1. Packet Leashes: A Defense against Wormhole Attacks in Wireless Networks Yih-Chun Hu (Carnegie Mellon University) Adrian Perrig (Carnegie Mellon University) David B. Johnson (Rice University) Presented by: Jón T. Grétarsson 5 April, 2005 CS577: Advanced Computer Networks

2. Outline Introduction Problem Statement Related Work Assumptions and Notation Detecting Wormhole Attacks Temporal Leashes and the TIK Protocol Evaluation Conclusions CS577: Advanced Computer Networks

3. Introduction CS577: Advanced Computer Networks

4. The Authors Yih-Chun Hu Adrian Perrig David B. Johnson CS577: Advanced Computer Networks

5. Problem Statement Wormholes! CS577: Advanced Computer Networks

6. Wormholes in MANET Packets are “tunneled” from one location to another If done reliably, no harm no foul If done selectively, much damage can be done! S D Wormhole Colluding Attackers CS577: Advanced Computer Networks

7. The Threat Permanent Denial-of-Service Disruption to Routing Protocols Unauthorized Access CS577: Advanced Computer Networks

8. Related Work CS577: Advanced Computer Networks

9. Related Work RF Watermarking Intrusion Detection 802.11i CS577: Advanced Computer Networks

10. Assumptions and Notation CS577: Advanced Computer Networks

11. Assumptions & Notation Resource Constrained Nodes Existing key distribution system HMAC - a message authentication code used for authentication Bidirectional links are not necessary CS577: Advanced Computer Networks

12. Detecting Wormhole Attacks CS577: Advanced Computer Networks

13. Leashes Somehow restrict the transmission distance of the packet Geographical Leashes Temporal Leashes CS577: Advanced Computer Networks

14. Geographical Leashes Node Location Loosely Synchronized Clocks Bounded Velocity of packet d sr is distance between two nodes ∆ is error in time CS577: Advanced Computer Networks

15. Temporal Leashes Requires tight synchronization of clocks MAC contention issues Digital signature scheme can guarantee timestamp CS577: Advanced Computer Networks

16. Temporal Leashes and the TIK Protocol CS577: Advanced Computer Networks

17. Authentication All information (timestamp, expiration, position) must be verified Traditional methods of verification are too expensive Merkle Hash Trees are the solution! CS577: Advanced Computer Networks

18. Merkle Hash Trees CS577: Advanced Computer Networks

19. TESLA with Instant Key Disclosure CS577: Advanced Computer Networks

20. Evaluation CS577: Advanced Computer Networks

21. How it was done Calculated required number of Hashes per second for algorithm Calculated computational power of portable devices CS577: Advanced Computer Networks

22. Results Suitable for laptops and PDA’s, but not for resource scarce networks Not enough space to store the packet! CS577: Advanced Computer Networks

23. Conclusions CS577: Advanced Computer Networks

24. Conclusions Wormholes are dangerous! They can degrade performance of Mobile Ad Hoc routing algorithms Both Geographical and Temporal leashes can detect wormholes TIK is an implementation of Temporal leashes that can be used when there is sufficiently tight time synchronization TIK is not usable in resource-scarce networks CS577: Advanced Computer Networks

25. Questions? Comments? Donations? CS577: Advanced Computer Networks

26. References Graphics borrowed from http://www.panda.uvic.ca/seminars/stor age/PacketLeashes.ppt, http://www.ece.cmu.edu/~adrian/project s/ secure-routing/infocom2003.pdf CS577: Advanced Computer Networks