Privacy Risks in Publication of Taxi GPS Data

Taxis equipped with location sensing devices are increasingly becoming popular. Such location traces can be used for traffic management, taxi dispatching, and improved city planning. However, trajectory data often contain detailed information about individuals, and disclosing such information may reveal their lifestyles, preferences, and sensitive personal information. We study the GPS data of taxis in Beijing with more than 12000 taxis, and find out there are significant privacy risks associated with publishing taxi GPS data sets. In this paper, we first analyze the dataset from spatial and temporal dimensions. Second, we show that parking point information can re-identify anonymized trajectories of taxi drivers. Third, we find taxi GPS data could also expose passengers' privacy based on origin and destination (OD) queries. As a result, more than 55% trajectories can be re-identified at a probability of 1. Meanwhile, experimental results show that it is possible, using simple algorithms, to learn the destination of target passenger based on the naive anonymized GPS data.