Physical Layer Secret Key Generation in Static Environments
share
We consider the problem of symmetric secret key generation in quasi-static/static environments, where the amount of common randomness obtained from the characteristics of the physical layer channel is limited. In order to provide a high-rate secret key generation mechanism, we introduce a method called induced randomness. In this method, locally generated randomness is assumed at the legitimate parties. Such randomness together with the uniqueness provided by the wireless channel coefficients are utilized to enable high-rate secret key generation. We describe the proposed secret key generation protocol for two scenarios; for the case where the legitimate parties have a direct link (the first scenario), and for the case where the legitimate parties do not have a direct link and communicate through an untrusted relay (the second scenario). After the exchange of the induced randomness, highly correlated samples are generated by the legitimate parties. These samples are then quantized, reconciled, and hashed to compensate for the information leakage to the eavesdropper and to allow verification of consistency of the generated key bit sequences. We utilize semantic security measures and information-theoretic inequalities to upper bound the probability of successful eavesdropping attack in terms of the mutual information measures that can be numerically computed. Given certain reasonable system parameters this bound is numerically evaluated to be 2^-31 and 2^-11.3 in the first and the second scenario, respectively. Furthermore, in the considered numerical setup, the bit generation rate is 64 bits/packet, the BER is 0.002 first and the second scenario, respectively, and the eavesdropper's average BER in both scenarios is almost 50 is upper bounded and evaluated in the numerical setup to be 0.0015 scenarios.
READ FULL TEXT