1. On The Untraceability of Anonymous RFID Authentication Protocol with Constant Key-Lookup Presented By Professor LI Yingjiu

2. 2 Outline Background Review the BMM protocol in AsiaCCS’08 Crack the Protocol by three-run interleave attack Crack the supply chain based on our attack Improve the BMM protocol Conclusion

3. Background It is still a challenge to balance the security and scalability. For example, –The OSK protocol needs O(N) hash calculation. –Numerous protocols based on tree-structure suffers from de-synchronization attack and compromising attack. It is emergent to setup a protocol balancing both the security and scalability. 3

4. BMM protocol in AsiaCCS’08 Burmester, Medeiros and Motta (BMM) proposed an RFID authentication protocol with constant key-lookup to balance the security requirement and scalability. The protocol is based on challenge- response technique. Guarantee spoofing attack, replay attack, de-synchronization attack, etc.. 4

5. Overview of BMM Protocol 5

6. Initiate System 6

7. Mutual Authentication Tag Reader 7

8. Update Process Tag Reader 8

9. Three-run Interleave Attack This attack can trace the same tag by ‘ps=r’. The reason is updating ‘ps’ inappropriately. Include three steps. 9

10. Three-run Interleave Attack---Run 1 10

11. Three-run Interleave Attack---Run 2 11 Not Update ‘r’

12. Three-run Interleave Attack---Run 3 12

13. Discussion Note that in the third run, a different challenge c’’ could be used by a trusted reader to challenge the tag. As long as the ‘r’ value is not updated in the second run, the ‘ps’ value is still the same as the one in the first run. 13

14. Crack the Whole Supply Chain Three assumptions: –Trusted zone –One-time authentication –Sticky adversary Two attack strategies: –Trace a single tag –Trace multiple tags 14

15. Crack a Supply Chain System Based on BMM Protocol 15

16. Trace a Single Tag 16

17. Trace Multiple Tags Adversary’s database for tracing multiple tags 17

18. Improve BMM Protocol 18

19. Conclusion Under a weak adversary model, an attacker can launch a three-run interleave attack to trace and identify a tag. Attackers can crack the whole supply chain using BMM protocol. We improve BMM protocol to prevent tags from tracing. The improved Protocol is same efficient as BMM protocol. 19

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