| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: twofish.c,v 1.4 2004/04/02 01:03:49 mdw Exp $ |
| 4 | * |
| 5 | * Implementation of the Twofish 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: twofish.c,v $ |
| 33 | * Revision 1.4 2004/04/02 01:03:49 mdw |
| 34 | * Miscellaneous constification. |
| 35 | * |
| 36 | * Revision 1.3 2002/01/13 13:37:59 mdw |
| 37 | * Add support for Twofish family keys. |
| 38 | * |
| 39 | * Revision 1.2 2000/06/22 18:58:00 mdw |
| 40 | * Twofish can handle keys with any byte-aligned size. |
| 41 | * |
| 42 | * Revision 1.1 2000/06/17 12:10:17 mdw |
| 43 | * New cipher. |
| 44 | * |
| 45 | */ |
| 46 | |
| 47 | /*----- Header files ------------------------------------------------------*/ |
| 48 | |
| 49 | #include <assert.h> |
| 50 | |
| 51 | #include <mLib/bits.h> |
| 52 | |
| 53 | #include "blkc.h" |
| 54 | #include "gcipher.h" |
| 55 | #include "twofish.h" |
| 56 | #include "twofish-tab.h" |
| 57 | #include "paranoia.h" |
| 58 | |
| 59 | /*----- Global variables --------------------------------------------------*/ |
| 60 | |
| 61 | const octet twofish_keysz[] = { KSZ_RANGE, TWOFISH_KEYSZ, 0, 32, 1 }; |
| 62 | |
| 63 | /*----- Important tables --------------------------------------------------*/ |
| 64 | |
| 65 | static const octet q0[256] = TWOFISH_Q0, q1[256] = TWOFISH_Q1; |
| 66 | static const uint32 qmds[4][256] = TWOFISH_QMDS; |
| 67 | static const octet rslog[] = TWOFISH_RSLOG, rsexp[] = TWOFISH_RSEXP; |
| 68 | static const octet rs[32] = TWOFISH_RS; |
| 69 | |
| 70 | /*----- Key initialization ------------------------------------------------*/ |
| 71 | |
| 72 | /* --- @h@ --- * |
| 73 | * |
| 74 | * Arguments: @uint32 x@ = input to the function |
| 75 | * @const uint32 *l@ = key values to mix in |
| 76 | * @unsigned k@ = number of key values there are |
| 77 | * |
| 78 | * Returns: The output of the function @h@. |
| 79 | * |
| 80 | * Use: Implements the Twofish function @h@. |
| 81 | */ |
| 82 | |
| 83 | static uint32 h(uint32 x, const uint32 *l, unsigned k) |
| 84 | { |
| 85 | /* --- Apply a series of @q@ tables to an integer --- */ |
| 86 | |
| 87 | # define Q(x, qa, qb, qc, qd) \ |
| 88 | ((qa[((x) >> 0) & 0xff] << 0) | \ |
| 89 | (qb[((x) >> 8) & 0xff] << 8) | \ |
| 90 | (qc[((x) >> 16) & 0xff] << 16) | \ |
| 91 | (qd[((x) >> 24) & 0xff] << 24)) |
| 92 | |
| 93 | /* --- Grind through the tables --- */ |
| 94 | |
| 95 | switch (k) { |
| 96 | case 4: x = Q(x, q1, q0, q0, q1) ^ l[3]; |
| 97 | case 3: x = Q(x, q1, q1, q0, q0) ^ l[2]; |
| 98 | case 2: x = Q(x, q0, q1, q0, q1) ^ l[1]; |
| 99 | x = Q(x, q0, q0, q1, q1) ^ l[0]; |
| 100 | break; |
| 101 | } |
| 102 | |
| 103 | #undef Q |
| 104 | |
| 105 | /* --- Apply the MDS matrix --- */ |
| 106 | |
| 107 | return (qmds[0][U8(x >> 0)] ^ qmds[1][U8(x >> 8)] ^ |
| 108 | qmds[2][U8(x >> 16)] ^ qmds[3][U8(x >> 24)]); |
| 109 | } |
| 110 | |
| 111 | /* --- @twofish_initfk@ --- * |
| 112 | * |
| 113 | * Arguments: @twofish_ctx *k@ = pointer to key block to fill in |
| 114 | * @const void *buf@ = pointer to buffer of key material |
| 115 | * @size_t sz@ = size of key material |
| 116 | * @const twofish_fk *fk@ = family-key information |
| 117 | * |
| 118 | * Returns: --- |
| 119 | * |
| 120 | * Use: Does the underlying Twofish key initialization with family |
| 121 | * key. Pass in a family-key structure initialized to |
| 122 | * all-bits-zero for a standard key schedule. |
| 123 | */ |
| 124 | |
| 125 | void twofish_initfk(twofish_ctx *k, const void *buf, size_t sz, |
| 126 | const twofish_fk *fk) |
| 127 | { |
| 128 | # define KMAX 4 |
| 129 | |
| 130 | uint32 mo[KMAX], me[KMAX]; |
| 131 | octet s[4][KMAX]; |
| 132 | |
| 133 | /* --- Expand the key into the three word arrays --- */ |
| 134 | |
| 135 | { |
| 136 | size_t ssz; |
| 137 | const octet *p, *q; |
| 138 | octet b[32]; |
| 139 | int i; |
| 140 | |
| 141 | /* --- Sort out the key size --- */ |
| 142 | |
| 143 | KSZ_ASSERT(twofish, sz); |
| 144 | if (sz <= 16) |
| 145 | ssz = 16; |
| 146 | else if (sz <= 24) |
| 147 | ssz = 24; |
| 148 | else if (sz <= 32) |
| 149 | ssz = 32; |
| 150 | else |
| 151 | assert(((void)"This can't happen (bad key size in twofish_init)", 0)); |
| 152 | |
| 153 | /* --- Extend the key if necessary --- */ |
| 154 | |
| 155 | if (sz == ssz) |
| 156 | p = buf; |
| 157 | else { |
| 158 | memcpy(b, buf, sz); |
| 159 | memset(b + sz, 0, ssz - sz); |
| 160 | p = b; |
| 161 | } |
| 162 | |
| 163 | /* --- Finally get the word count --- */ |
| 164 | |
| 165 | sz = ssz / 8; |
| 166 | |
| 167 | /* --- Extract words from the key --- * |
| 168 | * |
| 169 | * The @s@ table, constructed using the Reed-Solomon matrix, is cut into |
| 170 | * sequences of bytes, since this is actually more useful for computing |
| 171 | * the S-boxes. |
| 172 | */ |
| 173 | |
| 174 | q = p; |
| 175 | for (i = 0; i < sz; i++) { |
| 176 | octet ss[4]; |
| 177 | const octet *r = rs; |
| 178 | int j; |
| 179 | |
| 180 | /* --- Extract the easy subkeys --- */ |
| 181 | |
| 182 | me[i] = LOAD32_L(q) ^ fk->t0[2 * i]; |
| 183 | mo[i] = LOAD32_L(q + 4) ^ fk->t0[2 * i + 1]; |
| 184 | |
| 185 | /* --- Now do the Reed-Solomon thing --- */ |
| 186 | |
| 187 | for (j = 0; j < 4; j++) { |
| 188 | const octet *qq = q; |
| 189 | unsigned a = 0; |
| 190 | int k; |
| 191 | |
| 192 | for (k = 0; k < 8; k++) { |
| 193 | unsigned char x = *qq ^ fk->t1[i * 8 + k]; |
| 194 | if (x) a ^= rsexp[rslog[x] + *r]; |
| 195 | qq++; |
| 196 | r++; |
| 197 | } |
| 198 | |
| 199 | s[j][sz - 1 - i] = ss[j] = a; |
| 200 | } |
| 201 | q += 8; |
| 202 | } |
| 203 | |
| 204 | /* --- Clear away the temporary buffer --- */ |
| 205 | |
| 206 | if (p == b) |
| 207 | BURN(b); |
| 208 | } |
| 209 | |
| 210 | /* --- Construct the expanded key --- */ |
| 211 | |
| 212 | { |
| 213 | uint32 p = 0x01010101; |
| 214 | uint32 ip = 0; |
| 215 | int i; |
| 216 | |
| 217 | for (i = 0; i < 40; i += 2) { |
| 218 | uint32 a, b; |
| 219 | a = h(ip, me, sz); |
| 220 | b = h(ip + p, mo, sz); |
| 221 | b = ROL32(b, 8); |
| 222 | a += b; b += a; |
| 223 | k->k[i] = U32(a); |
| 224 | k->k[i + 1] = ROL32(b, 9); |
| 225 | ip += 2 * p; |
| 226 | } |
| 227 | |
| 228 | for (i = 0; i < 8; i++) |
| 229 | k->k[i] ^= fk->t23[i]; |
| 230 | for (i = 8; i < 40; i += 2) { |
| 231 | k->k[i] ^= fk->t4[0]; |
| 232 | k->k[i + 1] ^= fk->t4[1]; |
| 233 | } |
| 234 | } |
| 235 | |
| 236 | /* --- Construct the S-box tables --- */ |
| 237 | |
| 238 | { |
| 239 | unsigned i; |
| 240 | static const octet *q[4][KMAX + 1] = { |
| 241 | { q1, q0, q0, q1, q1 }, |
| 242 | { q0, q0, q1, q1, q0 }, |
| 243 | { q1, q1, q0, q0, q0 }, |
| 244 | { q0, q1, q1, q0, q1 } |
| 245 | }; |
| 246 | |
| 247 | for (i = 0; i < 4; i++) { |
| 248 | unsigned j; |
| 249 | uint32 x; |
| 250 | |
| 251 | for (j = 0; j < 256; j++) { |
| 252 | x = j; |
| 253 | |
| 254 | /* --- Push the byte through the q tables --- */ |
| 255 | |
| 256 | switch (sz) { |
| 257 | case 4: x = q[i][4][x] ^ s[i][3]; |
| 258 | case 3: x = q[i][3][x] ^ s[i][2]; |
| 259 | case 2: x = q[i][2][x] ^ s[i][1]; |
| 260 | x = q[i][1][x] ^ s[i][0]; |
| 261 | break; |
| 262 | } |
| 263 | |
| 264 | /* --- Write it in the key schedule --- */ |
| 265 | |
| 266 | k->g[i][j] = qmds[i][x]; |
| 267 | } |
| 268 | } |
| 269 | } |
| 270 | |
| 271 | /* --- Clear everything away --- */ |
| 272 | |
| 273 | BURN(me); |
| 274 | BURN(mo); |
| 275 | BURN(s); |
| 276 | } |
| 277 | |
| 278 | /* --- @twofish_init@ --- * |
| 279 | * |
| 280 | * Arguments: @twofish_ctx *k@ = pointer to key block to fill in |
| 281 | * @const void *buf@ = pointer to buffer of key material |
| 282 | * @size_t sz@ = size of key material |
| 283 | * |
| 284 | * Returns: --- |
| 285 | * |
| 286 | * Use: Initializes a Twofish key buffer. Twofish accepts key sizes |
| 287 | * of up to 256 bits (32 bytes). |
| 288 | */ |
| 289 | |
| 290 | void twofish_init(twofish_ctx *k, const void *buf, size_t sz) |
| 291 | { |
| 292 | static const twofish_fk fk = { { 0 } }; |
| 293 | twofish_initfk(k, buf, sz, &fk); |
| 294 | } |
| 295 | |
| 296 | /* --- @twofish_fkinit@ --- * |
| 297 | * |
| 298 | * Arguments: @twofish_fk *fk@ = pointer to family key block |
| 299 | * @const void *buf@ = pointer to buffer of key material |
| 300 | * @size_t sz@ = size of key material |
| 301 | * |
| 302 | * Returns: --- |
| 303 | * |
| 304 | * Use: Initializes a family-key buffer. This implementation allows |
| 305 | * family keys of any size acceptable to the Twofish algorithm. |
| 306 | */ |
| 307 | |
| 308 | void twofish_fkinit(twofish_fk *fk, const void *buf, size_t sz) |
| 309 | { |
| 310 | twofish_ctx k; |
| 311 | uint32 pt[4], ct[4]; |
| 312 | const octet *kk; |
| 313 | unsigned i; |
| 314 | |
| 315 | twofish_init(&k, buf, sz); |
| 316 | |
| 317 | for (i = 0; i < 4; i++) pt[i] = (uint32)-1; |
| 318 | twofish_eblk(&k, pt, fk->t0 + 4); |
| 319 | |
| 320 | kk = buf; sz /= 4; |
| 321 | for (i = 0; i < sz; i++) { fk->t0[i] = LOAD32_L(kk); kk += 4; } |
| 322 | |
| 323 | for (i = 0; i < 4; i++) pt[i] = 0; twofish_eblk(&k, pt, ct); |
| 324 | for (i = 0; i < 4; i++) STORE32_L(fk->t1 + i * 4, ct[i]); |
| 325 | pt[0] = 1; twofish_eblk(&k, pt, ct); |
| 326 | for (i = 0; i < 4; i++) STORE32_L(fk->t1 + 4 + i * 4, ct[i]); |
| 327 | |
| 328 | pt[0] = 2; twofish_eblk(&k, pt, fk->t23 + 0); |
| 329 | pt[0] = 3; twofish_eblk(&k, pt, fk->t23 + 4); |
| 330 | pt[0] = 4; twofish_eblk(&k, pt, ct); |
| 331 | fk->t4[0] = ct[0]; fk->t4[1] = ct[1]; |
| 332 | |
| 333 | BURN(k); |
| 334 | } |
| 335 | |
| 336 | /*----- Main encryption ---------------------------------------------------*/ |
| 337 | |
| 338 | /* --- Feistel function --- */ |
| 339 | |
| 340 | #define GG(k, t0, t1, x, y, kk) do { \ |
| 341 | t0 = (k->g[0][U8(x >> 0)] ^ \ |
| 342 | k->g[1][U8(x >> 8)] ^ \ |
| 343 | k->g[2][U8(x >> 16)] ^ \ |
| 344 | k->g[3][U8(x >> 24)]); \ |
| 345 | t1 = (k->g[1][U8(y >> 0)] ^ \ |
| 346 | k->g[2][U8(y >> 8)] ^ \ |
| 347 | k->g[3][U8(y >> 16)] ^ \ |
| 348 | k->g[0][U8(y >> 24)]); \ |
| 349 | t0 += t1; \ |
| 350 | t1 += t0; \ |
| 351 | t0 += kk[0]; \ |
| 352 | t1 += kk[1]; \ |
| 353 | } while (0) |
| 354 | |
| 355 | /* --- Round operations --- */ |
| 356 | |
| 357 | #define EROUND(k, w, x, y, z, kk) do { \ |
| 358 | uint32 _t0, _t1; \ |
| 359 | GG(k, _t0, _t1, w, x, kk); \ |
| 360 | kk += 2; \ |
| 361 | y ^= _t0; y = ROR32(y, 1); \ |
| 362 | z = ROL32(z, 1); z ^= _t1; \ |
| 363 | } while (0) |
| 364 | |
| 365 | #define DROUND(k, w, x, y, z, kk) do { \ |
| 366 | uint32 _t0, _t1; \ |
| 367 | kk -= 2; \ |
| 368 | GG(k, _t0, _t1, w, x, kk); \ |
| 369 | y = ROL32(y, 1); y ^= _t0; \ |
| 370 | z ^= _t1; z = ROR32(z, 1); \ |
| 371 | } while (0) |
| 372 | |
| 373 | /* --- Complete encryption functions --- */ |
| 374 | |
| 375 | #define EBLK(k, a, b, c, d, w, x, y, z) do { \ |
| 376 | const uint32 *_kk = k->k + 8; \ |
| 377 | uint32 _a = a, _b = b, _c = c, _d = d; \ |
| 378 | _a ^= k->k[0]; _b ^= k->k[1]; _c ^= k->k[2]; _d ^= k->k[3]; \ |
| 379 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 380 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 381 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 382 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 383 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 384 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 385 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 386 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 387 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 388 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 389 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 390 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 391 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 392 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 393 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 394 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 395 | _c ^= k->k[4]; _d ^= k->k[5]; _a ^= k->k[6]; _b ^= k->k[7]; \ |
| 396 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ |
| 397 | } while (0) |
| 398 | |
| 399 | #define DBLK(k, a, b, c, d, w, x, y, z) do { \ |
| 400 | const uint32 *_kk = k->k + 40; \ |
| 401 | uint32 _a = a, _b = b, _c = c, _d = d; \ |
| 402 | _a ^= k->k[4]; _b ^= k->k[5]; _c ^= k->k[6]; _d ^= k->k[7]; \ |
| 403 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 404 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 405 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 406 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 407 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 408 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 409 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 410 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 411 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 412 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 413 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 414 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 415 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 416 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 417 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 418 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 419 | _c ^= k->k[0]; _d ^= k->k[1]; _a ^= k->k[2]; _b ^= k->k[3]; \ |
| 420 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ |
| 421 | } while (0) |
| 422 | |
| 423 | /* --- @twofish_eblk@, @twofish_dblk@ --- * |
| 424 | * |
| 425 | * Arguments: @const twofish_ctx *k@ = pointer to key block |
| 426 | * @const uint32 s[4]@ = pointer to source block |
| 427 | * @uint32 d[4]@ = pointer to destination block |
| 428 | * |
| 429 | * Returns: --- |
| 430 | * |
| 431 | * Use: Low-level block encryption and decryption. |
| 432 | */ |
| 433 | |
| 434 | void twofish_eblk(const twofish_ctx *k, const uint32 *s, uint32 *d) |
| 435 | { |
| 436 | EBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); |
| 437 | } |
| 438 | |
| 439 | void twofish_dblk(const twofish_ctx *k, const uint32 *s, uint32 *d) |
| 440 | { |
| 441 | DBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); |
| 442 | } |
| 443 | |
| 444 | BLKC_TEST(TWOFISH, twofish) |
| 445 | |
| 446 | /*----- That's all, folks -------------------------------------------------*/ |