1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis */ 2 /* SPDX-License-Identifier: Unlicense */ 3 4 /** 5 @file xtea.c 6 Implementation of eXtended TEA, Tom St Denis 7 */ 8 #include "tomcrypt_private.h" 9 10 #ifdef LTC_XTEA 11 12 const struct ltc_cipher_descriptor xtea_desc = 13 { 14 "xtea", 15 1, 16 16, 16, 8, 32, 17 &xtea_setup, 18 &xtea_ecb_encrypt, 19 &xtea_ecb_decrypt, 20 &xtea_test, 21 &xtea_done, 22 &xtea_keysize, 23 NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL 24 }; 25 26 int xtea_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey) 27 { 28 ulong32 x, sum, K[4]; 29 30 LTC_ARGCHK(key != NULL); 31 LTC_ARGCHK(skey != NULL); 32 33 /* check arguments */ 34 if (keylen != 16) { 35 return CRYPT_INVALID_KEYSIZE; 36 } 37 38 if (num_rounds != 0 && num_rounds != 32) { 39 return CRYPT_INVALID_ROUNDS; 40 } 41 42 /* load key */ 43 LOAD32H(K[0], key+0); 44 LOAD32H(K[1], key+4); 45 LOAD32H(K[2], key+8); 46 LOAD32H(K[3], key+12); 47 48 for (x = sum = 0; x < 32; x++) { 49 skey->xtea.A[x] = (sum + K[sum&3]) & 0xFFFFFFFFUL; 50 sum = (sum + 0x9E3779B9UL) & 0xFFFFFFFFUL; 51 skey->xtea.B[x] = (sum + K[(sum>>11)&3]) & 0xFFFFFFFFUL; 52 } 53 54 #ifdef LTC_CLEAN_STACK 55 zeromem(&K, sizeof(K)); 56 #endif 57 58 return CRYPT_OK; 59 } 60 61 /** 62 Encrypts a block of text with LTC_XTEA 63 @param pt The input plaintext (8 bytes) 64 @param ct The output ciphertext (8 bytes) 65 @param skey The key as scheduled 66 @return CRYPT_OK if successful 67 */ 68 int xtea_ecb_encrypt(const unsigned char *pt, unsigned char *ct, const symmetric_key *skey) 69 { 70 ulong32 y, z; 71 int r; 72 73 LTC_ARGCHK(pt != NULL); 74 LTC_ARGCHK(ct != NULL); 75 LTC_ARGCHK(skey != NULL); 76 77 LOAD32H(y, &pt[0]); 78 LOAD32H(z, &pt[4]); 79 for (r = 0; r < 32; r += 4) { 80 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r])) & 0xFFFFFFFFUL; 81 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r])) & 0xFFFFFFFFUL; 82 83 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+1])) & 0xFFFFFFFFUL; 84 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+1])) & 0xFFFFFFFFUL; 85 86 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+2])) & 0xFFFFFFFFUL; 87 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+2])) & 0xFFFFFFFFUL; 88 89 y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+3])) & 0xFFFFFFFFUL; 90 z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+3])) & 0xFFFFFFFFUL; 91 } 92 STORE32H(y, &ct[0]); 93 STORE32H(z, &ct[4]); 94 return CRYPT_OK; 95 } 96 97 /** 98 Decrypts a block of text with LTC_XTEA 99 @param ct The input ciphertext (8 bytes) 100 @param pt The output plaintext (8 bytes) 101 @param skey The key as scheduled 102 @return CRYPT_OK if successful 103 */ 104 int xtea_ecb_decrypt(const unsigned char *ct, unsigned char *pt, const symmetric_key *skey) 105 { 106 ulong32 y, z; 107 int r; 108 109 LTC_ARGCHK(pt != NULL); 110 LTC_ARGCHK(ct != NULL); 111 LTC_ARGCHK(skey != NULL); 112 113 LOAD32H(y, &ct[0]); 114 LOAD32H(z, &ct[4]); 115 for (r = 31; r >= 0; r -= 4) { 116 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r])) & 0xFFFFFFFFUL; 117 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r])) & 0xFFFFFFFFUL; 118 119 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-1])) & 0xFFFFFFFFUL; 120 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-1])) & 0xFFFFFFFFUL; 121 122 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-2])) & 0xFFFFFFFFUL; 123 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-2])) & 0xFFFFFFFFUL; 124 125 z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-3])) & 0xFFFFFFFFUL; 126 y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-3])) & 0xFFFFFFFFUL; 127 } 128 STORE32H(y, &pt[0]); 129 STORE32H(z, &pt[4]); 130 return CRYPT_OK; 131 } 132 133 /** 134 Performs a self-test of the LTC_XTEA block cipher 135 @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled 136 */ 137 int xtea_test(void) 138 { 139 #ifndef LTC_TEST 140 return CRYPT_NOP; 141 #else 142 static const struct { 143 unsigned char key[16], pt[8], ct[8]; 144 } tests[] = { 145 { 146 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 147 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, 148 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, 149 { 0xde, 0xe9, 0xd4, 0xd8, 0xf7, 0x13, 0x1e, 0xd9 } 150 }, { 151 { 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x02, 152 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x04 }, 153 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, 154 { 0xa5, 0x97, 0xab, 0x41, 0x76, 0x01, 0x4d, 0x72 } 155 }, { 156 { 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x04, 157 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 0x06 }, 158 { 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x02 }, 159 { 0xb1, 0xfd, 0x5d, 0xa9, 0xcc, 0x6d, 0xc9, 0xdc } 160 }, { 161 { 0x78, 0x69, 0x5a, 0x4b, 0x3c, 0x2d, 0x1e, 0x0f, 162 0xf0, 0xe1, 0xd2, 0xc3, 0xb4, 0xa5, 0x96, 0x87 }, 163 { 0xf0, 0xe1, 0xd2, 0xc3, 0xb4, 0xa5, 0x96, 0x87 }, 164 { 0x70, 0x4b, 0x31, 0x34, 0x47, 0x44, 0xdf, 0xab } 165 }, { 166 { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 167 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f }, 168 { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 }, 169 { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 } 170 }, { 171 { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 172 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f }, 173 { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }, 174 { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 } 175 }, { 176 { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 177 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f }, 178 { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f }, 179 { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 } 180 }, { 181 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 182 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, 183 { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 }, 184 { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 } 185 }, { 186 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 187 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, 188 { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }, 189 { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d } 190 }, { 191 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 192 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, 193 { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }, 194 { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 } 195 } 196 }; 197 unsigned char tmp[2][8]; 198 symmetric_key skey; 199 int i, err, y; 200 for (i = 0; i < (int)(sizeof(tests)/sizeof(tests[0])); i++) { 201 zeromem(&skey, sizeof(skey)); 202 if ((err = xtea_setup(tests[i].key, 16, 0, &skey)) != CRYPT_OK) { 203 return err; 204 } 205 xtea_ecb_encrypt(tests[i].pt, tmp[0], &skey); 206 xtea_ecb_decrypt(tmp[0], tmp[1], &skey); 207 208 if (compare_testvector(tmp[0], 8, tests[i].ct, 8, "XTEA Encrypt", i) != 0 || 209 compare_testvector(tmp[1], 8, tests[i].pt, 8, "XTEA Decrypt", i) != 0) { 210 return CRYPT_FAIL_TESTVECTOR; 211 } 212 213 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */ 214 for (y = 0; y < 8; y++) tmp[0][y] = 0; 215 for (y = 0; y < 1000; y++) xtea_ecb_encrypt(tmp[0], tmp[0], &skey); 216 for (y = 0; y < 1000; y++) xtea_ecb_decrypt(tmp[0], tmp[0], &skey); 217 for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR; 218 } /* for */ 219 220 return CRYPT_OK; 221 #endif 222 } 223 224 /** Terminate the context 225 @param skey The scheduled key 226 */ 227 void xtea_done(symmetric_key *skey) 228 { 229 LTC_UNUSED_PARAM(skey); 230 } 231 232 /** 233 Gets suitable key size 234 @param keysize [in/out] The length of the recommended key (in bytes). This function will store the suitable size back in this variable. 235 @return CRYPT_OK if the input key size is acceptable. 236 */ 237 int xtea_keysize(int *keysize) 238 { 239 LTC_ARGCHK(keysize != NULL); 240 if (*keysize < 16) { 241 return CRYPT_INVALID_KEYSIZE; 242 } 243 *keysize = 16; 244 return CRYPT_OK; 245 } 246 247 248 #endif 249 250 251 252