Mobile traffic sensor network versus motion-MIX: tracing and protecting mobile wireless nodes

In this paper we focus on passive attacks that threaten the privacy of mobile wireless networks. We define the concept of "venue privacy attack" (VPA) to illustrate the emerging anonymity attacks to trace mobile wireless nodes. Then we propose "motion-MIX" as the countermeasure to defend against various venue privacy attacks. We study the necessary conditions to implement motion-MIXes. These conditions include identity-free routing, one-time packet content and various other concerns in the network protocol stack. Then we use a new asymptotic security model to verify motion-MIX's effectiveness against venue privacy attacks. In a scalable ad hoc network, we prove that the probability of security breach is negligible (aka. sub-polynomial) with respect to the polynomial-bounded network scale (i.e., number of node in the network). This notion is conforming to the existing security notions in computational cryptography, where the polynomial-bounded metric is key length.