xDUCON: Coordinating Usage Control Policies in Distributed Domains

In this paper, we present xDUCON a framework for coordinating and enforcing usage control policies across different collaborating organisations. xDUCON allows the specification of usage control policies that concisely capture conditions, authorisations, and obligations on both providers and consumers of resources. The xDUCON framework is based on the Shared Data Space (SDS) abstraction, where collaborating organisations share a data space containing tuples representing subjects, resources and usage policies. The SDS allows the coordination of the decision and enforcement points abstracting from the details of the actual deployment of the framework. As a consequence, xDUCON supports policies able to express richer and finer constraints compared to previous usage control models. Policies support entity mutability that is the changing of related subject and target attributes due to accesses being executed. The decision and enforcement points support ongoing control over long-lived sessions to evaluate the access rights of a subject while the access is being executed. If the context under which the rights were granted changes, xDUCON is able to revoke the access rights preventing the subject to use any longer the resource.