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/*
* Copyright (C) 2008 Martin Willi
* 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.
*
* $Id$
*/
#include <string.h>
#include "xcbc_signer.h"
#include "xcbc.h"
typedef struct private_xcbc_signer_t private_xcbc_signer_t;
/**
* Private data structure with signing context.
*/
struct private_xcbc_signer_t {
/**
* Public interface of xcbc_signer_t.
*/
xcbc_signer_t public;
/**
* Assigned xcbc function.
*/
xcbc_t *xcbc;
/**
* Block size (truncation of XCBC MAC)
*/
size_t block_size;
};
/**
* Implementation of signer_t.get_signature.
*/
static void get_signature(private_xcbc_signer_t *this,
chunk_t data, u_int8_t *buffer)
{
if (buffer == NULL)
{ /* append mode */
this->xcbc->get_mac(this->xcbc, data, NULL);
}
else
{
u_int8_t mac[this->xcbc->get_block_size(this->xcbc)];
this->xcbc->get_mac(this->xcbc, data, mac);
memcpy(buffer, mac, this->block_size);
}
}
/**
* Implementation of signer_t.allocate_signature.
*/
static void allocate_signature (private_xcbc_signer_t *this,
chunk_t data, chunk_t *chunk)
{
if (chunk == NULL)
{ /* append mode */
this->xcbc->get_mac(this->xcbc, data, NULL);
}
else
{
u_int8_t mac[this->xcbc->get_block_size(this->xcbc)];
this->xcbc->get_mac(this->xcbc, data, mac);
chunk->ptr = malloc(this->block_size);
chunk->len = this->block_size;
memcpy(chunk->ptr, mac, this->block_size);
}
}
/**
* Implementation of signer_t.verify_signature.
*/
static bool verify_signature(private_xcbc_signer_t *this,
chunk_t data, chunk_t signature)
{
u_int8_t mac[this->xcbc->get_block_size(this->xcbc)];
if (signature.len != this->block_size)
{
return FALSE;
}
this->xcbc->get_mac(this->xcbc, data, mac);
return memeq(signature.ptr, mac, this->block_size);
}
/**
* Implementation of signer_t.get_key_size.
*/
static size_t get_key_size(private_xcbc_signer_t *this)
{
return this->xcbc->get_block_size(this->xcbc);
}
/**
* Implementation of signer_t.get_block_size.
*/
static size_t get_block_size(private_xcbc_signer_t *this)
{
return this->block_size;
}
/**
* Implementation of signer_t.set_key.
*/
static void set_key(private_xcbc_signer_t *this, chunk_t key)
{
this->xcbc->set_key(this->xcbc, key);
}
/**
* Implementation of signer_t.destroy.
*/
static status_t destroy(private_xcbc_signer_t *this)
{
this->xcbc->destroy(this->xcbc);
free(this);
return SUCCESS;
}
/*
* Described in header
*/
xcbc_signer_t *xcbc_signer_create(integrity_algorithm_t algo)
{
private_xcbc_signer_t *this;
size_t trunc;
xcbc_t *xcbc;
switch (algo)
{
case AUTH_AES_XCBC_96:
xcbc = xcbc_create(ENCR_AES_CBC, 16);
trunc = 12;
break;
default:
return NULL;
}
if (xcbc == NULL)
{
return NULL;
}
this = malloc_thing(private_xcbc_signer_t);
this->xcbc = xcbc;
this->block_size = min(trunc, xcbc->get_block_size(xcbc));
/* interface functions */
this->public.signer_interface.get_signature = (void (*) (signer_t*, chunk_t, u_int8_t*))get_signature;
this->public.signer_interface.allocate_signature = (void (*) (signer_t*, chunk_t, chunk_t*))allocate_signature;
this->public.signer_interface.verify_signature = (bool (*) (signer_t*, chunk_t, chunk_t))verify_signature;
this->public.signer_interface.get_key_size = (size_t (*) (signer_t*))get_key_size;
this->public.signer_interface.get_block_size = (size_t (*) (signer_t*))get_block_size;
this->public.signer_interface.set_key = (void (*) (signer_t*,chunk_t))set_key;
this->public.signer_interface.destroy = (void (*) (signer_t*))destroy;
return &this->public;
}
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