Secret key acquisition under pilot contamination attack

Abstract

This work presents a novel secret key generation method from common randomness of frequency selective channel between legitimate nodes in the presence of an active eavesdropper (Eve). Pilot contamination attack (PCA) from Eve severely impedes secret key generation from the estimate of reciprocal channel between legitimate nodes. In order to mitigate the impact of PCA in the pilot phase, we propose two-step channel estimation technique where decoded data is used as reference for channel estimation, which preserves correlation between estimated channels of legitimate nodes. The proposed approach achieves low key disagreement probability (KDP) in the presence of signal contamination. We also present analysis of KDP under contamination attack. The simulation results demonstrate that the proposed method is less vulnerable to the active attack and our analysis of KDP agrees with simulation.