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1 | /* -*-c-*- |
2 | * |
7a28dc19 |
3 | * $Id: rijndael-mktab.c,v 1.3 2000/10/14 17:13:19 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 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: rijndael-mktab.c,v $ |
7a28dc19 |
33 | * Revision 1.3 2000/10/14 17:13:19 mdw |
34 | * Fix some compile errors. |
35 | * |
4d47e157 |
36 | * Revision 1.2 2000/06/18 23:12:15 mdw |
37 | * Change typesetting of Galois Field names. |
38 | * |
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39 | * Revision 1.1 2000/06/17 11:56:07 mdw |
40 | * New cipher. |
41 | * |
42 | */ |
43 | |
44 | /*----- Header files ------------------------------------------------------*/ |
45 | |
46 | #include <assert.h> |
47 | #include <stdio.h> |
48 | #include <stdlib.h> |
49 | |
50 | #include <mLib/bits.h> |
51 | |
52 | /*----- Magic variables ---------------------------------------------------*/ |
53 | |
54 | static octet s[256], si[256]; |
55 | static uint32 t[4][256], ti[4][256]; |
56 | static uint32 u[4][256]; |
57 | static octet rc[32]; |
58 | |
59 | /*----- Main code ---------------------------------------------------------*/ |
60 | |
61 | /* --- @mul@ --- * |
62 | * |
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63 | * Arguments: @unsigned x, y@ = polynomials over %$\gf{2^8}$% |
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64 | * @unsigned m@ = modulus |
65 | * |
66 | * Returns: The product of two polynomials. |
67 | * |
68 | * Use: Computes a product of polynomials, quite slowly. |
69 | */ |
70 | |
71 | static unsigned mul(unsigned x, unsigned y, unsigned m) |
72 | { |
73 | unsigned a = 0; |
74 | unsigned i; |
75 | |
76 | for (i = 0; i < 8; i++) { |
77 | if (y & 1) |
78 | a ^= x; |
79 | y >>= 1; |
80 | x <<= 1; |
81 | if (x & 0x100) |
82 | x ^= m; |
83 | } |
84 | |
85 | return (a); |
86 | } |
87 | |
88 | /* --- @sbox@ --- * |
89 | * |
90 | * Build the S-box. |
91 | * |
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92 | * This is built from inversion in the multiplicative group of |
93 | * %$\gf{2^8}[x]/(p(x))$%, where %$p(x) = x^8 + x^4 + x^3 + x + 1$%, followed |
94 | * by an affine transformation treating inputs as vectors over %$\gf{2}$%. |
95 | * The result is a horrible function. |
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96 | * |
97 | * The inversion is done slightly sneakily, by building log and antilog |
98 | * tables. Let %$a$% be an element of the finite field. If the inverse of |
99 | * %$a$% is %$a^{-1}$%, then %$\log a a^{-1} = 0$%. Hence |
100 | * %$\log a = -\log a^{-1}$%. This saves fiddling about with Euclidean |
101 | * algorithm. |
102 | */ |
103 | |
104 | #define S_MOD 0x11b |
105 | |
106 | static void sbox(void) |
107 | { |
108 | octet log[256], alog[256]; |
109 | unsigned x; |
110 | unsigned i; |
111 | unsigned g; |
112 | |
113 | /* --- Find a suitable generator, and build log tables --- */ |
114 | |
115 | log[0] = 0; |
116 | for (g = 2; g < 256; g++) { |
117 | x = 1; |
118 | for (i = 0; i < 256; i++) { |
119 | log[x] = i; |
120 | alog[i] = x; |
121 | x = mul(x, g, S_MOD); |
122 | if (x == 1 && i != 254) |
123 | goto again; |
124 | } |
125 | goto done; |
126 | again:; |
127 | } |
128 | fprintf(stderr, "couldn't find generator\n"); |
129 | exit(EXIT_FAILURE); |
130 | done:; |
131 | |
132 | /* --- Now grind through and do the affine transform --- * |
133 | * |
134 | * The matrix multiply is an AND and a parity op. The add is an XOR. |
135 | */ |
136 | |
137 | for (i = 0; i < 256; i++) { |
138 | unsigned j; |
139 | unsigned m = 0xf8; |
140 | unsigned v = i ? alog[255 - log[i]] : 0; |
141 | |
142 | assert(i == 0 || mul(i, v, S_MOD) == 1); |
143 | |
144 | x = 0; |
145 | for (j = 0; j < 8; j++) { |
146 | unsigned r; |
147 | r = v & m; |
148 | r = (r >> 4) ^ r; |
149 | r = (r >> 2) ^ r; |
150 | r = (r >> 1) ^ r; |
151 | x = (x << 1) | (r & 1); |
152 | m = ROR8(m, 1); |
153 | } |
154 | x ^= 0x63; |
155 | s[i] = x; |
156 | si[x] = i; |
157 | } |
158 | } |
159 | |
160 | /* --- @tbox@ --- * |
161 | * |
162 | * Construct the t tables for doing the round function efficiently. |
163 | */ |
164 | |
165 | static void tbox(void) |
166 | { |
167 | unsigned i; |
168 | |
169 | for (i = 0; i < 256; i++) { |
170 | uint32 a, b, c, d; |
171 | uint32 w; |
172 | |
173 | /* --- Build a forwards t-box entry --- */ |
174 | |
175 | a = s[i]; |
176 | b = a << 1; if (b & 0x100) b ^= S_MOD; |
177 | c = a ^ b; |
178 | w = (b << 0) | (a << 8) | (a << 16) | (c << 24); |
179 | t[0][i] = w; |
180 | t[1][i] = ROL32(w, 8); |
181 | t[2][i] = ROL32(w, 16); |
182 | t[3][i] = ROL32(w, 24); |
183 | |
184 | /* --- Build a backwards t-box entry --- */ |
185 | |
186 | a = mul(si[i], 0x0e, S_MOD); |
187 | b = mul(si[i], 0x09, S_MOD); |
188 | c = mul(si[i], 0x0d, S_MOD); |
189 | d = mul(si[i], 0x0b, S_MOD); |
190 | w = (a << 0) | (b << 8) | (c << 16) | (d << 24); |
191 | ti[0][i] = w; |
192 | ti[1][i] = ROL32(w, 8); |
193 | ti[2][i] = ROL32(w, 16); |
194 | ti[3][i] = ROL32(w, 24); |
195 | } |
196 | } |
197 | |
198 | /* --- @ubox@ --- * |
199 | * |
200 | * Construct the tables for performing the decryption key schedule. |
201 | */ |
202 | |
203 | static void ubox(void) |
204 | { |
205 | unsigned i; |
206 | |
207 | for (i = 0; i < 256; i++) { |
208 | uint32 a, b, c, d; |
209 | uint32 w; |
210 | a = mul(i, 0x0e, S_MOD); |
211 | b = mul(i, 0x09, S_MOD); |
212 | c = mul(i, 0x0d, S_MOD); |
213 | d = mul(i, 0x0b, S_MOD); |
214 | w = (a << 0) | (b << 8) | (c << 16) | (d << 24); |
215 | u[0][i] = w; |
216 | u[1][i] = ROL32(w, 8); |
217 | u[2][i] = ROL32(w, 16); |
218 | u[3][i] = ROL32(w, 24); |
219 | } |
220 | } |
221 | |
222 | /* --- Round constants --- */ |
223 | |
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224 | static void rcon(void) |
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225 | { |
226 | unsigned r = 1; |
227 | int i; |
228 | |
229 | for (i = 0; i < sizeof(rc); i++) { |
230 | rc[i] = r; |
231 | r <<= 1; |
232 | if (r & 0x100) |
233 | r ^= S_MOD; |
234 | } |
235 | } |
236 | |
237 | /* --- @main@ --- */ |
238 | |
239 | int main(void) |
240 | { |
241 | int i, j; |
242 | |
243 | puts("\ |
244 | /* -*-c-*-\n\ |
245 | *\n\ |
246 | * Rijndael tables [generated]\n\ |
247 | */\n\ |
248 | \n\ |
249 | #ifndef CATACOMB_RIJNDAEL_TAB_H\n\ |
250 | #define CATACOMB_RIJNDAEL_TAB_H\n\ |
251 | "); |
252 | |
253 | /* --- Write out the S-box --- */ |
254 | |
255 | sbox(); |
256 | fputs("\ |
257 | /* --- The byte substitution and its inverse --- */\n\ |
258 | \n\ |
259 | #define RIJNDAEL_S { \\\n\ |
260 | ", stdout); |
261 | for (i = 0; i < 256; i++) { |
262 | printf("0x%02x", s[i]); |
263 | if (i == 255) |
264 | fputs(" \\\n}\n\n", stdout); |
265 | else if (i % 8 == 7) |
266 | fputs(", \\\n ", stdout); |
267 | else |
268 | fputs(", ", stdout); |
269 | } |
270 | |
271 | fputs("\ |
272 | #define RIJNDAEL_SI { \\\n\ |
273 | ", stdout); |
274 | for (i = 0; i < 256; i++) { |
275 | printf("0x%02x", si[i]); |
276 | if (i == 255) |
277 | fputs(" \\\n}\n\n", stdout); |
278 | else if (i % 8 == 7) |
279 | fputs(", \\\n ", stdout); |
280 | else |
281 | fputs(", ", stdout); |
282 | } |
283 | |
284 | /* --- Write out the big t tables --- */ |
285 | |
286 | tbox(); |
287 | fputs("\ |
288 | /* --- The big round tables --- */\n\ |
289 | \n\ |
290 | #define RIJNDAEL_T { \\\n\ |
291 | { ", stdout); |
292 | for (j = 0; j < 4; j++) { |
293 | for (i = 0; i < 256; i++) { |
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294 | printf("0x%08lx", (unsigned long)t[j][i]); |
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295 | if (i == 255) { |
296 | if (j == 3) |
297 | fputs(" } \\\n}\n\n", stdout); |
298 | else |
299 | fputs(" }, \\\n\ |
300 | \\\n\ |
301 | { ", stdout); |
302 | } else if (i % 4 == 3) |
303 | fputs(", \\\n ", stdout); |
304 | else |
305 | fputs(", ", stdout); |
306 | } |
307 | } |
308 | |
309 | fputs("\ |
310 | #define RIJNDAEL_TI { \\\n\ |
311 | { ", stdout); |
312 | for (j = 0; j < 4; j++) { |
313 | for (i = 0; i < 256; i++) { |
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314 | printf("0x%08lx", (unsigned long)ti[j][i]); |
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315 | if (i == 255) { |
316 | if (j == 3) |
317 | fputs(" } \\\n}\n\n", stdout); |
318 | else |
319 | fputs(" }, \\\n\ |
320 | \\\n\ |
321 | { ", stdout); |
322 | } else if (i % 4 == 3) |
323 | fputs(", \\\n ", stdout); |
324 | else |
325 | fputs(", ", stdout); |
326 | } |
327 | } |
328 | |
329 | /* --- Write out the big u tables --- */ |
330 | |
331 | ubox(); |
332 | fputs("\ |
333 | /* --- The decryption key schedule tables --- */\n\ |
334 | \n\ |
335 | #define RIJNDAEL_U { \\\n\ |
336 | { ", stdout); |
337 | for (j = 0; j < 4; j++) { |
338 | for (i = 0; i < 256; i++) { |
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339 | printf("0x%08lx", (unsigned long)u[j][i]); |
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340 | if (i == 255) { |
341 | if (j == 3) |
342 | fputs(" } \\\n}\n\n", stdout); |
343 | else |
344 | fputs(" }, \\\n\ |
345 | \\\n\ |
346 | { ", stdout); |
347 | } else if (i % 4 == 3) |
348 | fputs(", \\\n ", stdout); |
349 | else |
350 | fputs(", ", stdout); |
351 | } |
352 | } |
353 | |
354 | /* --- Round constants --- */ |
355 | |
356 | rcon(); |
357 | fputs("\ |
358 | /* --- The round constants --- */\n\ |
359 | \n\ |
360 | #define RIJNDAEL_RCON { \\\n\ |
361 | ", stdout); |
362 | for (i = 0; i < sizeof(rc); i++) { |
363 | printf("0x%02x", rc[i]); |
364 | if (i == sizeof(rc) - 1) |
365 | fputs(" \\\n}\n\n", stdout); |
366 | else if (i % 8 == 7) |
367 | fputs(", \\\n ", stdout); |
368 | else |
369 | fputs(", ", stdout); |
370 | } |
371 | |
372 | /* --- Done --- */ |
373 | |
374 | puts("#endif"); |
375 | |
376 | if (fclose(stdout)) { |
377 | fprintf(stderr, "error writing data\n"); |
378 | exit(EXIT_FAILURE); |
379 | } |
380 | |
381 | return (0); |
382 | } |
383 | |
384 | /*----- That's all, folks -------------------------------------------------*/ |