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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@iahu.ca, http://libtomcrypt.org
*/
#include "mycrypt.h"
#ifdef CTR
int ctr_start(int cipher, const unsigned char *count, const unsigned char *key, int keylen,
int num_rounds, symmetric_CTR *ctr)
{
int x, err;
_ARGCHK(count != NULL);
_ARGCHK(key != NULL);
_ARGCHK(ctr != NULL);
/* bad param? */
if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
return err;
}
/* setup cipher */
if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ctr->key)) != CRYPT_OK) {
return err;
}
/* copy ctr */
ctr->blocklen = cipher_descriptor[cipher].block_length;
ctr->cipher = cipher;
ctr->padlen = 0;
ctr->mode = 0;
for (x = 0; x < ctr->blocklen; x++) {
ctr->ctr[x] = count[x];
}
cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key);
return CRYPT_OK;
}
#endif
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