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comparison src/ciphers/twofish/twofish.c @ 192:9cc34777b479 libtomcrypt

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propagate from branch 'au.asn.ucc.matt.ltc-orig' (head 9ba8f01f44320e9cb9f19881105ae84f84a43ea9) to branch 'au.asn.ucc.matt.dropbear.ltc' (head dbf51c569bc34956ad948e4cc87a0eeb2170b768)
author Matt Johnston <matt@ucc.asn.au>
date Sun, 08 May 2005 06:36:47 +0000
parents 1c15b283127b
children 19e5d79b7190
comparison
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164:cd1143579f00 192:9cc34777b479
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, [email protected], http://libtomcrypt.org
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
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 = sbox(0, x);
418 tmpx1 = 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 = sbox(0, x);
427 tmpx1 = 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 = sbox(0, x);
436 tmpx1 = 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 */
471 #ifdef LTC_CLEAN_STACK
472 static void _twofish_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
473 #else
474 void twofish_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
475 #endif
476 {
477 ulong32 a,b,c,d,ta,tb,tc,td,t1,t2, *k;
478 int r;
479 #if !defined(TWOFISH_SMALL) && !defined(__GNUC__)
480 ulong32 *S1, *S2, *S3, *S4;
481 #endif
482
483 LTC_ARGCHK(pt != NULL);
484 LTC_ARGCHK(ct != NULL);
485 LTC_ARGCHK(skey != NULL);
486
487 #if !defined(TWOFISH_SMALL) && !defined(__GNUC__)
488 S1 = skey->twofish.S[0];
489 S2 = skey->twofish.S[1];
490 S3 = skey->twofish.S[2];
491 S4 = skey->twofish.S[3];
492 #endif
493
494 LOAD32L(a,&pt[0]); LOAD32L(b,&pt[4]);
495 LOAD32L(c,&pt[8]); LOAD32L(d,&pt[12]);
496 a ^= skey->twofish.K[0];
497 b ^= skey->twofish.K[1];
498 c ^= skey->twofish.K[2];
499 d ^= skey->twofish.K[3];
500
501 k = skey->twofish.K + 8;
502 for (r = 8; r != 0; --r) {
503 t2 = g1_func(b, skey);
504 t1 = g_func(a, skey) + t2;
505 c = RORc(c ^ (t1 + k[0]), 1);
506 d = ROLc(d, 1) ^ (t2 + t1 + k[1]);
507
508 t2 = g1_func(d, skey);
509 t1 = g_func(c, skey) + t2;
510 a = RORc(a ^ (t1 + k[2]), 1);
511 b = ROLc(b, 1) ^ (t2 + t1 + k[3]);
512 k += 4;
513 }
514
515 /* output with "undo last swap" */
516 ta = c ^ skey->twofish.K[4];
517 tb = d ^ skey->twofish.K[5];
518 tc = a ^ skey->twofish.K[6];
519 td = b ^ skey->twofish.K[7];
520
521 /* store output */
522 STORE32L(ta,&ct[0]); STORE32L(tb,&ct[4]);
523 STORE32L(tc,&ct[8]); STORE32L(td,&ct[12]);
524 }
525
526 #ifdef LTC_CLEAN_STACK
527 void twofish_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
528 {
529 _twofish_ecb_encrypt(pt, ct, skey);
530 burn_stack(sizeof(ulong32) * 10 + sizeof(int));
531 }
532 #endif
533
534 /**
535 Decrypts a block of text with Twofish
536 @param ct The input ciphertext (16 bytes)
537 @param pt The output plaintext (16 bytes)
538 @param skey The key as scheduled
539 */
540 #ifdef LTC_CLEAN_STACK
541 static void _twofish_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
542 #else
543 void twofish_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
544 #endif
545 {
546 ulong32 a,b,c,d,ta,tb,tc,td,t1,t2, *k;
547 int r;
548 #if !defined(TWOFISH_SMALL) && !defined(__GNUC__)
549 ulong32 *S1, *S2, *S3, *S4;
550 #endif
551
552 LTC_ARGCHK(pt != NULL);
553 LTC_ARGCHK(ct != NULL);
554 LTC_ARGCHK(skey != NULL);
555
556 #if !defined(TWOFISH_SMALL) && !defined(__GNUC__)
557 S1 = skey->twofish.S[0];
558 S2 = skey->twofish.S[1];
559 S3 = skey->twofish.S[2];
560 S4 = skey->twofish.S[3];
561 #endif
562
563 /* load input */
564 LOAD32L(ta,&ct[0]); LOAD32L(tb,&ct[4]);
565 LOAD32L(tc,&ct[8]); LOAD32L(td,&ct[12]);
566
567 /* undo undo final swap */
568 a = tc ^ skey->twofish.K[6];
569 b = td ^ skey->twofish.K[7];
570 c = ta ^ skey->twofish.K[4];
571 d = tb ^ skey->twofish.K[5];
572
573 k = skey->twofish.K + 36;
574 for (r = 8; r != 0; --r) {
575 t2 = g1_func(d, skey);
576 t1 = g_func(c, skey) + t2;
577 a = ROLc(a, 1) ^ (t1 + k[2]);
578 b = RORc(b ^ (t2 + t1 + k[3]), 1);
579
580 t2 = g1_func(b, skey);
581 t1 = g_func(a, key) + t2;
582 c = ROLc(c, 1) ^ (t1 + k[0]);
583 d = RORc(d ^ (t2 + t1 + k[1]), 1);
584 k -= 4;
585 }
586
587 /* pre-white */
588 a ^= skey->twofish.K[0];
589 b ^= skey->twofish.K[1];
590 c ^= skey->twofish.K[2];
591 d ^= skey->twofish.K[3];
592
593 /* store */
594 STORE32L(a, &pt[0]); STORE32L(b, &pt[4]);
595 STORE32L(c, &pt[8]); STORE32L(d, &pt[12]);
596 }
597
598 #ifdef LTC_CLEAN_STACK
599 void twofish_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
600 {
601 _twofish_ecb_decrypt(ct, pt, skey);
602 burn_stack(sizeof(ulong32) * 10 + sizeof(int));
603 }
604 #endif
605
606 /**
607 Performs a self-test of the Twofish block cipher
608 @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled
609 */
610 int twofish_test(void)
611 {
612 #ifndef LTC_TEST
613 return CRYPT_NOP;
614 #else
615 static const struct {
616 int keylen;
617 unsigned char key[32], pt[16], ct[16];
618 } tests[] = {
619 { 16,
620 { 0x9F, 0x58, 0x9F, 0x5C, 0xF6, 0x12, 0x2C, 0x32,
621 0xB6, 0xBF, 0xEC, 0x2F, 0x2A, 0xE8, 0xC3, 0x5A },
622 { 0xD4, 0x91, 0xDB, 0x16, 0xE7, 0xB1, 0xC3, 0x9E,
623 0x86, 0xCB, 0x08, 0x6B, 0x78, 0x9F, 0x54, 0x19 },
624 { 0x01, 0x9F, 0x98, 0x09, 0xDE, 0x17, 0x11, 0x85,
625 0x8F, 0xAA, 0xC3, 0xA3, 0xBA, 0x20, 0xFB, 0xC3 }
626 }, {
627 24,
628 { 0x88, 0xB2, 0xB2, 0x70, 0x6B, 0x10, 0x5E, 0x36,
629 0xB4, 0x46, 0xBB, 0x6D, 0x73, 0x1A, 0x1E, 0x88,
630 0xEF, 0xA7, 0x1F, 0x78, 0x89, 0x65, 0xBD, 0x44 },
631 { 0x39, 0xDA, 0x69, 0xD6, 0xBA, 0x49, 0x97, 0xD5,
632 0x85, 0xB6, 0xDC, 0x07, 0x3C, 0xA3, 0x41, 0xB2 },
633 { 0x18, 0x2B, 0x02, 0xD8, 0x14, 0x97, 0xEA, 0x45,
634 0xF9, 0xDA, 0xAC, 0xDC, 0x29, 0x19, 0x3A, 0x65 }
635 }, {
636 32,
637 { 0xD4, 0x3B, 0xB7, 0x55, 0x6E, 0xA3, 0x2E, 0x46,
638 0xF2, 0xA2, 0x82, 0xB7, 0xD4, 0x5B, 0x4E, 0x0D,
639 0x57, 0xFF, 0x73, 0x9D, 0x4D, 0xC9, 0x2C, 0x1B,
640 0xD7, 0xFC, 0x01, 0x70, 0x0C, 0xC8, 0x21, 0x6F },
641 { 0x90, 0xAF, 0xE9, 0x1B, 0xB2, 0x88, 0x54, 0x4F,
642 0x2C, 0x32, 0xDC, 0x23, 0x9B, 0x26, 0x35, 0xE6 },
643 { 0x6C, 0xB4, 0x56, 0x1C, 0x40, 0xBF, 0x0A, 0x97,
644 0x05, 0x93, 0x1C, 0xB6, 0xD4, 0x08, 0xE7, 0xFA }
645 }
646 };
647
648
649 symmetric_key key;
650 unsigned char tmp[2][16];
651 int err, i, y;
652
653 for (i = 0; i < (int)(sizeof(tests)/sizeof(tests[0])); i++) {
654 if ((err = twofish_setup(tests[i].key, tests[i].keylen, 0, &key)) != CRYPT_OK) {
655 return err;
656 }
657 twofish_ecb_encrypt(tests[i].pt, tmp[0], &key);
658 twofish_ecb_decrypt(tmp[0], tmp[1], &key);
659 if (memcmp(tmp[0], tests[i].ct, 16) != 0 || memcmp(tmp[1], tests[i].pt, 16) != 0) {
660 return CRYPT_FAIL_TESTVECTOR;
661 }
662 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
663 for (y = 0; y < 16; y++) tmp[0][y] = 0;
664 for (y = 0; y < 1000; y++) twofish_ecb_encrypt(tmp[0], tmp[0], &key);
665 for (y = 0; y < 1000; y++) twofish_ecb_decrypt(tmp[0], tmp[0], &key);
666 for (y = 0; y < 16; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
667 }
668 return CRYPT_OK;
669 #endif
670 }
671
672 /** Terminate the context
673 @param skey The scheduled key
674 */
675 void twofish_done(symmetric_key *skey)
676 {
677 }
678
679 /**
680 Gets suitable key size
681 @param keysize [in/out] The length of the recommended key (in bytes). This function will store the suitable size back in this variable.
682 @return CRYPT_OK if the input key size is acceptable.
683 */
684 int twofish_keysize(int *keysize)
685 {
686 LTC_ARGCHK(keysize);
687 if (*keysize < 16)
688 return CRYPT_INVALID_KEYSIZE;
689 if (*keysize < 24) {
690 *keysize = 16;
691 return CRYPT_OK;
692 } else if (*keysize < 32) {
693 *keysize = 24;
694 return CRYPT_OK;
695 } else {
696 *keysize = 32;
697 return CRYPT_OK;
698 }
699 }
700
701 #endif
702
703
704