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comparison skipjack.c @ 3:7faae8f46238 libtomcrypt-orig

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author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:25:41 +0000
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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 /* Skipjack Implementation by Tom St Denis */
13 #include "mycrypt.h"
14
15 #ifdef SKIPJACK
16
17 const struct _cipher_descriptor skipjack_desc =
18 {
19 "skipjack",
20 17,
21 10, 10, 8, 32,
22 &skipjack_setup,
23 &skipjack_ecb_encrypt,
24 &skipjack_ecb_decrypt,
25 &skipjack_test,
26 &skipjack_keysize
27 };
28
29 static const unsigned char sbox[256] = {
30 0xa3,0xd7,0x09,0x83,0xf8,0x48,0xf6,0xf4,0xb3,0x21,0x15,0x78,0x99,0xb1,0xaf,0xf9,
31 0xe7,0x2d,0x4d,0x8a,0xce,0x4c,0xca,0x2e,0x52,0x95,0xd9,0x1e,0x4e,0x38,0x44,0x28,
32 0x0a,0xdf,0x02,0xa0,0x17,0xf1,0x60,0x68,0x12,0xb7,0x7a,0xc3,0xe9,0xfa,0x3d,0x53,
33 0x96,0x84,0x6b,0xba,0xf2,0x63,0x9a,0x19,0x7c,0xae,0xe5,0xf5,0xf7,0x16,0x6a,0xa2,
34 0x39,0xb6,0x7b,0x0f,0xc1,0x93,0x81,0x1b,0xee,0xb4,0x1a,0xea,0xd0,0x91,0x2f,0xb8,
35 0x55,0xb9,0xda,0x85,0x3f,0x41,0xbf,0xe0,0x5a,0x58,0x80,0x5f,0x66,0x0b,0xd8,0x90,
36 0x35,0xd5,0xc0,0xa7,0x33,0x06,0x65,0x69,0x45,0x00,0x94,0x56,0x6d,0x98,0x9b,0x76,
37 0x97,0xfc,0xb2,0xc2,0xb0,0xfe,0xdb,0x20,0xe1,0xeb,0xd6,0xe4,0xdd,0x47,0x4a,0x1d,
38 0x42,0xed,0x9e,0x6e,0x49,0x3c,0xcd,0x43,0x27,0xd2,0x07,0xd4,0xde,0xc7,0x67,0x18,
39 0x89,0xcb,0x30,0x1f,0x8d,0xc6,0x8f,0xaa,0xc8,0x74,0xdc,0xc9,0x5d,0x5c,0x31,0xa4,
40 0x70,0x88,0x61,0x2c,0x9f,0x0d,0x2b,0x87,0x50,0x82,0x54,0x64,0x26,0x7d,0x03,0x40,
41 0x34,0x4b,0x1c,0x73,0xd1,0xc4,0xfd,0x3b,0xcc,0xfb,0x7f,0xab,0xe6,0x3e,0x5b,0xa5,
42 0xad,0x04,0x23,0x9c,0x14,0x51,0x22,0xf0,0x29,0x79,0x71,0x7e,0xff,0x8c,0x0e,0xe2,
43 0x0c,0xef,0xbc,0x72,0x75,0x6f,0x37,0xa1,0xec,0xd3,0x8e,0x62,0x8b,0x86,0x10,0xe8,
44 0x08,0x77,0x11,0xbe,0x92,0x4f,0x24,0xc5,0x32,0x36,0x9d,0xcf,0xf3,0xa6,0xbb,0xac,
45 0x5e,0x6c,0xa9,0x13,0x57,0x25,0xb5,0xe3,0xbd,0xa8,0x3a,0x01,0x05,0x59,0x2a,0x46
46 };
47
48 /* simple x + 1 (mod 10) in one step. */
49 static const int keystep[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
50
51 /* simple x - 1 (mod 10) in one step */
52 static const int ikeystep[] = { 9, 0, 1, 2, 3, 4, 5, 6, 7, 8 };
53
54 int skipjack_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
55 {
56 int x;
57
58 _ARGCHK(key != NULL);
59 _ARGCHK(skey != NULL);
60
61 if (keylen != 10) {
62 return CRYPT_INVALID_KEYSIZE;
63 }
64
65 if (num_rounds != 32 && num_rounds != 0) {
66 return CRYPT_INVALID_ROUNDS;
67 }
68
69 /* make sure the key is in range for platforms where CHAR_BIT != 8 */
70 for (x = 0; x < 10; x++) {
71 skey->skipjack.key[x] = key[x] & 255;
72 }
73
74 return CRYPT_OK;
75 }
76
77 #define RULE_A \
78 tmp = g_func(w1, &kp, key->skipjack.key); \
79 w1 = tmp ^ w4 ^ x; \
80 w4 = w3; w3 = w2; \
81 w2 = tmp;
82
83 #define RULE_B \
84 tmp = g_func(w1, &kp, key->skipjack.key); \
85 tmp1 = w4; w4 = w3; \
86 w3 = w1 ^ w2 ^ x; \
87 w1 = tmp1; w2 = tmp;
88
89 #define RULE_A1 \
90 tmp = w1 ^ w2 ^ x; \
91 w1 = ig_func(w2, &kp, key->skipjack.key); \
92 w2 = w3; w3 = w4; w4 = tmp;
93
94 #define RULE_B1 \
95 tmp = ig_func(w2, &kp, key->skipjack.key); \
96 w2 = tmp ^ w3 ^ x; \
97 w3 = w4; w4 = w1; w1 = tmp;
98
99 static unsigned g_func(unsigned w, int *kp, unsigned char *key)
100 {
101 unsigned char g1,g2;
102
103 g1 = (w >> 8) & 255; g2 = w & 255;
104 g1 ^= sbox[g2^key[*kp]]; *kp = keystep[*kp];
105 g2 ^= sbox[g1^key[*kp]]; *kp = keystep[*kp];
106 g1 ^= sbox[g2^key[*kp]]; *kp = keystep[*kp];
107 g2 ^= sbox[g1^key[*kp]]; *kp = keystep[*kp];
108 return ((unsigned)g1<<8)|(unsigned)g2;
109 }
110
111 static unsigned ig_func(unsigned w, int *kp, unsigned char *key)
112 {
113 unsigned char g1,g2;
114
115 g1 = (w >> 8) & 255; g2 = w & 255;
116 *kp = ikeystep[*kp]; g2 ^= sbox[g1^key[*kp]];
117 *kp = ikeystep[*kp]; g1 ^= sbox[g2^key[*kp]];
118 *kp = ikeystep[*kp]; g2 ^= sbox[g1^key[*kp]];
119 *kp = ikeystep[*kp]; g1 ^= sbox[g2^key[*kp]];
120 return ((unsigned)g1<<8)|(unsigned)g2;
121 }
122
123 #ifdef CLEAN_STACK
124 static void _skipjack_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
125 #else
126 void skipjack_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
127 #endif
128 {
129 unsigned w1,w2,w3,w4,tmp,tmp1;
130 int x, kp;
131
132 _ARGCHK(pt != NULL);
133 _ARGCHK(ct != NULL);
134 _ARGCHK(key != NULL);
135
136 /* load block */
137 w1 = ((unsigned)pt[0]<<8)|pt[1];
138 w2 = ((unsigned)pt[2]<<8)|pt[3];
139 w3 = ((unsigned)pt[4]<<8)|pt[5];
140 w4 = ((unsigned)pt[6]<<8)|pt[7];
141
142 /* 8 rounds of RULE A */
143 for (x = 1, kp = 0; x < 9; x++) {
144 RULE_A;
145 }
146
147 /* 8 rounds of RULE B */
148 for (; x < 17; x++) {
149 RULE_B;
150 }
151
152 /* 8 rounds of RULE A */
153 for (; x < 25; x++) {
154 RULE_A;
155 }
156
157 /* 8 rounds of RULE B */
158 for (; x < 33; x++) {
159 RULE_B;
160 }
161
162 /* store block */
163 ct[0] = (w1>>8)&255; ct[1] = w1&255;
164 ct[2] = (w2>>8)&255; ct[3] = w2&255;
165 ct[4] = (w3>>8)&255; ct[5] = w3&255;
166 ct[6] = (w4>>8)&255; ct[7] = w4&255;
167 }
168
169 #ifdef CLEAN_STACK
170 void skipjack_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
171 {
172 _skipjack_ecb_encrypt(pt, ct, key);
173 burn_stack(sizeof(unsigned) * 8 + sizeof(int) * 2);
174 }
175 #endif
176
177 #ifdef CLEAN_STACK
178 static void _skipjack_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
179 #else
180 void skipjack_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
181 #endif
182 {
183 unsigned w1,w2,w3,w4,tmp;
184 int x, kp;
185
186 _ARGCHK(pt != NULL);
187 _ARGCHK(ct != NULL);
188 _ARGCHK(key != NULL);
189
190 /* load block */
191 w1 = ((unsigned)ct[0]<<8)|ct[1];
192 w2 = ((unsigned)ct[2]<<8)|ct[3];
193 w3 = ((unsigned)ct[4]<<8)|ct[5];
194 w4 = ((unsigned)ct[6]<<8)|ct[7];
195
196 /* 8 rounds of RULE B^-1
197
198 Note the value "kp = 8" comes from "kp = (32 * 4) mod 10" where 32*4 is 128 which mod 10 is 8
199 */
200 for (x = 32, kp = 8; x > 24; x--) {
201 RULE_B1;
202 }
203
204 /* 8 rounds of RULE A^-1 */
205 for (; x > 16; x--) {
206 RULE_A1;
207 }
208
209
210 /* 8 rounds of RULE B^-1 */
211 for (; x > 8; x--) {
212 RULE_B1;
213 }
214
215 /* 8 rounds of RULE A^-1 */
216 for (; x > 0; x--) {
217 RULE_A1;
218 }
219
220 /* store block */
221 pt[0] = (w1>>8)&255; pt[1] = w1&255;
222 pt[2] = (w2>>8)&255; pt[3] = w2&255;
223 pt[4] = (w3>>8)&255; pt[5] = w3&255;
224 pt[6] = (w4>>8)&255; pt[7] = w4&255;
225 }
226
227 #ifdef CLEAN_STACK
228 void skipjack_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
229 {
230 _skipjack_ecb_decrypt(ct, pt, key);
231 burn_stack(sizeof(unsigned) * 7 + sizeof(int) * 2);
232 }
233 #endif
234
235 int skipjack_test(void)
236 {
237 #ifndef LTC_TEST
238 return CRYPT_NOP;
239 #else
240 static const struct {
241 unsigned char key[10], pt[8], ct[8];
242 } tests[] = {
243 {
244 { 0x00, 0x99, 0x88, 0x77, 0x66, 0x55, 0x44, 0x33, 0x22, 0x11 },
245 { 0x33, 0x22, 0x11, 0x00, 0xdd, 0xcc, 0xbb, 0xaa },
246 { 0x25, 0x87, 0xca, 0xe2, 0x7a, 0x12, 0xd3, 0x00 }
247 }
248 };
249 unsigned char buf[2][8];
250 int x, y, err;
251 symmetric_key key;
252
253 for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {
254 /* setup key */
255 if ((err = skipjack_setup(tests[x].key, 10, 0, &key)) != CRYPT_OK) {
256 return err;
257 }
258
259 /* encrypt and decrypt */
260 skipjack_ecb_encrypt(tests[x].pt, buf[0], &key);
261 skipjack_ecb_decrypt(buf[0], buf[1], &key);
262
263 /* compare */
264 if (memcmp(buf[0], tests[x].ct, 8) != 0 || memcmp(buf[1], tests[x].pt, 8) != 0) {
265 return CRYPT_FAIL_TESTVECTOR;
266 }
267
268 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
269 for (y = 0; y < 8; y++) buf[0][y] = 0;
270 for (y = 0; y < 1000; y++) skipjack_ecb_encrypt(buf[0], buf[0], &key);
271 for (y = 0; y < 1000; y++) skipjack_ecb_decrypt(buf[0], buf[0], &key);
272 for (y = 0; y < 8; y++) if (buf[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
273 }
274
275 return CRYPT_OK;
276 #endif
277 }
278
279 int skipjack_keysize(int *desired_keysize)
280 {
281 _ARGCHK(desired_keysize != NULL);
282 if (*desired_keysize < 10) {
283 return CRYPT_INVALID_KEYSIZE;
284 } else if (*desired_keysize > 10) {
285 *desired_keysize = 10;
286 }
287 return CRYPT_OK;
288 }
289
290 #endif