Unique in the Crowd: The privacy bounds of human mobility, a Nature Scientific Reports paper by MIT researchers and colleagues at Belgium's Universite Catholique de Louvain, documents that 95% of "anonymous" location data from cellphone towers can be de-anonymized to the individual level. That is, given data from a region's cellular towers, the researchers can ascribe individuals to 95% of the data-points.
“We show that the uniqueness of human mobility traces is high, thereby emphasizing the importance of the idiosyncrasy of human movements for individual privacy,” they explain. “Indeed, this uniqueness means that little outside information is needed to re-identify the trace of a targeted individual even in a sparse, large-scale, and coarse mobility dataset. Given the amount of information that can be inferred from mobility data, as well as the potentially large number of simply anonymized mobility datasets available, this is a growing concern.”
The data they studied involved users in an unidentified European country, possibly Belgium, and involved anonymized data collected by their carriers between 2006 and 2007.
Anonymized Phone Location Data Not So Anonymous, Researchers Find [Wired/Kim Zetter]