mirror of
https://github.com/clearml/dropbear
synced 2025-06-26 18:17:32 +00:00
a938f4cfe1
to branch 'au.asn.ucc.matt.dropbear' (head 02c413252c90e9de8e03d91e9939dde3029f5c0a) --HG-- extra : convert_revision : 52ccb0ad0587a62bc64aecb939adbb76546aac16
92 lines
2.6 KiB
C
92 lines
2.6 KiB
C
/* 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 ctr_start.c
|
|
CTR implementation, start chain, Tom St Denis
|
|
*/
|
|
|
|
|
|
#ifdef LTC_CTR_MODE
|
|
|
|
/**
|
|
Initialize a CTR 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 ctr_mode The counter mode (CTR_COUNTER_LITTLE_ENDIAN or CTR_COUNTER_BIG_ENDIAN)
|
|
@param ctr The CTR state to initialize
|
|
@return CRYPT_OK if successful
|
|
*/
|
|
int ctr_start( int cipher,
|
|
const unsigned char *IV,
|
|
const unsigned char *key, int keylen,
|
|
int num_rounds, int ctr_mode,
|
|
symmetric_CTR *ctr)
|
|
{
|
|
int x, err;
|
|
|
|
LTC_ARGCHK(IV != NULL);
|
|
LTC_ARGCHK(key != NULL);
|
|
LTC_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 = ctr_mode & 1;
|
|
for (x = 0; x < ctr->blocklen; x++) {
|
|
ctr->ctr[x] = IV[x];
|
|
}
|
|
|
|
if (ctr_mode & LTC_CTR_RFC3686) {
|
|
/* increment the IV as per RFC 3686 */
|
|
if (ctr->mode == CTR_COUNTER_LITTLE_ENDIAN) {
|
|
/* little-endian */
|
|
for (x = 0; x < ctr->blocklen; x++) {
|
|
ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255;
|
|
if (ctr->ctr[x] != (unsigned char)0) {
|
|
break;
|
|
}
|
|
}
|
|
} else {
|
|
/* big-endian */
|
|
for (x = ctr->blocklen-1; x >= 0; x--) {
|
|
ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255;
|
|
if (ctr->ctr[x] != (unsigned char)0) {
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key);
|
|
}
|
|
|
|
#endif
|
|
|
|
/* $Source: /cvs/libtom/libtomcrypt/src/modes/ctr/ctr_start.c,v $ */
|
|
/* $Revision: 1.11 $ */
|
|
/* $Date: 2006/11/05 01:46:35 $ */
|