High Efficient Secret Key Reconciliation Scheme Based on Cascade Algorithm

In the quantum key generation scheme, key reconciliation is used to eliminate inconsistent key bitstream between partners. The speed of reconciliation and the retention length of data are the main indicators for evaluating a reconciliation method. The Cascade algorithm is developed based on the BINARY reconciliation. By forward backtracking, Cascade can correct even-numbered errors hidden in the data. However, its computational complexity seriously affects the reconciliation speed, and the final length of key generated is relatively low. In this paper, an optimization method BFR-Cascade algorithm is proposed to reduce the computational complexity. Meanwhile, the final unified deletion rule (FUDR) is applied to increase retention length of data. Compared with Cascade algorithm, the proposed method can achieve 54% higher reconciliation speed when the signal-to-noise ratio (SNR) is 8dB, and the retention length of data is increased by at least 44% through FUDR.