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, tomstdenis@gmail.com, http://libtomcrypt.com
10 */
11
12/**
13   @file rc5.c
14   RC5 code by Tom St Denis
15*/
16
17#include "tomcrypt.h"
18
19#ifdef RC5
20
21const struct ltc_cipher_descriptor rc5_desc =
22{
23    "rc5",
24    2,
25    8, 128, 8, 12,
26    &rc5_setup,
27    &rc5_ecb_encrypt,
28    &rc5_ecb_decrypt,
29    &rc5_test,
30    &rc5_done,
31    &rc5_keysize,
32    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
33};
34
35static const ulong32 stab[50] = {
360xb7e15163UL, 0x5618cb1cUL, 0xf45044d5UL, 0x9287be8eUL, 0x30bf3847UL, 0xcef6b200UL, 0x6d2e2bb9UL, 0x0b65a572UL,
370xa99d1f2bUL, 0x47d498e4UL, 0xe60c129dUL, 0x84438c56UL, 0x227b060fUL, 0xc0b27fc8UL, 0x5ee9f981UL, 0xfd21733aUL,
380x9b58ecf3UL, 0x399066acUL, 0xd7c7e065UL, 0x75ff5a1eUL, 0x1436d3d7UL, 0xb26e4d90UL, 0x50a5c749UL, 0xeedd4102UL,
390x8d14babbUL, 0x2b4c3474UL, 0xc983ae2dUL, 0x67bb27e6UL, 0x05f2a19fUL, 0xa42a1b58UL, 0x42619511UL, 0xe0990ecaUL,
400x7ed08883UL, 0x1d08023cUL, 0xbb3f7bf5UL, 0x5976f5aeUL, 0xf7ae6f67UL, 0x95e5e920UL, 0x341d62d9UL, 0xd254dc92UL,
410x708c564bUL, 0x0ec3d004UL, 0xacfb49bdUL, 0x4b32c376UL, 0xe96a3d2fUL, 0x87a1b6e8UL, 0x25d930a1UL, 0xc410aa5aUL,
420x62482413UL, 0x007f9dccUL
43};
44
45 /**
46    Initialize the RC5 block cipher
47    @param key The symmetric key you wish to pass
48    @param keylen The key length in bytes
49    @param num_rounds The number of rounds desired (0 for default)
50    @param skey The key in as scheduled by this function.
51    @return CRYPT_OK if successful
52 */
53#ifdef LTC_CLEAN_STACK
54static int _rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
55#else
56int rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
57#endif
58{
59    ulong32 L[64], *S, A, B, i, j, v, s, t, l;
60
61    LTC_ARGCHK(skey != NULL);
62    LTC_ARGCHK(key  != NULL);
63
64    /* test parameters */
65    if (num_rounds == 0) {
66       num_rounds = rc5_desc.default_rounds;
67    }
68
69    if (num_rounds < 12 || num_rounds > 24) {
70       return CRYPT_INVALID_ROUNDS;
71    }
72
73    /* key must be between 64 and 1024 bits */
74    if (keylen < 8 || keylen > 128) {
75       return CRYPT_INVALID_KEYSIZE;
76    }
77
78    skey->rc5.rounds = num_rounds;
79    S = skey->rc5.K;
80
81    /* copy the key into the L array */
82    for (A = i = j = 0; i < (ulong32)keylen; ) {
83        A = (A << 8) | ((ulong32)(key[i++] & 255));
84        if ((i & 3) == 0) {
85           L[j++] = BSWAP(A);
86           A = 0;
87        }
88    }
89
90    if ((keylen & 3) != 0) {
91       A <<= (ulong32)((8 * (4 - (keylen&3))));
92       L[j++] = BSWAP(A);
93    }
94
95    /* setup the S array */
96    t = (ulong32)(2 * (num_rounds + 1));
97    XMEMCPY(S, stab, t * sizeof(*S));
98
99    /* mix buffer */
100    s = 3 * MAX(t, j);
101    l = j;
102    for (A = B = i = j = v = 0; v < s; v++) {
103        A = S[i] = ROLc(S[i] + A + B, 3);
104        B = L[j] = ROL(L[j] + A + B, (A+B));
105        if (++i == t) { i = 0; }
106        if (++j == l) { j = 0; }
107    }
108    return CRYPT_OK;
109}
110
111#ifdef LTC_CLEAN_STACK
112int rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
113{
114   int x;
115   x = _rc5_setup(key, keylen, num_rounds, skey);
116   burn_stack(sizeof(ulong32) * 122 + sizeof(int));
117   return x;
118}
119#endif
120
121/**
122  Encrypts a block of text with RC5
123  @param pt The input plaintext (8 bytes)
124  @param ct The output ciphertext (8 bytes)
125  @param skey The key as scheduled
126  @return CRYPT_OK if successful
127*/
128#ifdef LTC_CLEAN_STACK
129static int _rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
130#else
131int rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
132#endif
133{
134   ulong32 A, B, *K;
135   int r;
136   LTC_ARGCHK(skey != NULL);
137   LTC_ARGCHK(pt   != NULL);
138   LTC_ARGCHK(ct   != NULL);
139
140   LOAD32L(A, &pt[0]);
141   LOAD32L(B, &pt[4]);
142   A += skey->rc5.K[0];
143   B += skey->rc5.K[1];
144   K  = skey->rc5.K + 2;
145
146   if ((skey->rc5.rounds & 1) == 0) {
147      for (r = 0; r < skey->rc5.rounds; r += 2) {
148          A = ROL(A ^ B, B) + K[0];
149          B = ROL(B ^ A, A) + K[1];
150          A = ROL(A ^ B, B) + K[2];
151          B = ROL(B ^ A, A) + K[3];
152          K += 4;
153      }
154   } else {
155      for (r = 0; r < skey->rc5.rounds; r++) {
156          A = ROL(A ^ B, B) + K[0];
157          B = ROL(B ^ A, A) + K[1];
158          K += 2;
159      }
160   }
161   STORE32L(A, &ct[0]);
162   STORE32L(B, &ct[4]);
163
164   return CRYPT_OK;
165}
166
167#ifdef LTC_CLEAN_STACK
168int rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
169{
170   int err = _rc5_ecb_encrypt(pt, ct, skey);
171   burn_stack(sizeof(ulong32) * 2 + sizeof(int));
172   return err;
173}
174#endif
175
176/**
177  Decrypts a block of text with RC5
178  @param ct The input ciphertext (8 bytes)
179  @param pt The output plaintext (8 bytes)
180  @param skey The key as scheduled
181  @return CRYPT_OK if successful
182*/
183#ifdef LTC_CLEAN_STACK
184static int _rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
185#else
186int rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
187#endif
188{
189   ulong32 A, B, *K;
190   int r;
191   LTC_ARGCHK(skey != NULL);
192   LTC_ARGCHK(pt   != NULL);
193   LTC_ARGCHK(ct   != NULL);
194
195   LOAD32L(A, &ct[0]);
196   LOAD32L(B, &ct[4]);
197   K = skey->rc5.K + (skey->rc5.rounds << 1);
198
199   if ((skey->rc5.rounds & 1) == 0) {
200       K -= 2;
201       for (r = skey->rc5.rounds - 1; r >= 0; r -= 2) {
202          B = ROR(B - K[3], A) ^ A;
203          A = ROR(A - K[2], B) ^ B;
204          B = ROR(B - K[1], A) ^ A;
205          A = ROR(A - K[0], B) ^ B;
206          K -= 4;
207        }
208   } else {
209      for (r = skey->rc5.rounds - 1; r >= 0; r--) {
210          B = ROR(B - K[1], A) ^ A;
211          A = ROR(A - K[0], B) ^ B;
212          K -= 2;
213      }
214   }
215   A -= skey->rc5.K[0];
216   B -= skey->rc5.K[1];
217   STORE32L(A, &pt[0]);
218   STORE32L(B, &pt[4]);
219
220   return CRYPT_OK;
221}
222
223#ifdef LTC_CLEAN_STACK
224int rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
225{
226   int err = _rc5_ecb_decrypt(ct, pt, skey);
227   burn_stack(sizeof(ulong32) * 2 + sizeof(int));
228   return err;
229}
230#endif
231
232/**
233  Performs a self-test of the RC5 block cipher
234  @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled
235*/
236int rc5_test(void)
237{
238 #ifndef LTC_TEST
239    return CRYPT_NOP;
240 #else
241   static const struct {
242       unsigned char key[16], pt[8], ct[8];
243   } tests[] = {
244   {
245       { 0x91, 0x5f, 0x46, 0x19, 0xbe, 0x41, 0xb2, 0x51,
246         0x63, 0x55, 0xa5, 0x01, 0x10, 0xa9, 0xce, 0x91 },
247       { 0x21, 0xa5, 0xdb, 0xee, 0x15, 0x4b, 0x8f, 0x6d },
248       { 0xf7, 0xc0, 0x13, 0xac, 0x5b, 0x2b, 0x89, 0x52 }
249   },
250   {
251       { 0x78, 0x33, 0x48, 0xe7, 0x5a, 0xeb, 0x0f, 0x2f,
252         0xd7, 0xb1, 0x69, 0xbb, 0x8d, 0xc1, 0x67, 0x87 },
253       { 0xF7, 0xC0, 0x13, 0xAC, 0x5B, 0x2B, 0x89, 0x52 },
254       { 0x2F, 0x42, 0xB3, 0xB7, 0x03, 0x69, 0xFC, 0x92 }
255   },
256   {
257       { 0xDC, 0x49, 0xdb, 0x13, 0x75, 0xa5, 0x58, 0x4f,
258         0x64, 0x85, 0xb4, 0x13, 0xb5, 0xf1, 0x2b, 0xaf },
259       { 0x2F, 0x42, 0xB3, 0xB7, 0x03, 0x69, 0xFC, 0x92 },
260       { 0x65, 0xc1, 0x78, 0xb2, 0x84, 0xd1, 0x97, 0xcc }
261   }
262   };
263   unsigned char tmp[2][8];
264   int x, y, err;
265   symmetric_key key;
266
267   for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {
268      /* setup key */
269      if ((err = rc5_setup(tests[x].key, 16, 12, &key)) != CRYPT_OK) {
270         return err;
271      }
272
273      /* encrypt and decrypt */
274      rc5_ecb_encrypt(tests[x].pt, tmp[0], &key);
275      rc5_ecb_decrypt(tmp[0], tmp[1], &key);
276
277      /* compare */
278      if (XMEMCMP(tmp[0], tests[x].ct, 8) != 0 || XMEMCMP(tmp[1], tests[x].pt, 8) != 0) {
279         return CRYPT_FAIL_TESTVECTOR;
280      }
281
282      /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
283      for (y = 0; y < 8; y++) tmp[0][y] = 0;
284      for (y = 0; y < 1000; y++) rc5_ecb_encrypt(tmp[0], tmp[0], &key);
285      for (y = 0; y < 1000; y++) rc5_ecb_decrypt(tmp[0], tmp[0], &key);
286      for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
287   }
288   return CRYPT_OK;
289  #endif
290}
291
292/** Terminate the context
293   @param skey    The scheduled key
294*/
295void rc5_done(symmetric_key *skey)
296{
297}
298
299/**
300  Gets suitable key size
301  @param keysize [in/out] The length of the recommended key (in bytes).  This function will store the suitable size back in this variable.
302  @return CRYPT_OK if the input key size is acceptable.
303*/
304int rc5_keysize(int *keysize)
305{
306   LTC_ARGCHK(keysize != NULL);
307   if (*keysize < 8) {
308      return CRYPT_INVALID_KEYSIZE;
309   } else if (*keysize > 128) {
310      *keysize = 128;
311   }
312   return CRYPT_OK;
313}
314
315#endif
316
317
318
319
320/* $Source: /cvs/libtom/libtomcrypt/src/ciphers/rc5.c,v $ */
321/* $Revision: 1.12 $ */
322/* $Date: 2006/11/08 23:01:06 $ */
323