A reference monitor for workflow systems with constrained task execution

ABSTRACT

We describe a model, independent of any underlying access control paradigm, for specifying authorization constraints such as separation of duty and cardinality constraints in workflow systems. We present a number of results enabling us to simplify the set of authorization constraints. These results form the theoretical foundation for an algorithm that can be used to determine whether a given constrained workflow can be satisfied: that is, does there exist an assignment of authorized users to workflow tasks that satisfies the authorization constraints? We show that this algorithm can be incorporated into a workflow reference monitor that guarantees that every workflow instance can complete. We derive the computational complexity of our algorithm and compare its performance to comparable work in the literature.

REFERENCES

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INDEX TERMS

Primary Classification:
  H. Information Systems
  H.2 DATABASE MANAGEMENT
      H.2.7 Database Administration
          Subjects: Security, integrity, and protection

Additional Classification:
  K. Computing Milieux
  K.6 MANAGEMENT OF COMPUTING AND INFORMATION SYSTEMS
      K.6.5 Security and Protection (D.4.6, K.4.2)

General Terms:
Security, Theory

Keywords:
authorization constraint, entailment constraint, reference monitor, workflow system