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/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single TCP/UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
* Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* @file Data Channel Cryptography SSL library-specific backend interface
*/
#ifndef CRYPTO_BACKEND_H_
#define CRYPTO_BACKEND_H_
#include "config.h"
#ifdef USE_OPENSSL
#include "crypto_openssl.h"
#endif
#include "basic.h"
void show_available_ciphers (void);
void show_available_digests (void);
void show_available_engines (void);
/*
*
* Random number functions, used in cases where we want
* reasonably strong cryptographic random number generation
* without depleting our entropy pool. Used for random
* IV values and a number of other miscellaneous tasks.
*
*/
/**
* Wrapper for secure random number generator. Retrieves len bytes of random
* data, and places it in output.
*
* @param output Output buffer
* @param len Length of the output buffer, in bytes
*
* @return \c 1 on success, \c 0 on failure
*/
int rand_bytes (uint8_t *output, int len);
/*
*
* Generic cipher key type functions
*
*/
/*
* Max size in bytes of any cipher key that might conceivably be used.
*
* This value is checked at compile time in crypto.c to make sure
* it is always at least EVP_MAX_KEY_LENGTH.
*
* We define our own value, since this parameter
* is used to control the size of static key files.
* If the OpenSSL library increases EVP_MAX_KEY_LENGTH,
* we don't want our key files to be suddenly rendered
* unusable.
*/
#define MAX_CIPHER_KEY_LENGTH 64
/*
*
* Generic message digest information functions
*
*/
/*
* Max size in bytes of any HMAC key that might conceivably be used.
*
* This value is checked at compile time in crypto.c to make sure
* it is always at least EVP_MAX_MD_SIZE. We define our own value
* for the same reason as above.
*/
#define MAX_HMAC_KEY_LENGTH 64
#endif /* CRYPTO_BACKEND_H_ */
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