LOCATION SHARING: PRIVACY THREATS AND PROTECTION

In recent years there has been a growing increase in the number of users that use smartphones,tablets, wearable technologies and other devices that users have with them constantly. The capability of these latest generation mobile devices to detect the position of the users has led to the emergence of ad-hoc services as well as geo-aware social networks (GeoSN). Even if the sharing of our locations can enhance many useful services, there are several practical cases that unveil the danger of sharing location indiscriminately. For instance, let’s suppose that a user has just told everyone that he is on vacation (and not at his house): if he adds how long his trip is, then thieves know exactly how much time they have to rob him. Many contributions in the scientific literature have shown how through the location information it is possible to infer several information about the user. It has been shown that it is possible to identify user’s identity, if he is anonymous in the LBS, and, if the user is not anonymous, it is feasible to infer user’s home location, habits and also politic preferences and sexual orientation. The scientific literature reflects this concerns, proposing many contributions that deal with privacy, in general, and location privacy, specifically. This dissertation deals with location privacy in Location Based Services and Geo-Social Networks. The goal is two-fold: on one hand we want to motivate the importance of the location privacy topic by identifying the privacy threats of sharing locations. In particular we study a new privacy threat, the co-location threat, and we further study an already known threat stemming from the use of distance preserving transformations.On the other hand, we want to propose privacy preserving techniques and tools: we propose a novel privacy preserving technique as well as presenting three (spatial and/or temporal) cloaking techniques, specifically designed for privacy techniques in which the privacy is granted by the use of a location’s generalisation.