A weighted graph approach to authorization delegation and conflict resolution

Solving conflicts in authorization delegation has not been considerably explored by researchers. In [5] we proposed a graph based framework supporting authorization delegation and conflict resolution. We proposed a predecessor-take-precedence based conflict resolution method, which gives higher priorities to the predecessors along the delegation paths to achieve the well-controlled delegations. In this paper, we further extend the model to allow grantors to express degrees of certainties about their delegations and grants of authorizations. This expression of certainty gives subjects more flexibility on the control of their delegations of access rights. A new conflict resolution policy based on weighted lengths of authorization paths is proposed. This policy deals with the conflicts in a more flexible way in that not only the relationship of predecessor-successor but also the weights of authorizations are taken into consideration. Cyclic authorizations are allowed to further enhance the expressive flexibility, and the undesired situations caused by them can be avoided through the proposed conflict resolution method. The intuitive graph interpretation provides a formal basis for the underlying semantics of our model.