Pieter Van Hertum

Marcos Cramer, Zohreh Baniasadi, Pieter Van Hertum

In ownership-based access control frameworks with the possibility of delegating permissions and administrative rights, delegation chains will form. There are different ways to treat delegation chains when revoking rights, which give rise to different revocation schemes. In this paper, we investigate the problem of delegation revocation from the perspective of the knowledge base paradigm. A knowledge base is a formal specification of domain knowledge in a rich formal language. Multiple forms of inference can be applied to this formal specification in order to solve various problems and tasks that arise in the domain. In other words, the paradigm proposes a strict separation of concerns between information and problem solving. The knowledge base that we use in this paper specifies the effects of the various revocation schemes. By applying different inferences to this knowledge base, we can solve the following tasks: to determine the state of the system after a certain delegation or revocation; to interactively simulate the progression of the system state through time; to determine whether a user has a certain permission or administrative right given a certain state of the system; to verify invariants of the system; and to determine which revocation schemes give rise to a certain specified set of desired outcomes.

Pieter Van Hertum, Ingmar Dasseville, Gerda Janssens et al.

The knowledge base paradigm aims to express domain knowledge in a rich formal language, and to use this domain knowledge as a knowledge base to solve various problems and tasks that arise in the domain by applying multiple forms of inference. As such, the paradigm applies a strict separation of concerns between information and problem solving. In this paper, we analyze the principles and feasibility of the knowledge base paradigm in the context of an important class of applications: interactive configuration problems. In interactive configuration problems, a configuration of interrelated objects under constraints is searched, where the system assists the user in reaching an intended configuration. It is widely recognized in industry that good software solutions for these problems are very difficult to develop. We investigate such problems from the perspective of the KB paradigm. We show that multiple functionalities in this domain can be achieved by applying different forms of logical inferences on a formal specification of the configuration domain. We report on a proof of concept of this approach in a real-life application with a banking company. To appear in Theory and Practice of Logic Programming (TPLP).

Marcos Cramer, Pieter Van Hertum, Diego Agustin Ambrossio et al.

In ownership-based access control frameworks with the possibility of delegating permissions and administrative rights, chains of delegated accesses will form. There are different ways to treat these delegation chains when revoking rights, which give rise to different revocation schemes. In this paper, we show how IDP - a knowledge base system that integrates technology from ASP, SAT and CP - can be used to efficiently implement executable revocation schemes for an ownership-based access control system based on a declarative specification of their properties.