Surprise: Phone Metadata Gives Away The Most Secret of Your Secrets

If you're one of the masses who inexplicably thinks that NSA phone surveillance doesn't matter, you're in for a shock: new research reveals that simple analysis of cellphone metadata can reveal masses about you, from medical conditions to firearm ownership.

A study by Jonathan Mayer and Patrick Mutchler from Stanford probed data from 546 volunteers to ascertain the limits of just what can be found from metadata such as that collected by the NSA. We already knew, of course, that it could be used to identify you—but it can paint an alarmingly detailed picture of you, too.

The results reveal just how rich a seam of information your metadata is. The participants gave up their phone's metadata via a special app, along with publicly available information from their Facebook profile. Then, the researchers set to work, digging though it all to find out as much as they could.

So, one participant in the study "communicated with multiple local neurology groups, a specialty pharmacy, a rare condition management service, and a hotline for a pharmaceutical used solely to treat relapsing multiple sclerosis"; another "had a long, early morning call with her sister. Two days later, she placed a series of calls to the local Planned Parenthood location. She placed brief additional calls two weeks later, and made a final call a month after."

Elsewhere, another "contacted a home improvement store, locksmiths, a hydroponics dealer, and a head shop," while a fourth placed "a number of calls to a firearm store that specializes in the AR semiautomatic rifle platform. They also spoke at length with customer service for a firearm manufacturer that produces an AR line."

They're just anecdotes, but they could find similar information about all the participants: over a three months period, 30 percent contacted a pharmacy, 10 percent called a recruiting service, and 8 percent got in touch with religious institutions. In other words, the researchers knew exactly what everyone was up to.

The take-home is perhaps best summed up by Mayer himself. "Reasonable minds can disagree about the policy and legal constraints that should be imposed on those databases," he writes. "The science, however, is clear: phone metadata is highly sensitive." [Jonathan Mayer]

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