A note on the formalisation of UCON
Proceedings of the 12th ACM symposium on Access control models and technologies
Adaptive model for user knowledge in the e-learning system
CompSysTech '08 Proceedings of the 9th International Conference on Computer Systems and Technologies and Workshop for PhD Students in Computing
Verification and enforcement of access control policies
Formal Methods in System Design
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Policies are increasingly used to govern the behaviour of complex distributed systems. Most policy models that allow policy composition, to address the complexity of policies, are only concerned with structural composition. In this paper we argue that it is natural to compose policies also along the temporal axis, i.e. express policies that can dynamically change over time or on the occurrence of events. We present a dynamic policy frame-work that has a sound semantics in Interval Temporal Logic and allows both structural and temporal composition. We provide examples of authorisation, delegation and obligation policies that can be activity-based, state-based or historybased, i.e. expressing decisions on the history of execution. Examples for the composition of policies show how the framework can be used to express policies for systems that operate in an environment that is characterised by uncertainty. Finally tool-support for the specification and analysis of dynamic policies is presented.