1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis */ 2 /* SPDX-License-Identifier: Unlicense */ 3 4 /** 5 @file rc5.c 6 LTC_RC5 code by Tom St Denis 7 */ 8 9 #include "tomcrypt_private.h" 10 11 #ifdef LTC_RC5 12 13 const struct ltc_cipher_descriptor rc5_desc = 14 { 15 "rc5", 16 2, 17 8, 128, 8, 12, 18 &rc5_setup, 19 &rc5_ecb_encrypt, 20 &rc5_ecb_decrypt, 21 &rc5_test, 22 &rc5_done, 23 &rc5_keysize, 24 NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL 25 }; 26 27 static const ulong32 stab[50] = { 28 0xb7e15163UL, 0x5618cb1cUL, 0xf45044d5UL, 0x9287be8eUL, 0x30bf3847UL, 0xcef6b200UL, 0x6d2e2bb9UL, 0x0b65a572UL, 29 0xa99d1f2bUL, 0x47d498e4UL, 0xe60c129dUL, 0x84438c56UL, 0x227b060fUL, 0xc0b27fc8UL, 0x5ee9f981UL, 0xfd21733aUL, 30 0x9b58ecf3UL, 0x399066acUL, 0xd7c7e065UL, 0x75ff5a1eUL, 0x1436d3d7UL, 0xb26e4d90UL, 0x50a5c749UL, 0xeedd4102UL, 31 0x8d14babbUL, 0x2b4c3474UL, 0xc983ae2dUL, 0x67bb27e6UL, 0x05f2a19fUL, 0xa42a1b58UL, 0x42619511UL, 0xe0990ecaUL, 32 0x7ed08883UL, 0x1d08023cUL, 0xbb3f7bf5UL, 0x5976f5aeUL, 0xf7ae6f67UL, 0x95e5e920UL, 0x341d62d9UL, 0xd254dc92UL, 33 0x708c564bUL, 0x0ec3d004UL, 0xacfb49bdUL, 0x4b32c376UL, 0xe96a3d2fUL, 0x87a1b6e8UL, 0x25d930a1UL, 0xc410aa5aUL, 34 0x62482413UL, 0x007f9dccUL 35 }; 36 37 /** 38 Initialize the LTC_RC5 block cipher 39 @param key The symmetric key you wish to pass 40 @param keylen The key length in bytes 41 @param num_rounds The number of rounds desired (0 for default) 42 @param skey The key in as scheduled by this function. 43 @return CRYPT_OK if successful 44 */ 45 #ifdef LTC_CLEAN_STACK 46 static int s_rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey) 47 #else 48 int rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey) 49 #endif 50 { 51 ulong32 L[64], *S, A, B, i, j, v, s, t, l; 52 53 LTC_ARGCHK(skey != NULL); 54 LTC_ARGCHK(key != NULL); 55 56 /* test parameters */ 57 if (num_rounds == 0) { 58 num_rounds = rc5_desc.default_rounds; 59 } 60 61 if (num_rounds < 12 || num_rounds > 24) { 62 return CRYPT_INVALID_ROUNDS; 63 } 64 65 /* key must be between 64 and 1024 bits */ 66 if (keylen < 8 || keylen > 128) { 67 return CRYPT_INVALID_KEYSIZE; 68 } 69 70 skey->rc5.rounds = num_rounds; 71 S = skey->rc5.K; 72 73 /* copy the key into the L array */ 74 for (A = i = j = 0; i < (ulong32)keylen; ) { 75 A = (A << 8) | ((ulong32)(key[i++] & 255)); 76 if ((i & 3) == 0) { 77 L[j++] = BSWAP(A); 78 A = 0; 79 } 80 } 81 82 if ((keylen & 3) != 0) { 83 A <<= (ulong32)((8 * (4 - (keylen&3)))); 84 L[j++] = BSWAP(A); 85 } 86 87 /* setup the S array */ 88 t = (ulong32)(2 * (num_rounds + 1)); 89 XMEMCPY(S, stab, t * sizeof(*S)); 90 91 /* mix buffer */ 92 s = 3 * MAX(t, j); 93 l = j; 94 for (A = B = i = j = v = 0; v < s; v++) { 95 A = S[i] = ROLc(S[i] + A + B, 3); 96 B = L[j] = ROL(L[j] + A + B, (A+B)); 97 if (++i == t) { i = 0; } 98 if (++j == l) { j = 0; } 99 } 100 return CRYPT_OK; 101 } 102 103 #ifdef LTC_CLEAN_STACK 104 int rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey) 105 { 106 int x; 107 x = s_rc5_setup(key, keylen, num_rounds, skey); 108 burn_stack(sizeof(ulong32) * 122 + sizeof(int)); 109 return x; 110 } 111 #endif 112 113 /** 114 Encrypts a block of text with LTC_RC5 115 @param pt The input plaintext (8 bytes) 116 @param ct The output ciphertext (8 bytes) 117 @param skey The key as scheduled 118 @return CRYPT_OK if successful 119 */ 120 #ifdef LTC_CLEAN_STACK 121 static int s_rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, const symmetric_key *skey) 122 #else 123 int rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, const symmetric_key *skey) 124 #endif 125 { 126 ulong32 A, B; 127 const ulong32 *K; 128 int r; 129 LTC_ARGCHK(skey != NULL); 130 LTC_ARGCHK(pt != NULL); 131 LTC_ARGCHK(ct != NULL); 132 133 if (skey->rc5.rounds < 12 || skey->rc5.rounds > 24) { 134 return CRYPT_INVALID_ROUNDS; 135 } 136 137 LOAD32L(A, &pt[0]); 138 LOAD32L(B, &pt[4]); 139 A += skey->rc5.K[0]; 140 B += skey->rc5.K[1]; 141 K = skey->rc5.K + 2; 142 143 if ((skey->rc5.rounds & 1) == 0) { 144 for (r = 0; r < skey->rc5.rounds; r += 2) { 145 A = ROL(A ^ B, B) + K[0]; 146 B = ROL(B ^ A, A) + K[1]; 147 A = ROL(A ^ B, B) + K[2]; 148 B = ROL(B ^ A, A) + K[3]; 149 K += 4; 150 } 151 } else { 152 for (r = 0; r < skey->rc5.rounds; r++) { 153 A = ROL(A ^ B, B) + K[0]; 154 B = ROL(B ^ A, A) + K[1]; 155 K += 2; 156 } 157 } 158 STORE32L(A, &ct[0]); 159 STORE32L(B, &ct[4]); 160 161 return CRYPT_OK; 162 } 163 164 #ifdef LTC_CLEAN_STACK 165 int rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, const symmetric_key *skey) 166 { 167 int err = s_rc5_ecb_encrypt(pt, ct, skey); 168 burn_stack(sizeof(ulong32) * 2 + sizeof(int)); 169 return err; 170 } 171 #endif 172 173 /** 174 Decrypts a block of text with LTC_RC5 175 @param ct The input ciphertext (8 bytes) 176 @param pt The output plaintext (8 bytes) 177 @param skey The key as scheduled 178 @return CRYPT_OK if successful 179 */ 180 #ifdef LTC_CLEAN_STACK 181 static int s_rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, const symmetric_key *skey) 182 #else 183 int rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, const symmetric_key *skey) 184 #endif 185 { 186 ulong32 A, B; 187 const ulong32 *K; 188 int r; 189 LTC_ARGCHK(skey != NULL); 190 LTC_ARGCHK(pt != NULL); 191 LTC_ARGCHK(ct != NULL); 192 193 if (skey->rc5.rounds < 12 || skey->rc5.rounds > 24) { 194 return CRYPT_INVALID_ROUNDS; 195 } 196 197 LOAD32L(A, &ct[0]); 198 LOAD32L(B, &ct[4]); 199 K = skey->rc5.K + (skey->rc5.rounds << 1); 200 201 if ((skey->rc5.rounds & 1) == 0) { 202 K -= 2; 203 for (r = skey->rc5.rounds - 1; r >= 0; r -= 2) { 204 B = ROR(B - K[3], A) ^ A; 205 A = ROR(A - K[2], B) ^ B; 206 B = ROR(B - K[1], A) ^ A; 207 A = ROR(A - K[0], B) ^ B; 208 K -= 4; 209 } 210 } else { 211 for (r = skey->rc5.rounds - 1; r >= 0; r--) { 212 B = ROR(B - K[1], A) ^ A; 213 A = ROR(A - K[0], B) ^ B; 214 K -= 2; 215 } 216 } 217 A -= skey->rc5.K[0]; 218 B -= skey->rc5.K[1]; 219 STORE32L(A, &pt[0]); 220 STORE32L(B, &pt[4]); 221 222 return CRYPT_OK; 223 } 224 225 #ifdef LTC_CLEAN_STACK 226 int rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, const symmetric_key *skey) 227 { 228 int err = s_rc5_ecb_decrypt(ct, pt, skey); 229 burn_stack(sizeof(ulong32) * 2 + sizeof(int)); 230 return err; 231 } 232 #endif 233 234 /** 235 Performs a self-test of the LTC_RC5 block cipher 236 @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled 237 */ 238 int rc5_test(void) 239 { 240 #ifndef LTC_TEST 241 return CRYPT_NOP; 242 #else 243 static const struct { 244 unsigned char key[16], pt[8], ct[8]; 245 } tests[] = { 246 { 247 { 0x91, 0x5f, 0x46, 0x19, 0xbe, 0x41, 0xb2, 0x51, 248 0x63, 0x55, 0xa5, 0x01, 0x10, 0xa9, 0xce, 0x91 }, 249 { 0x21, 0xa5, 0xdb, 0xee, 0x15, 0x4b, 0x8f, 0x6d }, 250 { 0xf7, 0xc0, 0x13, 0xac, 0x5b, 0x2b, 0x89, 0x52 } 251 }, 252 { 253 { 0x78, 0x33, 0x48, 0xe7, 0x5a, 0xeb, 0x0f, 0x2f, 254 0xd7, 0xb1, 0x69, 0xbb, 0x8d, 0xc1, 0x67, 0x87 }, 255 { 0xF7, 0xC0, 0x13, 0xAC, 0x5B, 0x2B, 0x89, 0x52 }, 256 { 0x2F, 0x42, 0xB3, 0xB7, 0x03, 0x69, 0xFC, 0x92 } 257 }, 258 { 259 { 0xDC, 0x49, 0xdb, 0x13, 0x75, 0xa5, 0x58, 0x4f, 260 0x64, 0x85, 0xb4, 0x13, 0xb5, 0xf1, 0x2b, 0xaf }, 261 { 0x2F, 0x42, 0xB3, 0xB7, 0x03, 0x69, 0xFC, 0x92 }, 262 { 0x65, 0xc1, 0x78, 0xb2, 0x84, 0xd1, 0x97, 0xcc } 263 } 264 }; 265 unsigned char tmp[2][8]; 266 int x, y, err; 267 symmetric_key key; 268 269 for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) { 270 /* setup key */ 271 if ((err = rc5_setup(tests[x].key, 16, 12, &key)) != CRYPT_OK) { 272 return err; 273 } 274 275 /* encrypt and decrypt */ 276 rc5_ecb_encrypt(tests[x].pt, tmp[0], &key); 277 rc5_ecb_decrypt(tmp[0], tmp[1], &key); 278 279 /* compare */ 280 if (compare_testvector(tmp[0], 8, tests[x].ct, 8, "RC5 Encrypt", x) != 0 || 281 compare_testvector(tmp[1], 8, tests[x].pt, 8, "RC5 Decrypt", x) != 0) { 282 return CRYPT_FAIL_TESTVECTOR; 283 } 284 285 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */ 286 for (y = 0; y < 8; y++) tmp[0][y] = 0; 287 for (y = 0; y < 1000; y++) rc5_ecb_encrypt(tmp[0], tmp[0], &key); 288 for (y = 0; y < 1000; y++) rc5_ecb_decrypt(tmp[0], tmp[0], &key); 289 for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR; 290 } 291 return CRYPT_OK; 292 #endif 293 } 294 295 /** Terminate the context 296 @param skey The scheduled key 297 */ 298 void rc5_done(symmetric_key *skey) 299 { 300 LTC_UNUSED_PARAM(skey); 301 } 302 303 /** 304 Gets suitable key size 305 @param keysize [in/out] The length of the recommended key (in bytes). This function will store the suitable size back in this variable. 306 @return CRYPT_OK if the input key size is acceptable. 307 */ 308 int rc5_keysize(int *keysize) 309 { 310 LTC_ARGCHK(keysize != NULL); 311 if (*keysize < 8) { 312 return CRYPT_INVALID_KEYSIZE; 313 } 314 if (*keysize > 128) { 315 *keysize = 128; 316 } 317 return CRYPT_OK; 318 } 319 320 #endif 321 322 323 324