Mitigating the intractability of the user authorization query problem in role-based access control (RBAC)

  • Authors:
  • Nima Mousavi;Mahesh V. Tripunitara

  • Affiliations:
  • ECE, University of Waterloo, Canada;ECE, University of Waterloo, Canada

  • Venue:
  • NSS'12 Proceedings of the 6th international conference on Network and System Security
  • Year:
  • 2012

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Abstract

We address the User Authorization Query problem (UAQ) in Role-Based Access Control (RBAC) which relates to sessions that a user creates to exercise permissions. Prior work has shown that UAQ is intractable (NP -hard). We give a precise formulation of UAQ as a joint optimization problem, and observe that in general, UAQ remains in NP . We then investigate two techniques to mitigate its intractability. (1) We efficiently reduce UAQ to boolean satisfiability in conjunctive normal form, a well-known NP -complete problem for which solvers exist that are efficient for large classes of instances. We point out that a prior attempt is not a reduction, is inefficient, and provides only limited support for joint optimization. (2) We show that UAQ is fixed-parameter polynomial in the upper-bound set of permissions under reasonable assumptions. We discuss an open-source implementation of (1) and (2), based on which we have conducted an empirical assessment.