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