Electromagnetic signatures of WLAN cards and network security

The proliferation of wireless devices and the availability of new wireless applications and services raise new privacy and security concerns. Although network-layer anonymity protects the identities of the communication endpoints, the physical layer of many wireless communication protocols offers no such guarantee. The electromagnetic signal transmitted over an open communication medium can be monitored, captured, and analyzed in an effort to trace and identify users of wireless devices. In this paper we present preliminary results on the feasibility of identifying wireless nodes in a network by measuring distinctive electromagnetic characteristics or "signatures" of wireless local area network (WLAN) cards