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/**
* @file hmac.h
*
* @brief Interface of hmac_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.
*/
#ifndef HMAC_H_
#define HMAC_H_
typedef struct hmac_t hmac_t;
#include <crypto/hashers/hasher.h>
/**
* @brief Message authentication using hash functions.
*
* This class implements the message authenticaion algorithm
* described in RFC2104. It uses a hash function, wich must
* be implemented as a hasher_t class.
*
* See http://www.faqs.org/rfcs/rfc2104.html for RFC.
* @see
* - hasher_t
* - prf_hmac_t
*
* @b Constructors:
* - hmac_create()
*
* @ingroup crypto
*/
struct hmac_t {
/**
* @brief Generate message authentication code.
*
* If buffer is NULL, no result is given back. A next call will
* append the data to already supplied data. If buffer is not NULL,
* the mac of all apended data is calculated, returned and the
* state of the hmac_t is reseted.
*
* @param this calling object
* @param data chunk of data to authenticate
* @param[out] buffer pointer where the generated bytes will be written
*/
void (*get_mac) (hmac_t *this, chunk_t data, u_int8_t *buffer);
/**
* @brief Generates message authentication code and
* allocate space for them.
*
* If chunk is NULL, no result is given back. A next call will
* append the data to already supplied. If chunk is not NULL,
* the mac of all apended data is calculated, returned and the
* state of the hmac_t reset;
*
* @param this calling object
* @param data chunk of data to authenticate
* @param[out] chunk chunk which will hold generated bytes
*/
void (*allocate_mac) (hmac_t *this, chunk_t data, chunk_t *chunk);
/**
* @brief Get the block size of this hmac_t object.
*
* @param this calling object
* @return block size in bytes
*/
size_t (*get_block_size) (hmac_t *this);
/**
* @brief Set the key for this hmac_t object.
*
* Any key length is accepted.
*
* @param this calling object
* @param key key to set
*/
void (*set_key) (hmac_t *this, chunk_t key);
/**
* @brief Destroys a hmac_t object.
*
* @param this calling object
*/
void (*destroy) (hmac_t *this);
};
/**
* @brief Creates a new hmac_t object.
*
* Creates a hasher_t object internally.
*
* @param hash_algorithm hash algorithm to use
* @return
* - hmac_t object
* - NULL if hash algorithm is not supported
*
* @ingroup transforms
*/
hmac_t *hmac_create(hash_algorithm_t hash_algorithm);
#endif /*HMAC_H_*/
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