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Abstract. Identifying and protecting the trusted computing base (TCB) of a system is an important task, which is typically performed by designing and enforcing a system security policy and verifying whether an existing policy satisfies security objectives. To efficiently support these, an intuitive and cognitive policy analysis mechanism is desired for policy designers or security administrators due to the high complexity of policy configurations in contemporary systems. In this paper, we present a graph-based policy analysis methodology to identify TCBs with the consideration of different system applications and services. Through identifying information flows violating the integrity protection of TCBs, we also propose resolving principles to using our developed graph-based policy analysis tool.

This chapter addresses the problem that traditional role-base access control (RBAC) models do not scale up well for modeling security policies spanning multiple organizations. After reviewing recently proposed Role and Organization Based Access Control (ROBAC) models, an administrative ROBAC model called AROBAC07 is presented and formalized in this chapter. Two examples are used to motivate and demonstrate the usefulness of ROBAC. Comparison between AROBAC07 and other administrative RBAC models are given. We show that ROBAC/AROBAC07 can significantly reduce administration complexity for applications involving a large number of organizational units. Finally, an application compartment-based delegation model is introduced, which provides a method to construct administrative role hierarchy in AROBAC07. We show that the AROBAC07 model provides convenient ways to decentralize administrative tasks for ROBAC systems and scales up well for role-based systems involving a large number of organizational units.

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