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3a65506d | 1 | /* -*-c-*- |
2 | * | |
3a65506d | 3 | * Build precomputed tables for the Rijndael block cipher |
4 | * | |
5 | * (c) 2000 Straylight/Edgeware | |
6 | */ | |
7 | ||
45c0fd36 | 8 | /*----- Licensing notice --------------------------------------------------* |
3a65506d | 9 | * |
10 | * This file is part of Catacomb. | |
11 | * | |
12 | * Catacomb is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU Library General Public License as | |
14 | * published by the Free Software Foundation; either version 2 of the | |
15 | * License, or (at your option) any later version. | |
45c0fd36 | 16 | * |
3a65506d | 17 | * Catacomb is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU Library General Public License for more details. | |
45c0fd36 | 21 | * |
3a65506d | 22 | * You should have received a copy of the GNU Library General Public |
23 | * License along with Catacomb; if not, write to the Free | |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, | |
25 | * MA 02111-1307, USA. | |
26 | */ | |
27 | ||
3a65506d | 28 | /*----- Header files ------------------------------------------------------*/ |
29 | ||
30 | #include <assert.h> | |
31 | #include <stdio.h> | |
32 | #include <stdlib.h> | |
33 | ||
34 | #include <mLib/bits.h> | |
35 | ||
36 | /*----- Magic variables ---------------------------------------------------*/ | |
37 | ||
38 | static octet s[256], si[256]; | |
39 | static uint32 t[4][256], ti[4][256]; | |
40 | static uint32 u[4][256]; | |
41 | static octet rc[32]; | |
42 | ||
43 | /*----- Main code ---------------------------------------------------------*/ | |
44 | ||
45 | /* --- @mul@ --- * | |
46 | * | |
4d47e157 | 47 | * Arguments: @unsigned x, y@ = polynomials over %$\gf{2^8}$% |
3a65506d | 48 | * @unsigned m@ = modulus |
49 | * | |
50 | * Returns: The product of two polynomials. | |
51 | * | |
52 | * Use: Computes a product of polynomials, quite slowly. | |
53 | */ | |
54 | ||
55 | static unsigned mul(unsigned x, unsigned y, unsigned m) | |
56 | { | |
57 | unsigned a = 0; | |
58 | unsigned i; | |
59 | ||
60 | for (i = 0; i < 8; i++) { | |
61 | if (y & 1) | |
62 | a ^= x; | |
63 | y >>= 1; | |
64 | x <<= 1; | |
65 | if (x & 0x100) | |
66 | x ^= m; | |
67 | } | |
68 | ||
69 | return (a); | |
70 | } | |
71 | ||
72 | /* --- @sbox@ --- * | |
73 | * | |
74 | * Build the S-box. | |
75 | * | |
4d47e157 | 76 | * This is built from inversion in the multiplicative group of |
77 | * %$\gf{2^8}[x]/(p(x))$%, where %$p(x) = x^8 + x^4 + x^3 + x + 1$%, followed | |
78 | * by an affine transformation treating inputs as vectors over %$\gf{2}$%. | |
79 | * The result is a horrible function. | |
3a65506d | 80 | * |
81 | * The inversion is done slightly sneakily, by building log and antilog | |
82 | * tables. Let %$a$% be an element of the finite field. If the inverse of | |
83 | * %$a$% is %$a^{-1}$%, then %$\log a a^{-1} = 0$%. Hence | |
84 | * %$\log a = -\log a^{-1}$%. This saves fiddling about with Euclidean | |
45c0fd36 | 85 | * algorithm. |
3a65506d | 86 | */ |
87 | ||
88 | #define S_MOD 0x11b | |
89 | ||
90 | static void sbox(void) | |
91 | { | |
92 | octet log[256], alog[256]; | |
93 | unsigned x; | |
94 | unsigned i; | |
95 | unsigned g; | |
96 | ||
97 | /* --- Find a suitable generator, and build log tables --- */ | |
98 | ||
99 | log[0] = 0; | |
100 | for (g = 2; g < 256; g++) { | |
101 | x = 1; | |
102 | for (i = 0; i < 256; i++) { | |
103 | log[x] = i; | |
104 | alog[i] = x; | |
105 | x = mul(x, g, S_MOD); | |
106 | if (x == 1 && i != 254) | |
107 | goto again; | |
108 | } | |
109 | goto done; | |
110 | again:; | |
111 | } | |
112 | fprintf(stderr, "couldn't find generator\n"); | |
113 | exit(EXIT_FAILURE); | |
114 | done:; | |
115 | ||
116 | /* --- Now grind through and do the affine transform --- * | |
117 | * | |
118 | * The matrix multiply is an AND and a parity op. The add is an XOR. | |
119 | */ | |
120 | ||
121 | for (i = 0; i < 256; i++) { | |
122 | unsigned j; | |
123 | unsigned m = 0xf8; | |
124 | unsigned v = i ? alog[255 - log[i]] : 0; | |
125 | ||
126 | assert(i == 0 || mul(i, v, S_MOD) == 1); | |
127 | ||
128 | x = 0; | |
129 | for (j = 0; j < 8; j++) { | |
130 | unsigned r; | |
131 | r = v & m; | |
132 | r = (r >> 4) ^ r; | |
133 | r = (r >> 2) ^ r; | |
134 | r = (r >> 1) ^ r; | |
135 | x = (x << 1) | (r & 1); | |
136 | m = ROR8(m, 1); | |
137 | } | |
138 | x ^= 0x63; | |
139 | s[i] = x; | |
140 | si[x] = i; | |
141 | } | |
142 | } | |
143 | ||
144 | /* --- @tbox@ --- * | |
145 | * | |
146 | * Construct the t tables for doing the round function efficiently. | |
147 | */ | |
148 | ||
149 | static void tbox(void) | |
150 | { | |
151 | unsigned i; | |
152 | ||
153 | for (i = 0; i < 256; i++) { | |
154 | uint32 a, b, c, d; | |
155 | uint32 w; | |
156 | ||
157 | /* --- Build a forwards t-box entry --- */ | |
158 | ||
159 | a = s[i]; | |
160 | b = a << 1; if (b & 0x100) b ^= S_MOD; | |
161 | c = a ^ b; | |
38333dc2 | 162 | w = (c << 0) | (a << 8) | (a << 16) | (b << 24); |
3a65506d | 163 | t[0][i] = w; |
38333dc2 MW |
164 | t[1][i] = ROR32(w, 8); |
165 | t[2][i] = ROR32(w, 16); | |
166 | t[3][i] = ROR32(w, 24); | |
3a65506d | 167 | |
168 | /* --- Build a backwards t-box entry --- */ | |
169 | ||
170 | a = mul(si[i], 0x0e, S_MOD); | |
171 | b = mul(si[i], 0x09, S_MOD); | |
172 | c = mul(si[i], 0x0d, S_MOD); | |
173 | d = mul(si[i], 0x0b, S_MOD); | |
38333dc2 | 174 | w = (d << 0) | (c << 8) | (b << 16) | (a << 24); |
3a65506d | 175 | ti[0][i] = w; |
38333dc2 MW |
176 | ti[1][i] = ROR32(w, 8); |
177 | ti[2][i] = ROR32(w, 16); | |
178 | ti[3][i] = ROR32(w, 24); | |
3a65506d | 179 | } |
180 | } | |
181 | ||
182 | /* --- @ubox@ --- * | |
183 | * | |
184 | * Construct the tables for performing the decryption key schedule. | |
185 | */ | |
186 | ||
187 | static void ubox(void) | |
188 | { | |
189 | unsigned i; | |
190 | ||
191 | for (i = 0; i < 256; i++) { | |
192 | uint32 a, b, c, d; | |
193 | uint32 w; | |
194 | a = mul(i, 0x0e, S_MOD); | |
195 | b = mul(i, 0x09, S_MOD); | |
196 | c = mul(i, 0x0d, S_MOD); | |
197 | d = mul(i, 0x0b, S_MOD); | |
38333dc2 | 198 | w = (d << 0) | (c << 8) | (b << 16) | (a << 24); |
3a65506d | 199 | u[0][i] = w; |
38333dc2 MW |
200 | u[1][i] = ROR32(w, 8); |
201 | u[2][i] = ROR32(w, 16); | |
202 | u[3][i] = ROR32(w, 24); | |
3a65506d | 203 | } |
204 | } | |
205 | ||
206 | /* --- Round constants --- */ | |
207 | ||
7a28dc19 | 208 | static void rcon(void) |
3a65506d | 209 | { |
210 | unsigned r = 1; | |
211 | int i; | |
212 | ||
213 | for (i = 0; i < sizeof(rc); i++) { | |
214 | rc[i] = r; | |
215 | r <<= 1; | |
216 | if (r & 0x100) | |
217 | r ^= S_MOD; | |
218 | } | |
219 | } | |
220 | ||
221 | /* --- @main@ --- */ | |
222 | ||
223 | int main(void) | |
224 | { | |
225 | int i, j; | |
226 | ||
227 | puts("\ | |
228 | /* -*-c-*-\n\ | |
229 | *\n\ | |
230 | * Rijndael tables [generated]\n\ | |
231 | */\n\ | |
232 | \n\ | |
233 | #ifndef CATACOMB_RIJNDAEL_TAB_H\n\ | |
234 | #define CATACOMB_RIJNDAEL_TAB_H\n\ | |
235 | "); | |
236 | ||
237 | /* --- Write out the S-box --- */ | |
238 | ||
239 | sbox(); | |
240 | fputs("\ | |
241 | /* --- The byte substitution and its inverse --- */\n\ | |
242 | \n\ | |
243 | #define RIJNDAEL_S { \\\n\ | |
244 | ", stdout); | |
245 | for (i = 0; i < 256; i++) { | |
246 | printf("0x%02x", s[i]); | |
247 | if (i == 255) | |
248 | fputs(" \\\n}\n\n", stdout); | |
249 | else if (i % 8 == 7) | |
250 | fputs(", \\\n ", stdout); | |
251 | else | |
252 | fputs(", ", stdout); | |
253 | } | |
254 | ||
255 | fputs("\ | |
256 | #define RIJNDAEL_SI { \\\n\ | |
257 | ", stdout); | |
258 | for (i = 0; i < 256; i++) { | |
259 | printf("0x%02x", si[i]); | |
260 | if (i == 255) | |
261 | fputs(" \\\n}\n\n", stdout); | |
262 | else if (i % 8 == 7) | |
263 | fputs(", \\\n ", stdout); | |
264 | else | |
265 | fputs(", ", stdout); | |
266 | } | |
267 | ||
268 | /* --- Write out the big t tables --- */ | |
269 | ||
270 | tbox(); | |
271 | fputs("\ | |
272 | /* --- The big round tables --- */\n\ | |
273 | \n\ | |
274 | #define RIJNDAEL_T { \\\n\ | |
275 | { ", stdout); | |
276 | for (j = 0; j < 4; j++) { | |
277 | for (i = 0; i < 256; i++) { | |
7a28dc19 | 278 | printf("0x%08lx", (unsigned long)t[j][i]); |
3a65506d | 279 | if (i == 255) { |
280 | if (j == 3) | |
281 | fputs(" } \\\n}\n\n", stdout); | |
282 | else | |
283 | fputs(" }, \\\n\ | |
284 | \\\n\ | |
285 | { ", stdout); | |
286 | } else if (i % 4 == 3) | |
45c0fd36 | 287 | fputs(", \\\n ", stdout); |
3a65506d | 288 | else |
289 | fputs(", ", stdout); | |
290 | } | |
45c0fd36 | 291 | } |
3a65506d | 292 | |
293 | fputs("\ | |
294 | #define RIJNDAEL_TI { \\\n\ | |
295 | { ", stdout); | |
296 | for (j = 0; j < 4; j++) { | |
297 | for (i = 0; i < 256; i++) { | |
7a28dc19 | 298 | printf("0x%08lx", (unsigned long)ti[j][i]); |
3a65506d | 299 | if (i == 255) { |
300 | if (j == 3) | |
301 | fputs(" } \\\n}\n\n", stdout); | |
302 | else | |
303 | fputs(" }, \\\n\ | |
304 | \\\n\ | |
305 | { ", stdout); | |
306 | } else if (i % 4 == 3) | |
45c0fd36 | 307 | fputs(", \\\n ", stdout); |
3a65506d | 308 | else |
309 | fputs(", ", stdout); | |
310 | } | |
311 | } | |
312 | ||
313 | /* --- Write out the big u tables --- */ | |
314 | ||
315 | ubox(); | |
316 | fputs("\ | |
317 | /* --- The decryption key schedule tables --- */\n\ | |
318 | \n\ | |
319 | #define RIJNDAEL_U { \\\n\ | |
320 | { ", stdout); | |
321 | for (j = 0; j < 4; j++) { | |
322 | for (i = 0; i < 256; i++) { | |
7a28dc19 | 323 | printf("0x%08lx", (unsigned long)u[j][i]); |
3a65506d | 324 | if (i == 255) { |
325 | if (j == 3) | |
326 | fputs(" } \\\n}\n\n", stdout); | |
327 | else | |
328 | fputs(" }, \\\n\ | |
329 | \\\n\ | |
330 | { ", stdout); | |
331 | } else if (i % 4 == 3) | |
45c0fd36 | 332 | fputs(", \\\n ", stdout); |
3a65506d | 333 | else |
334 | fputs(", ", stdout); | |
335 | } | |
45c0fd36 | 336 | } |
3a65506d | 337 | |
338 | /* --- Round constants --- */ | |
339 | ||
340 | rcon(); | |
341 | fputs("\ | |
342 | /* --- The round constants --- */\n\ | |
343 | \n\ | |
344 | #define RIJNDAEL_RCON { \\\n\ | |
345 | ", stdout); | |
346 | for (i = 0; i < sizeof(rc); i++) { | |
347 | printf("0x%02x", rc[i]); | |
348 | if (i == sizeof(rc) - 1) | |
349 | fputs(" \\\n}\n\n", stdout); | |
350 | else if (i % 8 == 7) | |
351 | fputs(", \\\n ", stdout); | |
352 | else | |
353 | fputs(", ", stdout); | |
45c0fd36 | 354 | } |
3a65506d | 355 | |
356 | /* --- Done --- */ | |
357 | ||
358 | puts("#endif"); | |
359 | ||
360 | if (fclose(stdout)) { | |
361 | fprintf(stderr, "error writing data\n"); | |
362 | exit(EXIT_FAILURE); | |
363 | } | |
364 | ||
365 | return (0); | |
366 | } | |
367 | ||
368 | /*----- That's all, folks -------------------------------------------------*/ |