| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: twofish.c,v 1.5 2004/04/08 01:36:15 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 | /*----- Header files ------------------------------------------------------*/ |
| 31 | |
| 32 | #include <assert.h> |
| 33 | |
| 34 | #include <mLib/bits.h> |
| 35 | |
| 36 | #include "blkc.h" |
| 37 | #include "gcipher.h" |
| 38 | #include "twofish.h" |
| 39 | #include "twofish-tab.h" |
| 40 | #include "paranoia.h" |
| 41 | |
| 42 | /*----- Global variables --------------------------------------------------*/ |
| 43 | |
| 44 | const octet twofish_keysz[] = { KSZ_RANGE, TWOFISH_KEYSZ, 0, 32, 1 }; |
| 45 | |
| 46 | /*----- Important tables --------------------------------------------------*/ |
| 47 | |
| 48 | static const octet q0[256] = TWOFISH_Q0, q1[256] = TWOFISH_Q1; |
| 49 | static const uint32 qmds[4][256] = TWOFISH_QMDS; |
| 50 | static const octet rslog[] = TWOFISH_RSLOG, rsexp[] = TWOFISH_RSEXP; |
| 51 | static const octet rs[32] = TWOFISH_RS; |
| 52 | |
| 53 | /*----- Key initialization ------------------------------------------------*/ |
| 54 | |
| 55 | /* --- @h@ --- * |
| 56 | * |
| 57 | * Arguments: @uint32 x@ = input to the function |
| 58 | * @const uint32 *l@ = key values to mix in |
| 59 | * @unsigned k@ = number of key values there are |
| 60 | * |
| 61 | * Returns: The output of the function @h@. |
| 62 | * |
| 63 | * Use: Implements the Twofish function @h@. |
| 64 | */ |
| 65 | |
| 66 | static uint32 h(uint32 x, const uint32 *l, unsigned k) |
| 67 | { |
| 68 | /* --- Apply a series of @q@ tables to an integer --- */ |
| 69 | |
| 70 | # define Q(x, qa, qb, qc, qd) \ |
| 71 | ((qa[((x) >> 0) & 0xff] << 0) | \ |
| 72 | (qb[((x) >> 8) & 0xff] << 8) | \ |
| 73 | (qc[((x) >> 16) & 0xff] << 16) | \ |
| 74 | (qd[((x) >> 24) & 0xff] << 24)) |
| 75 | |
| 76 | /* --- Grind through the tables --- */ |
| 77 | |
| 78 | switch (k) { |
| 79 | case 4: x = Q(x, q1, q0, q0, q1) ^ l[3]; |
| 80 | case 3: x = Q(x, q1, q1, q0, q0) ^ l[2]; |
| 81 | case 2: x = Q(x, q0, q1, q0, q1) ^ l[1]; |
| 82 | x = Q(x, q0, q0, q1, q1) ^ l[0]; |
| 83 | break; |
| 84 | } |
| 85 | |
| 86 | #undef Q |
| 87 | |
| 88 | /* --- Apply the MDS matrix --- */ |
| 89 | |
| 90 | return (qmds[0][U8(x >> 0)] ^ qmds[1][U8(x >> 8)] ^ |
| 91 | qmds[2][U8(x >> 16)] ^ qmds[3][U8(x >> 24)]); |
| 92 | } |
| 93 | |
| 94 | /* --- @twofish_initfk@ --- * |
| 95 | * |
| 96 | * Arguments: @twofish_ctx *k@ = pointer to key block to fill in |
| 97 | * @const void *buf@ = pointer to buffer of key material |
| 98 | * @size_t sz@ = size of key material |
| 99 | * @const twofish_fk *fk@ = family-key information |
| 100 | * |
| 101 | * Returns: --- |
| 102 | * |
| 103 | * Use: Does the underlying Twofish key initialization with family |
| 104 | * key. Pass in a family-key structure initialized to |
| 105 | * all-bits-zero for a standard key schedule. |
| 106 | */ |
| 107 | |
| 108 | void twofish_initfk(twofish_ctx *k, const void *buf, size_t sz, |
| 109 | const twofish_fk *fk) |
| 110 | { |
| 111 | # define KMAX 4 |
| 112 | |
| 113 | uint32 mo[KMAX], me[KMAX]; |
| 114 | octet s[4][KMAX]; |
| 115 | |
| 116 | /* --- Expand the key into the three word arrays --- */ |
| 117 | |
| 118 | { |
| 119 | size_t ssz; |
| 120 | const octet *p, *q; |
| 121 | octet b[32]; |
| 122 | int i; |
| 123 | |
| 124 | /* --- Sort out the key size --- */ |
| 125 | |
| 126 | KSZ_ASSERT(twofish, sz); |
| 127 | if (sz <= 16) |
| 128 | ssz = 16; |
| 129 | else if (sz <= 24) |
| 130 | ssz = 24; |
| 131 | else if (sz <= 32) |
| 132 | ssz = 32; |
| 133 | else |
| 134 | assert(((void)"This can't happen (bad key size in twofish_init)", 0)); |
| 135 | |
| 136 | /* --- Extend the key if necessary --- */ |
| 137 | |
| 138 | if (sz == ssz) |
| 139 | p = buf; |
| 140 | else { |
| 141 | memcpy(b, buf, sz); |
| 142 | memset(b + sz, 0, ssz - sz); |
| 143 | p = b; |
| 144 | } |
| 145 | |
| 146 | /* --- Finally get the word count --- */ |
| 147 | |
| 148 | sz = ssz / 8; |
| 149 | |
| 150 | /* --- Extract words from the key --- * |
| 151 | * |
| 152 | * The @s@ table, constructed using the Reed-Solomon matrix, is cut into |
| 153 | * sequences of bytes, since this is actually more useful for computing |
| 154 | * the S-boxes. |
| 155 | */ |
| 156 | |
| 157 | q = p; |
| 158 | for (i = 0; i < sz; i++) { |
| 159 | octet ss[4]; |
| 160 | const octet *r = rs; |
| 161 | int j; |
| 162 | |
| 163 | /* --- Extract the easy subkeys --- */ |
| 164 | |
| 165 | me[i] = LOAD32_L(q) ^ fk->t0[2 * i]; |
| 166 | mo[i] = LOAD32_L(q + 4) ^ fk->t0[2 * i + 1]; |
| 167 | |
| 168 | /* --- Now do the Reed-Solomon thing --- */ |
| 169 | |
| 170 | for (j = 0; j < 4; j++) { |
| 171 | const octet *qq = q; |
| 172 | unsigned a = 0; |
| 173 | int k; |
| 174 | |
| 175 | for (k = 0; k < 8; k++) { |
| 176 | unsigned char x = *qq ^ fk->t1[i * 8 + k]; |
| 177 | if (x) a ^= rsexp[rslog[x] + *r]; |
| 178 | qq++; |
| 179 | r++; |
| 180 | } |
| 181 | |
| 182 | s[j][sz - 1 - i] = ss[j] = a; |
| 183 | } |
| 184 | q += 8; |
| 185 | } |
| 186 | |
| 187 | /* --- Clear away the temporary buffer --- */ |
| 188 | |
| 189 | if (p == b) |
| 190 | BURN(b); |
| 191 | } |
| 192 | |
| 193 | /* --- Construct the expanded key --- */ |
| 194 | |
| 195 | { |
| 196 | uint32 p = 0x01010101; |
| 197 | uint32 ip = 0; |
| 198 | int i; |
| 199 | |
| 200 | for (i = 0; i < 40; i += 2) { |
| 201 | uint32 a, b; |
| 202 | a = h(ip, me, sz); |
| 203 | b = h(ip + p, mo, sz); |
| 204 | b = ROL32(b, 8); |
| 205 | a += b; b += a; |
| 206 | k->k[i] = U32(a); |
| 207 | k->k[i + 1] = ROL32(b, 9); |
| 208 | ip += 2 * p; |
| 209 | } |
| 210 | |
| 211 | for (i = 0; i < 8; i++) |
| 212 | k->k[i] ^= fk->t23[i]; |
| 213 | for (i = 8; i < 40; i += 2) { |
| 214 | k->k[i] ^= fk->t4[0]; |
| 215 | k->k[i + 1] ^= fk->t4[1]; |
| 216 | } |
| 217 | } |
| 218 | |
| 219 | /* --- Construct the S-box tables --- */ |
| 220 | |
| 221 | { |
| 222 | unsigned i; |
| 223 | static const octet *q[4][KMAX + 1] = { |
| 224 | { q1, q0, q0, q1, q1 }, |
| 225 | { q0, q0, q1, q1, q0 }, |
| 226 | { q1, q1, q0, q0, q0 }, |
| 227 | { q0, q1, q1, q0, q1 } |
| 228 | }; |
| 229 | |
| 230 | for (i = 0; i < 4; i++) { |
| 231 | unsigned j; |
| 232 | uint32 x; |
| 233 | |
| 234 | for (j = 0; j < 256; j++) { |
| 235 | x = j; |
| 236 | |
| 237 | /* --- Push the byte through the q tables --- */ |
| 238 | |
| 239 | switch (sz) { |
| 240 | case 4: x = q[i][4][x] ^ s[i][3]; |
| 241 | case 3: x = q[i][3][x] ^ s[i][2]; |
| 242 | case 2: x = q[i][2][x] ^ s[i][1]; |
| 243 | x = q[i][1][x] ^ s[i][0]; |
| 244 | break; |
| 245 | } |
| 246 | |
| 247 | /* --- Write it in the key schedule --- */ |
| 248 | |
| 249 | k->g[i][j] = qmds[i][x]; |
| 250 | } |
| 251 | } |
| 252 | } |
| 253 | |
| 254 | /* --- Clear everything away --- */ |
| 255 | |
| 256 | BURN(me); |
| 257 | BURN(mo); |
| 258 | BURN(s); |
| 259 | } |
| 260 | |
| 261 | /* --- @twofish_init@ --- * |
| 262 | * |
| 263 | * Arguments: @twofish_ctx *k@ = pointer to key block to fill in |
| 264 | * @const void *buf@ = pointer to buffer of key material |
| 265 | * @size_t sz@ = size of key material |
| 266 | * |
| 267 | * Returns: --- |
| 268 | * |
| 269 | * Use: Initializes a Twofish key buffer. Twofish accepts key sizes |
| 270 | * of up to 256 bits (32 bytes). |
| 271 | */ |
| 272 | |
| 273 | void twofish_init(twofish_ctx *k, const void *buf, size_t sz) |
| 274 | { |
| 275 | static const twofish_fk fk = { { 0 } }; |
| 276 | twofish_initfk(k, buf, sz, &fk); |
| 277 | } |
| 278 | |
| 279 | /* --- @twofish_fkinit@ --- * |
| 280 | * |
| 281 | * Arguments: @twofish_fk *fk@ = pointer to family key block |
| 282 | * @const void *buf@ = pointer to buffer of key material |
| 283 | * @size_t sz@ = size of key material |
| 284 | * |
| 285 | * Returns: --- |
| 286 | * |
| 287 | * Use: Initializes a family-key buffer. This implementation allows |
| 288 | * family keys of any size acceptable to the Twofish algorithm. |
| 289 | */ |
| 290 | |
| 291 | void twofish_fkinit(twofish_fk *fk, const void *buf, size_t sz) |
| 292 | { |
| 293 | twofish_ctx k; |
| 294 | uint32 pt[4], ct[4]; |
| 295 | const octet *kk; |
| 296 | unsigned i; |
| 297 | |
| 298 | twofish_init(&k, buf, sz); |
| 299 | |
| 300 | for (i = 0; i < 4; i++) pt[i] = (uint32)-1; |
| 301 | twofish_eblk(&k, pt, fk->t0 + 4); |
| 302 | |
| 303 | kk = buf; sz /= 4; |
| 304 | for (i = 0; i < sz; i++) { fk->t0[i] = LOAD32_L(kk); kk += 4; } |
| 305 | |
| 306 | for (i = 0; i < 4; i++) pt[i] = 0; twofish_eblk(&k, pt, ct); |
| 307 | for (i = 0; i < 4; i++) STORE32_L(fk->t1 + i * 4, ct[i]); |
| 308 | pt[0] = 1; twofish_eblk(&k, pt, ct); |
| 309 | for (i = 0; i < 4; i++) STORE32_L(fk->t1 + 4 + i * 4, ct[i]); |
| 310 | |
| 311 | pt[0] = 2; twofish_eblk(&k, pt, fk->t23 + 0); |
| 312 | pt[0] = 3; twofish_eblk(&k, pt, fk->t23 + 4); |
| 313 | pt[0] = 4; twofish_eblk(&k, pt, ct); |
| 314 | fk->t4[0] = ct[0]; fk->t4[1] = ct[1]; |
| 315 | |
| 316 | BURN(k); |
| 317 | } |
| 318 | |
| 319 | /*----- Main encryption ---------------------------------------------------*/ |
| 320 | |
| 321 | /* --- Feistel function --- */ |
| 322 | |
| 323 | #define GG(k, t0, t1, x, y, kk) do { \ |
| 324 | t0 = (k->g[0][U8(x >> 0)] ^ \ |
| 325 | k->g[1][U8(x >> 8)] ^ \ |
| 326 | k->g[2][U8(x >> 16)] ^ \ |
| 327 | k->g[3][U8(x >> 24)]); \ |
| 328 | t1 = (k->g[1][U8(y >> 0)] ^ \ |
| 329 | k->g[2][U8(y >> 8)] ^ \ |
| 330 | k->g[3][U8(y >> 16)] ^ \ |
| 331 | k->g[0][U8(y >> 24)]); \ |
| 332 | t0 += t1; \ |
| 333 | t1 += t0; \ |
| 334 | t0 += kk[0]; \ |
| 335 | t1 += kk[1]; \ |
| 336 | } while (0) |
| 337 | |
| 338 | /* --- Round operations --- */ |
| 339 | |
| 340 | #define EROUND(k, w, x, y, z, kk) do { \ |
| 341 | uint32 _t0, _t1; \ |
| 342 | GG(k, _t0, _t1, w, x, kk); \ |
| 343 | kk += 2; \ |
| 344 | y ^= _t0; y = ROR32(y, 1); \ |
| 345 | z = ROL32(z, 1); z ^= _t1; \ |
| 346 | } while (0) |
| 347 | |
| 348 | #define DROUND(k, w, x, y, z, kk) do { \ |
| 349 | uint32 _t0, _t1; \ |
| 350 | kk -= 2; \ |
| 351 | GG(k, _t0, _t1, w, x, kk); \ |
| 352 | y = ROL32(y, 1); y ^= _t0; \ |
| 353 | z ^= _t1; z = ROR32(z, 1); \ |
| 354 | } while (0) |
| 355 | |
| 356 | /* --- Complete encryption functions --- */ |
| 357 | |
| 358 | #define EBLK(k, a, b, c, d, w, x, y, z) do { \ |
| 359 | const uint32 *_kk = k->k + 8; \ |
| 360 | uint32 _a = a, _b = b, _c = c, _d = d; \ |
| 361 | _a ^= k->k[0]; _b ^= k->k[1]; _c ^= k->k[2]; _d ^= k->k[3]; \ |
| 362 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 363 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 364 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 365 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 366 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 367 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 368 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 369 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 370 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 371 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 372 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 373 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 374 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 375 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 376 | EROUND(k, _a, _b, _c, _d, _kk); \ |
| 377 | EROUND(k, _c, _d, _a, _b, _kk); \ |
| 378 | _c ^= k->k[4]; _d ^= k->k[5]; _a ^= k->k[6]; _b ^= k->k[7]; \ |
| 379 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ |
| 380 | } while (0) |
| 381 | |
| 382 | #define DBLK(k, a, b, c, d, w, x, y, z) do { \ |
| 383 | const uint32 *_kk = k->k + 40; \ |
| 384 | uint32 _a = a, _b = b, _c = c, _d = d; \ |
| 385 | _a ^= k->k[4]; _b ^= k->k[5]; _c ^= k->k[6]; _d ^= k->k[7]; \ |
| 386 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 387 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 388 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 389 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 390 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 391 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 392 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 393 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 394 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 395 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 396 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 397 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 398 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 399 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 400 | DROUND(k, _a, _b, _c, _d, _kk); \ |
| 401 | DROUND(k, _c, _d, _a, _b, _kk); \ |
| 402 | _c ^= k->k[0]; _d ^= k->k[1]; _a ^= k->k[2]; _b ^= k->k[3]; \ |
| 403 | w = U32(_c); x = U32(_d); y = U32(_a); z = U32(_b); \ |
| 404 | } while (0) |
| 405 | |
| 406 | /* --- @twofish_eblk@, @twofish_dblk@ --- * |
| 407 | * |
| 408 | * Arguments: @const twofish_ctx *k@ = pointer to key block |
| 409 | * @const uint32 s[4]@ = pointer to source block |
| 410 | * @uint32 d[4]@ = pointer to destination block |
| 411 | * |
| 412 | * Returns: --- |
| 413 | * |
| 414 | * Use: Low-level block encryption and decryption. |
| 415 | */ |
| 416 | |
| 417 | void twofish_eblk(const twofish_ctx *k, const uint32 *s, uint32 *d) |
| 418 | { |
| 419 | EBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); |
| 420 | } |
| 421 | |
| 422 | void twofish_dblk(const twofish_ctx *k, const uint32 *s, uint32 *d) |
| 423 | { |
| 424 | DBLK(k, s[0], s[1], s[2], s[3], d[0], d[1], d[2], d[3]); |
| 425 | } |
| 426 | |
| 427 | BLKC_TEST(TWOFISH, twofish) |
| 428 | |
| 429 | /*----- That's all, folks -------------------------------------------------*/ |