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/*
* RTMP Diffie-Hellmann utilities
* Copyright (c) 2012 Samuel Pitoiset
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVFORMAT_RTMPDH_H
#define AVFORMAT_RTMPDH_H
#include <stdint.h>
#include "config.h"
#if CONFIG_GMP
#include <gmp.h>
typedef mpz_ptr FFBigNum;
#elif CONFIG_GCRYPT
#include <gcrypt.h>
typedef gcry_mpi_t FFBigNum;
#elif CONFIG_OPENSSL
#include <openssl/bn.h>
#include <openssl/dh.h>
typedef BIGNUM *FFBigNum;
#endif
typedef struct FF_DH {
FFBigNum p;
FFBigNum g;
FFBigNum pub_key;
FFBigNum priv_key;
long length;
} FF_DH;
/**
* Initialize a Diffie-Hellmann context.
*
* @param key_len length of the key
* @return a new Diffie-Hellmann context on success, NULL otherwise
*/
FF_DH *ff_dh_init(int key_len);
/**
* Free a Diffie-Hellmann context.
*
* @param dh a Diffie-Hellmann context to free
*/
void ff_dh_free(FF_DH *dh);
/**
* Generate a public key.
*
* @param dh a Diffie-Hellmann context
* @return zero on success, negative value otherwise
*/
int ff_dh_generate_public_key(FF_DH *dh);
/**
* Write the public key into the given buffer.
*
* @param dh a Diffie-Hellmann context, containing the public key to write
* @param pub_key the buffer where the public key is written
* @param pub_key_len the length of the buffer
* @return zero on success, negative value otherwise
*/
int ff_dh_write_public_key(FF_DH *dh, uint8_t *pub_key, int pub_key_len);
/**
* Compute the shared secret key from the private FF_DH value and the
* other party's public value.
*
* @param dh a Diffie-Hellmann context, containing the private key
* @param pub_key the buffer containing the public key
* @param pub_key_len the length of the public key buffer
* @param secret_key the buffer where the secret key is written
* @param secret_key_len the length of the secret key buffer
* @return length of the shared secret key on success, negative value otherwise
*/
int ff_dh_compute_shared_secret_key(FF_DH *dh, const uint8_t *pub_key,
int pub_key_len, uint8_t *secret_key,
int secret_key_len);
#endif /* AVFORMAT_RTMPDH_H */
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