1 // SPDX-License-Identifier: BSD-2-Clause
2 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
3 *
4 * LibTomCrypt is a library that provides various cryptographic
5 * algorithms in a highly modular and flexible manner.
6 *
7 * The library is free for all purposes without any express
8 * guarantee it works.
9 */
10
11 /**
12 @file xtea.c
13 Implementation of LTC_XTEA, Tom St Denis
14 */
15 #include "tomcrypt_private.h"
16
17 #ifdef LTC_XTEA
18
19 const struct ltc_cipher_descriptor xtea_desc =
20 {
21 "xtea",
22 1,
23 16, 16, 8, 32,
24 &xtea_setup,
25 &xtea_ecb_encrypt,
26 &xtea_ecb_decrypt,
27 &xtea_test,
28 &xtea_done,
29 &xtea_keysize,
30 NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
31 };
32
xtea_setup(const unsigned char * key,int keylen,int num_rounds,symmetric_key * skey)33 int xtea_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
34 {
35 ulong32 x, sum, K[4];
36
37 LTC_ARGCHK(key != NULL);
38 LTC_ARGCHK(skey != NULL);
39
40 /* check arguments */
41 if (keylen != 16) {
42 return CRYPT_INVALID_KEYSIZE;
43 }
44
45 if (num_rounds != 0 && num_rounds != 32) {
46 return CRYPT_INVALID_ROUNDS;
47 }
48
49 /* load key */
50 LOAD32H(K[0], key+0);
51 LOAD32H(K[1], key+4);
52 LOAD32H(K[2], key+8);
53 LOAD32H(K[3], key+12);
54
55 for (x = sum = 0; x < 32; x++) {
56 skey->xtea.A[x] = (sum + K[sum&3]) & 0xFFFFFFFFUL;
57 sum = (sum + 0x9E3779B9UL) & 0xFFFFFFFFUL;
58 skey->xtea.B[x] = (sum + K[(sum>>11)&3]) & 0xFFFFFFFFUL;
59 }
60
61 #ifdef LTC_CLEAN_STACK
62 zeromem(&K, sizeof(K));
63 #endif
64
65 return CRYPT_OK;
66 }
67
68 /**
69 Encrypts a block of text with LTC_XTEA
70 @param pt The input plaintext (8 bytes)
71 @param ct The output ciphertext (8 bytes)
72 @param skey The key as scheduled
73 @return CRYPT_OK if successful
74 */
xtea_ecb_encrypt(const unsigned char * pt,unsigned char * ct,const symmetric_key * skey)75 int xtea_ecb_encrypt(const unsigned char *pt, unsigned char *ct, const symmetric_key *skey)
76 {
77 ulong32 y, z;
78 int r;
79
80 LTC_ARGCHK(pt != NULL);
81 LTC_ARGCHK(ct != NULL);
82 LTC_ARGCHK(skey != NULL);
83
84 LOAD32H(y, &pt[0]);
85 LOAD32H(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 STORE32H(y, &ct[0]);
100 STORE32H(z, &ct[4]);
101 return CRYPT_OK;
102 }
103
104 /**
105 Decrypts a block of text with LTC_XTEA
106 @param ct The input ciphertext (8 bytes)
107 @param pt The output plaintext (8 bytes)
108 @param skey The key as scheduled
109 @return CRYPT_OK if successful
110 */
xtea_ecb_decrypt(const unsigned char * ct,unsigned char * pt,const symmetric_key * skey)111 int xtea_ecb_decrypt(const unsigned char *ct, unsigned char *pt, const symmetric_key *skey)
112 {
113 ulong32 y, z;
114 int r;
115
116 LTC_ARGCHK(pt != NULL);
117 LTC_ARGCHK(ct != NULL);
118 LTC_ARGCHK(skey != NULL);
119
120 LOAD32H(y, &ct[0]);
121 LOAD32H(z, &ct[4]);
122 for (r = 31; r >= 0; r -= 4) {
123 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r])) & 0xFFFFFFFFUL;
124 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r])) & 0xFFFFFFFFUL;
125
126 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-1])) & 0xFFFFFFFFUL;
127 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-1])) & 0xFFFFFFFFUL;
128
129 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-2])) & 0xFFFFFFFFUL;
130 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-2])) & 0xFFFFFFFFUL;
131
132 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-3])) & 0xFFFFFFFFUL;
133 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-3])) & 0xFFFFFFFFUL;
134 }
135 STORE32H(y, &pt[0]);
136 STORE32H(z, &pt[4]);
137 return CRYPT_OK;
138 }
139
140 /**
141 Performs a self-test of the LTC_XTEA block cipher
142 @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled
143 */
xtea_test(void)144 int xtea_test(void)
145 {
146 #ifndef LTC_TEST
147 return CRYPT_NOP;
148 #else
149 static const struct {
150 unsigned char key[16], pt[8], ct[8];
151 } tests[] = {
152 {
153 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
154 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
155 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
156 { 0xde, 0xe9, 0xd4, 0xd8, 0xf7, 0x13, 0x1e, 0xd9 }
157 }, {
158 { 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x02,
159 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x04 },
160 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
161 { 0xa5, 0x97, 0xab, 0x41, 0x76, 0x01, 0x4d, 0x72 }
162 }, {
163 { 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x04,
164 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 0x06 },
165 { 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x02 },
166 { 0xb1, 0xfd, 0x5d, 0xa9, 0xcc, 0x6d, 0xc9, 0xdc }
167 }, {
168 { 0x78, 0x69, 0x5a, 0x4b, 0x3c, 0x2d, 0x1e, 0x0f,
169 0xf0, 0xe1, 0xd2, 0xc3, 0xb4, 0xa5, 0x96, 0x87 },
170 { 0xf0, 0xe1, 0xd2, 0xc3, 0xb4, 0xa5, 0x96, 0x87 },
171 { 0x70, 0x4b, 0x31, 0x34, 0x47, 0x44, 0xdf, 0xab }
172 }, {
173 { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
174 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
175 { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
176 { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 }
177 }, {
178 { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
179 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
180 { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
181 { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 }
182 }, {
183 { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
184 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
185 { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
186 { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
187 }, {
188 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
189 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
190 { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
191 { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 }
192 }, {
193 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
194 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
195 { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
196 { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d }
197 }, {
198 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
199 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
200 { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 },
201 { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
202 }
203 };
204 unsigned char tmp[2][8];
205 symmetric_key skey;
206 int i, err, y;
207 for (i = 0; i < (int)(sizeof(tests)/sizeof(tests[0])); i++) {
208 zeromem(&skey, sizeof(skey));
209 if ((err = xtea_setup(tests[i].key, 16, 0, &skey)) != CRYPT_OK) {
210 return err;
211 }
212 xtea_ecb_encrypt(tests[i].pt, tmp[0], &skey);
213 xtea_ecb_decrypt(tmp[0], tmp[1], &skey);
214
215 if (compare_testvector(tmp[0], 8, tests[i].ct, 8, "XTEA Encrypt", i) != 0 ||
216 compare_testvector(tmp[1], 8, tests[i].pt, 8, "XTEA Decrypt", i) != 0) {
217 return CRYPT_FAIL_TESTVECTOR;
218 }
219
220 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
221 for (y = 0; y < 8; y++) tmp[0][y] = 0;
222 for (y = 0; y < 1000; y++) xtea_ecb_encrypt(tmp[0], tmp[0], &skey);
223 for (y = 0; y < 1000; y++) xtea_ecb_decrypt(tmp[0], tmp[0], &skey);
224 for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
225 } /* for */
226
227 return CRYPT_OK;
228 #endif
229 }
230
231 /** Terminate the context
232 @param skey The scheduled key
233 */
xtea_done(symmetric_key * skey)234 void xtea_done(symmetric_key *skey)
235 {
236 LTC_UNUSED_PARAM(skey);
237 }
238
239 /**
240 Gets suitable key size
241 @param keysize [in/out] The length of the recommended key (in bytes). This function will store the suitable size back in this variable.
242 @return CRYPT_OK if the input key size is acceptable.
243 */
xtea_keysize(int * keysize)244 int xtea_keysize(int *keysize)
245 {
246 LTC_ARGCHK(keysize != NULL);
247 if (*keysize < 16) {
248 return CRYPT_INVALID_KEYSIZE;
249 }
250 *keysize = 16;
251 return CRYPT_OK;
252 }
253
254
255 #endif
256
257
258
259
260 /* ref: $Format:%D$ */
261 /* git commit: $Format:%H$ */
262 /* commit time: $Format:%ai$ */
263