Implicit Authorization for Social Location Disclosure

Being increasingly equipped with highly-accurate positioning technologies, today’s mobile phones enable their owners to transmit their current position over the cellular network and share it with others. So-called location-based community services make use of this possibility, for example for locating friends, co-workers or family members. Of course, these services give target persons control about the way location data may be accessed by others. So far, this is done by the target explicitly granting or denying permissions through authorization policies or ad-hoc authorization. Unfortunately, apart from bringing along high management effort, the concept of explicit authorization in such a privacy-sensitive application entails the disadvantage of social difficulties. In this paper we introduce the concept of implicit authorization, which has reciprocity as its central element: Another person is granted access to a certain target’s location information implicitly by the target accessing the information of that other person as well. The technique aims to reduce social pressure on the target person when deciding whether a certain person may locate her or not. Also, the target person is relieved from management overhead. Several realizations of implicit authorization are proposed. They differ in the service pattern (reactive/proactive) they are useful for and the way a once given access grant is revoked.