/*
  * RTMP Diffie-Hellmann utilities
  * Copyright (c) 2012 Samuel Pitoiset
  *

  * This file is part of FFmpeg.

  *

  * FFmpeg 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.
  *

  * FFmpeg 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 FFmpeg; 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 "avformat.h"
 #include "config.h"
 

 #if CONFIG_GMP || CONFIG_GCRYPT
 #if CONFIG_GMP

 #include <gmp.h>
 
 typedef mpz_ptr FFBigNum;
 #elif CONFIG_GCRYPT
 #include <gcrypt.h>
 
 typedef gcry_mpi_t FFBigNum;
 #endif
 
 typedef struct FF_DH {

     FFBigNum p;
     FFBigNum g;
     FFBigNum pub_key;
     FFBigNum priv_key;
     long length;

 } FF_DH;
 
 #elif CONFIG_OPENSSL
 #include <openssl/bn.h>
 #include <openssl/dh.h>
 
 typedef BIGNUM *FFBigNum;
 typedef DH FF_DH;
 #endif
 
 /**
  * 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 */