/*
 * Copyright (C) 2018 Tobias Brunner
 * Copyright (C) 2005-2006 Martin Willi
 * Copyright (C) 2005 Jan Hutter
 * HSR 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.
 */

/**
 * @defgroup prf prf
 * @{ @ingroup crypto
 */

#ifndef PRF_H_
#define PRF_H_

typedef enum pseudo_random_function_t pseudo_random_function_t;
typedef struct prf_t prf_t;

#include <utils/utils.h>
#include <utils/chunk.h>

/**
 * Pseudo random function, as in IKEv2 RFC 3.3.2.
 *
 * PRF algorithms not defined in IKEv2 are allocated in "private use" space.
 */
enum pseudo_random_function_t {
	PRF_UNDEFINED = 1024,
	/** RFC2104 */
	PRF_HMAC_MD5 = 1,
	/** RFC2104 */
	PRF_HMAC_SHA1 = 2,
	/** RFC2104 */
	PRF_HMAC_TIGER = 3,
	/** RFC4434 */
	PRF_AES128_XCBC = 4,
	/** RFC4868 */
	PRF_HMAC_SHA2_256 = 5,
	/** RFC4868. */
	PRF_HMAC_SHA2_384 = 6,
	/** RFC4868 */
	PRF_HMAC_SHA2_512 = 7,
	/** RFC4615 */
	PRF_AES128_CMAC = 8,
	/** FIPS 186-2-change1 */
	PRF_FIPS_SHA1_160 = 1025,
	/** FIPS 186-2-change1, uses fixed output size of 160bit */
	PRF_FIPS_DES = 1026,
	/** Keyed hash algorithm using SHA1, used in EAP-AKA:
	 * This PRF uses SHA1, but XORs the key into the IV. No "Final()" operation
	 * is applied to the SHA1 state. */
	PRF_KEYED_SHA1 = 1027,
	/** draft-kanno-ipsecme-camellia-xcbc, not yet assigned by IANA */
	PRF_CAMELLIA128_XCBC = 1028,
};

/**
 * enum name for encryption_algorithm_t.
 */
extern enum_name_t *pseudo_random_function_names;

/**
 * Generic interface for pseudo-random-functions.
 */
struct prf_t {

	/**
	 * Generates pseudo random bytes and writes them in the buffer.
	 *
	 * @param seed		a chunk containing the seed for the next bytes
	 * @param buffer	pointer where the generated bytes will be written
	 * @return			TRUE if bytes generated successfully
	 */
	bool (*get_bytes)(prf_t *this, chunk_t seed,
					  uint8_t *buffer) __attribute__((warn_unused_result));

	/**
	 * Generates pseudo random bytes and allocate space for them.
	 *
	 * @param seed		a chunk containing the seed for the next bytes
	 * @param chunk		chunk which will hold generated bytes
	 * @return			TRUE if bytes allocated and generated successfully
	 */
	bool (*allocate_bytes)(prf_t *this, chunk_t seed,
						   chunk_t *chunk) __attribute__((warn_unused_result));

	/**
	 * Get the block size of this prf_t object.
	 *
	 * @return			block size in bytes
	 */
	size_t (*get_block_size)(prf_t *this);

	/**
	 * Get the key size of this prf_t object.
	 *
	 * This is a suggestion only, all implemented PRFs accept variable key
	 * length.
	 *
	 * @return			key size in bytes
	 */
	size_t (*get_key_size)(prf_t *this);

	/**
	 * Set the key for this prf_t object.
	 *
	 * @param key		key to set
	 * @return			TRUE if key set successfully
	 */
	bool (*set_key)(prf_t *this,
					chunk_t key) __attribute__((warn_unused_result));

	/**
	 * Destroys a prf object.
	 */
	void (*destroy)(prf_t *this);
};

/**
 * Conversion of ASN.1 OID to PRF algorithm.
 *
 * @param oid			ASN.1 OID
 * @return				encryption algorithm, PRF_UNDEFINED if OID unsupported
 */
pseudo_random_function_t pseudo_random_function_from_oid(int oid);

#endif /** PRF_H_ @}*/
