Online experiment identifies web visitors by 80 percent

A team of researchers has identified 80 percent of the almost 300 users in the United States who browsed the web and voluntarily participated in an online experiment.

The experiment, called the Footprints Project, was launched over the summer and ended in October, during which researchers with Stanford University and Princeton University were allowed to access the participants' anonymous web browsing history, including information about active Twitter usage.

Based on that information alone, Footprints identified 11 out of 13 people who visited the project's website at Stanford on its first day of operation.

By participating in Footprints, people gave the researchers permission to gather the names of any websites that a participant clicked on through Twitter, a social media network, while using Google Chrome browser. The researchers explained on the website that "this is similar to information that can be collected without your knowledge by websites and advertisers. This set of webpages uniquely fingerprints you, and we compare this fingerprint to the profiles of hundreds of millions of active Twitter users to determine who you are."

How did it work? Imagine that Jane Doe, John Smith and Susie Q all participated anonymously, and that each of these three volunteers follow 100 Twitter accounts. All three might follow the official Stanford Engineering Twitter account. But Jane and John also follow the New York Times' Twitter account for their news, while Susie instead follows the Los Angeles Times as her newspaper of choice. Researchers can then deduce that the person who visited links tweeted from Stanford Engineering and the New York Times is more likely to be Jane or John, not Susie.

"I think the first thing I messaged was: 'This is kind of scary,'" said Stanford undergraduate Ansh Shukla, a senior studying mathematics, who worked on the project with Stanford Engineering assistant professor Sharad Goel and Stanford computer science PhD student Jessica Su.

"Although we happen to use Twitter, it's not like Twitter is uniquely vulnerable," Shukla was quoted as saying in a news release from the School of Engineering at Stanford, a private research university in northern California on the U.S. west coast. "It doesn't take a lot of recorded characteristics to have people become unique."

Knowing that online privacy risks are not new, the researchers believed that their latest research is "another nail in the coffin" to the idea that the average person with the average web browser can be private online. "You should kind of go into the internet assuming that everything you go to someone might learn about someday," Shukla explained.

Even though many advertisers and internet companies might not initially know your name, he said, they likely have most of your anonymous browsing history -- even if you regularly clear your cookies. This data might be used by a commercial entity to link an anonymous person with a real identity -- something that's lucrative for an advertiser -- by cross-referencing databases.

The project is part of a growing body of research that brings heightened alarm to privacy vulnerabilities on the web. For most websites browsed, users often implicitly consent to be tracked through a terms of service or policy regarding "cookie," a small file of identifying information left on a computer when users browse online.

While Shukla hopes that as people realize how easy it is to track their digital footprints, the project will lead to a change of policy, such as collecting far less data, Goel noted that most people don't even realize they are leaving behind digital footprints. "We conceived this as a consciousness-raising project," he said, adding that he and his team plan to write a journal article about the Footprints experiment. Endit