A privacy service for context-aware mobile computing

Privacy issues related to the access of context information are becoming increasingly important as we move toward ubiquitous and mobile computing environments. In this article, we describe the design and implementation of a privacy service, called Context Privacy Service (COPS), to control how, when and to whom disclose a user's context information. Based on the results of an end-user survey and experience reported by other research groups, we identified the main service requirements and designed COPS aiming flexibility, generality, simplicity and fine-grained privacy control. COPS is an optional service of our context-provisioning middleware MoCA and allows users of context- and location-aware applications to define and manage their privacy policies regarding disclosure of their context information. The main features supported by COPS are group-based access control, pessimistic and optimistic approaches for access control, hierarchical privacy rules, mixed-initiative interaction, and rule specificity analysis.