1. 1 Testing Implementations of Access Control and Authentication Graduate Students: Ammar Masood K. Jayaram School of Electrical and Computer Engineering Department of Computer Science Purdue University Faculty: Arif Ghafoor (ECE) Aditya Mathur (CS) May 10, 2006 Oak Ridge National Lab, Oak Ridge, TN

2. 2 Research Objective To develop and experiment with novel techniques for the generation of tests to test implementations of authentication protocols and access control policies.

3. 3 Target security mechanisms Role based access control (RBAC) with or without temporal constraints. Authentication protocols (e.g. TLS)

4. 4 Proposed Test Infrastructure (Access control) Access Control policy Policy verifier plugin Policy (internal representation) Policy model Policy tests Modeling plugin Test generator plugin Test harness IUT

5. 5 Challenges Modeling: Naïve FSM or timed automata models are prohibitively large even for policies with 10 users and 5 roles (and 3 clocks). How to reduce model size and the tests generated? Test generation: How to generate tests to detect (ideally) all policy violation faults that might lead to violation of the policy? Test execution: Distributed policy enforcement?

6. 6 Proposed Approach Express behavior implied by a policy as an FSM. Apply heuristics to scale down the model. Use the W- method, or its restricted form, to generate tests from the scaled down model. Generate additional tests using a combination of stress and random testing aimed at faults that might go undetected due to scaling.

7. 7 Sample model Two users, one role. Only one user can activate the role. Number of states≤3 2. AS: assign. DS: De-assign. AC: activate. DC: deactivate. X ij : do X for user i role j.

8. 8 Fault model

9. 9 Tests generated

10. 10 What is next… Modeling: Handling timing constraints? (timed automata, fault model, heuristics) Handling authentication protocols? (Statecharts, insecure paths, test generation) Dealing with concurrency? Experimentation: With large/realistic policies and commercial authentication protocols to assess the efficiency and effectiveness of the test generation methods. Prototype tool development (Money???)