A Lightweight and Efficient Key Generation Scheme From OFDM Subcarriers’ Channel Responses

Abstract

This letter presents a physical layer secret key generation (PLSKG) protocol utilizing the amplitude of channel frequency response (CFR) of Orthogonal Frequency Division Multiplexing (OFDM) subcarriers. Firstly, least squares estimation estimates the CFR. Next, a partition moving average (PMA) algorithm encodes the CFR. PMA re-uses the CFR within a partition by encoding at different overlap sizes, thus increasing the key generation rate (KGR). Then, a 2-bit differential-based quantization at every overlap for each partition is followed for an improved KGR and randomness. Finally, a cyclic redundancy check is performed to select strings with consistent results as candidate key, eliminating streams from less correlated measurements, thus ensuring a 0-bit mismatch. Simulation results have verified that our scheme achieves random 0-bit disagreement keys with a high average key length and reduced complexity compared to the other existing lightweight schemes.