A New Scheme for Improving Channel-Based Secret Key Generation Rates

Physical layer key generation from the wireless channel is an emerging area of interest to provide confidentiality and authentication. One of the main challenges in this domain is to increase the length of the generated secret key while maintaining its randomness and uniformity. In this letter, new dimensions for wireless channel-based key generation are proposed for orthogonal frequency division multiplexing (OFDM) systems. The novel perspective of the proposed work lies in the generation of key bits not only from the magnitudes of OFDM subchannels as it has conventionally been done but also from the number and positions/indices of those subchannels, whose channel gains are above the mean of the respective subblock. The effectiveness of the proposed algorithms is evaluated in terms of key generation rate and key mismatch rate. It is shown in the simulation results that the involvement of the proposed dimensions can double the key generation rate compared to conventional algorithms.