Authenticated side channel via physical layer fingerprinting

Fingerprint embedding at the physical layer is a demonstrably powerful technique for secure message authentication. In this article, we build upon the general framework for embedding physical layer fingerprints to create an authenticated side channel for minimal cost. The authentication is enabled with the use of a low-power tag superimposed upon the message waveform; the signaling over the side channel is performed with the choice of tag that depends on secret keys shared by the legitimate transmitter and receiver. The side channel may be used for various purposes, including key exchange. We present a design and analysis of the establishment, operation, and performance of the side channel. To conclude, we discuss simulation results that validate the theory and demonstrate the viability of the approach.