A note on information-theoretic secret key exchange over wireless channels

For wireless channels, a number of information-theoretic secret key exchange protocols have been proposed and analyzed for their efficiency in the literature. We contend that for such protocols in a realistic adversarial model that includes an active adversary, average number of message-bits that need to be exchanged to obtain one-bit of secret key is an important performance metric, which has been previously overlooked in the literature. Using this insight, we analytically study a recently popular class of information-theoretic secret key exchange protocols that is based on wireless channel fading. We obtain analytical results for specific cases and provide fundamental insights into the competitive performance of this class of information-theoretic secret key exchange protocols.