1. Robust Group Key Management with Revocation and Collusion Resistance for SCADA in Smart Grid Rong Jiang 2013.07.31

2. Agenda  Introduction  The proposed group key management  Security analysis and performance evaluation  Conclusion 2/19

3. SCADA  Supervisory Control And Data Acquisition (SCADA) systems are used to monitor and manage the electric distribution, transmission and generation environments.  the group communication is an essential part  a status scan request  measured value scan request  an emergent shutdown message or a set-the-clock-time message  Requirement: availability 3/19

4. SCADA system architecture HMI: Human-Machine Interface MTU: Master Terminal Unit RTU: Remote Terminal Unit 4/19

5. Security Model and Design Goal  Security Model  Group confidentiality  Backward secrecy  Forward secrecy  t-collusion-resistant  Design Goal  Availability  Efficiency 5/19

6. preliminary knowledge  Session key  DDHC(dual directional hash chain)  bivariate polynomial 6/19

7. Description of LiSH  Initialization  Re-keying  Self-healing mechanism  Adding new member nodes  re-initialization mechanism 7/19

8. Initialization 8/19

9. Initialization l is the length of key buffer; T refresh is the rekeying period : random numbers 9/19

10. Re-keying :the set of users all revoked in and before s j :a set of irrelevant users :self-healing set :broadcast polynomial 10/19 the KDC periodically discloses the next secret number C and constructs a self- healing set T and a revocation set R to expel some illegal nodes.

11. Re-keying 11/19

12. 12/19

13. Self-healing mechanism 13/19

14. Adding new member nodes 14/19

15. Determination of self-healing period 15/19

16. Security Analysis  Theorem 1: LiSH is a session key distribution with privacy and achieves self-healing with time-limited t-revocation capability.  Theorem 2: LiSH achieves t-wise forward and backward secrecy.  Theorem 4: LiSH is resistant to attacks to Dutta [13] and Du [17]’s schemes mentioned in section II. 16/19

17. Performance Evaluation 17/19

18. Conclusion  In this paper, we have proposed a robust and efficient group key management, named LiSH, to secure SCADA system in smart grid.  The proposed LiSH scheme is characterized by adopting self-healing key to tolerant failures of the sub-MTUs. Security analysis has shown that the proposed LiSH is a collusion-free and self- healing key distribution scheme with t-wise forward and backward security.  In addition, performance evaluation has also demonstrated its efficiency. 18/19

19. Thank you! 19/19