Tox is a

peer-to-peer Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network. They are said to form a peer-to-peer ...

instant-messaging and video-calling protocol that offers end-to-end encryption. The stated goal of the project is to provide secure yet easily accessible communication for everyone. A reference implementation of the protocol is published as free and open-source software under the terms of the GNU GPL-3.0-or-later.

History

The initial commit to

GitHub GitHub, Inc. () is an Internet hosting service for software development and version control using Git. It provides the distributed version control of Git plus access control, bug tracking, software feature requests, task management, co ...

was pushed on June 23, 2013, by a user named irungentoo. Pre-alpha testing binaries were made available for users from February 3, 2014, onward. On July 12, 2014, Tox entered an alpha stage in development and a redesigned download page was created for the occasion.

Features

Encryption of traffic

Users are assigned a public and private key, and they connect to each other directly in a fully distributed, peer-to-peer network. Users have the ability to message friends, join chat rooms with friends or strangers, voice/video chat, and send each other files. All traffic over Tox is end-to-end encrypted using the NaCl library, which provides authenticated encryption and

perfect forward secrecy In cryptography, forward secrecy (FS), also known as perfect forward secrecy (PFS), is a feature of specific key agreement protocols that gives assurances that session keys will not be compromised even if long-term secrets used in the session key e ...

Additional messaging features

Tox clients aim to provide support for various secure and anonymised communication features; while every client supports messaging, additional features like group messaging, voice and video calling, voice and video conferencing, typing indicators, message read-receipts,

file sharing File sharing is the practice of distributing or providing access to digital media, such as computer programs, multimedia (audio, images and video), documents or electronic books. Common methods of storage, transmission and dispersion include r ...

, profile encryption, and desktop streaming are supported to various degrees by mobile and desktop clients. Additional features can be implemented by any client as long as they are supported by the core protocol. Features that are not related to the core networking system are left up to the client. Client developers are strongly encouraged to adhere to the Tox Client Standard in order to maintain cross-client compatibility and uphold best security practices.

Usability as an instant messenger

Though several apps that use the Tox protocol seem similar in function to regular instant messaging apps, the lack of central servers similar to

XMPP Extensible Messaging and Presence Protocol (XMPP, originally named Jabber) is an open communication protocol designed for instant messaging (IM), presence information, and contact list maintenance. Based on XML (Extensible Markup Language), ...

Matrix Matrix most commonly refers to: * ''The Matrix'' (franchise), an American media franchise ** '' The Matrix'', a 1999 science-fiction action film ** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchi ...

currently has the consequence that both parties of the chat need to be online for the message to be sent and received. The Tox enabled messengers deal with this in separate ways, some prevent the user from sending the message if the other party has disconnected while others show the message as being sent when in reality it is stored in the sender's phone waiting to be delivered when the receiving party reconnects to the network.

Architecture

Core

The Tox core is a library establishing the protocol and API. User front-ends, or clients, are built on the top of the core. Anyone can create a client utilizing the core. Technical documents describing the design of the Core, written by the core developer irungentoo, are available publicly.

Protocol

The core of Tox is an implementation of the Tox protocol, an example of the application layer of the OSI model and arguably the presentation layer. Implementations of the Tox protocol not done by the project exist. Tox uses the Opus audio format for audio streaming and the VP8 video compression format for video streaming.

Encryption

Tox uses the cryptographic primitives present in the NaCl crypto library, via libsodium. Specifically, Tox employs

Curve25519 In cryptography, Curve25519 is an elliptic curve used in elliptic-curve cryptography (ECC) offering 128 bits of security (256-bit key size) and designed for use with the elliptic curve Diffie–Hellman (ECDH) key agreement scheme. It is one ...

for its key exchanges, xsalsa20 for symmetric encryption, and Poly1305 for MACs. Because the tox protocol can be used by many different applications, and because the tox network broadcasts the used client, it is also possible for clients to use additional encryption when sending to clients which support the same features.

Clients

A client is a program that uses the Tox core library to communicate with other users of the Tox protocol. Various clients are available for a wide range of systems; the following list is incomplete. There are also Tox protocol plugins for

Pidgin A pidgin , or pidgin language, is a grammatically simplified means of communication that develops between two or more groups of people that do not have a language in common: typically, its vocabulary and grammar are limited and often drawn from s ...

(no longer maintained, but working as of 2018-03-30) and Miranda NG.

Disassociation with Tox Foundation

At July 11, 2015, Tox developers officially announced their disassociation with Tox Foundation, due to "a dispute over the misuse of donated funds" by Tox Foundation head and CEO, according to LWN.net. Due to domains being in control of the Tox Foundation, main development of the project was transferred to a new infrastructure, servers, and new domain.

Reception

Tox received some significant publicity in its early conceptual stage, catching the attention of global online tech news sites. On August 15, 2013, Tox was number five on

's top trending list. Concerns about metadata leaks were raised, and developers responded by implementing

Onion routing Onion routing is a technique for anonymous communication over a computer network. In an onion network, messages are encapsulated in layers of encryption, analogous to layers of an onion. The encrypted data is transmitted through a series of net ...

for the friend-finding process. Tox was accepted into the Google Summer of Code as a Mentoring Organization in 2014 and 2015.

References

External links

* {{telecommunications 2013 software Android (operating system) software Communication software Cross-platform software Distributed computing Free communication software Free instant messaging clients Free software programmed in C Instant messaging clients Instant messaging clients for Linux Instant messaging clients that use GTK IOS software MacOS instant messaging clients Onion routing Peer-to-peer Secure communication Videotelephony VoIP protocols VoIP software Windows instant messaging clients