A few things everyone can do now:

  1. Please consider running a relay to help the Tor network grow.
  2. Tell your friends! Get them to run relays. Get them to run hidden services. Get them to tell their friends.
  3. If you like Tor's goals, please take a moment to donate to support further Tor development. We're also looking for more sponsors — if you know any companies, NGOs, agencies, or other organizations that want anonymity / privacy / communications security, let them know about us.
  4. We're looking for more good examples of Tor users and Tor use cases. If you use Tor for a scenario or purpose not yet described on that page, and you're comfortable sharing it with us, we'd love to hear from you.


  1. Help translate the documentation into other languages. See the translation guidelines if you want to help out. We especially need Arabic or Farsi translations, for the many Tor users in censored areas.
  2. Evaluate and document our list of programs that can be configured to use Tor.
  3. We have a huge list of potentially useful programs that interface with Tor. Which ones are useful in which situations? Please help us test them out and document your results.


  1. Monitor some of our public mailing lists, like tor-talk, tor-relays, tor-dev, or tbb-dev, and summarize noteworthy exchanges into articles for Tor Weekly News.
  2. Create a presentation that can be used for various user group meetings around the world.
  3. Create a video about the positive uses of Tor, what Tor is, or how to use it. Some have already started on Tor's Media server, Howcast, and YouTube.
  4. Create a poster around a theme, such as "Tor for Freedom!"
  5. Create a t-shirt design that incorporates "Congratulations! You are using Tor!" in any language.
  6. Spread the word about Tor at a symposium or conference and use these Tor brochures in PDF and ODG format and translated to at least ten different languages as conversation starter.

Google Summer of Code

Tor is also taking part in this year's Google Summer of Code! To apply but you need to be either a present student or just graduated. See our page for Google Summer of Code for more information.


Below are a list of Tor related projects we're developing and/or maintaining. Most discussions happen on IRC so if you're interested in any of these (or you have a project idea of your own), then please join us in #tor-dev. Don't be shy to ask questions, and don't hesitate to ask even if the main contributors aren't active at that moment.

For a presentation summarizing many of these projects see...

Name Category Language Activity Contributors
Tor Core C Heavy nickm, athena, arma
Tor Browser Bundle Javascript, XUL, Scripting Heavy mikeperry, Pearl Crescent
HTTPS Everywhere Browser Add-on Javascript Heavy pde, mikeperry
Nyx User Interface Python, Curses Heavy atagar
Orbot User Interface Java Moderage n8fr8
Tails OS image Sys Admin Heavy #tails
tor-ramdisk OS image Sys Admin Light blueness
Torsocks Usability C Light David Goulet
Tor Messenger Bundle JavaScript, XUL, Scripting Heavy arlolra, boklm, sukhe
TorBirdy Browser Add-on JavaScript Light sukhe
Obfsproxy Client Add-on Python None asn
Flash Proxy Client Add-on Python, JavaScript, Go Light dcf, infinity0, Arlo Breault
Shadow Simulator C, Python Heavy robgjansen
Chutney Simulator Python Light nickm
Stem Library Python Heavy atagar
Txtorcon Library Python, Twisted Light meejah
Tlsdate Utility C None ioerror
Metrics Client Service Java Moderate karsten
Atlas Client Service JavaScript None
Globe Client Service JavaScript None
Compass Client Service Python None
Onionoo Backend Service Java Light karsten
ExitMap Backend Service Python Light phw
DocTor Backend Service Python Light atagar
Weather Client Service Python None kaner
GetTor Client Service Python Light ilv
TorCheck Client Service Go None Arlo
BridgeDB Backend Service Python Light isis
Ooni Probe Scanner Python Moderate hellais, aagbsn
TorPS Backend Service Python None Aaron Johnson
TorFlow Backend Service Python None aagbsn
Tor2web Client Service Python Heavy evilaliv3, hellais
Anonbib Website Python Light arma, nickm
* Project is still in an alpha state.

Tor (code, bug tracker)

Central project, providing the core software for using and participating in the Tor network. Numerous people contribute to the project to varying extents, but the chief architects are Nick Mathewson and Roger Dingledine.

Project Ideas:
Help improve Tor hidden services

Tor Browser (code, bug tracker, design doc)

Tor Browser is an easy-to-use, portable package of Tor, HTTPS-Everywhere, NoScript, TorLauncher, Torbutton, and a Firefox fork, all preconfigured to work together out of the box. The modified copy of Firefox aims to resolve the privacy and security issues in mainline version.

Project Ideas:
Feedback Extension for Tor Browser

HTTPS Everywhere (code, bug tracker)

HTTPS Everywhere is a Firefox and Chrome extension that encrypts your communications with many major websites, making your browsing more secure.

Nyx (code, bug tracker)

Nyx (previously arm) is a terminal status monitor for Tor intended for command-line aficionados, ssh connections, and anyone with a tty terminal. This works much like top does for system usage, providing real time statistics for bandwidth, resource usage, connections, and quite a bit more.

Project Ideas:
Expand Nyx

Orbot (code, bug tracker)

Provides Tor on the Android platform. The project is under active development, updates to latest Tor releases, and working to stay up to date with all changes in Android and mobile threats.

The Amnesic Incognito Live System (code, bug tracker, documentation, design, contribute)

The Amnesic Incognito Live System is a live CD/USB distribution preconfigured so that everything is safely routed through Tor and leaves no trace on the local system. This is a merger of the Amnesia and Incognito projects, and still under very active development.

Tor-ramdisk (code, documentation)

Tor-ramdisk is a uClibc-based micro Linux distribution whose sole purpose is to securely host a Tor server purely in RAM.

Torsocks (code, bug tracker)

Utility for adapting other applications to work with Tor. Development has slowed and compatibility issues remain with some platforms, but it's otherwise feature complete.

Tor Messenger (code, bug tracker)

Tor Messenger is a cross-platform chat program that aims to be secure by default and sends all of its traffic over Tor.

TorBirdy (code, bug tracker)

TorBirdy is Torbutton for Thunderbird and related Mozilla mail clients.

Obfsproxy (code, bug tracker)

A proxy that shapes Tor traffic, making it harder for censors to detect and block Tor. This has both a C and python implementation.

Flash Proxy (code, bug tracker)

Pluggable transport using proxies running in web browsers to defeat address-based blocking.

Chutney (code, bug tracker)

Integration test suite that spawns a local tor network, checking the interactions of its components.

Shadow (code, bug tracker)

Shadow is a discrete-event network simulator that runs the real Tor software as a plug-in. Shadow is open-source software that enables accurate, efficient, controlled, and repeatable Tor experimentation. For another simulator, see ExperimenTor.

Stem (code, bug tracker)

Python controller library for scripts and controller applications using Tor.

Project Ideas:
Stem Descriptor Parsing in Go

Txtorcon (code, bug tracker)

Twisted-based asynchronous Tor control protocol implementation. Includes unit-tests, examples, state-tracking code and configuration abstraction. Used by OONI and APAF.

Project Ideas:
Convert txtorcon to use txaio
Convert txtorcon to py.test

Tlsdate (code)

tlsdate: secure parasitic rdate replacement

tlsdate sets the local clock by securely connecting with TLS to remote servers and extracting the remote time out of the secure handshake. Unlike ntpdate, tlsdate uses TCP, for instance connecting to a remote HTTPS or TLS enabled service, and provides some protection against adversaries that try to feed you malicious time information.

Metrics (code: db, web)

Processing and analytics of consensus data, provided to users via the metrics portal. This has been under active development for several years by Karsten Loesing. See also TorPerf.

Atlas (code)

Atlas is a web application to discover Tor relays and bridges. It provides useful information on how relays are configured along with graphics about their past usage.

This is the spiritual successor to TorStatus, the original codebase for which was written in PHP, and rewritten by students from Wesleyan as Django.

Globe (code, bug tracker)

Globe is a web application that allows you to search for Tor relays and bridges. It gives you a detailed overview of properties and configurations of a relay or bridge.

Compass (code, bug tracker)

Compass is a web and command line application that filters and aggregates the Tor relays based on various attributes.

Onionoo (code, bug tracker)

Onionoo is a JSON based protocol to learn information about currently running Tor relays and bridges.

ExitMap (code, bug tracker)

Scanner for the Tor network by Philipp Winter to detect malicious and misconfigured exits. For more information about how it works see his Spoiled Onions research paper.

Project Ideas:
Exitmap Improvements

DocTor (code, bug tracker)

DocTor is a notification service that monitors newly published descriptor information for issues. This is primarily a service to help the tor directory authority operators, but it also checks for a handful of other issues like sybil attacks.

Weather (code, bug tracker)

Provides automatic notification to subscribed relay operators when their relay's unreachable. This underwent a rewrite by the Wesleyan HFOSS team, which went live in early 2011.

GetTor (code, bug tracker)

E-mail autoresponder providing Tor's packages over SMTP. This has been relatively unchanged for quite a while.

TorCheck (code, bug tracker)

Site for determining if the visitor is using Tor or not.

BridgeDB (code, bug tracker)

Backend bridge distributor, handling the various pools they're distributed in. This was actively developed until Fall of 2010.

Ooni Probe (code, bug tracker)

Censorship scanner, checking your local connection for blocked or modified content.

TorPS (code)

The Tor Path Simulator (TorPS) is a tool for efficiently simulating path selection in Tor. It chooses circuits and assigns user streams to those circuits in the same way that Tor does. TorPS is fast enough to perform thousands of simulations over periods of months.

TorFlow (code, bug tracker)

Library and collection of services for actively monitoring the Tor network. These include the Bandwidth Scanners (measuring throughput of relays) and SoaT (scans for malicious or misconfigured exit nodes). SoaT was last actively developed in the Summer of 2010, and the Bandwidth Scanners a few months later. Both have been under active use since then, but development has stopped.

Tor2web (code)

Tor2web allows Internet users to browse websites running in Tor hidden services. It trades user anonymity for usability by allowing anonymous content to be distributed to non-anonymous users.

Anonymity Bibliography (code)

Anonbib is a list of important papers in the field of anonymity. It's also a set of scripts to generate the website from Latex (bibtex). If we're missing any important papers, please let us know!

Project Ideas

You may find some of these projects to be good ideas for Google Summer of Code. We have labelled each idea with which of our core developers would be good mentors. If one or more of these ideas looks promising to you, please contact us to discuss your plans rather than sending blind applications. You may also want to propose your own project idea — which often results in the best applications.

  1. Help improve Tor hidden services
    Language: C
    Likely Mentors: George (asn), David Goulet (dgoulet)

    We're working on a revamp of the entire Tor hidden service design to improve the security and reliability of the hidden service system.

    This is a big project: see proposal 224 for the latest design. Are you interested in implementing some part of that?

    This is a very ambitious project, so we're deliberately not suggesting particular sub-topics. If you're interested in participating, try to read and understand the existing design and the design proposal for the new design, and then talk to us about what part you want to work on.

    As part of the application process for this project, please contribute a nontrivial patch to Tor -- ideally, one that will affect some part of the codebase that you want to work on.

  2. Exitmap Improvements
    Language: Python
    Likely Mentors: Philipp (phw)

    The Tor Project makes use of the Python tool Exitmap to systematically scan for malicious and misbehaving exit relays. Once such a relay is found, it is assigned the BadExit flag which prevents clients from selecting the relay as last hop in their circuit.

    Exitmap supports scanning modules which implement a specific scan over exit relays. Examples are the DNS module which checks for DNS poisoning or the patching check module which looks out for tampered file downloads.

    This project is meant to extend exitmap in several ways. First, it should be made fully autonomous. That means that exitmap should be able to run in the background, periodically fetch new relay descriptors, and have a smart algorithm which keeps scanning all exit relays periodically. Second, exitmap should be able to emulate some user interaction and dynamically "explore" the web in order to detect tampering. Third, unit tests should be added for existing and new code in order to make the code base more robust.

  3. Expand Nyx
    Language: Python
    Likely Mentors: Damian (atagar)

    Nyx (previously known as arm) is an ncurses monitor that provides Tor relay operators...

    Nyx is presently under development in preparation for its next release. If you like python, terminals, and collaborating on an active codebase this just might be the project for you!

    Proposals should involve a grab-bag of moderately small improvements you'd like to make. You're encouraged to brainstorm ideas of their own but here's a few to get ya started...

    • Bring back the interpreter panel. This panel was dropped when refactoring Nyx, but it would be a neat component to bring back. You can find old code for it in the history and Stem (the library backing Nyx) has a much improved variant of this we can leverage. This task would involve writing the curses code around Stem's interpreter functions.
    • Windows support. Like most curses applications Nyx doesn't run natively on Windows. We've had dozens of users request this and it should be possible. This would involve supporting PDCurses and expanding Stem to be able to query the cpu/memory usage of the tor process.
    • Unit testing! Nyx has started adding tests but it's still very minimal. Achieving any substantial code coverage will require us to figure out how to unit test curses components.
    • Onionoo provides additional relay information that could enrich our connection panel such as geoip and rdns. Trick is that at present we can only query it on a per-relay basis which would leak our connections (no-go for security). However, if we could get information about all relays in bulk it would sidestep this. For some old thoughts on this see here.
    • Relay setup wizard. Our last release had this (screenshots: 1, 2, 3). This has been removed because including it directly in Nyx confused users, but we might want to resurrect it as a separate setup-tor-relay command.
    • Improved dialog for selecting events to log.
    • ... and more! Again, don't hesitate to propose ideas of your own.

    As part of your application for this project please get your hands wet with the codebase by contributing patches for Nyx and Stem!

  4. Stem Descriptor Parsing in Go
    Language: Go, Python
    Likely Mentors: Damian (atagar), Philipp (phw)

    Tor consists of two parts: the application and a distributed network of a few thousand volunteer relays. Information about these relays is public, and made up of documents called descriptors. We have three libraries capable of reading these documents...

    Stem is the most feature rich but slowest, and conversely Zoossh is fastest but limited. But what if Stem used CFFI bindings to do the heavy lifting in Go? Could we unify these libraries, getting the feature set of Stem with the performance of Zoossh?

    Applicants should be familiar with both Python and Go. As part of your application for this project please write a demo CFFI binding for Stem as a proof of concept. Bonus points if you get your hands wet by contributing patches!

  5. Convert txtorcon to use txaio
    Language: Python, asyncio, Twisted
    Likely Mentors: meejah

    txtorcon is currently supports only Twisted users. Re-working txtorcon to use the txaio library would allow users to choose between Twisted and asyncio for the client code.

    This would involve fairly extensive refactoring to txtorcon, as it currently makes heavy use of @inlineCallbacks which doesn't work with txaio. A prospective student should be very familiar with event-based programming in general, and be familiar with one of Twisted or asyncio. See also: https://github.com/meejah/txtorcon/issues/135

  6. Convert txtorcon to py.test
    Language: Python, Twisted
    Likely Mentors: meejah

    Currently txtorcon uses the built-in "unittest" module, as well as Twisted's Deferred-respecting extensions on top. However, meejah has found py.test's "fixture" approach to be much more powerful in other situations.

    This project would be to port at least part of txtorcon's test-suite to use py.test style tests and fixtures and evaluate: are the tests easier to read? are there fewer lines of code? If so, the rest of the suite should be ported and txtorcon switched over to use py.test exclusively.

    As some of txtorcon's tests aren't very well-written, this would take a prospective student who is very strong in unit-testing knowledge. As txtorcon is event-based, familiarity with that style of programming (preferrably with Twisted) is ideal. See also: https://github.com/meejah/txtorcon/issues/136

  7. Implement and Integrate CONIKS for Tor Messenger
    Language: C, JavaScript
    Likely Mentors: Marcela (masomel), Arlo (arlolra)

    CONIKS is an end-user key management and verification system for end-to-end secure communication services, which improves upon existing key management systems by providing both strong security and better usability using a model called key transparency. CONIKS does this by requiring providers to manage tamper-evident, publicly-auditable key directories, which contain mappings from usernames to public keys, on behalf of their users. This design makes it easier for users (both "default" users and power users) to establish trust since they don't have to worry about or even see keys, but users also don't have to trust the provider to be well-behaved because the CONIKS client can run as part of the secure messaging app and automatically check that the service provider doesn’t map spurious keys to their users' usernames, and it can verify that observed name-to-key mappings are consistent with what other clients in the system are seeing. Unlike existing key transparency solutions, CONIKS also provides strong privacy guarantees by employing cryptographic primitives for robust data obfuscation.

    The CONIKS system design, protocols, and proof-of-concept are described in great detail in the CONIKS research paper, and basic reference implementations of a CONIKS key server and a CONIKS client are avialable on Github.

    This project has two main components: (1) designing and implementing a CONIKS key server tailored to Tor Messenger users, and (2) building a CONIKS client which integrates with the Tor Messenger client. One challenge the applicant will face is ensuring that the key server design is efficient and scalable for large volumes of users, concurrent traffic and guarantees this scalability even as Tor Messenger's user base grows. On the client side, the main challenges will be to focus on space efficiency as well as minimizing computational overhead when implementing the CONIKS consistency checks, and determining how to best communicate CONIKS consistency check results to users in the UI. Since Tor Messenger does not hand out online identities per se, as most online communication services do (like, say, Twitter, in which each user has a unique handle), the CONIKS key server for Tor Messenger will have to map usernames from third-party communication services to the encryption keys used in Tor Messenger. One additional important challenge that the applicant will have to help address is ensuring that each such third-party username remains unique in the Tor Messenger space and that such external, third-party identities are indeed controlled by the expected user of that third-party communication service.

    Some design and implementation questions have been discussed in Ticket #17961.

    The applicant should have some familiarity with well-known crypto primitives and algorithms, as well as have a basic understanding of the key transparency model. Client side integration will require some basic use of JavaScript. Consider submitting a patch for one of the open key verification issues as part of the application process.

  8. Panopticlick
    Likely Mentors: Georg (GeKo), Günes Acar, Nicolas (boklm)

    The Panopticlick project by the EFF revolutionized how people think about browser fingerprinting, both by developing tests and metrics to measure browser fingerprintability, and by crowdsourcing the evaluation and contribution of individual browser features to overall fingerprintability.

    Unfortunately, the way Panopticlick is designed makes it difficult to evaluate defenses to browser fingerprinting, especially for browsers with a relatively small userbase such as Tor Browser. This is because any approach we take to reduce fingerprinting automatically makes our users more distinct from the previous users who submitted their fingerprint data to the EFF. Indeed, it is also impossible to ever expect that users of one browser will ever be able to blend in with users of another browser (Chrome users will always be distinguishable from Firefox users for example, based on feature set alone).

    To address this, we would like to have our own fingerprint test suite to evaluate the fingerprintability of each browser feature for users running a specific Tor Browser version. There are also additional fingerprinting tests we can add beyond those deployed by Panopticlick.

    For this project, the student would develop a website that users can voluntarily visit to test and record their Tor Browser fingerprint. The user should get feedback on how she performed and the test results should be available in a machine readable format (e.g. JSON), broken down by Tor Browser version. In a second step one could think about adding more sophisticated tests or supporting other browser vendors that might want to test the uniformity amongst their userbase as well. Of course, results from each browser would also need to be broken down by both browser implementation and version, so that results would only reflect the population of that specific implementation.

  9. Make Stegotorus deployment ready
    Language: C++
    Likely Mentors: vmon

    Stegotorus is a PT framework which streamline the development stealthier pluggable transport. An HTTP pluggable transport is already implemented in Stegotorus framework and can be used when encrypted payloads are throttled and only ephemeral connections are tolerated.

    The majority of work on Stegotorus is done and it can be deployed with a relatively minor improvements including:

    • #8098 A config file file for Stegotorus

      Stegotorus needs many configuration settings specially on the bridge side. This include also the configuration required by each steg module. Currently the configuration is fed to Stegotorus as command line arguments but a file like torrc is needed so all tweaking can be read from there.

      Current Status and work needed to be done: The code for reading the config file is written by SRI but it is not yet used in the Stegotorus to read the config.

    • #8101 Debugging the transparent proxy

      Stegotorus http module uses other websites payload to hide and serve censored traffic. As such it needs to decide if the request is genuinely to the auxiliary website, in that case becomes a transparent proxy and serves the website content as requested, or if the request is actually a request to serve censored material which should be delivered to steg modules.

      Current Status: This is completely implemented. However, the transparent proxy sometimes crashes and need to be triaged, debugged and fixed.

    • #11337 refactoring the steg module code

      The http steg module code, although not essentials to the core of the Stegotorus. needs some improvement and clean up. The solution is to refactor the steg modules as children of FileStegMod.

      Current status and work needed to be done: This has already been done but still needs testing and refactoring before it can be reliably merge to the master branch.

    • #8089 Adding Elligator to Stegotorus handshake and test

      The current Stegotorus handshake is distinguishable from random byte string, which can be used to flag and detect Stegotorus traffic deterministically and need to be implemented similar to ScrambleSuite. Also because the capacity of client to server channel might be slim depending on the choice of steg module it is desirable to be implemented using Elliptic curve crypto. Hence, Elligator protocol is ideal solution for this situation. All we need is to replace Stegotorus handshake by Elligator.

      Current Status and work needed to be done: Elligator handshake code is included in stegotorus code base, it is only needed to be called by instead of the current handshake and be tested.

    • Make Stegotorus memory safe by using shared pointers

      Stegotorus has large code base and it is not written in a memory safe languages. To facilitate its audit, we need to replace (almost all) use of pointers to shared pointers.

      Current Status: No progress has not been done.

    • Security Audit and writing more unit test

      To be able to deploy Stegotorus for real world use we need to audit the code and write more unit test covering new aspects of the Stegotorus (new http transport, proxy server, Elligator handshake)

      Current Status: No progress has been done.

    • SRI branch merging

      Stegotorus has been forked from the initial development from SRI. Now that SRI is hosting Stegotorus publicly it is desirable to merge the two branches so we can benefit from both developments.

      Current Status: No progress has been done.

    • #8099 deterministic build

      To make deterministic build possible we need to build many of Stegotorus dependency from scratch. Boost library is a a huge dependency for Stegotorus to access the file system. As we are only planning to deploy Stegotorus bridges on Linux machines we can simplify such access without that dependency. By dropping such dependency, it should be straight forward to have deterministic build for Stegotorus.

      Current Status: No progress has been done.

  10. Expand the OS and Server Support of the Let's Encrypt Client
    Language: Python, Bash
    Likely Mentors: Brad Warren (bmw)

    Let's Encrypt is a free and open certificate authority that allows its users to setup HTTPS on their web server in a matter of seconds. The project uses a new protocol called ACME to automatically perform domain validation and certificate issuance.

    The Let's Encrypt client currently works on most Unix-like OSes and is able to automatically set up HTTPS on many Apache configurations. The purpose of this project is to expand Let's Encrypt support to new systems.

    Potential targets include:

    • Better OS X support including a port or Homebrew package
    • A Let's Encrypt client for Windows / IIS
    • Handling of more obscure Apache configurations
    • Automated HTTPS configuration for other web servers such as Nginx or lighttpd
    • Improved support people using shared hosting who are unable to use the full Let's Encrypt client on their server
  11. Ahmia - Hidden Service Search
    Language: Python, Django
    Likely Mentors: Juha Nurmi (numes), George (asn)

    Ahmia is open-source search engine software for Tor hidden service deep dark web sites. You can test the running search engine at ahmia.fi. For more information see our blog post about Ahmia's GSoC2014 development.

    Ahmia is a working search engine that indexes, searches, and catalogs content published on Tor Hidden Services. Furthermore, it is an environment to share meaningful insights, statistics, insights, and news about the Tor network itself. In this context, there is a lot of work to do.

    The Ahmia web service is written using the Django web framework. As a result, the server-side language is Python. On the client-side, most of the pages are plain HTML. There are some pages that require JavaScript, but the search itself works without client-side JavaScript.

    There are several possible directions for this project, including...

    1. Improving the search results (very important)
      • Tweaking search algorithms
      • Adjust Elasticsearch
      • Enrich the data that is used to rank the search results
    2. Improving UX and UI (very important)
      • Showing relevant knowledge
      • Design the navigation and information architecture
      • HTML5, CSS and Django development
    3. Review code and infrastructure
      • Review code and fix bugs
      • Writing Django test cases
      • Linux configurations, automatizations
    4. Gather statistics over time and publish them
      • Gather different kind of stats about Hidden Services
      • Publish these stats using HTTP REST API
      • Using this API show meaningful tables, charts and visualizations
  12. IP hijacking detection for the Tor Network
    Likely Mentors: Aaron Gibson (aagbsn)

    IP hijacking occurs when a bad actor creates false routing information to redirect Internet traffic to or through themselves. This activity is straightforward to detect, because the Internet routing tables are public information, but currently there are no public services that monitor the Tor network. The Tor Network is a dynamic set of relays, so monitoring must be Tor-aware in order to keep the set of monitored relays accurate. Additionally, consensus archives and historical Internet routing table snapshots are publicly available, and this analysis can be performed retroactively.

    The implications of IP hijacking are that Tor traffic can be redirected through a network that an attacker controls, even if the attacker does not normally have this capability - i.e. they are not in the network path. For example, an adversary could hijack the prefix of a Tor Guard relay, in order to learn who its clients are, or hijack a Tor Exit relay to tamper with requests or name resolution.

    This project comprises building a service that compares network prefixes of relays in the consensus with present and historic routing table snapshots from looking glass services such as Routeviews, or aggregators such as Caida BGPStream and then issues email alerts to the contact-info in the relay descriptor and a mailing list. Network operators are responsive to route injections, and these alerts can be used to notify network operators to take immediate action, as well as collect information about the occurrence of these type of attacks.

  13. Tails server: Self-hosted services behind Tails-powered Tor hidden services
    Likely Mentors: anonym, George (asn)

    Let's talk about group collaboration, communication and data sharing infrastructure, such as chat servers, wikis, or file repositories.

    Hosting such data and infrastructure in the cloud generally implies to trust the service providers not to disclose content, usage or users location information to third-parties. Hence, there are many threat models in which cloud hosting is not suitable.

    Tor partly answers the users location part; this is great, but content is left unprotected.

    There are two main ways to protect such content: either to encrypt it client-side (security by design), or to avoid putting it into untrusted hands in the first place.

    Cloud solutions that offer security by design are rare and generally not mature yet. The Tails server project is about exploring the other side of the alternative: avoiding to put private data into untrusted hands in the first place.

    This is made possible thanks to Tor hidden services, that allow users to offer location-hidden services, and make self-hosting possible in many threat models. Self-hosting has its own lot of problems, however, particularly in contexts where the physical security of the hosting place is not assured. Combining Tor hidden services with Tails' amnesia property and limited support for persistent encrypted data allows to protect content, to a great degree, even in such contexts.

    In short, setting up a new Tails server would be done by:

    1. Alice plugs a USB stick into a running desktop Tails system.
    2. Alice uses a GUI to easily configure the needed services.
    3. Alice unplugs the USB stick, that now contains encrypted services configuration and data storage space.
    4. Alice plugs that USB stick (and possibly a Tails Live CD) into the old laptop that was dedicated to run Tails server.
    5. Once booted, Alice enters the encryption passphrase either directly using the keyboard or through a web interface listening on the local network.
    6. Then, Bob can use the configured services once he gets a hold on the hidden service address. (The petname system for Tor hidden services project would be very complementary to this one, by the way.)

    Tails server should content itself with hardware that is a bit old (such as a PIII-450 laptop with 256MB of RAM) and/or half broken (e.g. non-functional hard-disk, screen or keyboard).

    The challenges behind this project are:

    • Design and write the services configuration GUI [keywords: edit configuration files, upgrade between major Debian versions, debconf].
    • How to create the hidden service key? [keywords: Vidalia, control protocol].
    • Adapt the Tails boot process to allow switching to "server mode" when appropriate.
    • Add support, to the Tails persistence setup process, for asking an encryption passphrase without X, and possibly with a broken keyboard and/or screen [keywords: local network, SSL/TLS?, certificate?].

    This project can easily grow quite large, so the first task would probably be to clarify what it would need to get an initial (minimal but working) implementation ready to be shipped to users.

    This project does not require to be an expert in one specific field, but it requires to be experienced and at ease with a large scope of software development tools, processes, and operating system knowledge.

    Undertaking this project requires in-depth knowledge of Debian-like systems (self-test: do the "dpkg conffile" and "debconf preseeding" words sound new to your ear?); the Debian Live persistence system being written in shell, being at ease with robust shell scripting is a must; to end with, at least two pieces of software need to be written from scratch (a GUI and a webapp): the preferred languages for these tasks would be Python and Perl. Using Behaviour Driven Development methods to convey expectations and acceptance criteria would be most welcome.

    For more information see https://tails.boum.org/todo/server_edition/

  14. Feedback Extension for Tor Browser
    Likely Mentors: Nima (mrphs), Will (willscott), Sukhbir (sukhe)

    Design and implement an extension for Tor Browser that can be used to gather end-user UI/UX feedback on an opt-in basis. While the design and implementation is left as an exercise for the applicant (and also serves as the qualification task), examples of the information we are looking to gather can include troubleshooting network connectivity issues, testing the various pluggable transports, or gathering information about the network of the users.

    Please propose the extension design in a way that the information is strictly on an opt-in basis and scrubs any information that can be used to identify a user, and also come up with a way to send the gathered information to a central server, whether to an onion address (if the user has Tor running), or otherwise. To start with, we are looking to gather only text as part of the feedback process.

  15. Bring up new ideas!
    Don't like any of these? Look at the Tor development roadmap for more ideas, or just try out Tor and Tor Browser, and find out what you think needs fixing. Some of the current proposals might also be short on developers.

Tor Tip

Tor is written for and supported by people like you. Donate today!