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comparison src/ciphers/xtea.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 39d5d58461d6
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 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
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 */
75 void xtea_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
76 {
77 unsigned long y, z;
78 int r;
79
80 LTC_ARGCHK(pt != NULL);
81 LTC_ARGCHK(ct != NULL);
82 LTC_ARGCHK(skey != NULL);
83
84 LOAD32L(y, &pt[0]);
85 LOAD32L(z, &pt[4]);
86 for (r = 0; r < 32; r += 4) {
87 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r])) & 0xFFFFFFFFUL;
88 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r])) & 0xFFFFFFFFUL;
89
90 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+1])) & 0xFFFFFFFFUL;
91 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+1])) & 0xFFFFFFFFUL;
92
93 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+2])) & 0xFFFFFFFFUL;
94 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+2])) & 0xFFFFFFFFUL;
95
96 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+3])) & 0xFFFFFFFFUL;
97 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+3])) & 0xFFFFFFFFUL;
98 }
99 STORE32L(y, &ct[0]);
100 STORE32L(z, &ct[4]);
101 }
102
103 /**
104 Decrypts a block of text with XTEA
105 @param ct The input ciphertext (8 bytes)
106 @param pt The output plaintext (8 bytes)
107 @param skey The key as scheduled
108 */
109 void xtea_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
110 {
111 unsigned long y, z;
112 int r;
113
114 LTC_ARGCHK(pt != NULL);
115 LTC_ARGCHK(ct != NULL);
116 LTC_ARGCHK(skey != NULL);
117
118 LOAD32L(y, &ct[0]);
119 LOAD32L(z, &ct[4]);
120 for (r = 31; r >= 0; r -= 4) {
121 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r])) & 0xFFFFFFFFUL;
122 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r])) & 0xFFFFFFFFUL;
123
124 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-1])) & 0xFFFFFFFFUL;
125 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-1])) & 0xFFFFFFFFUL;
126
127 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-2])) & 0xFFFFFFFFUL;
128 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-2])) & 0xFFFFFFFFUL;
129
130 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-3])) & 0xFFFFFFFFUL;
131 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-3])) & 0xFFFFFFFFUL;
132 }
133 STORE32L(y, &pt[0]);
134 STORE32L(z, &pt[4]);
135 }
136
137 /**
138 Performs a self-test of the XTEA block cipher
139 @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled
140 */
141 int xtea_test(void)
142 {
143 #ifndef LTC_TEST
144 return CRYPT_NOP;
145 #else
146 static const unsigned char key[16] =
147 { 0x78, 0x56, 0x34, 0x12, 0xf0, 0xcd, 0xcb, 0x9a,
148 0x48, 0x37, 0x26, 0x15, 0xc0, 0xbf, 0xae, 0x9d };
149 static const unsigned char pt[8] =
150 { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 };
151 static const unsigned char ct[8] =
152 { 0x75, 0xd7, 0xc5, 0xbf, 0xcf, 0x58, 0xc9, 0x3f };
153 unsigned char tmp[2][8];
154 symmetric_key skey;
155 int err, y;
156
157 if ((err = xtea_setup(key, 16, 0, &skey)) != CRYPT_OK) {
158 return err;
159 }
160 xtea_ecb_encrypt(pt, tmp[0], &skey);
161 xtea_ecb_decrypt(tmp[0], tmp[1], &skey);
162
163 if (memcmp(tmp[0], ct, 8) != 0 || memcmp(tmp[1], pt, 8) != 0) {
164 return CRYPT_FAIL_TESTVECTOR;
165 }
166
167 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
168 for (y = 0; y < 8; y++) tmp[0][y] = 0;
169 for (y = 0; y < 1000; y++) xtea_ecb_encrypt(tmp[0], tmp[0], &skey);
170 for (y = 0; y < 1000; y++) xtea_ecb_decrypt(tmp[0], tmp[0], &skey);
171 for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
172
173 return CRYPT_OK;
174 #endif
175 }
176
177 /** Terminate the context
178 @param skey The scheduled key
179 */
180 void xtea_done(symmetric_key *skey)
181 {
182 }
183
184 /**
185 Gets suitable key size
186 @param keysize [in/out] The length of the recommended key (in bytes). This function will store the suitable size back in this variable.
187 @return CRYPT_OK if the input key size is acceptable.
188 */
189 int xtea_keysize(int *keysize)
190 {
191 LTC_ARGCHK(keysize != NULL);
192 if (*keysize < 16) {
193 return CRYPT_INVALID_KEYSIZE;
194 }
195 *keysize = 16;
196 return CRYPT_OK;
197 }
198
199
200 #endif
201
202
203