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/* crypto_core.h
*
* Functions for the core 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 CORE_CRYPTO_H
#define CORE_CRYPTO_H
#include "network.h"
/* return zero if the buffer contains only zeros. */
uint8_t crypto_iszero(uint8_t *buffer, uint32_t blen);
/* Use this instead of memcmp; not vulnerable to timing attacks.
returns 0 if both mem locations of length are equal. */
unsigned int crypto_cmp(uint8_t *mem1, uint8_t *mem2, uint32_t length);
/* 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);
/* Encrypts plain of length length to encrypted of length + 16 using a
* secret key crypto_box_KEYBYTES big and a 24 byte nonce.
*
* return -1 if there was a problem.
* return length of encrypted data if everything was fine.
*/
int encrypt_data_symmetric(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 a
* secret key crypto_box_KEYBYTES big 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_symmetric(uint8_t *secret_key, uint8_t *nonce, uint8_t *encrypted, uint32_t length, uint8_t *plain);
/* Increment the given nonce by 1. */
void increment_nonce(uint8_t *nonce);
/* increment the given nonce by num */
void increment_nonce_number(uint8_t *nonce, uint32_t num);
/* Fill the given nonce with random bytes. */
void random_nonce(uint8_t *nonce);
/* Fill a key crypto_box_KEYBYTES big with random bytes */
void new_symmetric_key(uint8_t *key);
/*Gives a nonce guaranteed to be different from previous ones.*/
void new_nonce(uint8_t *nonce);
#define MAX_CRYPTO_REQUEST_SIZE 1024
#define CRYPTO_PACKET_FRIEND_REQ 32 /* Friend request crypto packet ID. */
#define CRYPTO_PACKET_HARDENING 48 /* Hardening crypto packet ID. */
#define CRYPTO_PACKET_NAT_PING 254 /* NAT ping crypto packet ID. */
#define CRYPTO_PACKET_GROUP_CHAT_GET_NODES 48 /* Group chat get Nodes packet */
#define CRYPTO_PACKET_GROUP_CHAT_SEND_NODES 49 /* Group chat send Nodes packet */
#define CRYPTO_PACKET_GROUP_CHAT_BROADCAST 50 /* Group chat broadcast packet */
/* Create a request to peer.
* send_public_key and send_secret_key are the pub/secret keys of the sender.
* recv_public_key is public key of reciever.
* packet must be an array of MAX_CRYPTO_REQUEST_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).
*
* return -1 on failure.
* return the length of the created packet on success.
*/
int create_request(uint8_t *send_public_key, uint8_t *send_secret_key, uint8_t *packet, uint8_t *recv_public_key,
uint8_t *data, uint32_t length, uint8_t request_id);
/* puts the senders public key in the request in public_key, the data from the request
in data if a friend or ping request was sent to us and returns the length of the data.
packet is the request packet and length is its length
return -1 if not valid request. */
int handle_request(uint8_t *self_public_key, uint8_t *self_secret_key, uint8_t *public_key, uint8_t *data,
uint8_t *request_id, uint8_t *packet, uint16_t length);
#endif
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