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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.
*/
#include "tomcrypt.h"
/**
@file cfb_start.c
CFB implementation, start chain, Tom St Denis
*/
#ifdef LTC_CFB_MODE
/**
Initialize a CFB context
@param cipher The index of the cipher desired
@param IV The initialization 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 cfb The CFB state to initialize
@return CRYPT_OK if successful
*/
int cfb_start(int cipher, const unsigned char *IV, const unsigned char *key,
int keylen, int num_rounds, symmetric_CFB *cfb)
{
int x, err;
LTC_ARGCHK(IV != NULL);
LTC_ARGCHK(key != NULL);
LTC_ARGCHK(cfb != NULL);
if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
return err;
}
/* copy data */
cfb->cipher = cipher;
cfb->blocklen = cipher_descriptor[cipher].block_length;
for (x = 0; x < cfb->blocklen; x++)
cfb->IV[x] = IV[x];
/* init the cipher */
if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &cfb->key)) != CRYPT_OK) {
return err;
}
/* encrypt the IV */
cfb->padlen = 0;
return cipher_descriptor[cfb->cipher].ecb_encrypt(cfb->IV, cfb->IV, &cfb->key);
}
#endif
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */
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