Wireless communication is playing an increasingly important role in many spheres of society. It has become an essential (and in some cases ubiquitous) means of communication. The number of cell phones has already exceeded that of landline wired phones, and soon there will be more smart phones than PCs. Wireless LANs are commonplace; they are routinely used at home, work, and many other public venues, such as cafes and malls. Most current wireless networks are employed in the context of personal communication where end users are people. In such networks wireless communication typically occurs only at the first and last hops. For example, cell phones communicate indirectly via base stations that are, in turn, connected to wired networks. Similarly, wireless LANs are usually connected to wired access points that are, in turn, connected to larger wired LANs and/or Internet service providers (ISPs). We refer to these networks collectively as infrastructure-based wireless networks. Since communication originating (or terminating) in cell phones or WiFi-capable devices usually transits a fixed network infra structure, few (if any) new security and privacy issues arise from such networks.