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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://libtom.org
*/
#include "tomcrypt.h"
/**
@file ofb_start.c
OFB implementation, start chain, Tom St Denis
*/
#ifdef LTC_OFB_MODE
/**
Initialize a OFB context
@param cipher The index of the cipher desired
@param IV The initial vector
@param key The secret key
@param keylen The length of the secret key (octets)
@param num_rounds Number of rounds in the cipher desired (0 for default)
@param ofb The OFB state to initialize
@return CRYPT_OK if successful
*/
int ofb_start(int cipher, const unsigned char *IV, const unsigned char *key,
int keylen, int num_rounds, symmetric_OFB *ofb)
{
int x, err;
LTC_ARGCHK(IV != NULL);
LTC_ARGCHK(key != NULL);
LTC_ARGCHK(ofb != NULL);
if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
return err;
}
/* copy details */
ofb->cipher = cipher;
ofb->blocklen = cipher_descriptor[cipher].block_length;
for (x = 0; x < ofb->blocklen; x++) {
ofb->IV[x] = IV[x];
}
/* init the cipher */
ofb->padlen = ofb->blocklen;
return cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ofb->key);
}
#endif
/* $Source$ */
/* $Revision$ */
/* $Date$ */
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