Location Privacy in Chain-Based Protocols for Location-Based Services

Mobile communication devices have rapidly proliferated in all developed countries. Most of these devices can determine their location, and their computation and storage capacities have greatly increased in recent years. Therefore, location-based services (LBS) will become cornerstones of the new information society. Most of the time, LBS are provided by trusted companies such as telecommunications companies. However, the wide availability of these technologies can foster the appearance of alternative non-trusted providers. When location information is exchanged amongst untrusted parties,the privacy of the participants could be in jeopardy. Thus, some methods have been proposed in the literature to provide users with location privacy, and most of them rely on a trusted third party (TTP) that is used to centralise all location information prior to sending it to a non-trusted provider. Unfortunately, in many situations TTPs are not available. In this paper, we provide a brief overview of the state of the art of LBS privacy, we recall a novel TTP-free proposal and, finally, we analyse its robustness against the attack of several passive malicious users.