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