Dynamic Collaborative Environments

Access control is used in computer systems to control access to confidential data. In this thesis we develop flexible access control models for users in dynamic col-laborative environments, such as hospitals, or consultancy firms. We propose Audit-based Compliance Control (AC2). In AC2 user actions are not checked immediately (a-priori), like in conventional access control, but users must account for their actions at a later time (a-posteriori), by providing ma-chine-checkable justification proofs to one or more auditors. This allows users to exchange and access confidential data, like health records in a hospital, in an ad hoc manner. A similar design choice was made recently for the Dutch electronic health record infrastructure (AORTA). We also take a more conventional approach by proposing two extensions to Role-based Access Control (RBAC). These extensions give users more ways of autho-rizing and deploying RBAC policy changes, thus favoring dynamic collaboration between users. Marnix Dekker graduated in Theoretical Phys-ics from the University of Utrecht, and worked subsequently as a software developer in Pisa. He did his PhD research at TNO Informatio