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/**
* @file hasher.h
*
* @brief Generic interface for hash functions
*
*/
/*
* 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.
*/
#ifndef HASHER_H_
#define HASHER_H_
#include <types.h>
typedef enum hash_algorithm_t hash_algorithm_t;
/**
* algorithms to use for hashing
*/
enum hash_algorithm_t {
HASH_SHA1,
HASH_MD5
};
typedef struct hasher_t hasher_t;
/**
* Object representing a hasher
*/
struct hasher_t {
/**
* @brief hash data and write it in the buffer
*
* If the parameter hash is NULL, no result is written back
* an more data can be appended to already hashed data.
* If not, the result is written back and the hasher is reset.
*
* @warning: the hash output parameter must hold at least
* #hash_t.get_block_size bytes.
*
* @param this calling hasher
* @param data data to hash
* @param [out]buffer pointer where the hash will be written
* @return
* - SUCCESS in any case
*/
status_t (*get_hash) (hasher_t *this, chunk_t data, u_int8_t *hash);
/**
* @brief hash data and allocate space for the hash
*
* If the parameter hash is NULL, no result is written back
* an more data can be appended to already hashed data.
* If not, the result is written back and the hasher is reset.
*
* @param this calling hasher
* @param data chunk with data to hash
* @param [out]hash chunk which will hold allocated hash
* @return
* - SUCCESS in any case
* - OUT_OF_RES if space could not be allocated
*/
status_t (*allocate_hash) (hasher_t *this, chunk_t data, chunk_t *hash);
/**
* @brief get the block size of this hashing function
*
* @param this calling hasher
* @return block size in bytes
*/
size_t (*get_block_size) (hasher_t *this);
/**
* @brief reset the hashers state, which allows
* computation of a completly new hash.
*
* @param this calling hasher
* @return - SUCCESS in any case
*/
status_t (*reset) (hasher_t *this);
/**
* @brief Destroys a hasher object.
*
* @param this hasher_t object to destroy
* @return
* SUCCESS in any case
*/
status_t (*destroy) (hasher_t *this);
};
/**
* Creates a new hasher_t object
*
* @param hash_algorithm Algorithm to use for hashing
* @return
* - hasher_t if successfully
* - NULL if out of ressources
*/
hasher_t *hasher_create(hash_algorithm_t hash_algorithm);
#endif /*HASHER_H_*/
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