Report : It 's easy to identify smartphone users by their movements . Researchers from MIT and elsewhere tracked 1.5 million people for two years . Each mobile user 's daily movements are unique and create a ` ` . '' Some advocates worry how law enforcement and others may use that data .
Report : It 's easy to identify smartphone users by their movements . Researchers from MIT and elsewhere tracked 1.5 million people for 15 months . Each mobile user 's daily movements are unique and create a `` fingerprint '' Privacy advocates worry how law enforcement and others may use that data .