Trust management with safe privilege propagation

Abstract

Trust management uses delegation to enable decentralized authorization across administrative domains. Delegation passes one's authority over resources to trusted entities and thus enables more flexible and scalable authorization. However, unrestricted delegation may result in privilege proliferation and breach the privacy of information systems. The delegation models of existing trust management systems do not provide effective control on delegation propagation, and the correctness of constraint enforcement mechanisms is not formally analyzed, which may lead to privilege proliferation. In this paper, we propose a role-based constrained delegation model (RCDM), which restricts the propagation scope of delegation trees by a novel delegation constraint mechanism named spatial constraint. This paper also introduces a rule-based language to specify the policies and the deduction algorithm for constrained delegation defined in RCDM. The soundness and completeness properties of the deduction algorithm ensure the safety and availability of our delegation model. © Springer-Verlag Berlin Heidelberg 2005.