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/*
* Copyright (C) 2012 Tobias Brunner
* Hochschule fuer Technik Rapperswil
*
* 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 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* 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.
*/
#include <string.h>
#include "cmac_signer.h"
#include "cmac.h"
typedef struct private_cmac_signer_t private_cmac_signer_t;
/**
* Private data structure with signing context.
*/
struct private_cmac_signer_t {
/**
* Public interface.
*/
cmac_signer_t public;
/**
* Assigned cmac function.
*/
cmac_t *cmac;
/**
* Block size (truncation of CMAC MAC)
*/
size_t block_size;
};
METHOD(signer_t, get_signature, void,
private_cmac_signer_t *this, chunk_t data, u_int8_t *buffer)
{
if (buffer == NULL)
{ /* append mode */
this->cmac->get_mac(this->cmac, data, NULL);
}
else
{
u_int8_t mac[this->cmac->get_block_size(this->cmac)];
this->cmac->get_mac(this->cmac, data, mac);
memcpy(buffer, mac, this->block_size);
}
}
METHOD(signer_t, allocate_signature, void,
private_cmac_signer_t *this, chunk_t data, chunk_t *chunk)
{
if (chunk == NULL)
{ /* append mode */
this->cmac->get_mac(this->cmac, data, NULL);
}
else
{
u_int8_t mac[this->cmac->get_block_size(this->cmac)];
this->cmac->get_mac(this->cmac, data, mac);
chunk->ptr = malloc(this->block_size);
chunk->len = this->block_size;
memcpy(chunk->ptr, mac, this->block_size);
}
}
METHOD(signer_t, verify_signature, bool,
private_cmac_signer_t *this, chunk_t data, chunk_t signature)
{
u_int8_t mac[this->cmac->get_block_size(this->cmac)];
if (signature.len != this->block_size)
{
return FALSE;
}
this->cmac->get_mac(this->cmac, data, mac);
return memeq(signature.ptr, mac, this->block_size);
}
METHOD(signer_t, get_key_size, size_t,
private_cmac_signer_t *this)
{
return this->cmac->get_block_size(this->cmac);
}
METHOD(signer_t, get_block_size, size_t,
private_cmac_signer_t *this)
{
return this->block_size;
}
METHOD(signer_t, set_key, void,
private_cmac_signer_t *this, chunk_t key)
{
this->cmac->set_key(this->cmac, key);
}
METHOD(signer_t, destroy, void,
private_cmac_signer_t *this)
{
this->cmac->destroy(this->cmac);
free(this);
}
/*
* Described in header
*/
cmac_signer_t *cmac_signer_create(integrity_algorithm_t algo)
{
private_cmac_signer_t *this;
size_t truncation;
cmac_t *cmac;
switch (algo)
{
case AUTH_AES_CMAC_96:
cmac = cmac_create(ENCR_AES_CBC, 16);
truncation = 12;
break;
default:
return NULL;
}
if (cmac == NULL)
{
return NULL;
}
INIT(this,
.public = {
.signer = {
.get_signature = _get_signature,
.allocate_signature = _allocate_signature,
.verify_signature = _verify_signature,
.get_key_size = _get_key_size,
.get_block_size = _get_block_size,
.set_key = _set_key,
.destroy = _destroy,
},
},
.cmac = cmac,
.block_size = min(truncation, cmac->get_block_size(cmac)),
);
return &this->public;
}
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