1. Security for the Optimized Link- State Routing Protocol for Wireless Ad Hoc Networks Stephen Asherson Computer Science MSc Student DNA Lab 1

2. Outline Wireless Ad hoc Networks Wireless Ad hoc Routing Protocols  OLSR Routing Protocol Security of Wireless Networks Security of Ad hoc Routing Protocols MSc Project  Security for the OLSR Routing Protocol  Implementation and Testing 2

3. Wireless Ad hoc Networks(1)  Conventional wireless networks consist of wireless clients talking to an Access Point (AP)  Wireless Ad hoc networks are decentralised Dynamic, nodes can join and leave at any time Nodes communicate directly with other nodes in wireless range Out-of-range nodes are reached via intermediate nodes in a multi-hop nature 3

4. Wireless Ad hoc Networks(2) Regular Wireless NetworkWireless Ad hoc Network 4

5. Wireless Ad hoc Networks(3)  If node A needs to reach node B, how does A know which path leads to B? This is the responsibility of an Ad hoc Routing Protocol 5

6. Wireless Ad hoc Routing Protocols(1)  Nodes out of range communicate via intermediate nodes Serve as routers Perform data forwarding  Several routes may exist between any two nodes  A simple data multicast approach would work Highly inefficient Waste of network resources 6

7. Wireless Ad hoc Routing Protocols(2)  Ad hoc routing protocols attempt to discover optimal routes to all nodes  There is a large classification of wireless ad hoc routing protocols  Classified in two main categories Table-Driven (Proactive) On-Demand (Reactive) 7

8. Wireless Ad hoc Routing Protocols(3)  Proactive Protocols Rely on constant communications with other nodes to maintain an overview of networks routes High overhead; Readily available routes  Reactive Protocols Initiate route discovery only when a route to a node is required More efficient; Delay in establishing route 8

9. The OLSR Routing Protocol(1)  The Optimized Link-State Routing (OLSR) protocol is a proactive routing protocol for wireless ad hoc networks  OLSR consists of the following main tasks: Link and Neighbour detection Multi-Point Relay Selection Topology information diffusion 9

10. The OLSR Routing Protocol(2)  Link and neighbour detection through periodic emission of “Hello” messages  Topology information is diffused using topology control (TC) messages via multi-point relay nodes 10

11. The OLSR Routing Protocol(3)  Generic Packet Format 11

12. The OLSR Routing Protocol(4)  Messages are processed and transmitted from source to destination independently of one another  The generic OLSR packet is simply a point-to- point carrier for the messages between two immediate neighbours 12

13. Security in Wireless Networks(1)  Wireless networks are highly vulnerable due to the open nature of the technology  Authenticity, confidentiality, and integrity mechanisms are essential Eavesdropping Spoofing Data modification 13

14. Security in Wireless Networks(2)  The IEEE 802.11i standard is a security amendment for the IEEE 802.11 wireless standard  IEEE 802.11i specifies the security mechanisms offered in the Medium Access Control (MAC) layer Point-to-point security association between two entities 14

15. Security in Wireless Networks(3)  In a multi-hop environment, MAC layer security is not enough  End to end security may require security mechanisms employed higher up in the stack 15

16. Security in Wireless Networks(4) 16

17. Security of Ad hoc Routing Protocols(1)  Ad hoc routing protocols are generally designed with efficiency as a priority Security adds overhead Security is often neglected in the initial design  There is an implicit assumption that nodes are trustworthy 17

18. Security in the OLSR Protocol(1)  The project aim Incorporate end to end security mechanisms for each control message  Authentication  Integrity  Replay protection – timestamps  Mutable field protection Optional encryption/decryption of OLSR packets between neighbouring points 18

19. Security in the OLSR Protocol(2)  Application level security 19

20. Security in the OLSR Protocol(3)  Security-aware OLSR control message 20

21. Signature Schemes  Two signature schemes have been used in the implementation Shamir’s Identity-based scheme One-time Signature scheme known as Hash to Obtain Random Subset(HORS)  Aim was to perform a comparison of the two schemes when used to sign OLSR messages 21

22. Shamir’s Identity-based scheme  Based on RSA public key system  Like RSA, is computationally expensive  A user’s public key is derived from public knowledge of the user, such as it’s IP address or email address  Prevents the need for public key distribution amongst nodes 22

23. Hash To Obtain Random Subset(HORS) one-time signature scheme  Based on the use of one-way functions  Fast and efficient signature creation and verification  Public/Private key pair limited to a few signatures  Large key and signature sizes  Public key distribution complexities 23

24. Implementation and Testing  Signature schemes and security extension implemented in C OLSRd implementation from www.olsr.orgwww.olsr.org  Test the overhead incurred by the security Traffic, delay, and processing overhead Delay in route establishment  Testing will be done on 10 node indoor wireless testbed 24

25. The End Thank you! 25