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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com
*/
#include "tomcrypt.h"
/**
@file ofb_encrypt.c
OFB implementation, encrypt data, Tom St Denis
*/
#ifdef LTC_OFB_MODE
/**
OFB encrypt
@param pt Plaintext
@param ct [out] Ciphertext
@param len Length of plaintext (octets)
@param ofb OFB state
@return CRYPT_OK if successful
*/
int ofb_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_OFB *ofb)
{
int err;
LTC_ARGCHK(pt != NULL);
LTC_ARGCHK(ct != NULL);
LTC_ARGCHK(ofb != NULL);
if ((err = cipher_is_valid(ofb->cipher)) != CRYPT_OK) {
return err;
}
/* is blocklen/padlen valid? */
if (ofb->blocklen < 0 || ofb->blocklen > (int)sizeof(ofb->IV) ||
ofb->padlen < 0 || ofb->padlen > (int)sizeof(ofb->IV)) {
return CRYPT_INVALID_ARG;
}
while (len-- > 0) {
if (ofb->padlen == ofb->blocklen) {
if ((err = cipher_descriptor[ofb->cipher].ecb_encrypt(ofb->IV, ofb->IV, &ofb->key)) != CRYPT_OK) {
return err;
}
ofb->padlen = 0;
}
*ct++ = *pt++ ^ ofb->IV[(ofb->padlen)++];
}
return CRYPT_OK;
}
#endif
/* $Source: /cvs/libtom/libtomcrypt/src/modes/ofb/ofb_encrypt.c,v $ */
/* $Revision: 1.7 $ */
/* $Date: 2006/11/26 01:45:14 $ */
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