Privacy and anonymity in location data management

A growing number of applications and services include among their parameters a spatio-temporal characterization of some of the involved entities. These applications are enabled by positioning technologies that can provide real-time data about the location of moving objects. Depending on the considered adversary model, location data management for these applications requires the application of privacy preserving techniques at transaction time (online techniques), or upon the subsequent release of portions of transaction history (offline techniques). This chapter provides a brief survey of proposals for both classes of techniques, further classifying them accordingly to their specific goal, reference architecture, and evaluation methods. A technically deeper discussion is devoted to online anonymization when the adversary can recognize traces of requests from the same user, and to online location obfuscation in proximity services, like friend-finder services.