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/**
* @file hmac_signer.c
*
* @brief Implementation of hmac_signer_t.
*
*/
/*
* Copyright (C) 2005-2006 Martin Willi
* Copyright (C) 2005 Jan Hutter
* 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 "hmac_signer.h"
#include <crypto/prfs/hmac_prf.h>
typedef struct private_hmac_signer_t private_hmac_signer_t;
/**
* Private data structure with signing context.
*/
struct private_hmac_signer_t {
/**
* Public interface of hmac_signer_t.
*/
hmac_signer_t public;
/**
* Assigned hmac function.
*/
prf_t *hmac_prf;
/**
* Block size (truncation of HMAC Hash)
*/
size_t block_size;
};
/**
* Implementation of signer_t.get_signature.
*/
static void get_signature (private_hmac_signer_t *this, chunk_t data, u_int8_t *buffer)
{
u_int8_t full_mac[this->hmac_prf->get_block_size(this->hmac_prf)];
this->hmac_prf->get_bytes(this->hmac_prf, data, full_mac);
/* copy MAC depending on truncation */
memcpy(buffer, full_mac, this->block_size);
}
/**
* Implementation of signer_t.allocate_signature.
*/
static void allocate_signature (private_hmac_signer_t *this, chunk_t data, chunk_t *chunk)
{
chunk_t signature;
u_int8_t full_mac[this->hmac_prf->get_block_size(this->hmac_prf)];
this->hmac_prf->get_bytes(this->hmac_prf,data,full_mac);
signature.ptr = malloc(this->block_size);
signature.len = this->block_size;
/* copy signature */
memcpy(signature.ptr, full_mac, this->block_size);
*chunk = signature;
}
/**
* Implementation of signer_t.verify_signature.
*/
static bool verify_signature(private_hmac_signer_t *this, chunk_t data, chunk_t signature)
{
u_int8_t full_mac[this->hmac_prf->get_block_size(this->hmac_prf)];
this->hmac_prf->get_bytes(this->hmac_prf, data, full_mac);
if (signature.len != this->block_size)
{
return FALSE;
}
/* compare mac aka signature :-) */
if (memcmp(signature.ptr, full_mac, this->block_size) == 0)
{
return TRUE;
}
else
{
return FALSE;
}
}
/**
* Implementation of signer_t.get_key_size.
*/
static size_t get_key_size(private_hmac_signer_t *this)
{
/* for HMAC signer, IKEv2 uses block size as key size */
return this->hmac_prf->get_block_size(this->hmac_prf);
}
/**
* Implementation of signer_t.get_block_size.
*/
static size_t get_block_size(private_hmac_signer_t *this)
{
return this->block_size;
}
/**
* Implementation of signer_t.set_key.
*/
static void set_key(private_hmac_signer_t *this, chunk_t key)
{
this->hmac_prf->set_key(this->hmac_prf, key);
}
/**
* Implementation of signer_t.destroy.
*/
static status_t destroy(private_hmac_signer_t *this)
{
this->hmac_prf->destroy(this->hmac_prf);
free(this);
return SUCCESS;
}
/*
* Described in header
*/
hmac_signer_t *hmac_signer_create(hash_algorithm_t hash_algoritm, size_t block_size)
{
size_t hmac_block_size;
private_hmac_signer_t *this = malloc_thing(private_hmac_signer_t);
this->hmac_prf = (prf_t *) hmac_prf_create(hash_algoritm);
if (this->hmac_prf == NULL)
{
/* algorithm not supported */
free(this);
return NULL;
}
/* prevent invalid truncation */
hmac_block_size = this->hmac_prf->get_block_size(this->hmac_prf);
this->block_size = min(block_size, hmac_block_size);
/* 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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