Link-Layer Encryption Effect on Achievable Capacity in Wireless Network Coding

In recent years, network coding has been enthusiastically promoted for certain wireless settings as a means of improving throughput and achieving higher capacity. Naturally, such proposals focused on communication issues, while paying less attention to security implications. This paper considers the effect of link-layer encryption (LLE) on network coding in wireless networks. LLE is a feature in current wireless networking standards (such as IEEE 802.11i) and its purpose is to mitigate traffic analysis attacks that are possible even in the presence of end-to-end encryption. We model single-source multicast using wireless network coding and show that, unfortunately, LLE significantly decreases the achievable capacity. Our goal is to understand the bounds of network coding and explore trade-offs between better security through LLE and greater capacity through network coding.