Moving window scheme for extracting secret keys in stationary environments

Abstract

In this study, the authors propose a novel secret key generation scheme to address the consecutively identical secret key bits problem in stationary environments. First, by randomising the phase of probe signals with stochastic coefficients, they sum the channel estimates in a moving window to get new records with remarkable fluctuations. Then, they propose an adaptive equal probability quantisation approach to ensure the randomness of the secret key. Furthermore, considering the worst scenario, the security of the scheme is evaluated in terms of the adversary's mean square error (MSE) for the single-antenna system. While for the multi-antenna system, they propose an artificial noise-aided strategy to compromise the adversary's MSE performance. The simulation results reveal that the security of the scheme is guaranteed and a better security performance is achieved compared with the prior works. Finally, they validate the feasibility of the proposed scheme in real stationary environments. The testing results show that their scheme achieves remarkable performance in bit mismatch rate and key generation rate, and the generated keys pass the National Institute of Standards and Technology test.