Privacy Preservation in Location Based Services

Location based service (LBS) is one of the most popular mobile services today, which offers wide range of services that are based on information about the physical location of a user or device. Typical LBS includes real-time turn-by-turn directions, points of interest (POI), and social network services such as Facebook, Foursquare, Loopt, and Qype. However, user location privacy is a major concern in today's mobile applications and there has been significant research dedicated to address this issue. Various location privacy preserving mechanisms (LPPM) have been used to preserve privacy of the location information of mobile users. This survey aims to present privacy preserving mechanisms employed in the location based services. Moreover, the LPPMs are classified into cryptographic and non-cryptographic mechanisms, and a taxonomy of mechanisms is also discussed. Multiple defense mechanism attributes/goals for the protection of location privacy have been described in the literature. Furthermore, classification and comparison of different mechanisms and location privacy attacks are presented based on their protection attributes and adversarial goals. Strengths and weaknesses of different mechanisms are also highlighted.