87 lines
2.6 KiB
C
87 lines
2.6 KiB
C
|
/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
|
||
|
|
/* SPDX-License-Identifier: Unlicense */
|
||
|
|
#include "tomcrypt_private.h"
|
||
|
|
|
||
|
|
/**
|
||
|
|
@file f8_start.c
|
||
|
|
F8 implementation, start chain, Tom St Denis
|
||
|
|
*/
|
||
|
|
|
||
|
|
|
||
|
|
#ifdef LTC_F8_MODE
|
||
|
|
|
||
|
|
/**
|
||
|
|
Initialize an F8 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 salt_key The salting key for the IV
|
||
|
|
@param skeylen The length of the salting key (octets)
|
||
|
|
@param num_rounds Number of rounds in the cipher desired (0 for default)
|
||
|
|
@param f8 The F8 state to initialize
|
||
|
|
@return CRYPT_OK if successful
|
||
|
|
*/
|
||
|
|
int f8_start( int cipher, const unsigned char *IV,
|
||
|
|
const unsigned char *key, int keylen,
|
||
|
|
const unsigned char *salt_key, int skeylen,
|
||
|
|
int num_rounds, symmetric_F8 *f8)
|
||
|
|
{
|
||
|
|
int x, err;
|
||
|
|
unsigned char tkey[MAXBLOCKSIZE];
|
||
|
|
|
||
|
|
LTC_ARGCHK(IV != NULL);
|
||
|
|
LTC_ARGCHK(key != NULL);
|
||
|
|
LTC_ARGCHK(salt_key != NULL);
|
||
|
|
LTC_ARGCHK(f8 != NULL);
|
||
|
|
|
||
|
|
if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
|
||
|
|
return err;
|
||
|
|
}
|
||
|
|
|
||
|
|
#ifdef LTC_FAST
|
||
|
|
if (cipher_descriptor[cipher].block_length % sizeof(LTC_FAST_TYPE)) {
|
||
|
|
return CRYPT_INVALID_ARG;
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/* copy details */
|
||
|
|
f8->blockcnt = 0;
|
||
|
|
f8->cipher = cipher;
|
||
|
|
f8->blocklen = cipher_descriptor[cipher].block_length;
|
||
|
|
f8->padlen = f8->blocklen;
|
||
|
|
|
||
|
|
/* now get key ^ salt_key [extend salt_ket with 0x55 as required to match length] */
|
||
|
|
zeromem(tkey, sizeof(tkey));
|
||
|
|
for (x = 0; x < keylen && x < (int)sizeof(tkey); x++) {
|
||
|
|
tkey[x] = key[x];
|
||
|
|
}
|
||
|
|
for (x = 0; x < skeylen && x < (int)sizeof(tkey); x++) {
|
||
|
|
tkey[x] ^= salt_key[x];
|
||
|
|
}
|
||
|
|
for (; x < keylen && x < (int)sizeof(tkey); x++) {
|
||
|
|
tkey[x] ^= 0x55;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* now encrypt with tkey[0..keylen-1] the IV and use that as the IV */
|
||
|
|
if ((err = cipher_descriptor[cipher].setup(tkey, keylen, num_rounds, &f8->key)) != CRYPT_OK) {
|
||
|
|
return err;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* encrypt IV */
|
||
|
|
if ((err = cipher_descriptor[f8->cipher].ecb_encrypt(IV, f8->MIV, &f8->key)) != CRYPT_OK) {
|
||
|
|
cipher_descriptor[f8->cipher].done(&f8->key);
|
||
|
|
return err;
|
||
|
|
}
|
||
|
|
zeromem(tkey, sizeof(tkey));
|
||
|
|
zeromem(f8->IV, sizeof(f8->IV));
|
||
|
|
|
||
|
|
/* terminate this cipher */
|
||
|
|
cipher_descriptor[f8->cipher].done(&f8->key);
|
||
|
|
|
||
|
|
/* init the cipher */
|
||
|
|
return cipher_descriptor[cipher].setup(key, keylen, num_rounds, &f8->key);
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif
|