COSMOS: A Context-Centric Access Control Middleware for Mobile Environments

User/terminal mobility during service provisioning and high heterogeneity of wireless portable devices identify novel challenges for service delivery in ubiquitous pervasive environments. An emerging architecture solution in the wireless Internet is to have middleware components (mobile proxies) over the fixed network that follow the movements and act on behalf of the limited wireless clients. It is crucial that mobile proxies have full visibility of their context, i.e., the set of available and relevant resources depending on access control rules, client location, user preferences, privacy requirements, terminal characteristics, and current state of hosting environments. The paper presents the design and implementation of a context-centric access control middleware, called COSMOS, for the wireless Internet. COSMOS dynamically determines the contexts of mobile proxies, and effectively rules the access to them, by taking into account different types of metadata (user profiles and system/user-level authorization policies), expressed at a high level of abstraction and cleanly separated from the service logic. The paper also shows how COSMOS facilitates the development of articulated access control strategies in the case study of a context-dependent movie-info service deployed over IEEE 802.11 network localities.