yading@11: /*
yading@11:  * RTMP Diffie-Hellmann utilities
yading@11:  * Copyright (c) 2012 Samuel Pitoiset
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #ifndef AVFORMAT_RTMPDH_H
yading@11: #define AVFORMAT_RTMPDH_H
yading@11: 
yading@11: #include "avformat.h"
yading@11: #include "config.h"
yading@11: 
yading@11: #if CONFIG_NETTLE || CONFIG_GCRYPT
yading@11: #if CONFIG_NETTLE
yading@11: #include <gmp.h>
yading@11: #include <nettle/bignum.h>
yading@11: 
yading@11: typedef mpz_ptr FFBigNum;
yading@11: #elif CONFIG_GCRYPT
yading@11: #include <gcrypt.h>
yading@11: 
yading@11: typedef gcry_mpi_t FFBigNum;
yading@11: #endif
yading@11: 
yading@11: typedef struct FF_DH {
yading@11:   FFBigNum p;
yading@11:   FFBigNum g;
yading@11:   FFBigNum pub_key;
yading@11:   FFBigNum priv_key;
yading@11:   long length;
yading@11: } FF_DH;
yading@11: 
yading@11: #elif CONFIG_OPENSSL
yading@11: #include <openssl/bn.h>
yading@11: #include <openssl/dh.h>
yading@11: 
yading@11: typedef BIGNUM *FFBigNum;
yading@11: typedef DH FF_DH;
yading@11: #endif
yading@11: 
yading@11: /**
yading@11:  * Initialize a Diffie-Hellmann context.
yading@11:  *
yading@11:  * @param key_len length of the key
yading@11:  * @return a new Diffie-Hellmann context on success, NULL otherwise
yading@11:  */
yading@11: FF_DH *ff_dh_init(int key_len);
yading@11: 
yading@11: /**
yading@11:  * Free a Diffie-Hellmann context.
yading@11:  *
yading@11:  * @param dh a Diffie-Hellmann context to free
yading@11:  */
yading@11: void ff_dh_free(FF_DH *dh);
yading@11: 
yading@11: /**
yading@11:  * Generate a public key.
yading@11:  *
yading@11:  * @param dh a Diffie-Hellmann context
yading@11:  * @return zero on success, negative value otherwise
yading@11:  */
yading@11: int ff_dh_generate_public_key(FF_DH *dh);
yading@11: 
yading@11: /**
yading@11:  * Write the public key into the given buffer.
yading@11:  *
yading@11:  * @param dh            a Diffie-Hellmann context, containing the public key to write
yading@11:  * @param pub_key       the buffer where the public key is written
yading@11:  * @param pub_key_len   the length of the buffer
yading@11:  * @return zero on success, negative value otherwise
yading@11:  */
yading@11: int ff_dh_write_public_key(FF_DH *dh, uint8_t *pub_key, int pub_key_len);
yading@11: 
yading@11: /**
yading@11:  * Compute the shared secret key from the private FF_DH value and the
yading@11:  * other party's public value.
yading@11:  *
yading@11:  * @param dh            a Diffie-Hellmann context, containing the private key
yading@11:  * @param pub_key       the buffer containing the public key
yading@11:  * @param pub_key_len   the length of the buffer
yading@11:  * @param secret_key    the buffer where the secret key is written
yading@11:  * @return length of the shared secret key on success, negative value otherwise
yading@11:  */
yading@11: int ff_dh_compute_shared_secret_key(FF_DH *dh, const uint8_t *pub_key,
yading@11:                                     int pub_key_len, uint8_t *secret_key);
yading@11: 
yading@11: #endif /* AVFORMAT_RTMPDH_H */