Delegation is the process whereby an active entity in a distributed environment authorizes another entity to access resources. In today's distributed systems, a user often needs to act on another user's behalf with some subset of his/her rights. Most systems have attempted to resolve such delegation requirements with ad-hoc mechanisms by compromising existing disorganized policies or simply attaching additional components to their applications. Still, there is a strong need in the large, distributed systems for a mechanism that provides effective privilege delegation and revocation management. This paper describes a rule-based framework for role-based delegation and revocation. The basic idea behind a role-based delegation is that users themselves may delegate role authorities to others to carry out some functions authorized to the former. We present a role-based delegation model called RDM2000 (role-based delegation model 2000) supporting hierarchical roles and multistep delegation. Different approaches for delegation and revocation are explored. A rulebased language for specifying and enforcing policies on RDM2000 is proposed. We describe a proofof-concept prototype implementation of RDM2000 to demonstrate the feasibility of the proposed framework and provide secure protocols for managing delegations. The prototype is a web-based application for law enforcement agencies allowing reliable delegation and revocation. The future directions are also discussed.

In current role-based systems, security officers handle assignments of users to roles. However, fully depending on this functionality may increase management efforts in a distributed environment because of the continuous involvement from security officers. The emerging technology of role-based delegation provides a means for implementing RBAC in a distributed environment with empowerment of individual users. The basic idea behind a role-based delegation is that users themselves may delegate role authorities to other users to carry out some functions on behalf of the former. This paper presents a role-based delegation model called RDM2000 (role-based delegation model 2000), which is an extension of RBDM0 by supporting hierarchical roles and multi-step delegation. The paper explores different approaches for delegation and revocation. Also, a rule-based language for specifying and enforcing the policies based on RDM2000 is introduced.

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As organizations implement information strategies that call for sharing access to resources in the networked environment, mechanisms must be provided to protect the resources from adversaries. The proposed delegation framework addresses the issue of how to advocate selective information sharing in rolebased systems while minimizing the risks of unauthorized access. We introduce a systematic approach to specify delegation and revocation policies using a set of rules. We demonstrate the feasibility of our framework through policy specification, enforcement, and a proof-of-concept implementation on specific domains, e.g. the healthcare environment. We believe that our work can be applied to organizations that rely heavily on collaborative tasks.

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