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

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Branch renaming
author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:25:41 +0000
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-1:000000000000 3:7faae8f46238
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 #include "mycrypt.h"
13
14 #ifdef XTEA
15
16 const struct _cipher_descriptor xtea_desc =
17 {
18 "xtea",
19 1,
20 16, 16, 8, 32,
21 &xtea_setup,
22 &xtea_ecb_encrypt,
23 &xtea_ecb_decrypt,
24 &xtea_test,
25 &xtea_keysize
26 };
27
28 int xtea_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
29 {
30 unsigned long x, sum, K[4];
31
32 _ARGCHK(key != NULL);
33 _ARGCHK(skey != NULL);
34
35 /* check arguments */
36 if (keylen != 16) {
37 return CRYPT_INVALID_KEYSIZE;
38 }
39
40 if (num_rounds != 0 && num_rounds != 32) {
41 return CRYPT_INVALID_ROUNDS;
42 }
43
44 /* load key */
45 LOAD32L(K[0], key+0);
46 LOAD32L(K[1], key+4);
47 LOAD32L(K[2], key+8);
48 LOAD32L(K[3], key+12);
49
50 for (x = sum = 0; x < 32; x++) {
51 skey->xtea.A[x] = (sum + K[sum&3]) & 0xFFFFFFFFUL;
52 sum = (sum + 0x9E3779B9UL) & 0xFFFFFFFFUL;
53 skey->xtea.B[x] = (sum + K[(sum>>11)&3]) & 0xFFFFFFFFUL;
54 }
55
56 #ifdef CLEAN_STACK
57 zeromem(&K, sizeof(K));
58 #endif
59
60 return CRYPT_OK;
61 }
62
63 void xtea_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
64 {
65 unsigned long y, z;
66 int r;
67
68 _ARGCHK(pt != NULL);
69 _ARGCHK(ct != NULL);
70 _ARGCHK(key != NULL);
71
72 LOAD32L(y, &pt[0]);
73 LOAD32L(z, &pt[4]);
74 for (r = 0; r < 32; r += 4) {
75 y = (y + ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r])) & 0xFFFFFFFFUL;
76 z = (z + ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r])) & 0xFFFFFFFFUL;
77
78 y = (y + ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r+1])) & 0xFFFFFFFFUL;
79 z = (z + ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r+1])) & 0xFFFFFFFFUL;
80
81 y = (y + ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r+2])) & 0xFFFFFFFFUL;
82 z = (z + ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r+2])) & 0xFFFFFFFFUL;
83
84 y = (y + ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r+3])) & 0xFFFFFFFFUL;
85 z = (z + ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r+3])) & 0xFFFFFFFFUL;
86 }
87 STORE32L(y, &ct[0]);
88 STORE32L(z, &ct[4]);
89 }
90
91 void xtea_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
92 {
93 unsigned long y, z;
94 int r;
95
96 _ARGCHK(pt != NULL);
97 _ARGCHK(ct != NULL);
98 _ARGCHK(key != NULL);
99
100 LOAD32L(y, &ct[0]);
101 LOAD32L(z, &ct[4]);
102 for (r = 31; r >= 0; r -= 4) {
103 z = (z - ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r])) & 0xFFFFFFFFUL;
104 y = (y - ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r])) & 0xFFFFFFFFUL;
105
106 z = (z - ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r-1])) & 0xFFFFFFFFUL;
107 y = (y - ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r-1])) & 0xFFFFFFFFUL;
108
109 z = (z - ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r-2])) & 0xFFFFFFFFUL;
110 y = (y - ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r-2])) & 0xFFFFFFFFUL;
111
112 z = (z - ((((y<<4)^(y>>5)) + y) ^ key->xtea.B[r-3])) & 0xFFFFFFFFUL;
113 y = (y - ((((z<<4)^(z>>5)) + z) ^ key->xtea.A[r-3])) & 0xFFFFFFFFUL;
114 }
115 STORE32L(y, &pt[0]);
116 STORE32L(z, &pt[4]);
117 }
118
119 int xtea_test(void)
120 {
121 #ifndef LTC_TEST
122 return CRYPT_NOP;
123 #else
124 static const unsigned char key[16] =
125 { 0x78, 0x56, 0x34, 0x12, 0xf0, 0xcd, 0xcb, 0x9a,
126 0x48, 0x37, 0x26, 0x15, 0xc0, 0xbf, 0xae, 0x9d };
127 static const unsigned char pt[8] =
128 { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 };
129 static const unsigned char ct[8] =
130 { 0x75, 0xd7, 0xc5, 0xbf, 0xcf, 0x58, 0xc9, 0x3f };
131 unsigned char tmp[2][8];
132 symmetric_key skey;
133 int err, y;
134
135 if ((err = xtea_setup(key, 16, 0, &skey)) != CRYPT_OK) {
136 return err;
137 }
138 xtea_ecb_encrypt(pt, tmp[0], &skey);
139 xtea_ecb_decrypt(tmp[0], tmp[1], &skey);
140
141 if (memcmp(tmp[0], ct, 8) != 0 || memcmp(tmp[1], pt, 8) != 0) {
142 return CRYPT_FAIL_TESTVECTOR;
143 }
144
145 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
146 for (y = 0; y < 8; y++) tmp[0][y] = 0;
147 for (y = 0; y < 1000; y++) xtea_ecb_encrypt(tmp[0], tmp[0], &skey);
148 for (y = 0; y < 1000; y++) xtea_ecb_decrypt(tmp[0], tmp[0], &skey);
149 for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
150
151 return CRYPT_OK;
152 #endif
153 }
154
155 int xtea_keysize(int *desired_keysize)
156 {
157 _ARGCHK(desired_keysize != NULL);
158 if (*desired_keysize < 16) {
159 return CRYPT_INVALID_KEYSIZE;
160 }
161 *desired_keysize = 16;
162 return CRYPT_OK;
163 }
164
165
166 #endif
167
168
169