Anonymization of Location Data Does Not Work: A Large-Scale Measurement Study

The authors examine a very large-scale data set of more than 30 billion call records made by 25 million cell phone users across all 50 states of the US and attempt to determine to what extent anonymized location data can reveal private user information. Their approach is to infer, from the call records, the "Top N" locations for each user and correlate this in-formation with publicly-available side information such as census data. For example, the measured "Top 2" locations likely correspond to home and work locations, the "Top 3" to home, work, and shopping/school/commute path locations.