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 #include "tomcrypt.h"
12
13 /**
14 @file cbc_encrypt.c
15 CBC implementation, encrypt block, Tom St Denis
16 */
17
18
19 #ifdef LTC_CBC_MODE
20
21 /**
22 CBC encrypt
23 @param pt Plaintext
24 @param ct [out] Ciphertext
25 @param len The number of bytes to process (must be multiple of block length)
26 @param cbc CBC state
27 @return CRYPT_OK if successful
28 */
cbc_encrypt(const unsigned char * pt,unsigned char * ct,unsigned long len,symmetric_CBC * cbc)29 int cbc_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_CBC *cbc)
30 {
31 int x, err;
32
33 LTC_ARGCHK(pt != NULL);
34 LTC_ARGCHK(ct != NULL);
35 LTC_ARGCHK(cbc != NULL);
36
37 if ((err = cipher_is_valid(cbc->cipher)) != CRYPT_OK) {
38 return err;
39 }
40
41 /* is blocklen valid? */
42 if (cbc->blocklen < 1 || cbc->blocklen > (int)sizeof(cbc->IV)) {
43 return CRYPT_INVALID_ARG;
44 }
45
46 if (len % cbc->blocklen) {
47 return CRYPT_INVALID_ARG;
48 }
49 #ifdef LTC_FAST
50 if (cbc->blocklen % sizeof(LTC_FAST_TYPE)) {
51 return CRYPT_INVALID_ARG;
52 }
53 #endif
54
55 if (cipher_descriptor[cbc->cipher].accel_cbc_encrypt != NULL) {
56 return cipher_descriptor[cbc->cipher].accel_cbc_encrypt(pt, ct, len / cbc->blocklen, cbc->IV, &cbc->key);
57 } else {
58 while (len) {
59 /* xor IV against plaintext */
60 #if defined(LTC_FAST)
61 for (x = 0; x < cbc->blocklen; x += sizeof(LTC_FAST_TYPE)) {
62 *((LTC_FAST_TYPE*)((unsigned char *)cbc->IV + x)) ^= *((LTC_FAST_TYPE*)((unsigned char *)pt + x));
63 }
64 #else
65 for (x = 0; x < cbc->blocklen; x++) {
66 cbc->IV[x] ^= pt[x];
67 }
68 #endif
69
70 /* encrypt */
71 if ((err = cipher_descriptor[cbc->cipher].ecb_encrypt(cbc->IV, ct, &cbc->key)) != CRYPT_OK) {
72 return err;
73 }
74
75 /* store IV [ciphertext] for a future block */
76 #if defined(LTC_FAST)
77 for (x = 0; x < cbc->blocklen; x += sizeof(LTC_FAST_TYPE)) {
78 *((LTC_FAST_TYPE*)((unsigned char *)cbc->IV + x)) = *((LTC_FAST_TYPE*)((unsigned char *)ct + x));
79 }
80 #else
81 for (x = 0; x < cbc->blocklen; x++) {
82 cbc->IV[x] = ct[x];
83 }
84 #endif
85
86 ct += cbc->blocklen;
87 pt += cbc->blocklen;
88 len -= cbc->blocklen;
89 }
90 }
91 return CRYPT_OK;
92 }
93
94 #endif
95
96 /* $Source: /cvs/libtom/libtomcrypt/src/modes/cbc/cbc_encrypt.c,v $ */
97 /* $Revision: 1.13 $ */
98 /* $Date: 2006/11/21 00:18:23 $ */
99