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35682d2f | 1 | /* -*-c-*- |
35682d2f | 2 | * |
3 | * Build precomputed tables for the Square block cipher | |
4 | * | |
5 | * (c) 2000 Straylight/Edgeware | |
6 | */ | |
7 | ||
45c0fd36 | 8 | /*----- Licensing notice --------------------------------------------------* |
35682d2f | 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 | * |
35682d2f | 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 | * |
35682d2f | 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 | ||
35682d2f | 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 | * | |
47 | * Arguments: @unsigned x, y@ = polynomials over %$\gf{2^8}$% | |
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 | * | |
76 | * This is built from inversion in the multiplicative group of | |
ba74e11e | 77 | * %$\gf{2^8}[x]/(p(x))$%, where %$p(x) = x^8+x^7+x^6+x^5+x^4+x^2+1$%, |
78 | * followed by an affine transformation treating inputs as vectors over | |
79 | * %$\gf{2}$%. The result is a horrible function. | |
35682d2f | 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. |
35682d2f | 86 | */ |
87 | ||
88 | #define S_MOD 0x1f5 | |
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 | octet m[] = { 0xd6, 0x7b, 0x3d, 0x1f, 0x0f, 0x05, 0x03, 0x01 }; | |
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[j]; | |
132 | r = (r >> 4) ^ r; | |
133 | r = (r >> 2) ^ r; | |
134 | r = (r >> 1) ^ r; | |
135 | x = (x << 1) | (r & 1); | |
136 | } | |
137 | x ^= 0xb1; | |
138 | s[i] = x; | |
139 | si[x] = i; | |
140 | } | |
141 | } | |
142 | ||
143 | /* --- @tbox@ --- * | |
144 | * | |
145 | * Construct the t tables for doing the round function efficiently. | |
146 | */ | |
147 | ||
148 | static void tbox(void) | |
149 | { | |
150 | unsigned i; | |
151 | ||
152 | for (i = 0; i < 256; i++) { | |
153 | uint32 a, b, c, d; | |
154 | uint32 w; | |
155 | ||
156 | /* --- Build a forwards t-box entry --- */ | |
157 | ||
158 | a = s[i]; | |
159 | b = a << 1; if (b & 0x100) b ^= S_MOD; | |
160 | c = a ^ b; | |
161 | w = (b << 0) | (a << 8) | (a << 16) | (c << 24); | |
162 | t[0][i] = w; | |
163 | t[1][i] = ROL32(w, 8); | |
164 | t[2][i] = ROL32(w, 16); | |
165 | t[3][i] = ROL32(w, 24); | |
166 | ||
167 | /* --- Build a backwards t-box entry --- */ | |
168 | ||
169 | a = mul(si[i], 0x0e, S_MOD); | |
170 | b = mul(si[i], 0x09, S_MOD); | |
171 | c = mul(si[i], 0x0d, S_MOD); | |
172 | d = mul(si[i], 0x0b, S_MOD); | |
173 | w = (a << 0) | (b << 8) | (c << 16) | (d << 24); | |
174 | ti[0][i] = w; | |
175 | ti[1][i] = ROL32(w, 8); | |
176 | ti[2][i] = ROL32(w, 16); | |
177 | ti[3][i] = ROL32(w, 24); | |
178 | } | |
179 | } | |
180 | ||
181 | /* --- @ubox@ --- * | |
182 | * | |
183 | * Construct the tables for performing the key schedule. | |
184 | */ | |
185 | ||
186 | static void ubox(void) | |
187 | { | |
188 | unsigned i; | |
189 | ||
190 | for (i = 0; i < 256; i++) { | |
191 | uint32 a, b, c; | |
192 | uint32 w; | |
193 | a = i; | |
194 | b = a << 1; if (b & 0x100) b ^= S_MOD; | |
195 | c = a ^ b; | |
196 | w = (b << 0) | (a << 8) | (a << 16) | (c << 24); | |
197 | u[0][i] = w; | |
198 | u[1][i] = ROL32(w, 8); | |
199 | u[2][i] = ROL32(w, 16); | |
200 | u[3][i] = ROL32(w, 24); | |
201 | } | |
202 | } | |
203 | ||
204 | /* --- Round constants --- */ | |
205 | ||
206 | void rcon(void) | |
207 | { | |
208 | unsigned r = 1; | |
209 | int i; | |
210 | ||
211 | for (i = 0; i < sizeof(rc); i++) { | |
212 | rc[i] = r; | |
213 | r <<= 1; | |
214 | if (r & 0x100) | |
215 | r ^= S_MOD; | |
216 | } | |
217 | } | |
218 | ||
219 | /* --- @main@ --- */ | |
220 | ||
221 | int main(void) | |
222 | { | |
223 | int i, j; | |
224 | ||
225 | puts("\ | |
226 | /* -*-c-*-\n\ | |
227 | *\n\ | |
228 | * Square tables [generated]\n\ | |
229 | */\n\ | |
230 | \n\ | |
e5b61a8d MW |
231 | #include <mLib/bits.h>\n\ |
232 | \n\ | |
35682d2f | 233 | "); |
234 | ||
235 | /* --- Write out the S-box --- */ | |
236 | ||
237 | sbox(); | |
238 | fputs("\ | |
239 | /* --- The byte substitution and its inverse --- */\n\ | |
240 | \n\ | |
e5b61a8d | 241 | const octet square_s[256] = {\n\ |
35682d2f | 242 | ", stdout); |
243 | for (i = 0; i < 256; i++) { | |
244 | printf("0x%02x", s[i]); | |
245 | if (i == 255) | |
e5b61a8d | 246 | fputs("\n};\n\n", stdout); |
35682d2f | 247 | else if (i % 8 == 7) |
e5b61a8d | 248 | fputs(",\n ", stdout); |
35682d2f | 249 | else |
250 | fputs(", ", stdout); | |
251 | } | |
252 | ||
253 | fputs("\ | |
e5b61a8d | 254 | const octet square_si[256] = {\n\ |
35682d2f | 255 | ", stdout); |
256 | for (i = 0; i < 256; i++) { | |
257 | printf("0x%02x", si[i]); | |
258 | if (i == 255) | |
e5b61a8d | 259 | fputs("\n};\n\n", stdout); |
35682d2f | 260 | else if (i % 8 == 7) |
e5b61a8d | 261 | fputs(",\n ", stdout); |
35682d2f | 262 | else |
263 | fputs(", ", stdout); | |
264 | } | |
265 | ||
266 | /* --- Write out the big t tables --- */ | |
267 | ||
268 | tbox(); | |
269 | fputs("\ | |
270 | /* --- The big round tables --- */\n\ | |
271 | \n\ | |
e5b61a8d | 272 | const uint32 square_t[4][256] = {\n\ |
35682d2f | 273 | { ", stdout); |
274 | for (j = 0; j < 4; j++) { | |
275 | for (i = 0; i < 256; i++) { | |
276 | printf("0x%08x", t[j][i]); | |
277 | if (i == 255) { | |
278 | if (j == 3) | |
e5b61a8d | 279 | fputs(" }\n};\n\n", stdout); |
35682d2f | 280 | else |
e5b61a8d | 281 | fputs(" },\n\n { ", stdout); |
35682d2f | 282 | } else if (i % 4 == 3) |
e5b61a8d | 283 | fputs(",\n ", stdout); |
35682d2f | 284 | else |
285 | fputs(", ", stdout); | |
286 | } | |
45c0fd36 | 287 | } |
35682d2f | 288 | |
289 | fputs("\ | |
e5b61a8d | 290 | const uint32 square_ti[4][256] = {\n\ |
35682d2f | 291 | { ", stdout); |
292 | for (j = 0; j < 4; j++) { | |
293 | for (i = 0; i < 256; i++) { | |
294 | printf("0x%08x", ti[j][i]); | |
295 | if (i == 255) { | |
296 | if (j == 3) | |
e5b61a8d | 297 | fputs(" }\n};\n\n", stdout); |
35682d2f | 298 | else |
e5b61a8d | 299 | fputs(" },\n\n { ", stdout); |
35682d2f | 300 | } else if (i % 4 == 3) |
e5b61a8d | 301 | fputs(",\n ", stdout); |
35682d2f | 302 | else |
303 | fputs(", ", stdout); | |
304 | } | |
305 | } | |
306 | ||
307 | /* --- Write out the big u tables --- */ | |
308 | ||
309 | ubox(); | |
310 | fputs("\ | |
311 | /* --- The key schedule tables --- */\n\ | |
312 | \n\ | |
e5b61a8d | 313 | const uint32 square_u[4][256] = {\n\ |
35682d2f | 314 | { ", stdout); |
315 | for (j = 0; j < 4; j++) { | |
316 | for (i = 0; i < 256; i++) { | |
317 | printf("0x%08x", u[j][i]); | |
318 | if (i == 255) { | |
319 | if (j == 3) | |
e5b61a8d | 320 | fputs(" }\n};\n\n", stdout); |
35682d2f | 321 | else |
e5b61a8d | 322 | fputs(" },\n\n { ", stdout); |
35682d2f | 323 | } else if (i % 4 == 3) |
e5b61a8d | 324 | fputs(",\n ", stdout); |
35682d2f | 325 | else |
326 | fputs(", ", stdout); | |
327 | } | |
45c0fd36 | 328 | } |
35682d2f | 329 | |
330 | /* --- Round constants --- */ | |
331 | ||
332 | rcon(); | |
333 | fputs("\ | |
334 | /* --- The round constants --- */\n\ | |
335 | \n\ | |
e5b61a8d | 336 | const octet square_rcon[32] = {\n\ |
35682d2f | 337 | ", stdout); |
338 | for (i = 0; i < sizeof(rc); i++) { | |
339 | printf("0x%02x", rc[i]); | |
340 | if (i == sizeof(rc) - 1) | |
e5b61a8d | 341 | fputs("\n};\n", stdout); |
35682d2f | 342 | else if (i % 8 == 7) |
e5b61a8d | 343 | fputs(",\n ", stdout); |
35682d2f | 344 | else |
345 | fputs(", ", stdout); | |
45c0fd36 | 346 | } |
35682d2f | 347 | |
348 | /* --- Done --- */ | |
349 | ||
35682d2f | 350 | if (fclose(stdout)) { |
351 | fprintf(stderr, "error writing data\n"); | |
352 | exit(EXIT_FAILURE); | |
353 | } | |
354 | ||
355 | return (0); | |
356 | } | |
357 | ||
358 | /*----- That's all, folks -------------------------------------------------*/ |