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 cfb_encrypt.c
15  CFB implementation, encrypt data, Tom St Denis
16*/
17
18#ifdef LTC_CFB_MODE
19
20/**
21  CFB encrypt
22  @param pt     Plaintext
23  @param ct     [out] Ciphertext
24  @param len    Length of plaintext (octets)
25  @param cfb    CFB state
26  @return CRYPT_OK if successful
27*/
28int cfb_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_CFB *cfb)
29{
30   int err;
31
32   LTC_ARGCHK(pt != NULL);
33   LTC_ARGCHK(ct != NULL);
34   LTC_ARGCHK(cfb != NULL);
35
36   if ((err = cipher_is_valid(cfb->cipher)) != CRYPT_OK) {
37       return err;
38   }
39
40   /* is blocklen/padlen valid? */
41   if (cfb->blocklen < 0 || cfb->blocklen > (int)sizeof(cfb->IV) ||
42       cfb->padlen   < 0 || cfb->padlen   > (int)sizeof(cfb->pad)) {
43      return CRYPT_INVALID_ARG;
44   }
45
46   while (len-- > 0) {
47       if (cfb->padlen == cfb->blocklen) {
48          if ((err = cipher_descriptor[cfb->cipher].ecb_encrypt(cfb->pad, cfb->IV, &cfb->key)) != CRYPT_OK) {
49             return err;
50          }
51          cfb->padlen = 0;
52       }
53       cfb->pad[cfb->padlen] = (*ct = *pt ^ cfb->IV[cfb->padlen]);
54       ++pt;
55       ++ct;
56       ++(cfb->padlen);
57   }
58   return CRYPT_OK;
59}
60
61#endif
62
63/* $Source: /cvs/libtom/libtomcrypt/src/modes/cfb/cfb_encrypt.c,v $ */
64/* $Revision: 1.7 $ */
65/* $Date: 2006/11/26 01:45:14 $ */
66