35682d2f |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: square-mktab.c,v 1.1 2000/07/27 18:10:27 mdw Exp $ |
4 | * |
5 | * Build precomputed tables for the Square 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: square-mktab.c,v $ |
33 | * Revision 1.1 2000/07/27 18:10:27 mdw |
34 | * Build precomuted tables for Square. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include <assert.h> |
41 | #include <stdio.h> |
42 | #include <stdlib.h> |
43 | |
44 | #include <mLib/bits.h> |
45 | |
46 | /*----- Magic variables ---------------------------------------------------*/ |
47 | |
48 | static octet s[256], si[256]; |
49 | static uint32 t[4][256], ti[4][256]; |
50 | static uint32 u[4][256]; |
51 | static octet rc[32]; |
52 | |
53 | /*----- Main code ---------------------------------------------------------*/ |
54 | |
55 | /* --- @mul@ --- * |
56 | * |
57 | * Arguments: @unsigned x, y@ = polynomials over %$\gf{2^8}$% |
58 | * @unsigned m@ = modulus |
59 | * |
60 | * Returns: The product of two polynomials. |
61 | * |
62 | * Use: Computes a product of polynomials, quite slowly. |
63 | */ |
64 | |
65 | static unsigned mul(unsigned x, unsigned y, unsigned m) |
66 | { |
67 | unsigned a = 0; |
68 | unsigned i; |
69 | |
70 | for (i = 0; i < 8; i++) { |
71 | if (y & 1) |
72 | a ^= x; |
73 | y >>= 1; |
74 | x <<= 1; |
75 | if (x & 0x100) |
76 | x ^= m; |
77 | } |
78 | |
79 | return (a); |
80 | } |
81 | |
82 | /* --- @sbox@ --- * |
83 | * |
84 | * Build the S-box. |
85 | * |
86 | * This is built from inversion in the multiplicative group of |
87 | * %$\gf{2^8}[x]/(p(x))$%, where %$p(x) = x^8 + x^4 + x^3 + x + 1$%, followed |
88 | * by an affine transformation treating inputs as vectors over %$\gf{2}$%. |
89 | * The result is a horrible function. |
90 | * |
91 | * The inversion is done slightly sneakily, by building log and antilog |
92 | * tables. Let %$a$% be an element of the finite field. If the inverse of |
93 | * %$a$% is %$a^{-1}$%, then %$\log a a^{-1} = 0$%. Hence |
94 | * %$\log a = -\log a^{-1}$%. This saves fiddling about with Euclidean |
95 | * algorithm. |
96 | */ |
97 | |
98 | #define S_MOD 0x1f5 |
99 | |
100 | static void sbox(void) |
101 | { |
102 | octet log[256], alog[256]; |
103 | unsigned x; |
104 | unsigned i; |
105 | unsigned g; |
106 | |
107 | /* --- Find a suitable generator, and build log tables --- */ |
108 | |
109 | log[0] = 0; |
110 | for (g = 2; g < 256; g++) { |
111 | x = 1; |
112 | for (i = 0; i < 256; i++) { |
113 | log[x] = i; |
114 | alog[i] = x; |
115 | x = mul(x, g, S_MOD); |
116 | if (x == 1 && i != 254) |
117 | goto again; |
118 | } |
119 | goto done; |
120 | again:; |
121 | } |
122 | fprintf(stderr, "couldn't find generator\n"); |
123 | exit(EXIT_FAILURE); |
124 | done:; |
125 | |
126 | /* --- Now grind through and do the affine transform --- * |
127 | * |
128 | * The matrix multiply is an AND and a parity op. The add is an XOR. |
129 | */ |
130 | |
131 | for (i = 0; i < 256; i++) { |
132 | unsigned j; |
133 | octet m[] = { 0xd6, 0x7b, 0x3d, 0x1f, 0x0f, 0x05, 0x03, 0x01 }; |
134 | unsigned v = i ? alog[255 - log[i]] : 0; |
135 | |
136 | assert(i == 0 || mul(i, v, S_MOD) == 1); |
137 | |
138 | x = 0; |
139 | for (j = 0; j < 8; j++) { |
140 | unsigned r; |
141 | r = v & m[j]; |
142 | r = (r >> 4) ^ r; |
143 | r = (r >> 2) ^ r; |
144 | r = (r >> 1) ^ r; |
145 | x = (x << 1) | (r & 1); |
146 | } |
147 | x ^= 0xb1; |
148 | s[i] = x; |
149 | si[x] = i; |
150 | } |
151 | } |
152 | |
153 | /* --- @tbox@ --- * |
154 | * |
155 | * Construct the t tables for doing the round function efficiently. |
156 | */ |
157 | |
158 | static void tbox(void) |
159 | { |
160 | unsigned i; |
161 | |
162 | for (i = 0; i < 256; i++) { |
163 | uint32 a, b, c, d; |
164 | uint32 w; |
165 | |
166 | /* --- Build a forwards t-box entry --- */ |
167 | |
168 | a = s[i]; |
169 | b = a << 1; if (b & 0x100) b ^= S_MOD; |
170 | c = a ^ b; |
171 | w = (b << 0) | (a << 8) | (a << 16) | (c << 24); |
172 | t[0][i] = w; |
173 | t[1][i] = ROL32(w, 8); |
174 | t[2][i] = ROL32(w, 16); |
175 | t[3][i] = ROL32(w, 24); |
176 | |
177 | /* --- Build a backwards t-box entry --- */ |
178 | |
179 | a = mul(si[i], 0x0e, S_MOD); |
180 | b = mul(si[i], 0x09, S_MOD); |
181 | c = mul(si[i], 0x0d, S_MOD); |
182 | d = mul(si[i], 0x0b, S_MOD); |
183 | w = (a << 0) | (b << 8) | (c << 16) | (d << 24); |
184 | ti[0][i] = w; |
185 | ti[1][i] = ROL32(w, 8); |
186 | ti[2][i] = ROL32(w, 16); |
187 | ti[3][i] = ROL32(w, 24); |
188 | } |
189 | } |
190 | |
191 | /* --- @ubox@ --- * |
192 | * |
193 | * Construct the tables for performing the key schedule. |
194 | */ |
195 | |
196 | static void ubox(void) |
197 | { |
198 | unsigned i; |
199 | |
200 | for (i = 0; i < 256; i++) { |
201 | uint32 a, b, c; |
202 | uint32 w; |
203 | a = i; |
204 | b = a << 1; if (b & 0x100) b ^= S_MOD; |
205 | c = a ^ b; |
206 | w = (b << 0) | (a << 8) | (a << 16) | (c << 24); |
207 | u[0][i] = w; |
208 | u[1][i] = ROL32(w, 8); |
209 | u[2][i] = ROL32(w, 16); |
210 | u[3][i] = ROL32(w, 24); |
211 | } |
212 | } |
213 | |
214 | /* --- Round constants --- */ |
215 | |
216 | void rcon(void) |
217 | { |
218 | unsigned r = 1; |
219 | int i; |
220 | |
221 | for (i = 0; i < sizeof(rc); i++) { |
222 | rc[i] = r; |
223 | r <<= 1; |
224 | if (r & 0x100) |
225 | r ^= S_MOD; |
226 | } |
227 | } |
228 | |
229 | /* --- @main@ --- */ |
230 | |
231 | int main(void) |
232 | { |
233 | int i, j; |
234 | |
235 | puts("\ |
236 | /* -*-c-*-\n\ |
237 | *\n\ |
238 | * Square tables [generated]\n\ |
239 | */\n\ |
240 | \n\ |
241 | #ifndef CATACOMB_SQUARE_TAB_H\n\ |
242 | #define CATACOMB_SQUARE_TAB_H\n\ |
243 | "); |
244 | |
245 | /* --- Write out the S-box --- */ |
246 | |
247 | sbox(); |
248 | fputs("\ |
249 | /* --- The byte substitution and its inverse --- */\n\ |
250 | \n\ |
251 | #define SQUARE_S { \\\n\ |
252 | ", stdout); |
253 | for (i = 0; i < 256; i++) { |
254 | printf("0x%02x", s[i]); |
255 | if (i == 255) |
256 | fputs(" \\\n}\n\n", stdout); |
257 | else if (i % 8 == 7) |
258 | fputs(", \\\n ", stdout); |
259 | else |
260 | fputs(", ", stdout); |
261 | } |
262 | |
263 | fputs("\ |
264 | #define SQUARE_SI { \\\n\ |
265 | ", stdout); |
266 | for (i = 0; i < 256; i++) { |
267 | printf("0x%02x", si[i]); |
268 | if (i == 255) |
269 | fputs(" \\\n}\n\n", stdout); |
270 | else if (i % 8 == 7) |
271 | fputs(", \\\n ", stdout); |
272 | else |
273 | fputs(", ", stdout); |
274 | } |
275 | |
276 | /* --- Write out the big t tables --- */ |
277 | |
278 | tbox(); |
279 | fputs("\ |
280 | /* --- The big round tables --- */\n\ |
281 | \n\ |
282 | #define SQUARE_T { \\\n\ |
283 | { ", stdout); |
284 | for (j = 0; j < 4; j++) { |
285 | for (i = 0; i < 256; i++) { |
286 | printf("0x%08x", t[j][i]); |
287 | if (i == 255) { |
288 | if (j == 3) |
289 | fputs(" } \\\n}\n\n", stdout); |
290 | else |
291 | fputs(" }, \\\n\ |
292 | \\\n\ |
293 | { ", stdout); |
294 | } else if (i % 4 == 3) |
295 | fputs(", \\\n ", stdout); |
296 | else |
297 | fputs(", ", stdout); |
298 | } |
299 | } |
300 | |
301 | fputs("\ |
302 | #define SQUARE_TI { \\\n\ |
303 | { ", stdout); |
304 | for (j = 0; j < 4; j++) { |
305 | for (i = 0; i < 256; i++) { |
306 | printf("0x%08x", ti[j][i]); |
307 | if (i == 255) { |
308 | if (j == 3) |
309 | fputs(" } \\\n}\n\n", stdout); |
310 | else |
311 | fputs(" }, \\\n\ |
312 | \\\n\ |
313 | { ", stdout); |
314 | } else if (i % 4 == 3) |
315 | fputs(", \\\n ", stdout); |
316 | else |
317 | fputs(", ", stdout); |
318 | } |
319 | } |
320 | |
321 | /* --- Write out the big u tables --- */ |
322 | |
323 | ubox(); |
324 | fputs("\ |
325 | /* --- The key schedule tables --- */\n\ |
326 | \n\ |
327 | #define SQUARE_U { \\\n\ |
328 | { ", stdout); |
329 | for (j = 0; j < 4; j++) { |
330 | for (i = 0; i < 256; i++) { |
331 | printf("0x%08x", u[j][i]); |
332 | if (i == 255) { |
333 | if (j == 3) |
334 | fputs(" } \\\n}\n\n", stdout); |
335 | else |
336 | fputs(" }, \\\n\ |
337 | \\\n\ |
338 | { ", stdout); |
339 | } else if (i % 4 == 3) |
340 | fputs(", \\\n ", stdout); |
341 | else |
342 | fputs(", ", stdout); |
343 | } |
344 | } |
345 | |
346 | /* --- Round constants --- */ |
347 | |
348 | rcon(); |
349 | fputs("\ |
350 | /* --- The round constants --- */\n\ |
351 | \n\ |
352 | #define SQUARE_RCON { \\\n\ |
353 | ", stdout); |
354 | for (i = 0; i < sizeof(rc); i++) { |
355 | printf("0x%02x", rc[i]); |
356 | if (i == sizeof(rc) - 1) |
357 | fputs(" \\\n}\n\n", stdout); |
358 | else if (i % 8 == 7) |
359 | fputs(", \\\n ", stdout); |
360 | else |
361 | fputs(", ", stdout); |
362 | } |
363 | |
364 | /* --- Done --- */ |
365 | |
366 | puts("#endif"); |
367 | |
368 | if (fclose(stdout)) { |
369 | fprintf(stderr, "error writing data\n"); |
370 | exit(EXIT_FAILURE); |
371 | } |
372 | |
373 | return (0); |
374 | } |
375 | |
376 | /*----- That's all, folks -------------------------------------------------*/ |