The Slatest

How Much Data Does Your Phone Number Reveal About You? A Lot.

People show their smartphones on December 25, 2013 in Dinan, northwestern France. AFP PHOTO / PHILIPPE HUGUEN (Photo credit should read PHILIPPE HUGUEN/AFP/Getty Images)

Photo by PHILIPPE HUGUEN/AFP/Getty Images

Last month Steve Vladeck and Slate’s Dahlia Lithwick took the “meh” out of metadata when they showed how someone’s aggregate metadata can reveal tons of personal information about their life. This week, on the heels of a federal judge’s ruling that the NSA’s phone program is likely unconstitutional, a new study showed just how easy it is to match telephone metadata to the identity of its owner.

According to the study’s authors Jonathan Mayer and Patrick Mutchler, the task of matching more than a thousand data points to actual phone users was “trivial”:

“We randomly sampled 5,000 numbers from our crowdsourced MetaPhone dataset and queried the Yelp, Google Places, and Facebook directories. With little marginal effort and just those three sources—all free and public—we matched 1,356 (27.1%) of the numbers. Specifically, there were 378 hits (7.6%) on Yelp, 684 (13.7%) on Google Places, and 618 (12.3%) on Facebook.”

The Atlantic highlighted the authors’ conclusion that, “If a few academic researchers can get this far this quickly, it’s difficult to believe the NSA would have any trouble identifying the overwhelming majority of American phone numbers.”

The report is now making its rounds online, where some of the reporting underscores the contrast between the study’s revealing findings and statements by government officials about the non-invasive nature of NSA data collection.