toxcore/core/net_crypto.h

/* net_crypto.h
 *
 * Functions for the core network crypto.
 *
 *  Copyright (C) 2013 Tox project All Rights Reserved.
 *
 *  This file is part of Tox.
 *
 *  Tox is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  Tox 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 Tox.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef NET_CRYPTO_H
#define NET_CRYPTO_H

#include "Lossless_UDP.h"
#include "DHT.h"

#ifdef __cplusplus
extern "C" {
#endif

/* Our public key. */
extern uint8_t self_public_key[crypto_box_PUBLICKEYBYTES];
extern uint8_t self_secret_key[crypto_box_SECRETKEYBYTES];

#define ENCRYPTION_PADDING (crypto_box_ZEROBYTES - crypto_box_BOXZEROBYTES)

/* returns zero if the buffer contains only zeros */
uint8_t crypto_iszero(uint8_t* buffer, uint32_t blen);

/* encrypts plain of length length to encrypted of length + 16 using the
    public key(32 bytes) of the receiver and the secret key of the sender and a 24 byte nonce
    return -1 if there was a problem.
    return length of encrypted data if everything was fine. */
int encrypt_data(uint8_t *public_key, uint8_t *secret_key, uint8_t *nonce,
                    uint8_t *plain, uint32_t length, uint8_t *encrypted);


/* decrypts encrypted of length length to plain of length length - 16 using the
    public key(32 bytes) of the sender, the secret key of the receiver and a 24 byte nonce
    return -1 if there was a problem(decryption failed)
    return length of plain data if everything was fine. */
int decrypt_data(uint8_t *public_key, uint8_t *secret_key, uint8_t *nonce,
                    uint8_t *encrypted, uint32_t length, uint8_t *plain);

/* Fast encrypt/decrypt operations. Use if this is not a one-time communication. 
   encrypt_precompute does the shared-key generation once so it does not have
   to be preformed on every encrypt/decrypt. */
void encrypt_precompute(uint8_t *public_key, uint8_t *secret_key, uint8_t *enc_key);

/* Fast encrypt. Depends on enc_key from encrypt_precompute. */
int encrypt_data_fast(uint8_t *enc_key, uint8_t *nonce, 
                      uint8_t *plain, uint32_t length, uint8_t *encrypted);

/* Fast decrypt. Depends on enc_ley from encrypt_precompute. */
int decrypt_data_fast(uint8_t *enc_key, uint8_t *nonce,
                      uint8_t *encrypted, uint32_t length, uint8_t *plain);


/* fill the given nonce with random bytes. */
void random_nonce(uint8_t *nonce);

/* return 0 if there is no received data in the buffer
    return -1  if the packet was discarded.
    return length of received data if successful */
int read_cryptpacket(int crypt_connection_id, uint8_t *data);

/* return 0 if data could not be put in packet queue
    return 1 if data was put into the queue */
int write_cryptpacket(int crypt_connection_id, uint8_t *data, uint32_t length);

/* create a request to peer with public_key.
    packet must be an array of MAX_DATA_SIZE big.
    Data represents the data we send with the request with length being the length of the data.
    request_id is the id of the request (32 = friend request, 254 = ping request)
    returns -1 on failure
    returns the length of the created packet on success */
int create_request(uint8_t *packet, uint8_t * public_key, uint8_t *data, uint32_t length, uint8_t request_id);


typedef int (*cryptopacket_handler_callback)(IP_Port ip_port, uint8_t * source_pubkey, uint8_t *data, uint32_t len);
/* Function to call when request beginning with byte is received */
void cryptopacket_registerhandler(uint8_t byte, cryptopacket_handler_callback cb);

/* Start a secure connection with other peer who has public_key and ip_port
    returns -1 if failure
    returns crypt_connection_id of the initialized connection if everything went well. */
int crypto_connect(uint8_t *public_key, IP_Port ip_port);

/* kill a crypto connection
    return 0 if killed successfully
    return 1 if there was a problem. */
int crypto_kill(int crypt_connection_id);

/* handle an incoming connection
    return -1 if no crypto inbound connection
    return incoming connection id (Lossless_UDP one) if there is an incoming crypto connection
    Put the public key of the peer in public_key, the secret_nonce from the handshake into secret_nonce
    and the session public key for the connection in session_key
    to accept it see: accept_crypto_inbound(...)
    to refuse it just call kill_connection(...) on the connection id */
int crypto_inbound(uint8_t *public_key, uint8_t * secret_nonce, uint8_t *session_key);

/* accept an incoming connection using the parameters provided by crypto_inbound
    return -1 if not successful
    returns the crypt_connection_id if successful */
int accept_crypto_inbound(int connection_id, uint8_t *public_key, uint8_t * secret_nonce, uint8_t *session_key);

/* return 0 if no connection, 1 we have sent a handshake, 2 if connexion is not confirmed yet
    (we have received a handshake but no empty data packet), 3 if the connection is established.
    4 if the connection is timed out and waiting to be killed */
int is_cryptoconnected(int crypt_connection_id);


/* Generate our public and private keys
    Only call this function the first time the program starts. */
void new_keys(void);

/* save the public and private keys to the keys array
    Length must be crypto_box_PUBLICKEYBYTES + crypto_box_SECRETKEYBYTES */
void save_keys(uint8_t * keys);

/* load the public and private keys from the keys array
    Length must be crypto_box_PUBLICKEYBYTES + crypto_box_SECRETKEYBYTES */
void load_keys(uint8_t * keys);

/* run this to (re)initialize net_crypto
    sets all the global connection variables to their default values. */
void initNetCrypto(void);

/* main loop */
void doNetCrypto(void);

#ifdef __cplusplus
}
#endif

#endif