For the past year and a half, J. Alex Halderman has been leading a double life.
By day, Halderman was an assistant professor of computer science and electrical engineering at the University of Michigan. By night, he and a team of fellow experts combined their technical prowess to craft software which renders anti-censorship efforts moot. If it sounds similar to a comic book superhero team fighting for the rights of those who don’t even know their true identities, well – that’s because it sort of is.
Halderman announced this week at the Freedom to Tinker blog that a team composed of himself, students Scott Wolchok, Eric Wustrow and University of Waterloo computer science professor Ian Goldberg had finished work on a censorship circumvention program called Telex.
Though Telex is not ready for widespread usage (currently the software is only available for in-lab testing, Halderman explained), the professor has high hopes for it. “Telex illustrates how it is possible to shift the balance of power in the censorship arms race, by thinking big about the problem,” Halderman wrote.
According to the official Telex site, the program builds on previous circumvention methods around governmental firewalls such as “tunneling” and offers users “a proxy server without an IP address”:
The user installs a Telex client app (perhaps by downloading it from an intermittently available website or by making a copy from a friend). When the user wants to visit a blacklisted site, the client establishes an encrypted HTTPS connection to a non-blacklisted web server outside the censor’s network, which could be a normal site that the user regularly visits. Since the connection looks normal, the censor allows it, but this connection is only a decoy. The client secretly marks the connection as a Telex request by inserting a cryptographic tag into the headers.
Using a combination of public-key steganography, cryptographic tags and deployed Telex stations, Telex can then detect tagged connections which attempt to access blocked sites and then reroute them to their destinations; neither blocked nor allowed sites have anything to do with the process.
Halderman believes that Telex’s novel end-to-middle proxying ability renders it safe from a censor’s counterattacks or being detected altogether, but stressed it is currently “a concept rather than a production system.” However, early testing seems positive.
“We have been using Telex for our daily web browsing for the past four months, and we’re pleased with the performance and stability,” he said. “We’ve even tested it using a client in Beijing and streamed HD YouTube videos, in spite of YouTube being censored there.”