1. A Lightweight Hop-by-Hop Authentication Protocol For Ad- Hoc Networks Speaker: Hsien-Pang Tsai Teacher: Kai-Wei Ke Date:2005/01/20

2. 2005/1/202 Outline Introduction LHAP Security Analysis Performance Analysis Conclusion

3. 2005/1/203 Securing Ad hoc Networks Most ad hoc networks do not have any provisions for restricting or regulating the traffic. Recently researchers have proposed security extensions for authenticating routing control packets. A simple solution is to use a network-wide key shared by all nodes.

4. 2005/1/204 Public Key Algorithm Two problems with shared-key ：  Key management  Digital signatures (Authentication) Key feature of public key cryptosystem  Two keys: Public Key & Private Key  Computational infeasible to determine decryption key.

5. 2005/1/205 Public Key Algorithm (cont.) Public Key Encryption

6. 2005/1/206 Public Key Algorithm (cont.) Public Key authentication

7. 2005/1/207 Outline Introduction LHAP Security Analysis Performance Analysis Conclusion

8. 2005/1/208 LHAP Lightweight hop-by-hop authentication. A node joining an ad hoc network only needs to perform some inexpensive authentication with its neighbors. Residing in between the data link layer and the network layer.

9. 2005/1/209 Notation

10. 2005/1/2010 Trust Management Trust Bootstrapping

11. 2005/1/2011 Trust Management (1) Trust Maintenance  Each node broadcasts an KEYUPDATE message (with TTL=1) to its neighbors.  The KEYUPDATE message is authenticated with the next TESLA key in its key chain.  Preventing malicious nodes from forging traffic using the TRAFFIC keys node A has already released.

12. 2005/1/2012 Trust Management (2) Trust Termination  When a compromised node is detected, all the node will terminate their trust relationship with that node permanently.  When a node doesn’t receive a valid KEYUPDATE message from a neighbor within a TESLA interval, it will terminate it trust of this neighbor temporarily.

13. 2005/1/2013 Lightweight Traffic Authentication Each node generates a one-way key chain used for traffic authentication. Node A want to broadcast a packet M: Benefit:  Enable instant verification of traffic packets.  It is not necessary to disclose TRAFFIC keys periodically.

14. 2005/1/2014 Outline Introduction LHAP Security Analysis Performance Analysis Conclusion

15. 2005/1/2015 Security Analysis Outside attacks  Single outside attack  Collaborative outside attack  Hidden terminal attack Inside attacks  Single inside attack  Insider clone attack

16. 2005/1/2016 Outside Attacks Single outside attack

17. 2005/1/2017 Outside Attacks (1) Collaborative outside attack  Attacker P1 and P2 have a private channel.  P1 forwards every message it eavesdropped from node A, including KEYUPDATE messages and traffic packets.  Solution: Allow a receiving node to determine if they should be able to hear each other.

18. 2005/1/2018 Outside Attacks (2) Hidden terminal attack  IEEE 802.11 solves the problem using CSMA/CA with ACKs and optional RTS/CTS control packet.

19. 2005/1/2019 Insider Attacks Single insider attack  A compromised node might attempt to flood the network with many traffic packets. Insider clone attack  When a compromised nod shares its private key with its outside conspirators. Solution  Instruction Detection System (IDS).

20. 2005/1/2020 Outline Introduction LHAP Security Analysis Performance Analysis Conclusion

21. 2005/1/2021 Performance Analysis Computational Overhead  RSA digital signature verifications.  Hash computation Latency  A node verifies a traffic packet it receives by computing one or more hashes. Traffic Byte Overhead  A node adds a traffic key to every traffic packet it sends,…

22. 2005/1/2022 Performance Analysis (cont.)  JOIN message, a public key certificate and the size of a digital signature.  A node sends an ACK packet to every new neighbor…  KEYUPDATE message.

23. 2005/1/2023 Outline Introduction LHAP Security Analysis Performance Analysis Conclusion

24. 2005/1/2024 Conclusion Presented a lightweight hop-by-hop authentication protocol for network access control in ad hoc networks. Transparent to and independent of the routing protocol.

25. 2005/1/2025 Reference 1. Sencun Zhu, and Shouhuai Xu, “LHAP:A lightweight Hop-by-Hop Authentication Protocol For Ad-Hoc Networks”, ICDCSW’03, IEEE 2003. 2. Adrian Perrig, and Ran Canetti, “Efficient Authentication and Signing of Multicast Streams over Lossy Channels”, IEEE 2000.