On The Untraceability of Anonymous RFID

Authentication Protocol with Constant Key-Lookup

Presented By Professor LI Yingjiu

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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

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.

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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..

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Overview of BMM Protocol

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Initiate System

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Mutual Authentication

• Tag Reader

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Update Process

• Tag Reader

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Three-run Interleave Attack

• This attack can trace the same tag by ‘ps=r’.

• The reason is updating ‘ps’ inappropriately.

• Include three steps.

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Three-run Interleave Attack---Run 1

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Three-run Interleave Attack---Run 2

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Not Update ‘r’

Three-run Interleave Attack---Run 3

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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.

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Crack the Whole Supply Chain

• Three assumptions:– Trusted zone– One-time authentication– Sticky adversary

• Two attack strategies:– Trace a single tag– Trace multiple tags

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Crack a Supply Chain System Based on BMM Protocol

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Trace a Single Tag

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Trace Multiple Tags

• Adversary’s database for tracing multiple tags

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Improve BMM Protocol

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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.

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