crypt.c
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/**
* crypt.c: pseudo OO wrapper around libmcrypt.
* Copyright (C) 2011 Georg Hopp
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdarg.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <mcrypt.h>
#include <mhash.h>
#include "token/cclass.h"
#include "token/crypt.h"
INIT_CCLASS(CRYPT);
__construct(CRYPT)
{
_this->algorithm = va_arg(* params, const char * const);
_this->mode = va_arg(* params, const char * const);
_this->mcrypt = mcrypt_module_open(
(char *)_this->algorithm,
NULL,
(char *)_this->mode,
NULL);
_this->ivsize = mcrypt_enc_get_iv_size(_this->mcrypt);
_this->keysize = mcrypt_enc_get_key_size(_this->mcrypt);
}
__destruct(CRYPT)
{
if (_this->iv) {
free(_this->iv);
}
mcrypt_module_close(_this->mcrypt);
}
__jsonConst(CRYPT) {}
__toJson(CRYPT) {}
__clear(CRYPT) {}
void *
crypt_createIv(CRYPT _this)
{
int urandom;
size_t rsize = 0;
void * iv = NULL;
iv = calloc(_this->ivsize, sizeof(char));
urandom = open("/dev/urandom", O_RDONLY);
rsize = read(urandom, iv, _this->ivsize);
if (_this->ivsize != rsize) {
free(iv);
iv = NULL;
}
return iv;
}
static
void *
createKey(CRYPT _this, const char * const password)
{
void * key = NULL;
key = calloc(_this->keysize, sizeof(char));
mhash_keygen(
KEYGEN_MCRYPT,
MHASH_SHA256,
mhash_keygen_count(),
key,
_this->keysize,
NULL,
0,
(mutils_word8 *)password, // @TODO: bad karma...this might change password.
strlen(password));
return key;
}
void *
crypt_encrypt(
CRYPT _this,
const void * const data,
const char * const password,
size_t * length)
{
char * encrypted;
void * iv;
void * key;
key = createKey(_this, password);
if(_this->iv) {
iv = _this->iv;
} else {
iv = crypt_createIv(_this);
}
mcrypt_generic_init(_this->mcrypt, key, _this->keysize, iv);
encrypted = calloc(_this->ivsize + *length, sizeof(char));
memcpy(encrypted, iv, _this->ivsize);
memcpy(encrypted + _this->ivsize, data, *length);
mcrypt_generic(_this->mcrypt, encrypted + _this->ivsize, *length);
mcrypt_generic_deinit(_this->mcrypt);
*length += _this->ivsize;
free(key);
if (_this->iv != iv) {
free(iv);
}
return encrypted;
}
void *
crypt_decrypt(
CRYPT _this,
const void * const data,
const char * const password,
size_t * length)
{
char * decrypted;
void * iv;
void * key;
key = createKey(_this, password);
iv = calloc(_this->ivsize, sizeof(char));
memcpy(iv, data, _this->ivsize);
mcrypt_generic_init(_this->mcrypt, key, _this->keysize, iv);
*length -= _this->ivsize;
decrypted = calloc(*length, sizeof(char));
memcpy(decrypted, data + _this->ivsize, *length);
mdecrypt_generic(_this->mcrypt, decrypted, *length);
mcrypt_generic_deinit(_this->mcrypt);
free(key);
free(iv);
return decrypted;
}
// vim: set et ts=4 sw=4: