Efficient network camouflaging in wireless networks

摘要

Camouflaging is about making something invisible or less visible. Networkcamouflaging is about hiding certain traffic information (e.g. traffic pattern, trafficflow identity, etc.) from internal and external eavesdroppers such that importantinformation cannot be deduced from it for malicious use. It is one of the most challengingsecurity requirements to meet in computer networks. Existing camouflagingtechniques such as traffic padding, MIX-net, etc., incur significant performance degradationwhen protected networks are wireless networks, such as sensor networks andmobile ad hoc networks. The reason is that wireless networks are typically subject toresource constraints (e.g. bandwidth, power supply) and possess some unique characteristics(e.g. broadcast, node mobility) that traditional wired networks do notpossess. This necessitates developing new techniques that take account of propertiesof wireless networks and are able to achieve a good balance between performance andsecurity.In this three-part dissertation we investigate techniques for providing networkcamouflaging services in wireless networks. In the first part, we address a specificproblem in a hierarchical multi-task sensor network, i.e. hiding the links betweenobservable traffic patterns and user interests. To solve the problem, a temporally constant traffic pattern, called cover traffic pattern, is needed. We describe two traf-fic padding schemes that implement the cover traffic pattern and provide algorithmsfor achieving the optimal energy efficiencies with each scheme. In the second part,we explore the design of a MIX-net based anonymity system in mobile ad hoc networks.The objective is to hide the source-destination relationship with respect toeach connection. We survey existing MIX route determination algorithms that donot account for dynamic network topology changes, which may result in high packetloss rate and large packet latency. We then introduce adaptive algorithms to overcomethis problem. In the third part, we explore the notion of providing anonymitysupport at MAC layer in wireless networks, which employs the broadcast propertyof wireless transmission. We design an IEEE 802.11-compliant MAC protocol thatprovides receiver anonymity for unicast frames and offers better reliability than purebroadcast protocol.