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comparison libtomcrypt/src/ciphers/skipjack.c @ 285:1b9e69c058d2

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propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3) to branch 'au.asn.ucc.matt.dropbear' (head fdf4a7a3b97ae5046139915de7e40399cceb2c01)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:58 +0000
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281:997e6f7dc01e 285:1b9e69c058d2
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 skipjack.c
14 Skipjack Implementation by Tom St Denis
15 */
16 #include "tomcrypt.h"
17
18 #ifdef SKIPJACK
19
20 const struct ltc_cipher_descriptor skipjack_desc =
21 {
22 "skipjack",
23 17,
24 10, 10, 8, 32,
25 &skipjack_setup,
26 &skipjack_ecb_encrypt,
27 &skipjack_ecb_decrypt,
28 &skipjack_test,
29 &skipjack_done,
30 &skipjack_keysize,
31 NULL, NULL, NULL, NULL, NULL, NULL, NULL
32 };
33
34 static const unsigned char sbox[256] = {
35 0xa3,0xd7,0x09,0x83,0xf8,0x48,0xf6,0xf4,0xb3,0x21,0x15,0x78,0x99,0xb1,0xaf,0xf9,
36 0xe7,0x2d,0x4d,0x8a,0xce,0x4c,0xca,0x2e,0x52,0x95,0xd9,0x1e,0x4e,0x38,0x44,0x28,
37 0x0a,0xdf,0x02,0xa0,0x17,0xf1,0x60,0x68,0x12,0xb7,0x7a,0xc3,0xe9,0xfa,0x3d,0x53,
38 0x96,0x84,0x6b,0xba,0xf2,0x63,0x9a,0x19,0x7c,0xae,0xe5,0xf5,0xf7,0x16,0x6a,0xa2,
39 0x39,0xb6,0x7b,0x0f,0xc1,0x93,0x81,0x1b,0xee,0xb4,0x1a,0xea,0xd0,0x91,0x2f,0xb8,
40 0x55,0xb9,0xda,0x85,0x3f,0x41,0xbf,0xe0,0x5a,0x58,0x80,0x5f,0x66,0x0b,0xd8,0x90,
41 0x35,0xd5,0xc0,0xa7,0x33,0x06,0x65,0x69,0x45,0x00,0x94,0x56,0x6d,0x98,0x9b,0x76,
42 0x97,0xfc,0xb2,0xc2,0xb0,0xfe,0xdb,0x20,0xe1,0xeb,0xd6,0xe4,0xdd,0x47,0x4a,0x1d,
43 0x42,0xed,0x9e,0x6e,0x49,0x3c,0xcd,0x43,0x27,0xd2,0x07,0xd4,0xde,0xc7,0x67,0x18,
44 0x89,0xcb,0x30,0x1f,0x8d,0xc6,0x8f,0xaa,0xc8,0x74,0xdc,0xc9,0x5d,0x5c,0x31,0xa4,
45 0x70,0x88,0x61,0x2c,0x9f,0x0d,0x2b,0x87,0x50,0x82,0x54,0x64,0x26,0x7d,0x03,0x40,
46 0x34,0x4b,0x1c,0x73,0xd1,0xc4,0xfd,0x3b,0xcc,0xfb,0x7f,0xab,0xe6,0x3e,0x5b,0xa5,
47 0xad,0x04,0x23,0x9c,0x14,0x51,0x22,0xf0,0x29,0x79,0x71,0x7e,0xff,0x8c,0x0e,0xe2,
48 0x0c,0xef,0xbc,0x72,0x75,0x6f,0x37,0xa1,0xec,0xd3,0x8e,0x62,0x8b,0x86,0x10,0xe8,
49 0x08,0x77,0x11,0xbe,0x92,0x4f,0x24,0xc5,0x32,0x36,0x9d,0xcf,0xf3,0xa6,0xbb,0xac,
50 0x5e,0x6c,0xa9,0x13,0x57,0x25,0xb5,0xe3,0xbd,0xa8,0x3a,0x01,0x05,0x59,0x2a,0x46
51 };
52
53 /* simple x + 1 (mod 10) in one step. */
54 static const int keystep[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
55
56 /* simple x - 1 (mod 10) in one step */
57 static const int ikeystep[] = { 9, 0, 1, 2, 3, 4, 5, 6, 7, 8 };
58
59 /**
60 Initialize the Skipjack block cipher
61 @param key The symmetric key you wish to pass
62 @param keylen The key length in bytes
63 @param num_rounds The number of rounds desired (0 for default)
64 @param skey The key in as scheduled by this function.
65 @return CRYPT_OK if successful
66 */
67 int skipjack_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
68 {
69 int x;
70
71 LTC_ARGCHK(key != NULL);
72 LTC_ARGCHK(skey != NULL);
73
74 if (keylen != 10) {
75 return CRYPT_INVALID_KEYSIZE;
76 }
77
78 if (num_rounds != 32 && num_rounds != 0) {
79 return CRYPT_INVALID_ROUNDS;
80 }
81
82 /* make sure the key is in range for platforms where CHAR_BIT != 8 */
83 for (x = 0; x < 10; x++) {
84 skey->skipjack.key[x] = key[x] & 255;
85 }
86
87 return CRYPT_OK;
88 }
89
90 #define RULE_A \
91 tmp = g_func(w1, &kp, skey->skipjack.key); \
92 w1 = tmp ^ w4 ^ x; \
93 w4 = w3; w3 = w2; \
94 w2 = tmp;
95
96 #define RULE_B \
97 tmp = g_func(w1, &kp, skey->skipjack.key); \
98 tmp1 = w4; w4 = w3; \
99 w3 = w1 ^ w2 ^ x; \
100 w1 = tmp1; w2 = tmp;
101
102 #define RULE_A1 \
103 tmp = w1 ^ w2 ^ x; \
104 w1 = ig_func(w2, &kp, skey->skipjack.key); \
105 w2 = w3; w3 = w4; w4 = tmp;
106
107 #define RULE_B1 \
108 tmp = ig_func(w2, &kp, skey->skipjack.key); \
109 w2 = tmp ^ w3 ^ x; \
110 w3 = w4; w4 = w1; w1 = tmp;
111
112 static unsigned g_func(unsigned w, int *kp, unsigned char *key)
113 {
114 unsigned char g1,g2;
115
116 g1 = (w >> 8) & 255; g2 = w & 255;
117 g1 ^= sbox[g2^key[*kp]]; *kp = keystep[*kp];
118 g2 ^= sbox[g1^key[*kp]]; *kp = keystep[*kp];
119 g1 ^= sbox[g2^key[*kp]]; *kp = keystep[*kp];
120 g2 ^= sbox[g1^key[*kp]]; *kp = keystep[*kp];
121 return ((unsigned)g1<<8)|(unsigned)g2;
122 }
123
124 static unsigned ig_func(unsigned w, int *kp, unsigned char *key)
125 {
126 unsigned char g1,g2;
127
128 g1 = (w >> 8) & 255; g2 = w & 255;
129 *kp = ikeystep[*kp]; g2 ^= sbox[g1^key[*kp]];
130 *kp = ikeystep[*kp]; g1 ^= sbox[g2^key[*kp]];
131 *kp = ikeystep[*kp]; g2 ^= sbox[g1^key[*kp]];
132 *kp = ikeystep[*kp]; g1 ^= sbox[g2^key[*kp]];
133 return ((unsigned)g1<<8)|(unsigned)g2;
134 }
135
136 /**
137 Encrypts a block of text with Skipjack
138 @param pt The input plaintext (8 bytes)
139 @param ct The output ciphertext (8 bytes)
140 @param skey The key as scheduled
141 */
142 #ifdef LTC_CLEAN_STACK
143 static void _skipjack_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
144 #else
145 void skipjack_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
146 #endif
147 {
148 unsigned w1,w2,w3,w4,tmp,tmp1;
149 int x, kp;
150
151 LTC_ARGCHK(pt != NULL);
152 LTC_ARGCHK(ct != NULL);
153 LTC_ARGCHK(skey != NULL);
154
155 /* load block */
156 w1 = ((unsigned)pt[0]<<8)|pt[1];
157 w2 = ((unsigned)pt[2]<<8)|pt[3];
158 w3 = ((unsigned)pt[4]<<8)|pt[5];
159 w4 = ((unsigned)pt[6]<<8)|pt[7];
160
161 /* 8 rounds of RULE A */
162 for (x = 1, kp = 0; x < 9; x++) {
163 RULE_A;
164 }
165
166 /* 8 rounds of RULE B */
167 for (; x < 17; x++) {
168 RULE_B;
169 }
170
171 /* 8 rounds of RULE A */
172 for (; x < 25; x++) {
173 RULE_A;
174 }
175
176 /* 8 rounds of RULE B */
177 for (; x < 33; x++) {
178 RULE_B;
179 }
180
181 /* store block */
182 ct[0] = (w1>>8)&255; ct[1] = w1&255;
183 ct[2] = (w2>>8)&255; ct[3] = w2&255;
184 ct[4] = (w3>>8)&255; ct[5] = w3&255;
185 ct[6] = (w4>>8)&255; ct[7] = w4&255;
186 }
187
188 #ifdef LTC_CLEAN_STACK
189 void skipjack_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
190 {
191 _skipjack_ecb_encrypt(pt, ct, skey);
192 burn_stack(sizeof(unsigned) * 8 + sizeof(int) * 2);
193 }
194 #endif
195
196 /**
197 Decrypts a block of text with Skipjack
198 @param ct The input ciphertext (8 bytes)
199 @param pt The output plaintext (8 bytes)
200 @param skey The key as scheduled
201 */
202 #ifdef LTC_CLEAN_STACK
203 static void _skipjack_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
204 #else
205 void skipjack_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
206 #endif
207 {
208 unsigned w1,w2,w3,w4,tmp;
209 int x, kp;
210
211 LTC_ARGCHK(pt != NULL);
212 LTC_ARGCHK(ct != NULL);
213 LTC_ARGCHK(skey != NULL);
214
215 /* load block */
216 w1 = ((unsigned)ct[0]<<8)|ct[1];
217 w2 = ((unsigned)ct[2]<<8)|ct[3];
218 w3 = ((unsigned)ct[4]<<8)|ct[5];
219 w4 = ((unsigned)ct[6]<<8)|ct[7];
220
221 /* 8 rounds of RULE B^-1
222
223 Note the value "kp = 8" comes from "kp = (32 * 4) mod 10" where 32*4 is 128 which mod 10 is 8
224 */
225 for (x = 32, kp = 8; x > 24; x--) {
226 RULE_B1;
227 }
228
229 /* 8 rounds of RULE A^-1 */
230 for (; x > 16; x--) {
231 RULE_A1;
232 }
233
234
235 /* 8 rounds of RULE B^-1 */
236 for (; x > 8; x--) {
237 RULE_B1;
238 }
239
240 /* 8 rounds of RULE A^-1 */
241 for (; x > 0; x--) {
242 RULE_A1;
243 }
244
245 /* store block */
246 pt[0] = (w1>>8)&255; pt[1] = w1&255;
247 pt[2] = (w2>>8)&255; pt[3] = w2&255;
248 pt[4] = (w3>>8)&255; pt[5] = w3&255;
249 pt[6] = (w4>>8)&255; pt[7] = w4&255;
250 }
251
252 #ifdef LTC_CLEAN_STACK
253 void skipjack_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
254 {
255 _skipjack_ecb_decrypt(ct, pt, skey);
256 burn_stack(sizeof(unsigned) * 7 + sizeof(int) * 2);
257 }
258 #endif
259
260 /**
261 Performs a self-test of the Skipjack block cipher
262 @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled
263 */
264 int skipjack_test(void)
265 {
266 #ifndef LTC_TEST
267 return CRYPT_NOP;
268 #else
269 static const struct {
270 unsigned char key[10], pt[8], ct[8];
271 } tests[] = {
272 {
273 { 0x00, 0x99, 0x88, 0x77, 0x66, 0x55, 0x44, 0x33, 0x22, 0x11 },
274 { 0x33, 0x22, 0x11, 0x00, 0xdd, 0xcc, 0xbb, 0xaa },
275 { 0x25, 0x87, 0xca, 0xe2, 0x7a, 0x12, 0xd3, 0x00 }
276 }
277 };
278 unsigned char buf[2][8];
279 int x, y, err;
280 symmetric_key key;
281
282 for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {
283 /* setup key */
284 if ((err = skipjack_setup(tests[x].key, 10, 0, &key)) != CRYPT_OK) {
285 return err;
286 }
287
288 /* encrypt and decrypt */
289 skipjack_ecb_encrypt(tests[x].pt, buf[0], &key);
290 skipjack_ecb_decrypt(buf[0], buf[1], &key);
291
292 /* compare */
293 if (memcmp(buf[0], tests[x].ct, 8) != 0 || memcmp(buf[1], tests[x].pt, 8) != 0) {
294 return CRYPT_FAIL_TESTVECTOR;
295 }
296
297 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
298 for (y = 0; y < 8; y++) buf[0][y] = 0;
299 for (y = 0; y < 1000; y++) skipjack_ecb_encrypt(buf[0], buf[0], &key);
300 for (y = 0; y < 1000; y++) skipjack_ecb_decrypt(buf[0], buf[0], &key);
301 for (y = 0; y < 8; y++) if (buf[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
302 }
303
304 return CRYPT_OK;
305 #endif
306 }
307
308 /** Terminate the context
309 @param skey The scheduled key
310 */
311 void skipjack_done(symmetric_key *skey)
312 {
313 }
314
315 /**
316 Gets suitable key size
317 @param keysize [in/out] The length of the recommended key (in bytes). This function will store the suitable size back in this variable.
318 @return CRYPT_OK if the input key size is acceptable.
319 */
320 int skipjack_keysize(int *keysize)
321 {
322 LTC_ARGCHK(keysize != NULL);
323 if (*keysize < 10) {
324 return CRYPT_INVALID_KEYSIZE;
325 } else if (*keysize > 10) {
326 *keysize = 10;
327 }
328 return CRYPT_OK;
329 }
330
331 #endif
332
333 /* $Source: /cvs/libtom/libtomcrypt/src/ciphers/skipjack.c,v $ */
334 /* $Revision: 1.7 $ */
335 /* $Date: 2005/05/05 14:35:58 $ */