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/**
* @file hmac_signer.c
*
* @brief Implementation of hmac_signer_t.
*
*/
/*
* Copyright (C) 2005 Jan Hutter, 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.
*/
#include "hmac_signer.h"
#include <utils/allocator.h>
#include <transforms/prfs/hmac_prf.h>
/**
* This class represents a hmac signer with 12 byte (96 bit) output
*/
#define BLOCK_SIZE 12
typedef struct private_hmac_signer_t private_hmac_signer_t;
/**
* private data structure with signing context.
*/
struct private_hmac_signer_t {
/**
* Public interface for this signer.
*/
hmac_signer_t public;
/*
* Assigned hmac function.
*/
prf_t *hmac_prf;
};
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 aka signature :-) */
memcpy(buffer,full_mac,BLOCK_SIZE);
}
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 = allocator_alloc(BLOCK_SIZE);
signature.len = BLOCK_SIZE;
/* copy mac aka signature :-) */
memcpy(signature.ptr,full_mac,BLOCK_SIZE);
*chunk = signature;
}
static void verify_signature (private_hmac_signer_t *this, chunk_t data, chunk_t signature, bool *valid)
{
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 != BLOCK_SIZE)
{
*valid = FALSE;
return;
}
/* compare mac aka signature :-) */
if (memcmp(signature.ptr,full_mac,BLOCK_SIZE) == 0)
{
*valid = TRUE;
}
else
{
*valid = FALSE;
}
}
static size_t get_block_size (private_hmac_signer_t *this)
{
return BLOCK_SIZE;
}
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);
allocator_free(this);
return SUCCESS;
}
/*
* Described in header
*/
hmac_signer_t *hmac_signer_create(hash_algorithm_t hash_algoritm)
{
private_hmac_signer_t *this = allocator_alloc_thing(private_hmac_signer_t);
this->hmac_prf = (prf_t *) hmac_prf_create(hash_algoritm);
if (this->hmac_prf == NULL)
{
/* algorithm not supported */
allocator_free(this);
return NULL;
}
/* 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 = (void (*) (signer_t*, chunk_t, chunk_t,bool *))verify_signature;
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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