All That 'Anonymous' Cellphone Data Tracking Can Actually Identify You

(Image: Christine Daniloff/MIT of an original by Yves-Alexandre de Montjoye et al via MIT News)

It's one thing if a cellphone service provider has been ordered to reveal data on a specific user that allows law enforcement to triangulate a person's movements. But a new study is showing how anonymized data that is pretty readily available can not only be used in tracking but easily identifies individuals.

Using an anonymized data set, MIT and the Université Catholique de Louvain researchers were able to uniquely identify 95 percent of the 1.5 million cellphone users on whom data was collected for 15 months in a European town, MIT News reported.

"In other words, to extract the complete location information for a single person from an 'anonymized' data set of more than a million people, all you would need to do is place him or her within a couple of hundred yards of a cellphone transmitter, sometime over the course of an hour, four times in one year," MIT News explains.

Just how available are these datasets? Popular Science describes them as "fairly publicly available." Things collecting this location data that can then identify a user include location-tracking apps -- think Twitter, Four-Square and others that tag a person to a specific geographical location.

The researchers hope their findings will help policy analysts better understand the privacy implications of aggregated location data. Or as Popular Science explained it:

The danger of being able to identify cellphone users so easily is that you could deduce some pretty private information just from where people go. You could see if someone attends certain religious or political meetings, visits an HIV/AIDS or reproductive clinic, or hangs out with an ex or a business rival.

“There’s a concern with this data, to what extent can we preserve anonymity,” Luis Bettencourt, a professor at the Santa Fe Institute who was not involved in the study, told MIT News. “What they are showing here, quite clearly, is that it’s very hard to preserve anonymity.”

Although geo-tracking data might come with a whole host of privacy implications, some see a value in the datasets as they can be used show patterns of people's movements to improve society. Bettencourt said it can help researchers "understand how people use urban space." Gigaom pointed out a few examples of positive uses of such data, which include improving traffic patterns, business practices and even healthcare.

The research was published this week in Scientific Reports.

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• Law Enforcement Wants Your Text Messages Stored For Investigations