1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis 2 * 3 * LibTomCrypt is a library that provides various cryptographic 4 * algorithms in a highly modular and flexible manner. 5 * 6 * The library is free for all purposes without any express 7 * guarantee it works. 8 * 9 * Tom St Denis, tomstdenis (at) gmail.com, http://libtomcrypt.com 10 */ 11 12 /** 13 @file twofish.c 14 Implementation of Twofish by Tom St Denis 15 */ 16 #include "tomcrypt.h" 17 18 #ifdef TWOFISH 19 20 /* first TWOFISH_ALL_TABLES must ensure TWOFISH_TABLES is defined */ 21 #ifdef TWOFISH_ALL_TABLES 22 #ifndef TWOFISH_TABLES 23 #define TWOFISH_TABLES 24 #endif 25 #endif 26 27 const struct ltc_cipher_descriptor twofish_desc = 28 { 29 "twofish", 30 7, 31 16, 32, 16, 16, 32 &twofish_setup, 33 &twofish_ecb_encrypt, 34 &twofish_ecb_decrypt, 35 &twofish_test, 36 &twofish_done, 37 &twofish_keysize, 38 NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL 39 }; 40 41 /* the two polynomials */ 42 #define MDS_POLY 0x169 43 #define RS_POLY 0x14D 44 45 /* The 4x4 MDS Linear Transform */ 46 #if 0 47 static const unsigned char MDS[4][4] = { 48 { 0x01, 0xEF, 0x5B, 0x5B }, 49 { 0x5B, 0xEF, 0xEF, 0x01 }, 50 { 0xEF, 0x5B, 0x01, 0xEF }, 51 { 0xEF, 0x01, 0xEF, 0x5B } 52 }; 53 #endif 54 55 /* The 4x8 RS Linear Transform */ 56 static const unsigned char RS[4][8] = { 57 { 0x01, 0xA4, 0x55, 0x87, 0x5A, 0x58, 0xDB, 0x9E }, 58 { 0xA4, 0x56, 0x82, 0xF3, 0X1E, 0XC6, 0X68, 0XE5 }, 59 { 0X02, 0XA1, 0XFC, 0XC1, 0X47, 0XAE, 0X3D, 0X19 }, 60 { 0XA4, 0X55, 0X87, 0X5A, 0X58, 0XDB, 0X9E, 0X03 } 61 }; 62 63 /* sbox usage orderings */ 64 static const unsigned char qord[4][5] = { 65 { 1, 1, 0, 0, 1 }, 66 { 0, 1, 1, 0, 0 }, 67 { 0, 0, 0, 1, 1 }, 68 { 1, 0, 1, 1, 0 } 69 }; 70 71 #ifdef TWOFISH_TABLES 72 73 #include "twofish_tab.c" 74 75 #define sbox(i, x) ((ulong32)SBOX[i][(x)&255]) 76 77 #else 78 79 /* The Q-box tables */ 80 static const unsigned char qbox[2][4][16] = { 81 { 82 { 0x8, 0x1, 0x7, 0xD, 0x6, 0xF, 0x3, 0x2, 0x0, 0xB, 0x5, 0x9, 0xE, 0xC, 0xA, 0x4 }, 83 { 0xE, 0XC, 0XB, 0X8, 0X1, 0X2, 0X3, 0X5, 0XF, 0X4, 0XA, 0X6, 0X7, 0X0, 0X9, 0XD }, 84 { 0XB, 0XA, 0X5, 0XE, 0X6, 0XD, 0X9, 0X0, 0XC, 0X8, 0XF, 0X3, 0X2, 0X4, 0X7, 0X1 }, 85 { 0XD, 0X7, 0XF, 0X4, 0X1, 0X2, 0X6, 0XE, 0X9, 0XB, 0X3, 0X0, 0X8, 0X5, 0XC, 0XA } 86 }, 87 { 88 { 0X2, 0X8, 0XB, 0XD, 0XF, 0X7, 0X6, 0XE, 0X3, 0X1, 0X9, 0X4, 0X0, 0XA, 0XC, 0X5 }, 89 { 0X1, 0XE, 0X2, 0XB, 0X4, 0XC, 0X3, 0X7, 0X6, 0XD, 0XA, 0X5, 0XF, 0X9, 0X0, 0X8 }, 90 { 0X4, 0XC, 0X7, 0X5, 0X1, 0X6, 0X9, 0XA, 0X0, 0XE, 0XD, 0X8, 0X2, 0XB, 0X3, 0XF }, 91 { 0xB, 0X9, 0X5, 0X1, 0XC, 0X3, 0XD, 0XE, 0X6, 0X4, 0X7, 0XF, 0X2, 0X0, 0X8, 0XA } 92 } 93 }; 94 95 /* computes S_i[x] */ 96 #ifdef LTC_CLEAN_STACK 97 static ulong32 _sbox(int i, ulong32 x) 98 #else 99 static ulong32 sbox(int i, ulong32 x) 100 #endif 101 { 102 unsigned char a0,b0,a1,b1,a2,b2,a3,b3,a4,b4,y; 103 104 /* a0,b0 = [x/16], x mod 16 */ 105 a0 = (unsigned char)((x>>4)&15); 106 b0 = (unsigned char)((x)&15); 107 108 /* a1 = a0 ^ b0 */ 109 a1 = a0 ^ b0; 110 111 /* b1 = a0 ^ ROR(b0, 1) ^ 8a0 */ 112 b1 = (a0 ^ ((b0<<3)|(b0>>1)) ^ (a0<<3)) & 15; 113 114 /* a2,b2 = t0[a1], t1[b1] */ 115 a2 = qbox[i][0][(int)a1]; 116 b2 = qbox[i][1][(int)b1]; 117 118 /* a3 = a2 ^ b2 */ 119 a3 = a2 ^ b2; 120 121 /* b3 = a2 ^ ROR(b2, 1) ^ 8a2 */ 122 b3 = (a2 ^ ((b2<<3)|(b2>>1)) ^ (a2<<3)) & 15; 123 124 /* a4,b4 = t2[a3], t3[b3] */ 125 a4 = qbox[i][2][(int)a3]; 126 b4 = qbox[i][3][(int)b3]; 127 128 /* y = 16b4 + a4 */ 129 y = (b4 << 4) + a4; 130 131 /* return result */ 132 return (ulong32)y; 133 } 134 135 #ifdef LTC_CLEAN_STACK 136 static ulong32 sbox(int i, ulong32 x) 137 { 138 ulong32 y; 139 y = _sbox(i, x); 140 burn_stack(sizeof(unsigned char) * 11); 141 return y; 142 } 143 #endif /* LTC_CLEAN_STACK */ 144 145 #endif /* TWOFISH_TABLES */ 146 147 /* computes ab mod p */ 148 static ulong32 gf_mult(ulong32 a, ulong32 b, ulong32 p) 149 { 150 ulong32 result, B[2], P[2]; 151 152 P[1] = p; 153 B[1] = b; 154 result = P[0] = B[0] = 0; 155 156 /* unrolled branchless GF multiplier */ 157 result ^= B[a&1]; a >>= 1; B[1] = P[B[1]>>7] ^ (B[1] << 1); 158 result ^= B[a&1]; a >>= 1; B[1] = P[B[1]>>7] ^ (B[1] << 1); 159 result ^= B[a&1]; a >>= 1; B[1] = P[B[1]>>7] ^ (B[1] << 1); 160 result ^= B[a&1]; a >>= 1; B[1] = P[B[1]>>7] ^ (B[1] << 1); 161 result ^= B[a&1]; a >>= 1; B[1] = P[B[1]>>7] ^ (B[1] << 1); 162 result ^= B[a&1]; a >>= 1; B[1] = P[B[1]>>7] ^ (B[1] << 1); 163 result ^= B[a&1]; a >>= 1; B[1] = P[B[1]>>7] ^ (B[1] << 1); 164 result ^= B[a&1]; 165 166 return result; 167 } 168 169 /* computes [y0 y1 y2 y3] = MDS . [x0] */ 170 #ifndef TWOFISH_TABLES 171 static ulong32 mds_column_mult(unsigned char in, int col) 172 { 173 ulong32 x01, x5B, xEF; 174 175 x01 = in; 176 x5B = gf_mult(in, 0x5B, MDS_POLY); 177 xEF = gf_mult(in, 0xEF, MDS_POLY); 178 179 switch (col) { 180 case 0: 181 return (x01 << 0 ) | 182 (x5B << 8 ) | 183 (xEF << 16) | 184 (xEF << 24); 185 case 1: 186 return (xEF << 0 ) | 187 (xEF << 8 ) | 188 (x5B << 16) | 189 (x01 << 24); 190 case 2: 191 return (x5B << 0 ) | 192 (xEF << 8 ) | 193 (x01 << 16) | 194 (xEF << 24); 195 case 3: 196 return (x5B << 0 ) | 197 (x01 << 8 ) | 198 (xEF << 16) | 199 (x5B << 24); 200 } 201 /* avoid warnings, we'd never get here normally but just to calm compiler warnings... */ 202 return 0; 203 } 204 205 #else /* !TWOFISH_TABLES */ 206 207 #define mds_column_mult(x, i) mds_tab[i][x] 208 209 #endif /* TWOFISH_TABLES */ 210 211 /* Computes [y0 y1 y2 y3] = MDS . [x0 x1 x2 x3] */ 212 static void mds_mult(const unsigned char *in, unsigned char *out) 213 { 214 int x; 215 ulong32 tmp; 216 for (tmp = x = 0; x < 4; x++) { 217 tmp ^= mds_column_mult(in[x], x); 218 } 219 STORE32L(tmp, out); 220 } 221 222 #ifdef TWOFISH_ALL_TABLES 223 /* computes [y0 y1 y2 y3] = RS . [x0 x1 x2 x3 x4 x5 x6 x7] */ 224 static void rs_mult(const unsigned char *in, unsigned char *out) 225 { 226 ulong32 tmp; 227 tmp = rs_tab0[in[0]] ^ rs_tab1[in[1]] ^ rs_tab2[in[2]] ^ rs_tab3[in[3]] ^ 228 rs_tab4[in[4]] ^ rs_tab5[in[5]] ^ rs_tab6[in[6]] ^ rs_tab7[in[7]]; 229 STORE32L(tmp, out); 230 } 231 232 #else /* !TWOFISH_ALL_TABLES */ 233 234 /* computes [y0 y1 y2 y3] = RS . [x0 x1 x2 x3 x4 x5 x6 x7] */ 235 static void rs_mult(const unsigned char *in, unsigned char *out) 236 { 237 int x, y; 238 for (x = 0; x < 4; x++) { 239 out[x] = 0; 240 for (y = 0; y < 8; y++) { 241 out[x] ^= gf_mult(in[y], RS[x][y], RS_POLY); 242 } 243 } 244 } 245 246 #endif 247 248 /* computes h(x) */ 249 static void h_func(const unsigned char *in, unsigned char *out, unsigned char *M, int k, int offset) 250 { 251 int x; 252 unsigned char y[4]; 253 for (x = 0; x < 4; x++) { 254 y[x] = in[x]; 255 } 256 switch (k) { 257 case 4: 258 y[0] = (unsigned char)(sbox(1, (ulong32)y[0]) ^ M[4 * (6 + offset) + 0]); 259 y[1] = (unsigned char)(sbox(0, (ulong32)y[1]) ^ M[4 * (6 + offset) + 1]); 260 y[2] = (unsigned char)(sbox(0, (ulong32)y[2]) ^ M[4 * (6 + offset) + 2]); 261 y[3] = (unsigned char)(sbox(1, (ulong32)y[3]) ^ M[4 * (6 + offset) + 3]); 262 case 3: 263 y[0] = (unsigned char)(sbox(1, (ulong32)y[0]) ^ M[4 * (4 + offset) + 0]); 264 y[1] = (unsigned char)(sbox(1, (ulong32)y[1]) ^ M[4 * (4 + offset) + 1]); 265 y[2] = (unsigned char)(sbox(0, (ulong32)y[2]) ^ M[4 * (4 + offset) + 2]); 266 y[3] = (unsigned char)(sbox(0, (ulong32)y[3]) ^ M[4 * (4 + offset) + 3]); 267 case 2: 268 y[0] = (unsigned char)(sbox(1, sbox(0, sbox(0, (ulong32)y[0]) ^ M[4 * (2 + offset) + 0]) ^ M[4 * (0 + offset) + 0])); 269 y[1] = (unsigned char)(sbox(0, sbox(0, sbox(1, (ulong32)y[1]) ^ M[4 * (2 + offset) + 1]) ^ M[4 * (0 + offset) + 1])); 270 y[2] = (unsigned char)(sbox(1, sbox(1, sbox(0, (ulong32)y[2]) ^ M[4 * (2 + offset) + 2]) ^ M[4 * (0 + offset) + 2])); 271 y[3] = (unsigned char)(sbox(0, sbox(1, sbox(1, (ulong32)y[3]) ^ M[4 * (2 + offset) + 3]) ^ M[4 * (0 + offset) + 3])); 272 } 273 mds_mult(y, out); 274 } 275 276 #ifndef TWOFISH_SMALL 277 278 /* for GCC we don't use pointer aliases */ 279 #if defined(__GNUC__) 280 #define S1 skey->twofish.S[0] 281 #define S2 skey->twofish.S[1] 282 #define S3 skey->twofish.S[2] 283 #define S4 skey->twofish.S[3] 284 #endif 285 286 /* the G function */ 287 #define g_func(x, dum) (S1[byte(x,0)] ^ S2[byte(x,1)] ^ S3[byte(x,2)] ^ S4[byte(x,3)]) 288 #define g1_func(x, dum) (S2[byte(x,0)] ^ S3[byte(x,1)] ^ S4[byte(x,2)] ^ S1[byte(x,3)]) 289 290 #else 291 292 #ifdef LTC_CLEAN_STACK 293 static ulong32 _g_func(ulong32 x, symmetric_key *key) 294 #else 295 static ulong32 g_func(ulong32 x, symmetric_key *key) 296 #endif 297 { 298 unsigned char g, i, y, z; 299 ulong32 res; 300 301 res = 0; 302 for (y = 0; y < 4; y++) { 303 z = key->twofish.start; 304 305 /* do unkeyed substitution */ 306 g = sbox(qord[y][z++], (x >> (8*y)) & 255); 307 308 /* first subkey */ 309 i = 0; 310 311 /* do key mixing+sbox until z==5 */ 312 while (z != 5) { 313 g = g ^ key->twofish.S[4*i++ + y]; 314 g = sbox(qord[y][z++], g); 315 } 316 317 /* multiply g by a column of the MDS */ 318 res ^= mds_column_mult(g, y); 319 } 320 return res; 321 } 322 323 #define g1_func(x, key) g_func(ROLc(x, 8), key) 324 325 #ifdef LTC_CLEAN_STACK 326 static ulong32 g_func(ulong32 x, symmetric_key *key) 327 { 328 ulong32 y; 329 y = _g_func(x, key); 330 burn_stack(sizeof(unsigned char) * 4 + sizeof(ulong32)); 331 return y; 332 } 333 #endif /* LTC_CLEAN_STACK */ 334 335 #endif /* TWOFISH_SMALL */ 336 337 /** 338 Initialize the Twofish block cipher 339 @param key The symmetric key you wish to pass 340 @param keylen The key length in bytes 341 @param num_rounds The number of rounds desired (0 for default) 342 @param skey The key in as scheduled by this function. 343 @return CRYPT_OK if successful 344 */ 345 #ifdef LTC_CLEAN_STACK 346 static int _twofish_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey) 347 #else 348 int twofish_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey) 349 #endif 350 { 351 #ifndef TWOFISH_SMALL 352 unsigned char S[4*4], tmpx0, tmpx1; 353 #endif 354 int k, x, y; 355 unsigned char tmp[4], tmp2[4], M[8*4]; 356 ulong32 A, B; 357 358 LTC_ARGCHK(key != NULL); 359 LTC_ARGCHK(skey != NULL); 360 361 /* invalid arguments? */ 362 if (num_rounds != 16 && num_rounds != 0) { 363 return CRYPT_INVALID_ROUNDS; 364 } 365 366 if (keylen != 16 && keylen != 24 && keylen != 32) { 367 return CRYPT_INVALID_KEYSIZE; 368 } 369 370 /* k = keysize/64 [but since our keysize is in bytes...] */ 371 k = keylen / 8; 372 373 /* copy the key into M */ 374 for (x = 0; x < keylen; x++) { 375 M[x] = key[x] & 255; 376 } 377 378 /* create the S[..] words */ 379 #ifndef TWOFISH_SMALL 380 for (x = 0; x < k; x++) { 381 rs_mult(M+(x*8), S+(x*4)); 382 } 383 #else 384 for (x = 0; x < k; x++) { 385 rs_mult(M+(x*8), skey->twofish.S+(x*4)); 386 } 387 #endif 388 389 /* make subkeys */ 390 for (x = 0; x < 20; x++) { 391 /* A = h(p * 2x, Me) */ 392 for (y = 0; y < 4; y++) { 393 tmp[y] = x+x; 394 } 395 h_func(tmp, tmp2, M, k, 0); 396 LOAD32L(A, tmp2); 397 398 /* B = ROL(h(p * (2x + 1), Mo), 8) */ 399 for (y = 0; y < 4; y++) { 400 tmp[y] = (unsigned char)(x+x+1); 401 } 402 h_func(tmp, tmp2, M, k, 1); 403 LOAD32L(B, tmp2); 404 B = ROLc(B, 8); 405 406 /* K[2i] = A + B */ 407 skey->twofish.K[x+x] = (A + B) & 0xFFFFFFFFUL; 408 409 /* K[2i+1] = (A + 2B) <<< 9 */ 410 skey->twofish.K[x+x+1] = ROLc(B + B + A, 9); 411 } 412 413 #ifndef TWOFISH_SMALL 414 /* make the sboxes (large ram variant) */ 415 if (k == 2) { 416 for (x = 0; x < 256; x++) { 417 tmpx0 = (unsigned char)sbox(0, x); 418 tmpx1 = (unsigned char)sbox(1, x); 419 skey->twofish.S[0][x] = mds_column_mult(sbox(1, (sbox(0, tmpx0 ^ S[0]) ^ S[4])),0); 420 skey->twofish.S[1][x] = mds_column_mult(sbox(0, (sbox(0, tmpx1 ^ S[1]) ^ S[5])),1); 421 skey->twofish.S[2][x] = mds_column_mult(sbox(1, (sbox(1, tmpx0 ^ S[2]) ^ S[6])),2); 422 skey->twofish.S[3][x] = mds_column_mult(sbox(0, (sbox(1, tmpx1 ^ S[3]) ^ S[7])),3); 423 } 424 } else if (k == 3) { 425 for (x = 0; x < 256; x++) { 426 tmpx0 = (unsigned char)sbox(0, x); 427 tmpx1 = (unsigned char)sbox(1, x); 428 skey->twofish.S[0][x] = mds_column_mult(sbox(1, (sbox(0, sbox(0, tmpx1 ^ S[0]) ^ S[4]) ^ S[8])),0); 429 skey->twofish.S[1][x] = mds_column_mult(sbox(0, (sbox(0, sbox(1, tmpx1 ^ S[1]) ^ S[5]) ^ S[9])),1); 430 skey->twofish.S[2][x] = mds_column_mult(sbox(1, (sbox(1, sbox(0, tmpx0 ^ S[2]) ^ S[6]) ^ S[10])),2); 431 skey->twofish.S[3][x] = mds_column_mult(sbox(0, (sbox(1, sbox(1, tmpx0 ^ S[3]) ^ S[7]) ^ S[11])),3); 432 } 433 } else { 434 for (x = 0; x < 256; x++) { 435 tmpx0 = (unsigned char)sbox(0, x); 436 tmpx1 = (unsigned char)sbox(1, x); 437 skey->twofish.S[0][x] = mds_column_mult(sbox(1, (sbox(0, sbox(0, sbox(1, tmpx1 ^ S[0]) ^ S[4]) ^ S[8]) ^ S[12])),0); 438 skey->twofish.S[1][x] = mds_column_mult(sbox(0, (sbox(0, sbox(1, sbox(1, tmpx0 ^ S[1]) ^ S[5]) ^ S[9]) ^ S[13])),1); 439 skey->twofish.S[2][x] = mds_column_mult(sbox(1, (sbox(1, sbox(0, sbox(0, tmpx0 ^ S[2]) ^ S[6]) ^ S[10]) ^ S[14])),2); 440 skey->twofish.S[3][x] = mds_column_mult(sbox(0, (sbox(1, sbox(1, sbox(0, tmpx1 ^ S[3]) ^ S[7]) ^ S[11]) ^ S[15])),3); 441 } 442 } 443 #else 444 /* where to start in the sbox layers */ 445 /* small ram variant */ 446 switch (k) { 447 case 4 : skey->twofish.start = 0; break; 448 case 3 : skey->twofish.start = 1; break; 449 default: skey->twofish.start = 2; break; 450 } 451 #endif 452 return CRYPT_OK; 453 } 454 455 #ifdef LTC_CLEAN_STACK 456 int twofish_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey) 457 { 458 int x; 459 x = _twofish_setup(key, keylen, num_rounds, skey); 460 burn_stack(sizeof(int) * 7 + sizeof(unsigned char) * 56 + sizeof(ulong32) * 2); 461 return x; 462 } 463 #endif 464 465 /** 466 Encrypts a block of text with Twofish 467 @param pt The input plaintext (16 bytes) 468 @param ct The output ciphertext (16 bytes) 469 @param skey The key as scheduled 470 @return CRYPT_OK if successful 471 */ 472 #ifdef LTC_CLEAN_STACK 473 static int _twofish_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey) 474 #else 475 int twofish_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey) 476 #endif 477 { 478 ulong32 a,b,c,d,ta,tb,tc,td,t1,t2, *k; 479 int r; 480 #if !defined(TWOFISH_SMALL) && !defined(__GNUC__) 481 ulong32 *S1, *S2, *S3, *S4; 482 #endif 483 484 LTC_ARGCHK(pt != NULL); 485 LTC_ARGCHK(ct != NULL); 486 LTC_ARGCHK(skey != NULL); 487 488 #if !defined(TWOFISH_SMALL) && !defined(__GNUC__) 489 S1 = skey->twofish.S[0]; 490 S2 = skey->twofish.S[1]; 491 S3 = skey->twofish.S[2]; 492 S4 = skey->twofish.S[3]; 493 #endif 494 495 LOAD32L(a,&pt[0]); LOAD32L(b,&pt[4]); 496 LOAD32L(c,&pt[8]); LOAD32L(d,&pt[12]); 497 a ^= skey->twofish.K[0]; 498 b ^= skey->twofish.K[1]; 499 c ^= skey->twofish.K[2]; 500 d ^= skey->twofish.K[3]; 501 502 k = skey->twofish.K + 8; 503 for (r = 8; r != 0; --r) { 504 t2 = g1_func(b, skey); 505 t1 = g_func(a, skey) + t2; 506 c = RORc(c ^ (t1 + k[0]), 1); 507 d = ROLc(d, 1) ^ (t2 + t1 + k[1]); 508 509 t2 = g1_func(d, skey); 510 t1 = g_func(c, skey) + t2; 511 a = RORc(a ^ (t1 + k[2]), 1); 512 b = ROLc(b, 1) ^ (t2 + t1 + k[3]); 513 k += 4; 514 } 515 516 /* output with "undo last swap" */ 517 ta = c ^ skey->twofish.K[4]; 518 tb = d ^ skey->twofish.K[5]; 519 tc = a ^ skey->twofish.K[6]; 520 td = b ^ skey->twofish.K[7]; 521 522 /* store output */ 523 STORE32L(ta,&ct[0]); STORE32L(tb,&ct[4]); 524 STORE32L(tc,&ct[8]); STORE32L(td,&ct[12]); 525 526 return CRYPT_OK; 527 } 528 529 #ifdef LTC_CLEAN_STACK 530 int twofish_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey) 531 { 532 int err = _twofish_ecb_encrypt(pt, ct, skey); 533 burn_stack(sizeof(ulong32) * 10 + sizeof(int)); 534 return err; 535 } 536 #endif 537 538 /** 539 Decrypts a block of text with Twofish 540 @param ct The input ciphertext (16 bytes) 541 @param pt The output plaintext (16 bytes) 542 @param skey The key as scheduled 543 @return CRYPT_OK if successful 544 */ 545 #ifdef LTC_CLEAN_STACK 546 static int _twofish_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey) 547 #else 548 int twofish_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey) 549 #endif 550 { 551 ulong32 a,b,c,d,ta,tb,tc,td,t1,t2, *k; 552 int r; 553 #if !defined(TWOFISH_SMALL) && !defined(__GNUC__) 554 ulong32 *S1, *S2, *S3, *S4; 555 #endif 556 557 LTC_ARGCHK(pt != NULL); 558 LTC_ARGCHK(ct != NULL); 559 LTC_ARGCHK(skey != NULL); 560 561 #if !defined(TWOFISH_SMALL) && !defined(__GNUC__) 562 S1 = skey->twofish.S[0]; 563 S2 = skey->twofish.S[1]; 564 S3 = skey->twofish.S[2]; 565 S4 = skey->twofish.S[3]; 566 #endif 567 568 /* load input */ 569 LOAD32L(ta,&ct[0]); LOAD32L(tb,&ct[4]); 570 LOAD32L(tc,&ct[8]); LOAD32L(td,&ct[12]); 571 572 /* undo undo final swap */ 573 a = tc ^ skey->twofish.K[6]; 574 b = td ^ skey->twofish.K[7]; 575 c = ta ^ skey->twofish.K[4]; 576 d = tb ^ skey->twofish.K[5]; 577 578 k = skey->twofish.K + 36; 579 for (r = 8; r != 0; --r) { 580 t2 = g1_func(d, skey); 581 t1 = g_func(c, skey) + t2; 582 a = ROLc(a, 1) ^ (t1 + k[2]); 583 b = RORc(b ^ (t2 + t1 + k[3]), 1); 584 585 t2 = g1_func(b, skey); 586 t1 = g_func(a, skey) + t2; 587 c = ROLc(c, 1) ^ (t1 + k[0]); 588 d = RORc(d ^ (t2 + t1 + k[1]), 1); 589 k -= 4; 590 } 591 592 /* pre-white */ 593 a ^= skey->twofish.K[0]; 594 b ^= skey->twofish.K[1]; 595 c ^= skey->twofish.K[2]; 596 d ^= skey->twofish.K[3]; 597 598 /* store */ 599 STORE32L(a, &pt[0]); STORE32L(b, &pt[4]); 600 STORE32L(c, &pt[8]); STORE32L(d, &pt[12]); 601 return CRYPT_OK; 602 } 603 604 #ifdef LTC_CLEAN_STACK 605 int twofish_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey) 606 { 607 int err =_twofish_ecb_decrypt(ct, pt, skey); 608 burn_stack(sizeof(ulong32) * 10 + sizeof(int)); 609 return err; 610 } 611 #endif 612 613 /** 614 Performs a self-test of the Twofish block cipher 615 @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled 616 */ 617 int twofish_test(void) 618 { 619 #ifndef LTC_TEST 620 return CRYPT_NOP; 621 #else 622 static const struct { 623 int keylen; 624 unsigned char key[32], pt[16], ct[16]; 625 } tests[] = { 626 { 16, 627 { 0x9F, 0x58, 0x9F, 0x5C, 0xF6, 0x12, 0x2C, 0x32, 628 0xB6, 0xBF, 0xEC, 0x2F, 0x2A, 0xE8, 0xC3, 0x5A }, 629 { 0xD4, 0x91, 0xDB, 0x16, 0xE7, 0xB1, 0xC3, 0x9E, 630 0x86, 0xCB, 0x08, 0x6B, 0x78, 0x9F, 0x54, 0x19 }, 631 { 0x01, 0x9F, 0x98, 0x09, 0xDE, 0x17, 0x11, 0x85, 632 0x8F, 0xAA, 0xC3, 0xA3, 0xBA, 0x20, 0xFB, 0xC3 } 633 }, { 634 24, 635 { 0x88, 0xB2, 0xB2, 0x70, 0x6B, 0x10, 0x5E, 0x36, 636 0xB4, 0x46, 0xBB, 0x6D, 0x73, 0x1A, 0x1E, 0x88, 637 0xEF, 0xA7, 0x1F, 0x78, 0x89, 0x65, 0xBD, 0x44 }, 638 { 0x39, 0xDA, 0x69, 0xD6, 0xBA, 0x49, 0x97, 0xD5, 639 0x85, 0xB6, 0xDC, 0x07, 0x3C, 0xA3, 0x41, 0xB2 }, 640 { 0x18, 0x2B, 0x02, 0xD8, 0x14, 0x97, 0xEA, 0x45, 641 0xF9, 0xDA, 0xAC, 0xDC, 0x29, 0x19, 0x3A, 0x65 } 642 }, { 643 32, 644 { 0xD4, 0x3B, 0xB7, 0x55, 0x6E, 0xA3, 0x2E, 0x46, 645 0xF2, 0xA2, 0x82, 0xB7, 0xD4, 0x5B, 0x4E, 0x0D, 646 0x57, 0xFF, 0x73, 0x9D, 0x4D, 0xC9, 0x2C, 0x1B, 647 0xD7, 0xFC, 0x01, 0x70, 0x0C, 0xC8, 0x21, 0x6F }, 648 { 0x90, 0xAF, 0xE9, 0x1B, 0xB2, 0x88, 0x54, 0x4F, 649 0x2C, 0x32, 0xDC, 0x23, 0x9B, 0x26, 0x35, 0xE6 }, 650 { 0x6C, 0xB4, 0x56, 0x1C, 0x40, 0xBF, 0x0A, 0x97, 651 0x05, 0x93, 0x1C, 0xB6, 0xD4, 0x08, 0xE7, 0xFA } 652 } 653 }; 654 655 656 symmetric_key key; 657 unsigned char tmp[2][16]; 658 int err, i, y; 659 660 for (i = 0; i < (int)(sizeof(tests)/sizeof(tests[0])); i++) { 661 if ((err = twofish_setup(tests[i].key, tests[i].keylen, 0, &key)) != CRYPT_OK) { 662 return err; 663 } 664 twofish_ecb_encrypt(tests[i].pt, tmp[0], &key); 665 twofish_ecb_decrypt(tmp[0], tmp[1], &key); 666 if (XMEMCMP(tmp[0], tests[i].ct, 16) != 0 || XMEMCMP(tmp[1], tests[i].pt, 16) != 0) { 667 #if 0 668 printf("Twofish failed test %d, %d, %d\n", i, XMEMCMP(tmp[0], tests[i].ct, 16), XMEMCMP(tmp[1], tests[i].pt, 16)); 669 #endif 670 return CRYPT_FAIL_TESTVECTOR; 671 } 672 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */ 673 for (y = 0; y < 16; y++) tmp[0][y] = 0; 674 for (y = 0; y < 1000; y++) twofish_ecb_encrypt(tmp[0], tmp[0], &key); 675 for (y = 0; y < 1000; y++) twofish_ecb_decrypt(tmp[0], tmp[0], &key); 676 for (y = 0; y < 16; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR; 677 } 678 return CRYPT_OK; 679 #endif 680 } 681 682 /** Terminate the context 683 @param skey The scheduled key 684 */ 685 void twofish_done(symmetric_key *skey) 686 { 687 } 688 689 /** 690 Gets suitable key size 691 @param keysize [in/out] The length of the recommended key (in bytes). This function will store the suitable size back in this variable. 692 @return CRYPT_OK if the input key size is acceptable. 693 */ 694 int twofish_keysize(int *keysize) 695 { 696 LTC_ARGCHK(keysize); 697 if (*keysize < 16) 698 return CRYPT_INVALID_KEYSIZE; 699 if (*keysize < 24) { 700 *keysize = 16; 701 return CRYPT_OK; 702 } else if (*keysize < 32) { 703 *keysize = 24; 704 return CRYPT_OK; 705 } else { 706 *keysize = 32; 707 return CRYPT_OK; 708 } 709 } 710 711 #endif 712 713 714 715 716 /* $Source: /cvs/libtom/libtomcrypt/src/ciphers/twofish/twofish.c,v $ */ 717 /* $Revision: 1.14 $ */ 718 /* $Date: 2006/12/04 21:34:03 $ */ 719
