cbc_encrypt.c revision f7fc46c63fdc8f39234fea409b8dbe116d73ebf8 
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*/
29int 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