Anonymity networks, which sit on top of the public Internet, are designed to conceal people’s Web-browsing habits from prying eyes. The most popular of these, Tor, has been around for more than a decade and is used by millions of people every day.
Recent research, however, has shown that adversaries can infer a great deal about the sources of supposedly anonymous communications by monitoring data traffic through just a few well-chosen nodes in an anonymity network. At the Association for Computing Machinery Symposium on Operating Systems Principles in October, a team of MIT researchers presented a new, untraceable text-messaging system designed to thwart even the most powerful of adversaries.
The system provides a strong mathematical guarantee of user anonymity, while, according to experimental results, permitting the exchange of text messages once a minute or so.
“Tor operates under the assumption that there’s not a global adversary that’s paying attention to every single link in the world,” says Nickolai Zeldovich, an associate professor of computer science and engineering, whose group developed the new system. “Maybe these days this is not as good of an assumption. Tor also assumes that no single bad guy controls a large number of nodes in their system. We’re also now thinking, maybe there are people who can compromise half of your servers.”