A Highly Robust Secret Key Reconcile System Based on Cyclic Shift Buffer and HARQ Mechanism

Secret keys generated from wireless channel can provide high level of security. The error correction code (ECC) based information reconciliation method owns the benefits of high security and efficiency. In this paper, we designed a highly robust secret key reconcile system using low-density parity-check (LDPC) codes to correct disagreed key bits. In this system, we cache some high-quality secret key bits in a cyclic shift buffer (CSB) for compensation, which can effectively reduce the over-all key disagreement rate (KDR). Combined with a simple hybrid automatic repeat request (HARQ) implementation, this system significantly improves the correction success rate of information reconciliation. We built a realtime secret key generation system using universal software radio peripheral (USRP). Extensive experiments were carried out in different channel state information (CSI) scenarios. The proposed system can improve the success rate of secret key generation effectively in all experiment scenarios, especially in the case of low USRP Tx/Rx gain setups.