Using the Physical Layer for Wireless Authentication in Time-Variant Channels

The wireless medium contains domain-specific information that can be used to complement and enhance traditional security mechanisms. In this paper the authors propose ways to exploit the spatial variability of the radio channel response in a rich scattering environment, as is typical of indoor environments. Specifically, they describe a physical-layer authentication algorithm that utilizes channel probing and hypothesis testing to determine whether current and prior communication attempts are made by the same transmit terminal. In this way, legitimate users can be reliably authenticated and false users can be reliably detected. They analyze the ability of a receiver to discriminate between transmitters (users) according to their channel frequency responses.