Arti is our ongoing project to create a working embeddable Tor client in Rust. It’s not ready to replace the main Tor implementation in C, but we believe that it’s the future.

Right now, our focus is on making Arti production-quality, by stress-testing the code, hunting for likely bugs and adding missing features that we know from experience that users will need. We're going to try not to break backward compatibility too much, but we'll do so when we think it's a good idea.

What's new in 0.2.0?

For a complete list of changes, have a look at the CHANGELOG.

From a user's point of view, most of the changes in this version of Arti are for improved performance and reliability. We've started doing experiments on different kinds of network issues, and have improved Arti's behavior on IPv6-only networks and many kinds of network failure. We also now use less memory for directory storage (on the order of several megabytes in a running client).

The flashiest new user-facing feature is the dns_port option (like Tor's DnsPort) that you can use to send some types of DNS requests over Tor.

For developers, the most important change to be aware of is the new configuration code. When we're done, we think it will be far easier to configure an application that uses Arti. (It's a work in progress, and unfortunately will probably lead to more API changes in the future between now and 1.0.0.

Other important developer-facing features are:

• A new, far more flexible API for stream isolation. It allows applications to create sophisticated sets of isolation rules, beyond those currently possible with the C Tor implementation.
• An API for a "dormant mode" for inactive clients. (When in dormant mode, scheduled events are suspended.)
• Support for replacing the directory provider code with an arbitrary implementation, for applications that need specialized directory download and caching behavior.

There are also a bunch of smaller features, bugfixes, and infrastructure improvements; again, see the CHANGELOG for a more complete list.

And what's next?

Between now and our 1.0.0 milestone in September, we're aiming to make Arti a production-quality Tor client for direct internet access. (Onion services aren't funded yet, but we hope to change that soon.)

To do so, we need to bring Arti up to par with the C tor implementation in terms of its network performance, CPU usage, resiliency, and security features. You can follow our progress on our 1.0.0 milestone.

We still plan to continue regular releases between now and then.

Here's how to try it out

We rely on users and volunteers to find problems in our software and suggest directions for its improvement. Although Arti isn't yet ready for production use, you can test it as a SOCKS proxy (if you're willing to compile from source) and as an embeddable library (if you don't mind a little API instability).

Assuming you've installed Arti (with cargo install arti, or directly from a cloned repository), you can use it to start a simple SOCKS proxy for making connections via Tor with:

$ arti proxy -p 9150

and use it more or less as you would use the C Tor implementation!

(It doesn't support onion services yet. If compilation doesn't work, make sure you have development files for libsqlite installed on your platform.)

If you want to build a program with Arti, you probably want to start with the arti-client crate. Be sure to check out the examples too.

For more information, check out the README file. (For now, it assumes that you're comfortable building Rust programs from the command line). Our CONTRIBUTING file has more information on installing development tools, and on using Arti inside of Tor Browser. (If you want to try that, please be aware that Arti doesn't support onion services yet.)

When you find bugs, please report them on our bugtracker. You can request an account or report a bug anonymously.

And if this documentation doesn't make sense, please ask questions! The questions you ask today might help improve the documentation tomorrow.

Call for feedback

Our priority for the coming months is to make Arti a production-quality Tor client, for the purposes of direct connections to the internet. (Onion services will come later.) We know some of the steps we'll need to take to get there, but not all of them: we need to know what's missing for your use-cases.

Whether you're a user or a developer, please give Arti a try, and let us know what you think. The sooner we learn what you need, the better our chances of getting it into an early milestone.

Acknowledgments

Thanks to everybody who has contributed to this release, including Christian Grigis, Dimitris Apostolou, Lennart Kloock, Michael, solanav, Steven Murdoch, and Trinity Pointard.

And thanks, of course, to Zcash Community Grants (formerly Zcash Open Major Grants (ZOMG)) for funding this project!