| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: rijndael-mktab.c,v 1.1 2000/06/17 11:56:07 mdw Exp $ |
| 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 $ |
| 33 | * Revision 1.1 2000/06/17 11:56:07 mdw |
| 34 | * New cipher. |
| 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 %$\mathrm{GF}(2^8)$% |
| 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 multiplicative inversion in the group |
| 87 | * %$\mathrm{GF}(2^8)[x]/p(x)$%, where %$p(x) = x^8 + x^4 + x^3 + x + 1$%, |
| 88 | * followed by an affine transformation treating inputs as vectors over |
| 89 | * %$\mathrm{GF}(2)$%. 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 0x11b |
| 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 | unsigned m = 0xf8; |
| 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; |
| 142 | r = (r >> 4) ^ r; |
| 143 | r = (r >> 2) ^ r; |
| 144 | r = (r >> 1) ^ r; |
| 145 | x = (x << 1) | (r & 1); |
| 146 | m = ROR8(m, 1); |
| 147 | } |
| 148 | x ^= 0x63; |
| 149 | s[i] = x; |
| 150 | si[x] = i; |
| 151 | } |
| 152 | } |
| 153 | |
| 154 | /* --- @tbox@ --- * |
| 155 | * |
| 156 | * Construct the t tables for doing the round function efficiently. |
| 157 | */ |
| 158 | |
| 159 | static void tbox(void) |
| 160 | { |
| 161 | unsigned i; |
| 162 | |
| 163 | for (i = 0; i < 256; i++) { |
| 164 | uint32 a, b, c, d; |
| 165 | uint32 w; |
| 166 | |
| 167 | /* --- Build a forwards t-box entry --- */ |
| 168 | |
| 169 | a = s[i]; |
| 170 | b = a << 1; if (b & 0x100) b ^= S_MOD; |
| 171 | c = a ^ b; |
| 172 | w = (b << 0) | (a << 8) | (a << 16) | (c << 24); |
| 173 | t[0][i] = w; |
| 174 | t[1][i] = ROL32(w, 8); |
| 175 | t[2][i] = ROL32(w, 16); |
| 176 | t[3][i] = ROL32(w, 24); |
| 177 | |
| 178 | /* --- Build a backwards t-box entry --- */ |
| 179 | |
| 180 | a = mul(si[i], 0x0e, S_MOD); |
| 181 | b = mul(si[i], 0x09, S_MOD); |
| 182 | c = mul(si[i], 0x0d, S_MOD); |
| 183 | d = mul(si[i], 0x0b, S_MOD); |
| 184 | w = (a << 0) | (b << 8) | (c << 16) | (d << 24); |
| 185 | ti[0][i] = w; |
| 186 | ti[1][i] = ROL32(w, 8); |
| 187 | ti[2][i] = ROL32(w, 16); |
| 188 | ti[3][i] = ROL32(w, 24); |
| 189 | } |
| 190 | } |
| 191 | |
| 192 | /* --- @ubox@ --- * |
| 193 | * |
| 194 | * Construct the tables for performing the decryption key schedule. |
| 195 | */ |
| 196 | |
| 197 | static void ubox(void) |
| 198 | { |
| 199 | unsigned i; |
| 200 | |
| 201 | for (i = 0; i < 256; i++) { |
| 202 | uint32 a, b, c, d; |
| 203 | uint32 w; |
| 204 | a = mul(i, 0x0e, S_MOD); |
| 205 | b = mul(i, 0x09, S_MOD); |
| 206 | c = mul(i, 0x0d, S_MOD); |
| 207 | d = mul(i, 0x0b, S_MOD); |
| 208 | w = (a << 0) | (b << 8) | (c << 16) | (d << 24); |
| 209 | u[0][i] = w; |
| 210 | u[1][i] = ROL32(w, 8); |
| 211 | u[2][i] = ROL32(w, 16); |
| 212 | u[3][i] = ROL32(w, 24); |
| 213 | } |
| 214 | } |
| 215 | |
| 216 | /* --- Round constants --- */ |
| 217 | |
| 218 | void rcon(void) |
| 219 | { |
| 220 | unsigned r = 1; |
| 221 | int i; |
| 222 | |
| 223 | for (i = 0; i < sizeof(rc); i++) { |
| 224 | rc[i] = r; |
| 225 | r <<= 1; |
| 226 | if (r & 0x100) |
| 227 | r ^= S_MOD; |
| 228 | } |
| 229 | } |
| 230 | |
| 231 | /* --- @main@ --- */ |
| 232 | |
| 233 | int main(void) |
| 234 | { |
| 235 | int i, j; |
| 236 | |
| 237 | puts("\ |
| 238 | /* -*-c-*-\n\ |
| 239 | *\n\ |
| 240 | * Rijndael tables [generated]\n\ |
| 241 | */\n\ |
| 242 | \n\ |
| 243 | #ifndef CATACOMB_RIJNDAEL_TAB_H\n\ |
| 244 | #define CATACOMB_RIJNDAEL_TAB_H\n\ |
| 245 | "); |
| 246 | |
| 247 | /* --- Write out the S-box --- */ |
| 248 | |
| 249 | sbox(); |
| 250 | fputs("\ |
| 251 | /* --- The byte substitution and its inverse --- */\n\ |
| 252 | \n\ |
| 253 | #define RIJNDAEL_S { \\\n\ |
| 254 | ", stdout); |
| 255 | for (i = 0; i < 256; i++) { |
| 256 | printf("0x%02x", s[i]); |
| 257 | if (i == 255) |
| 258 | fputs(" \\\n}\n\n", stdout); |
| 259 | else if (i % 8 == 7) |
| 260 | fputs(", \\\n ", stdout); |
| 261 | else |
| 262 | fputs(", ", stdout); |
| 263 | } |
| 264 | |
| 265 | fputs("\ |
| 266 | #define RIJNDAEL_SI { \\\n\ |
| 267 | ", stdout); |
| 268 | for (i = 0; i < 256; i++) { |
| 269 | printf("0x%02x", si[i]); |
| 270 | if (i == 255) |
| 271 | fputs(" \\\n}\n\n", stdout); |
| 272 | else if (i % 8 == 7) |
| 273 | fputs(", \\\n ", stdout); |
| 274 | else |
| 275 | fputs(", ", stdout); |
| 276 | } |
| 277 | |
| 278 | /* --- Write out the big t tables --- */ |
| 279 | |
| 280 | tbox(); |
| 281 | fputs("\ |
| 282 | /* --- The big round tables --- */\n\ |
| 283 | \n\ |
| 284 | #define RIJNDAEL_T { \\\n\ |
| 285 | { ", stdout); |
| 286 | for (j = 0; j < 4; j++) { |
| 287 | for (i = 0; i < 256; i++) { |
| 288 | printf("0x%08x", t[j][i]); |
| 289 | if (i == 255) { |
| 290 | if (j == 3) |
| 291 | fputs(" } \\\n}\n\n", stdout); |
| 292 | else |
| 293 | fputs(" }, \\\n\ |
| 294 | \\\n\ |
| 295 | { ", stdout); |
| 296 | } else if (i % 4 == 3) |
| 297 | fputs(", \\\n ", stdout); |
| 298 | else |
| 299 | fputs(", ", stdout); |
| 300 | } |
| 301 | } |
| 302 | |
| 303 | fputs("\ |
| 304 | #define RIJNDAEL_TI { \\\n\ |
| 305 | { ", stdout); |
| 306 | for (j = 0; j < 4; j++) { |
| 307 | for (i = 0; i < 256; i++) { |
| 308 | printf("0x%08x", ti[j][i]); |
| 309 | if (i == 255) { |
| 310 | if (j == 3) |
| 311 | fputs(" } \\\n}\n\n", stdout); |
| 312 | else |
| 313 | fputs(" }, \\\n\ |
| 314 | \\\n\ |
| 315 | { ", stdout); |
| 316 | } else if (i % 4 == 3) |
| 317 | fputs(", \\\n ", stdout); |
| 318 | else |
| 319 | fputs(", ", stdout); |
| 320 | } |
| 321 | } |
| 322 | |
| 323 | /* --- Write out the big u tables --- */ |
| 324 | |
| 325 | ubox(); |
| 326 | fputs("\ |
| 327 | /* --- The decryption key schedule tables --- */\n\ |
| 328 | \n\ |
| 329 | #define RIJNDAEL_U { \\\n\ |
| 330 | { ", stdout); |
| 331 | for (j = 0; j < 4; j++) { |
| 332 | for (i = 0; i < 256; i++) { |
| 333 | printf("0x%08x", u[j][i]); |
| 334 | if (i == 255) { |
| 335 | if (j == 3) |
| 336 | fputs(" } \\\n}\n\n", stdout); |
| 337 | else |
| 338 | fputs(" }, \\\n\ |
| 339 | \\\n\ |
| 340 | { ", stdout); |
| 341 | } else if (i % 4 == 3) |
| 342 | fputs(", \\\n ", stdout); |
| 343 | else |
| 344 | fputs(", ", stdout); |
| 345 | } |
| 346 | } |
| 347 | |
| 348 | /* --- Round constants --- */ |
| 349 | |
| 350 | rcon(); |
| 351 | fputs("\ |
| 352 | /* --- The round constants --- */\n\ |
| 353 | \n\ |
| 354 | #define RIJNDAEL_RCON { \\\n\ |
| 355 | ", stdout); |
| 356 | for (i = 0; i < sizeof(rc); i++) { |
| 357 | printf("0x%02x", rc[i]); |
| 358 | if (i == sizeof(rc) - 1) |
| 359 | fputs(" \\\n}\n\n", stdout); |
| 360 | else if (i % 8 == 7) |
| 361 | fputs(", \\\n ", stdout); |
| 362 | else |
| 363 | fputs(", ", stdout); |
| 364 | } |
| 365 | |
| 366 | /* --- Done --- */ |
| 367 | |
| 368 | puts("#endif"); |
| 369 | |
| 370 | if (fclose(stdout)) { |
| 371 | fprintf(stderr, "error writing data\n"); |
| 372 | exit(EXIT_FAILURE); |
| 373 | } |
| 374 | |
| 375 | return (0); |
| 376 | } |
| 377 | |
| 378 | /*----- That's all, folks -------------------------------------------------*/ |