Security implications of cooperative communications in wireless networks

Cooperative communications is an innovative technique that is expected to change the behavior of wireless networks in the near feature. In the MAC layer, this technique defines new protocols by enabling additional collaboration from stations that otherwise will not directly participate in the transmission. A typical example of such a protocol is CoopMAC [1], a cooperative MAC protocol that involves an intermediate station or helper in the communication between a transmitter and a receiver. Under this scheme, the transmitter sends its packets to the receiver by forwarding them through the helper. In this way the protocol takes advantage of spatial diversity and faster two-hop transmission, significantly improving the performance of the network. In such an environment, where the sender relies on an intermediate helper to forward its packets to the original destination, numerous security issues may arise. The present security schemes need to be adapted in order to support end-to-end security in the source-helper-destination communication model. In this paper we discuss the potential security issues that cooperation may raise and propose two new security schemes to address those concerns. To evaluate the feasibility of the proposed algorithms, we implement them using open source drivers platform, which is explained in the paper in detail. Moreover, the paper also discusses the design challenges encounterd and share the experience and insights gained during implementation. Our implementations of the suggested techniques allow the WEP, WPA and WPA2 (802.11i) security protocols to successfully operate in the new cooperative environment.