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comparison libtomcrypt/src/ciphers/xtea.c @ 399:a707e6148060

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merge of '5fdf69ca60d1683cdd9f4c2595134bed26394834' and '6b61c50f4cf888bea302ac8fcf5dbb573b443251'
author Matt Johnston <matt@ucc.asn.au>
date Sat, 03 Feb 2007 08:20:34 +0000
parents 0cbe8f6dbf9e
children f849a5ca2efc
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394:17d097fc111c 399:a707e6148060
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.com
10 */
11
12 /**
13 @file xtea.c
14 Implementation of XTEA, Tom St Denis
15 */
16 #include "tomcrypt.h"
17
18 #ifdef XTEA
19
20 const struct ltc_cipher_descriptor xtea_desc =
21 {
22 "xtea",
23 1,
24 16, 16, 8, 32,
25 &xtea_setup,
26 &xtea_ecb_encrypt,
27 &xtea_ecb_decrypt,
28 &xtea_test,
29 &xtea_done,
30 &xtea_keysize,
31 NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
32 };
33
34 int xtea_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
35 {
36 unsigned long x, sum, K[4];
37
38 LTC_ARGCHK(key != NULL);
39 LTC_ARGCHK(skey != NULL);
40
41 /* check arguments */
42 if (keylen != 16) {
43 return CRYPT_INVALID_KEYSIZE;
44 }
45
46 if (num_rounds != 0 && num_rounds != 32) {
47 return CRYPT_INVALID_ROUNDS;
48 }
49
50 /* load key */
51 LOAD32L(K[0], key+0);
52 LOAD32L(K[1], key+4);
53 LOAD32L(K[2], key+8);
54 LOAD32L(K[3], key+12);
55
56 for (x = sum = 0; x < 32; x++) {
57 skey->xtea.A[x] = (sum + K[sum&3]) & 0xFFFFFFFFUL;
58 sum = (sum + 0x9E3779B9UL) & 0xFFFFFFFFUL;
59 skey->xtea.B[x] = (sum + K[(sum>>11)&3]) & 0xFFFFFFFFUL;
60 }
61
62 #ifdef LTC_CLEAN_STACK
63 zeromem(&K, sizeof(K));
64 #endif
65
66 return CRYPT_OK;
67 }
68
69 /**
70 Encrypts a block of text with XTEA
71 @param pt The input plaintext (8 bytes)
72 @param ct The output ciphertext (8 bytes)
73 @param skey The key as scheduled
74 @return CRYPT_OK if successful
75 */
76 int xtea_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
77 {
78 unsigned long y, z;
79 int r;
80
81 LTC_ARGCHK(pt != NULL);
82 LTC_ARGCHK(ct != NULL);
83 LTC_ARGCHK(skey != NULL);
84
85 LOAD32L(y, &pt[0]);
86 LOAD32L(z, &pt[4]);
87 for (r = 0; r < 32; r += 4) {
88 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r])) & 0xFFFFFFFFUL;
89 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r])) & 0xFFFFFFFFUL;
90
91 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+1])) & 0xFFFFFFFFUL;
92 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+1])) & 0xFFFFFFFFUL;
93
94 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+2])) & 0xFFFFFFFFUL;
95 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+2])) & 0xFFFFFFFFUL;
96
97 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+3])) & 0xFFFFFFFFUL;
98 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+3])) & 0xFFFFFFFFUL;
99 }
100 STORE32L(y, &ct[0]);
101 STORE32L(z, &ct[4]);
102 return CRYPT_OK;
103 }
104
105 /**
106 Decrypts a block of text with XTEA
107 @param ct The input ciphertext (8 bytes)
108 @param pt The output plaintext (8 bytes)
109 @param skey The key as scheduled
110 @return CRYPT_OK if successful
111 */
112 int xtea_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
113 {
114 unsigned long y, z;
115 int r;
116
117 LTC_ARGCHK(pt != NULL);
118 LTC_ARGCHK(ct != NULL);
119 LTC_ARGCHK(skey != NULL);
120
121 LOAD32L(y, &ct[0]);
122 LOAD32L(z, &ct[4]);
123 for (r = 31; r >= 0; r -= 4) {
124 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r])) & 0xFFFFFFFFUL;
125 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r])) & 0xFFFFFFFFUL;
126
127 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-1])) & 0xFFFFFFFFUL;
128 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-1])) & 0xFFFFFFFFUL;
129
130 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-2])) & 0xFFFFFFFFUL;
131 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-2])) & 0xFFFFFFFFUL;
132
133 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-3])) & 0xFFFFFFFFUL;
134 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-3])) & 0xFFFFFFFFUL;
135 }
136 STORE32L(y, &pt[0]);
137 STORE32L(z, &pt[4]);
138 return CRYPT_OK;
139 }
140
141 /**
142 Performs a self-test of the XTEA block cipher
143 @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled
144 */
145 int xtea_test(void)
146 {
147 #ifndef LTC_TEST
148 return CRYPT_NOP;
149 #else
150 static const unsigned char key[16] =
151 { 0x78, 0x56, 0x34, 0x12, 0xf0, 0xcd, 0xcb, 0x9a,
152 0x48, 0x37, 0x26, 0x15, 0xc0, 0xbf, 0xae, 0x9d };
153 static const unsigned char pt[8] =
154 { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 };
155 static const unsigned char ct[8] =
156 { 0x75, 0xd7, 0xc5, 0xbf, 0xcf, 0x58, 0xc9, 0x3f };
157 unsigned char tmp[2][8];
158 symmetric_key skey;
159 int err, y;
160
161 if ((err = xtea_setup(key, 16, 0, &skey)) != CRYPT_OK) {
162 return err;
163 }
164 xtea_ecb_encrypt(pt, tmp[0], &skey);
165 xtea_ecb_decrypt(tmp[0], tmp[1], &skey);
166
167 if (XMEMCMP(tmp[0], ct, 8) != 0 || XMEMCMP(tmp[1], pt, 8) != 0) {
168 return CRYPT_FAIL_TESTVECTOR;
169 }
170
171 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
172 for (y = 0; y < 8; y++) tmp[0][y] = 0;
173 for (y = 0; y < 1000; y++) xtea_ecb_encrypt(tmp[0], tmp[0], &skey);
174 for (y = 0; y < 1000; y++) xtea_ecb_decrypt(tmp[0], tmp[0], &skey);
175 for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
176
177 return CRYPT_OK;
178 #endif
179 }
180
181 /** Terminate the context
182 @param skey The scheduled key
183 */
184 void xtea_done(symmetric_key *skey)
185 {
186 }
187
188 /**
189 Gets suitable key size
190 @param keysize [in/out] The length of the recommended key (in bytes). This function will store the suitable size back in this variable.
191 @return CRYPT_OK if the input key size is acceptable.
192 */
193 int xtea_keysize(int *keysize)
194 {
195 LTC_ARGCHK(keysize != NULL);
196 if (*keysize < 16) {
197 return CRYPT_INVALID_KEYSIZE;
198 }
199 *keysize = 16;
200 return CRYPT_OK;
201 }
202
203
204 #endif
205
206
207
208
209 /* $Source: /cvs/libtom/libtomcrypt/src/ciphers/xtea.c,v $ */
210 /* $Revision: 1.12 $ */
211 /* $Date: 2006/11/08 23:01:06 $ */