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1 | /* -*-c-*- |
2 | * |
b817bfc6 |
3 | * $Id: rijndael-mktab.c,v 1.4 2004/04/08 01:36:15 mdw Exp $ |
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4 | * |
5 | * Build precomputed tables for the Rijndael block cipher |
6 | * |
7 | * (c) 2000 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
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. |
18 | * |
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. |
23 | * |
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 | |
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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 %$\gf{2^8}$% |
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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. |
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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 |
87 | * algorithm. |
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; |
164 | w = (b << 0) | (a << 8) | (a << 16) | (c << 24); |
165 | t[0][i] = w; |
166 | t[1][i] = ROL32(w, 8); |
167 | t[2][i] = ROL32(w, 16); |
168 | t[3][i] = ROL32(w, 24); |
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); |
176 | w = (a << 0) | (b << 8) | (c << 16) | (d << 24); |
177 | ti[0][i] = w; |
178 | ti[1][i] = ROL32(w, 8); |
179 | ti[2][i] = ROL32(w, 16); |
180 | ti[3][i] = ROL32(w, 24); |
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); |
200 | w = (a << 0) | (b << 8) | (c << 16) | (d << 24); |
201 | u[0][i] = w; |
202 | u[1][i] = ROL32(w, 8); |
203 | u[2][i] = ROL32(w, 16); |
204 | u[3][i] = ROL32(w, 24); |
205 | } |
206 | } |
207 | |
208 | /* --- Round constants --- */ |
209 | |
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210 | static void rcon(void) |
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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]); |
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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) |
289 | fputs(", \\\n ", stdout); |
290 | else |
291 | fputs(", ", stdout); |
292 | } |
293 | } |
294 | |
295 | fputs("\ |
296 | #define RIJNDAEL_TI { \\\n\ |
297 | { ", stdout); |
298 | for (j = 0; j < 4; j++) { |
299 | for (i = 0; i < 256; i++) { |
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300 | printf("0x%08lx", (unsigned long)ti[j][i]); |
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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) |
309 | fputs(", \\\n ", stdout); |
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]); |
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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) |
334 | fputs(", \\\n ", stdout); |
335 | else |
336 | fputs(", ", stdout); |
337 | } |
338 | } |
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); |
356 | } |
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 -------------------------------------------------*/ |