Inside 1to1:Privacy

Privacy By Obfuscation

June 1, 2009

By Larry Dobrow


As part of its efforts to defend the Child Online Protection Act, in 2005 the Justice Department asked Google, AOL, MSN, and Yahoo! to release records of their users' search queries. Google refused, citing user privacy, among other concerns, and fighting the subpoena to federal court where the company ultimately agreed to release less specific data. The other companies complied with the original subpoena. Their ready compliance led to the birth of TrackMeNot.

Several years ago, Helen Nissenbaum read a story in the New York Times about the Department of Justice asking companies like AOL, MSN and Yahoo! to hand over their users' search records--and the companies not exactly hesitating to comply. A longtime privacy and philosophy advocate, and currently a professor in the department of media, culture, and communication at New York University, Nissenbaum took issue with their eager disclosure.

"I talked with my colleagues and it became clear to us that the search companies must be maintaining all these user search logs. But users didn't know this and didn't seem to have any say in the matter. That struck me as wrong," she recalls.

Nissenbaum weighed her options, ruling out working with the government to effect change ("urging legislators to support limits on access, or courts to extend Fourth Amendment protection," according to TrackMeNot's FAQ document) or bringing up the issue with the search companies themselves. In the end, though, she decided to take direct action. "I came up with this idea of 'privacy through obfuscation.' It seemed like a good technique for a weak party to use when engaged with a powerful party," she says. "Of course, I had no idea if it was actually doable."

Thus was born TrackMeNot, a downloadable browser extension that prevents search companies from data-profiling Internet users. It takes an opposite approach from other technologies that work to the same goal, however: Rather than encrypting searches or similarly concealing them via technology, TrackMeNot hides users' real searches amid a steady torrent of fake ones.

Here's how it works: TrackMeNot automatically sends out, at the pace of 10 per hour or more, a random series of search queries--what Nissenbaum terms as "ghost queries." The thinking: The more searches sent from a user's Internet hub, the more difficult it will be for the search companies to aggregate data or work up an accurate and/or invasive user profile. Over time, the TrackMeNot engine evolves each user's fake search queries just enough to give its efforts a realistic feel.

Nissenbaum, who co-designed TrackMeNot with Daniel Howe, a NYU doctoral candidate in computer science, touts the "activist component" that spurred her to action, believing that the most effective protective measures in such situations are the ones individuals take on their own. She likens TrackMeNot's development to a do-it-yourself effort of another sort: "If you're living in a neighborhood where there's crime, your first instinct is to protect yourself, to get bars on your windows and make sure there are good locks on your doors." To date, more than 500,000 people have downloaded the software--naturally, a privacy advocate such as herself isn't keeping exact score--even though it currently only works with Mozilla's Firefox browser.

She's not blind, of course, to the implications of software like TrackMeNot for marketers. If such technologies achieve widespread adoption, certainly they'll trip up would-be behavioral marketers--or at least force them to change tactics. And they'll have implications for entities like Google Flu Trends, which relies on true searches to render its assessments of global flu activity.

That said, Nissenbaum is a philosopher by education. She believes that marketers, epidemiologists, and others can and will work their way around such concerns. "Technology can be designed in ways that protect privacy. We've seen that happen in many, many places," she says.

Nissenbaum, Howe, and the TrackMeNot team have faced their share of challenges along the way, ranging from mundane tech problems to issues related to managing growth. Most of the latter ones tend to be spurred by TrackMeNot aficionados asking "have you thought of this?"-- for instance, queries about when the software will be outfitted to accommodate non-English speakers. Owing to a lack of time and resources, these suggestions aren't always addressed overnight.

Then there was criticism from certain corners of the tech, privacy, and search communities. TrackMeNot received some guff--unwarranted, Nissenbaum believes--for acting subversively. "They'd say things like 'you're making it easy for pedophiles and terrorists.' Or they'd say 'you're clogging up the networks,'" she explains.

One issue TrackMeNot moved aggressively to address was concern about the faux search terms. Initially, TrackMeNot used terms from the top 100 searches ("pretty lame stuff, like 'Britney Spears' and 'Super Bowl,'" Nissenbaum says). Some users objected, however, so the list of terms was expanded. In the future, users might be able to choose the terms they want from some kind of peer-assembled list. Right now, TrackMeNot lacks the technical sophistication to do this.

While none of the four major search companies have officially communicated with members of the TrackMeNot team, Nissenbaum has learned through friends-of-friends-of-friends that the search giants are aware of the software. She notes that, since TrackMeNot's debut two years ago, they've started to address users' worries about the sanctity of their search data. "Whether or not TrackMeNot has had anything to do with it, I don't know," she says with a laugh. "But maybe we've played a very small part in making them realize how people feel."

As for future plans for TrackMeNot, well, they're up in the air. Nissenbaum doesn't know, for instance, if a version of TrackMeNot that works with Internet Explorer or Google Chrome will be cobbled together. "Daniel and I have been very upfront about it: We want to live in a world where TrackMeNot doesn't have to exist," she says. "The more people use it, the more of a statement is made."