1. Muhammad Mahmudul Islam Ronald Pose Carlo Kopp School of Computer Science & Software Engineering Monash University Australia

2.  Problem statement  Limitations of WEP and 802.11i  Features of Link Layer Security Protocol (LLSP)  Overview of LLSP  Security analysis of LLSP  Overhead of LLSP  Future work  Questions

3. What is Security  Authentications, verifies the authenticity of the sender  Encryption, hides information  Integrity, prevents unauthorized modification Security in ad-hoc networks above link layer  Secure route discovery and route maintenance (e.g. SAR, ARIADNE, ARAN etc)  Secure communication on end-to-end basis (e.g. IPSec)  Monitor traffic pattern and take necessary steps to minimize malicious/selfish behaviors (e.g. Watchdog, Pathrater, CONFIDANT etc) Common assumption of these solutions  A secured layer has already been deployed that securely distributes various keys, certificates and update information Link Layer Security Protocol (LLSP) is a solution for the underlying secured layer

4. WEP  Lacks dynamic key management  One way handshaking, reusing keys and the weaknesses of RC4 make WEP vulnerable to MITM attacks  Vulnerable to DoS attacks since association and dissociation messages are not authenticated  Not designed for multi-hop ad-hoc networks 802.11i  Requires a trusted third party authentication server (RADIUS) for authenticating new nodes  Uses symmetric keys for authenticating new nodes and exchanging session keys  Not designed for multi-hop ad-hoc networks

5.  Uses capability to flexibly represent the access right and the identification of each link  Authenticate and encrypt every packet for each link  Guarantee the integrity of information.  Dynamic key management  Reduces replay, MITM and DoS attacks  Not dependent on any trusted third party authentication server  Does not require any MAC-IP binding  Does not need synchronized clocks  Independent of any routing protocol  No network wide flooding of any information  Scales properly with changes in network topology  Does not suffer from initial setup delay for each session  Specially designed for SAHN-like networks

6.  Multi-hop ad-hoc network  Ideal for cooperative nodes, e.g. connecting houses and business  Topology is quasi-static  Uses wireless technology  Multi-hop QoS routing  Decentralized  Multi Mbps broadband service  No charges for SAHN traffic  Can run alongside TCP/IP  Conceived by Ronald Pose & Carlo Kopp in 1997 at Monash University, Australia

7. Security Services Provided by LLSP  Type 1: Authenticates a new node  Type 2: Updates the capability (CAP) of a link  Type 3: Updates the shared key (SHK) of a link  Type 4: Authenticates received packets and  Type 5: Encrypts payload of MAC layer

8. Authenticate a New Node

9. Update SHK

10. Update CAP

11. Secure and Authenticate Data packets

12. Various Packet Formats of LLSP

13.  CAP of a link as a certificate  Encrypting CAP & SIG ensure the authenticity of each packet  SIG ensures integrity  Encrypting SIG and SEQ reduces replay attacks  Updating keys and CAP regularly makes guessing or recomputing difficult by unauthorized nodes  DoS attacks by flooding is not propagated, i.e. kept confined within the neighborhood of the malicious node

14. Authentication Type Transmission Rate (Mbps) Total Duration (ms) Type 1 169.86 267.24 5.565.58 1165.10 Type 2, Type 3 145.92 244.50 5.543.60 1143.34 Type 4, Type 5 Any In real-time using AES HW Duration of authentication processes with 802.11b and HW supported AES

15. Communication Overhead for single pair of node (1/2)

16. Communication Overhead for single pair of node (2/2)

17. Communication Overhead for 35 pairs of node (1/2)

18. Communication Overhead for 35 pairs of node (2/2)

19. Enhance the effectiveness and robustness of LLSP by integrating a monitoring system that can detect malicious/selfish activities of other nodes Integrate LLSP with channel access mechanisms of other wireless technologies (e.g. IEEE 802.11e, 802.16) and measure performance