Tor Goes Rust: Introducing Arti, a New Foundation for the Future of Tor

The development of "Arti," a Rust-based Tor implementation funded by Zcash, aims to enhance security and efficiency by addressing the limitations of the current C-based Tor.

The Tor Project is stirring the pot with "Arti," a new iteration of Tor built using Rust. This initiative, supported by Zcash Open Major Grants, aims to address the headaches of the old C-based Tor. If you've ever tangled with that version, you know it's a bit of a mess with its error-prone and convoluted code. Rust, known for its safety and efficiency, is expected to reduce bugs and improve security. The hope is that Rust's expressiveness and strong guarantees will speed up development, making life a tad easier for everyone involved.

The current C code isn't exactly easy. It's riddled with issues, especially when it comes to multithreaded cryptography. Thread-safety problems can creep in, leading to those annoying bugs and security vulnerabilities. But Rust's type system acts like a safety net, helping to avoid these pitfalls and making it simpler to write safe concurrent code. This means Arti's circuit cryptography can be multicore-ready right from the start, without too much extra hassle.

So, why a complete rewrite in Rust? The C codebase is so tangled that replacing it piece by piece just wouldn't cut it. A full overhaul allows for a more modular and embeddable design, addressing design issues that were a nightmare in C. Arti aims to be a flexible, cleaner version, with the potential to be embedded into other applications. Right now, Arti can connect to the Tor network, get a view of the Tor directory, and make anonymized connections. But don't get too excited yet - it's not ready for real privacy needs, missing some key security features.

The roadmap for Arti is laid out in phases, focusing on improving security, enhancing embedding features, and eventually reaching a production-quality client implementation. Down the line, they're planning to add anti-censorship features and support for onion services. Meanwhile, the old C version of Tor isn't going anywhere just yet. It'll still be supported and developed, but the spotlight is gradually shifting to Rust. The endgame is to have the Rust version fully take over once it's up to snuff. And hey, if you're a developer with a knack for Rust or Tor, they're welcoming contributions to help push Arti forward.

• https://blog.torproject.org/announcing-arti/...
• https://blog.torproject.org/announcing-arti/...