * | |
7 | * (c) 2000 Straylight/Edgeware | |
8 | */ | |
9 | ||
45c0fd36 | 10 | /*----- Licensing notice --------------------------------------------------* |
3a65506d | 11 | * |
12 | * This file is part of Catacomb. | |
13 | * | |
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. | |
45c0fd36 | 18 | * |
3a65506d | 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. | |
45c0fd36 | 23 | * |
3a65506d | 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, | |
27 | * MA 02111-1307, USA. | |
28 | */ | |
29 | ||
3a65506d | 30 | /*----- Header files ------------------------------------------------------*/ |
31 | ||
32 | #include <assert.h> | |
33 | #include <stdio.h> | |
34 | #include <stdlib.h> | |
35 | ||
36 | #include <mLib/bits.h> | |
37 | ||
38 | /*----- Magic variables ---------------------------------------------------*/ | |
39 | ||
40 | static octet s[256], si[256]; | |
41 | static uint32 t[4][256], ti[4][256]; | |
42 | static uint32 u[4][256]; | |
43 | static octet rc[32]; | |
44 | ||
45 | /*----- Main code ---------------------------------------------------------*/ | |
46 | ||
47 | /* --- @mul@ --- * | |
48 | * | |
4d47e157 | 49 | * Arguments: @unsigned x, y@ = polynomials over %$\gf{2^8}$% |
3a65506d | 50 | * @unsigned m@ = modulus |
51 | * | |
52 | * Returns: The product of two polynomials. | |
53 | * | |
54 | * Use: Computes a product of polynomials, quite slowly. | |
55 | */ | |
56 | ||
57 | static unsigned mul(unsigned x, unsigned y, unsigned m) | |
58 | { | |
59 | unsigned a = 0; | |
60 | unsigned i; | |
61 | ||
62 | for (i = 0; i < 8; i++) { | |
63 | if (y & 1) | |
64 | a ^= x; | |
65 | y >>= 1; | |
66 | x <<= 1; | |
67 | if (x & 0x100) | |
68 | x ^= m; | |
69 | } | |
70 | ||
71 | return (a); | |
72 | } | |
73 | ||
74 | /* --- @sbox@ --- * | |
75 | * | |
76 | * Build the S-box. | |
77 | * | |
4d47e157 | 78 | * This is built from inversion in the multiplicative group of |
79 | * %$\gf{2^8}[x]/(p(x))$%, where %$p(x) = x^8 + x^4 + x^3 + x + 1$%, followed | |
80 | * by an affine transformation treating inputs as vectors over %$\gf{2}$%. | |
81 | * The result is a horrible function. | |
3a65506d | 82 | * |
83 | * The inversion is done slightly sneakily, by building log and antilog | |
84 | * tables. Let %$a$% be an element of the finite field. If the inverse of | |
85 | * %$a$% is %$a^{-1}$%, then %$\log a a^{-1} = 0$%. Hence | |
86 | * %$\log a = -\log a^{-1}$%. This saves fiddling about with Euclidean | |
45c0fd36 | 87 | * algorithm. |
3a65506d | 88 | */ |
89 | ||
90 | #define S_MOD 0x11b | |
91 | ||
92 | static void sbox(void) | |
93 | { | |
94 | octet log[256], alog[256]; | |
95 | unsigned x; | |
96 | unsigned i; | |
97 | unsigned g; | |
98 | ||
99 | /* --- Find a suitable generator, and build log tables --- */ | |
100 | ||
101 | log[0] = 0; | |
102 | for (g = 2; g < 256; g++) { | |
103 | x = 1; | |
104 | for (i = 0; i < 256; i++) { | |
105 | log[x] = i; | |
106 | alog[i] = x; | |
107 | x = mul(x, g, S_MOD); | |
108 | if (x == 1 && i != 254) | |
109 | goto again; | |
110 | } | |
111 | goto done; | |
112 | again:; | |
113 | } | |
114 | fprintf(stderr, "couldn't find generator\n"); | |
115 | exit(EXIT_FAILURE); | |
116 | done:; | |
117 | ||
118 | /* --- Now grind through and do the affine transform --- * | |
119 | * | |
120 | * The matrix multiply is an AND and a parity op. The add is an XOR. | |
121 | */ | |
122 | ||
123 | for (i = 0; i < 256; i++) { | |
124 | unsigned j; | |
125 | unsigned m = 0xf8; | |
126 | unsigned v = i ? alog[255 - log[i]] : 0; | |
127 | ||
128 | assert(i == 0 || mul(i, v, S_MOD) == 1); | |
129 | ||
130 | x = 0; | |
131 | for (j = 0; j < 8; j++) { | |
132 | unsigned r; | |
133 | r = v & m; | |
134 | r = (r >> 4) ^ r; | |
135 | r = (r >> 2) ^ r; | |
136 | r = (r >> 1) ^ r; | |
137 | x = (x << 1) | (r & 1); | |
138 | m = ROR8(m, 1); | |
139 | } | |
140 | x ^= 0x63; | |
141 | s[i] = x; | |
142 | si[x] = i; | |
143 | } | |
144 | } | |
145 | ||
146 | /* --- @tbox@ --- * | |
147 | * | |
148 | * Construct the t tables for doing the round function efficiently. | |
149 | */ | |
150 | ||
151 | static void tbox(void) | |
152 | { | |
153 | unsigned i; | |
154 | ||
155 | for (i = 0; i < 256; i++) { | |
156 | uint32 a, b, c, d; | |
157 | uint32 w; | |
158 | ||
159 | /* --- Build a forwards t-box entry --- */ | |
160 | ||
161 | a = s[i]; | |
162 | b = a << 1; if (b & 0x100) b ^= S_MOD; | |
163 | c = a ^ b; | |
38333dc2 | 164 | w = (c << 0) | (a << 8) | (a << 16) | (b << 24); |
3a65506d | 165 | t[0][i] = w; |
38333dc2 MW |
166 | t[1][i] = ROR32(w, 8); |
167 | t[2][i] = ROR32(w, 16); | |
168 | t[3][i] = ROR32(w, 24); | |
3a65506d | 169 | |
170 | /* --- Build a backwards t-box entry --- */ | |
171 | ||
172 | a = mul(si[i], 0x0e, S_MOD); | |
173 | b = mul(si[i], 0x09, S_MOD); | |
174 | c = mul(si[i], 0x0d, S_MOD); | |
175 | d = mul(si[i], 0x0b, S_MOD); | |
38333dc2 | 176 | w = (d << 0) | (c << 8) | (b << 16) | (a << 24); |
3a65506d | 177 | ti[0][i] = w; |
38333dc2 MW |
178 | ti[1][i] = ROR32(w, 8); |
179 | ti[2][i] = ROR32(w, 16); | |
180 | ti[3][i] = ROR32(w, 24); | |
3a65506d | 181 | } |
182 | } | |
183 | ||
184 | /* --- @ubox@ --- * | |
185 | * | |
186 | * Construct the tables for performing the decryption key schedule. | |
187 | */ | |
188 | ||
189 | static void ubox(void) | |
190 | { | |
191 | unsigned i; | |
192 | ||
193 | for (i = 0; i < 256; i++) { | |
194 | uint32 a, b, c, d; | |
195 | uint32 w; | |
196 | a = mul(i, 0x0e, S_MOD); | |
197 | b = mul(i, 0x09, S_MOD); | |
198 | c = mul(i, 0x0d, S_MOD); | |
199 | d = mul(i, 0x0b, S_MOD); | |
38333dc2 | 200 | w = (d << 0) | (c << 8) | (b << 16) | (a << 24); |
3a65506d | 201 | u[0][i] = w; |
38333dc2 MW |
202 | u[1][i] = ROR32(w, 8); |
203 | u[2][i] = ROR32(w, 16); | |
204 | u[3][i] = ROR32(w, 24); | |
3a65506d | 205 | } |
206 | } | |
207 | ||
208 | /* --- Round constants --- */ | |
209 | ||
7a28dc19 | 210 | static void rcon(void) |
3a65506d | 211 | { |
212 | unsigned r = 1; | |
213 | int i; | |
214 | ||
215 | for (i = 0; i < sizeof(rc); i++) { | |
216 | rc[i] = r; | |
217 | r <<= 1; | |
218 | if (r & 0x100) | |
219 | r ^= S_MOD; | |
220 | } | |
221 | } | |
222 | ||
223 | /* --- @main@ --- */ | |
224 | ||
225 | int main(void) | |
226 | { | |
227 | int i, j; | |
228 | ||
229 | puts("\ | |
230 | /* -*-c-*-\n\ | |
231 | *\n\ | |
232 | * Rijndael tables [generated]\n\ | |
233 | */\n\ | |
234 | \n\ | |
235 | #ifndef CATACOMB_RIJNDAEL_TAB_H\n\ | |
236 | #define CATACOMB_RIJNDAEL_TAB_H\n\ | |
237 | "); | |
238 | ||
239 | /* --- Write out the S-box --- */ | |
240 | ||
241 | sbox(); | |
242 | fputs("\ | |
243 | /* --- The byte substitution and its inverse --- */\n\ | |
244 | \n\ | |
245 | #define RIJNDAEL_S { \\\n\ | |
246 | ", stdout); | |
247 | for (i = 0; i < 256; i++) { | |
248 | printf("0x%02x", s[i]); | |
249 | if (i == 255) | |
250 | fputs(" \\\n}\n\n", stdout); | |
251 | else if (i % 8 == 7) | |
252 | fputs(", \\\n ", stdout); | |
253 | else | |
254 | fputs(", ", stdout); | |
255 | } | |
256 | ||
257 | fputs("\ | |
258 | #define RIJNDAEL_SI { \\\n\ | |
259 | ", stdout); | |
260 | for (i = 0; i < 256; i++) { | |
261 | printf("0x%02x", si[i]); | |
262 | if (i == 255) | |
263 | fputs(" \\\n}\n\n", stdout); | |
264 | else if (i % 8 == 7) | |
265 | fputs(", \\\n ", stdout); | |
266 | else | |
267 | fputs(", ", stdout); | |
268 | } | |
269 | ||
270 | /* --- Write out the big t tables --- */ | |
271 | ||
272 | tbox(); | |
273 | fputs("\ | |
274 | /* --- The big round tables --- */\n\ | |
275 | \n\ | |
276 | #define RIJNDAEL_T { \\\n\ | |
277 | { ", stdout); | |
278 | for (j = 0; j < 4; j++) { | |
279 | for (i = 0; i < 256; i++) { | |
7a28dc19 | 280 | printf("0x%08lx", (unsigned long)t[j][i]); |
3a65506d | 281 | if (i == 255) { |
282 | if (j == 3) | |
283 | fputs(" } \\\n}\n\n", stdout); | |
284 | else | |
285 | fputs(" }, \\\n\ | |
286 | \\\n\ | |
287 | { ", stdout); | |
288 | } else if (i % 4 == 3) | |
45c0fd36 | 289 | fputs(", \\\n ", stdout); |
3a65506d | 290 | else |
291 | fputs(", ", stdout); | |
292 | } | |
45c0fd36 | 293 | } |
3a65506d | 294 | |
295 | fputs("\ | |
296 | #define RIJNDAEL_TI { \\\n\ | |
297 | { ", stdout); | |
298 | for (j = 0; j < 4; j++) { | |
299 | for (i = 0; i < 256; i++) { | |
7a28dc19 | 300 | printf("0x%08lx", (unsigned long)ti[j][i]); |
3a65506d | 301 | if (i == 255) { |
302 | if (j == 3) | |
303 | fputs(" } \\\n}\n\n", stdout); | |
304 | else | |
305 | fputs(" }, \\\n\ | |
306 | \\\n\ | |
307 | { ", stdout); | |
308 | } else if (i % 4 == 3) | |
45c0fd36 | 309 | fputs(", \\\n ", stdout); |
3a65506d | 310 | else |
311 | fputs(", ", stdout); | |
312 | } | |
313 | } | |
314 | ||
315 | /* --- Write out the big u tables --- */ | |
316 | ||
317 | ubox(); | |
318 | fputs("\ | |
319 | /* --- The decryption key schedule tables --- */\n\ | |
320 | \n\ | |
321 | #define RIJNDAEL_U { \\\n\ | |
322 | { ", stdout); | |
323 | for (j = 0; j < 4; j++) { | |
324 | for (i = 0; i < 256; i++) { | |
7a28dc19 | 325 | printf("0x%08lx", (unsigned long)u[j][i]); |
3a65506d | 326 | if (i == 255) { |
327 | if (j == 3) | |
328 | fputs(" } \\\n}\n\n", stdout); | |
329 | else | |
330 | fputs(" }, \\\n\ | |
331 | \\\n\ | |
332 | { ", stdout); | |
333 | } else if (i % 4 == 3) | |
45c0fd36 | 334 | fputs(", \\\n ", stdout); |
3a65506d | 335 | else |
336 | fputs(", ", stdout); | |
337 | } | |
45c0fd36 | 338 | } |
3a65506d | 339 | |
340 | /* --- Round constants --- */ | |
341 | ||
342 | rcon(); | |
343 | fputs("\ | |
344 | /* --- The round constants --- */\n\ | |
345 | \n\ | |
346 | #define RIJNDAEL_RCON { \\\n\ | |
347 | ", stdout); | |
348 | for (i = 0; i < sizeof(rc); i++) { | |
349 | printf("0x%02x", rc[i]); | |
350 | if (i == sizeof(rc) - 1) | |
351 | fputs(" \\\n}\n\n", stdout); | |
352 | else if (i % 8 == 7) | |
353 | fputs(", \\\n ", stdout); | |
354 | else | |
355 | fputs(", ", stdout); | |
45c0fd36 | 356 | } |
3a65506d | 357 | |
358 | /* --- Done --- */ | |
359 | ||
360 | puts("#endif"); | |
361 | ||
362 | if (fclose(stdout)) { | |
363 | fprintf(stderr, "error writing data\n"); | |
364 | exit(EXIT_FAILURE); | |
365 | } | |
366 | ||
367 | return (0); | |
368 | } | |
369 | ||
370 | /*----- That's all, folks -------------------------------------------------*/ |