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/*
* Copyright (C) 2012-2013 Tobias Brunner
* Copyright (C) 2012 Giuliano Grassi
* Copyright (C) 2012 Ralf Sager
* 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 esp_context esp_context
* @{ @ingroup libipsec
*/
#ifndef ESP_CONTEXT_H_
#define ESP_CONTEXT_H_
#include <library.h>
#include <crypto/aead.h>
typedef struct esp_context_t esp_context_t;
/**
* ESP context, handles sequence numbers and maintains cryptographic primitives
*/
struct esp_context_t {
/**
* Get AEAD wrapper or method to encrypt/decrypt/authenticate ESP packets.
*
* @return AEAD wrapper of method
*/
aead_t *(*get_aead)(esp_context_t *this);
/**
* Get the current outbound ESP sequence number or the highest authenticated
* inbound sequence number.
*
* @return current sequence number, in host byte order
*/
uint32_t (*get_seqno)(esp_context_t *this);
/**
* Allocate the next outbound ESP sequence number.
*
* @param seqno the sequence number, in host byte order
* @return FALSE if the sequence number cycled or inbound context
*/
bool (*next_seqno)(esp_context_t *this, uint32_t *seqno);
/**
* Verify an ESP sequence number. Checks whether a packet with this
* sequence number was already received, using the anti-replay window.
* This operation does not modify the internal state. After the sequence
* number is successfully verified and the ESP packet is authenticated,
* set_authenticated_seqno() should be called.
*
* @param seqno the sequence number to verify, in host byte order
* @return TRUE when sequence number is valid
*/
bool (*verify_seqno)(esp_context_t *this, uint32_t seqno);
/**
* Adds a sequence number that was successfully verified and
* authenticated. A user MUST call verify_seqno() immediately before
* calling this method.
*
* @param seqno verified and authenticated seq number in host byte order
*/
void (*set_authenticated_seqno)(esp_context_t *this,
uint32_t seqno);
/**
* Destroy an esp_context_t
*/
void (*destroy)(esp_context_t *this);
};
/**
* Create an esp_context_t instance
*
* @param enc_alg encryption algorithm
* @param enc_key encryption key
* @param int_alg integrity protection algorithm
* @param int_key integrity protection key
* @param inbound TRUE to create an inbound ESP context
* @return ESP context instance, or NULL if creation fails
*/
esp_context_t *esp_context_create(int enc_alg, chunk_t enc_key, int int_alg,
chunk_t int_key, bool inbound);
#endif /** ESP_CONTEXT_H_ @}*/
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