c-libp2p/include/libp2p/secio/secio.h

#pragma once

#include "libp2p/crypto/key.h"
#include "libp2p/crypto/rsa.h"

/**
 * A secure connection
 */

enum IPTrafficType { TCP, UDP };

struct SecureSession {
	// to get the connection started
	char* host;
	int port;
	enum IPTrafficType traffic_type;
	// once the connection is established
	struct Stream* stream;
	// filled in during negotiations
	char* chosen_curve;
	char* chosen_cipher;
	char* chosen_hash;
	unsigned char* shared_key; // a shared key based off of the ephemeral private key
	size_t shared_key_size;
	unsigned char* mac;
	size_t mac_size;
	int (*mac_function)(const unsigned char*, size_t, unsigned char*);
	// local only stuff
	char local_nonce[16];
	unsigned char* ephemeral_public_key; // bytes of x and y
	size_t ephemeral_public_key_size;
	struct StretchedKey* local_stretched_key;
	// remote stuff
	char remote_nonce[16];
	struct PublicKey remote_key;
	char* remote_peer_id;
	unsigned char* remote_ephemeral_public_key;
	size_t remote_ephemeral_public_key_size;
	struct StretchedKey* remote_stretched_key;
};

/***
 * performs initial communication over an insecure channel to share
 * keys, IDs, and initiate connection. This is a framed messaging system
 * @param session the secure session to be filled
 * @param private_key the local private key to use
 * @param remote_requested the other side is who asked for the upgrade
 * @returns true(1) on success, false(0) otherwise
 */
int libp2p_secio_handshake(struct SecureSession* session, struct RsaPrivateKey* private_key, int remote_requested);