title: Identity and privacy. Unique in the shopping mall: on the reidentifiability of credit card metadata.
abstract: Large-scale data sets of human behavior have the potential to fundamentally transform the way we fight diseases, design cities, or perform research. Metadata, however, contain sensitive information. Understanding the privacy of these data sets is key to their broad use and, ultimately, their impact. We study 3 months of credit card records for 1.1 million people and show that four spatiotemporal points are enough to uniquely reidentify 90% of individuals. We show that knowing the price of a transaction increases the risk of reidentification by 22%, on average. Finally, we show that even data sets that provide coarse information at any or all of the dimensions provide little anonymity and that women are more reidentifiable than men in credit card metadata.
authors: Media Lab, Massachusetts Institute of Technology (MIT), 20 Amherst Street, Cambridge, MA 02139, USA. yvesalexandre@demontjoye.com.
authors: Yves-Alexandre
authors: YA
authors: de Montjoye
authors: Department of Computer Science, Aarhus University, Aabogade 34, Aarhus, 8200, Denmark.
authors: Laura
authors: L
authors: Radaelli
authors: Media Lab, Massachusetts Institute of Technology (MIT), 20 Amherst Street, Cambridge, MA 02139, USA. School of Communication and Information, Rutgers University, 4 Huntington Street, New Brunswick, NJ 08901, USA.
authors: Vivek Kumar
authors: VK
authors: Singh
authors: Media Lab, Massachusetts Institute of Technology (MIT), 20 Amherst Street, Cambridge, MA 02139, USA.
authors: Alex Sandy
authors: AS
authors: Pentland
mesh_terms: D003132:Commerce; D003625:Data Collection; D005260:Female; D006801:Humans; D007182:Income; D033181:Information Dissemination; D008297:Male; D018907:Privacy; D012727:Sex Characteristics