An illustration of a computer programmer coding on a laptop with the Tor logo on the screen, surrounded by snippets of Rust programming language code, in a modern, well-lit office environment.

Arti: Implementing Tor in Rust Language.

Introduction to Arti: A New Dawn for Tor with Rust

Tor, originally an acronym for The Onion Router, is an open-source software that enables anonymous communication across a network by directing internet traffic through a worldwide overlay network consisting of more than seven thousand relays. Traditionally written in C, Tor has seen a significant transformation with the introduction of Arti, a project aimed at implementing the core functionalities of Tor entirely in the Rust programming language.

Why Rust?

Rust is known for its focus on safety and performance, providing memory safety guarantees through its ownership system without the need for a garbage collector. This makes Rust highly attractive for systems programming, as it minimizes common bugs and security vulnerabilities inherent in languages like C or C++ which rely on manual memory management. Given that Tor is a critical privacy tool used worldwide, enhancing its security and reliability is paramount. The Rust language, with its safe concurrency and resistance to memory bugs, emerges as an excellent candidate for rewriting sensitive internet traffic management tools such as Tor.

The Genesis of Arti

The initiative to rewrite Tor in Rust began with the broader Rust community and the Tor Project observing Rust’s potential benefits. As a part of the exploratory phase, smaller, non-critical components of Tor were first written in Rust to test feasibility and performance impacts. Encouraged by positive outcomes and community support, the Tor Project decided to experiment with a more integral rewrite, leading to the inception of Arti – a Rust-based implementation of the Tor client.

Goals and Objectives of Arti

The primary goal for Arti is not only to replicate the existing functionalities of Tor in Rust but also to simplify the codebase, making it more maintainable, robust, and accessible to new developers. This project aims to:

  • Enhance security by leveraging Rust’s safe programming guarantees,
  • Improve performance through Rust’s efficiency, especially in handling concurrency and network operations,
  • Reduce the complexity inherent in Tor’s codebase, potentially lowering the barrier for new contributors, and
  • Eventually, achieve feature parity with the C implementation of Tor, ensuring that users do not have to compromise on functionality.

Current Progress and Milestones

As of the latest updates, Arti is in an experimental stage, but it successfully implements the essential features required to connect to the Tor network and communicate using the Tor protocols. Although currently recommended for research and development use only, Arti is on a clear path towards becoming a fully functional Tor client.

Community and Development

The development of Arti has been heavily community-driven, supported by contributions from a diverse group of developers keen on Rust and passionate about privacy technologies. The Tor Project has fostered this community, providing necessary resources and coordination, while also ensuring that Arti aligns with the strategic goals and security standards of the existing Tor network.

Challenges and Considerations

One of the significant challenges in developing Arti is ensuring it meets all operational standards set by the existing C-based Tor client, which has been hardened by years of testing, deployment, and real-world use. Additionally, interoperability between Arti and other components of the Tor network, many of which are still in C, requires careful consideration to maintain overall network integrity and performance.

Future of Arti and Tor

Looking ahead, the Tor Project envisions a gradual transition where more components of the network are rewritten in Rust, eventually leading to a newer, safer, and more robust implementation. The success of Arti could pave the way for further Rust-based rewrites within the Tor ecosystem, potentially influencing other legacy systems in the cybersecurity domain to consider similar modernizations.

With the ongoing development of Arti and its eventual integration into the broader Tor network, the community remains optimistic about leveraging Rust’s capabilities to enhance Tor’s performance, security, and usability for millions of users globally.


By incorporating Rust’s modern, safety-focused features, Arti represents a significant step forward in the evolution of Tor. As this project continues to grow and mature, it holds the promise of transforming the landscape of privacy technology, ensuring that Tor remains a vital tool for secure, anonymous internet access in the years to come.


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