Analysis of Security Protocols for Wireless Networks

Security is a serious concern in wireless networks. In order to eliminate the vulnerabilities in previous Standards, the IEEE 802.11i Standard is designed to provide security enhancements in MAC layer. The authentication process consists of several components, including an 802.1X authentication phase using TLS over EAP, a 4-Way Handshake to establish a fresh session key, and an optional Group Key Handshake for group communications. The objective of this work is to analyze IEEE 802.11i with respect to data confidentiality, integrity, mutual authentication, and availability. Under our threat model, 802.11i appears to provide effective data confidentiality and integrity when CCMP is used. 802.11i may also provide satisfactory mutual authentication and key management, although there are some potential implementation oversights that may cause severe problems. On the other hand, we identified several Denial of Service attacks. Different solutions are proposed for these vulnerabilities, which result in an improved variant of 802.11i with a more efficient failure recovery mechanism. Some of the resulting improvements have been adopted by the IEEE 802.11 TGi in their final deliberation. We used a finite-state verification tool, called Murp, to analyze the 4-Way Handshake component. Our result shows that finite-state verification is quite effective for analyzing security protocols. Furthermore, we adopted Protocol Composition Logic to conduct a correctness proof of 802.11i, including SSL/TLS as a component. The proof is modular, comprising a separate proof for each protocol component and providing insight into the networking environment in which each component can be reliably used. Finally, we showed that 802.11i can significantly reduce the complexity of designing a secure routing protocol when it is deployed in wireless ad hoc networks.