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
s_rc5_setup(const unsigned char * key,int keylen,int num_rounds,symmetric_key * skey)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
rc5_setup(const unsigned char * key,int keylen,int num_rounds,symmetric_key * skey)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
s_rc5_ecb_encrypt(const unsigned char * pt,unsigned char * ct,const symmetric_key * skey)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
rc5_ecb_encrypt(const unsigned char * pt,unsigned char * ct,const symmetric_key * skey)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
s_rc5_ecb_decrypt(const unsigned char * ct,unsigned char * pt,const symmetric_key * skey)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
rc5_ecb_decrypt(const unsigned char * ct,unsigned char * pt,const symmetric_key * skey)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 */
rc5_test(void)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 */
rc5_done(symmetric_key * skey)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 */
rc5_keysize(int * keysize)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