Framework for Role-Based Delegation Models (RBDMs)

1. Framework for Role-Based Delegation Models (RBDMs) By: Ezedin S.Barka and Ravi Sandhu Laboratory Of Information Security Technology George Mason University {e.barka, sandhu}@isse.gmu.edu www.list.gmu.edu

2. Introduction • What is delegation? • Forms of delegation • Our focus • RBAC96 is the base for our work

3. What is delegation? • An active entity in a system delegates authority to another active entity to carry out some function on behalf of the former • Active entities • Human being • Computer • Software agent • Process • etc.

4. Forms of delegation • human to human • Human to machine • Machine to machine • Perhaps even machine to human

5. Human-to human role-based delegation • A user who is a member of a role to delegate his/her role to another user who belongs to some other role.

6. The RBAC96 Model

7. Example of role Hierarchy Project lead Production Engineer Quality Engineer Project Lead > Quality Engineer Quality Engineer > engineering Production engineerQuality engineer Engineering

8. The RBDM Framework • Identified a number of characteristics related to delegation between humans, • Permanence • Monotonicity • Administration • Levels of delegation • Multiple delegation • Bilateral agreements • Revocation

9. Permanence • Weather or not the delegating role member looses membership in the delegating role. • Permanent: is permanently replacement by the delegate user • delegating user can’t get the role back • Delegate member assumes full power in the role • Temporary: expires with time or by revocation • Delegating user maintain responsibility over the behavior of the delegate user in the delegated role

10. Monotonicity • Weather or not the delegating role member looses the power in the delegating role. • Monotonic: Upon delegation, the delegating user maintains his power in that role • Can override any action by the delegate user • Non-monotonic: During delegation, the delegating user looses his power in the delegated role • Never looses the revoking permissions • Regains full power upon delegation expiration

11. Totality • Size of the delegated permission in a role • Total: delegating all the permissions assigned to the role • Partial: delegating only subset of the role • Easier to address in hierarchical roles

12. Administration • who administer the delegation • Self-administered • The delegating user carryout the actual delegation process • Agent-based • A third party conducts the actual delegation • Needed when the delegating user is not available

13. Levels of delegation • How many times can the role be further delegated • Single-step Delegation • The role can be delegated only once • Multi-step delegation • The delegated role is further delegated • Adds a lots of complexities

14. Multiple delegation • Number of people to whom a delegating role member can delegate at any given time. • To a single person • Role is delegated to only one person at a time • To multiple people simultaneously • Role is delegated to more than one person at a time • Introduces accountability issues

15. Bilateral agreements • Both parties have to agree on the delegation

16. Revocation The process by which a delegating user take away the privileges delegated to another user • Cascading revocation • Usually a concern in the case of the two step delegation • grant-dependency revocation • Who can revoke • Only the delegating user can revoke • Any member of the delegating role can revoke

18. Models in this framework • Permanent delegation • RBDM-PD , work in progress • Temporary delegation • self administered • RBDM-FR, NISSC 2000 • RBDM-HR, NISSC 2000 • Agent-based • ABEDM, work in progress

19. Conclusion • Identified a number of characteristic related to delegation • Used a systematic approach to reduce the large number of possibilities to some useful cases • Used the reduced cases to build delegation models

20. Questions?