Design And Implement Of QKD Post-processing System Based On GPU

With the development of quantum computing, modern cryptography based on computational complexity is now seriously threatened by the strong parallel computing ability of quantum computation. The only encryption algorithm, which is proved absolutely safe, can’t be widely used because it still has some problem in key generation and distribution. However, QKD, which is short for quantum key distribution, solved this problem and made this encryption algorithm really useful. Presently, QKD processing system are mostly implemented on FPGA, but the source of FPGA is limited, clock frequency is limited and the rate of data source is technically limited, the kernel algorithm of each data processing module is limited by hardware and affected by channel disturbance, the processing speed is unable to satisfy the actual demand.The main content of this paper is to use GPU to implement QKD post-processing system and accelerate it. QKD post-processing system includes five modules, which are filter, error estimation, error reconciliation, security enhancement and channel authentication. In this paper, error reconciliation module and security enhancement module are implemented and improved.Error reconciliation module is used for correct the error in the code, and output the correct code, the process is quite complex, and it affects the efficiency of the whole system directly. Therefore, it is quite necessary to accelerate this part. The acceleration process includes three parts, first of all, the LDPC(Low Density Parity Check Code) error code reconciliation module is implemented with BP(Belief Propagation) algorithm on CPU, secondly, the process is improved, and the executing speed is highly improved, finally, the module is implemented on GPU, and the efficiency is improved again, which is better than that improved on CPU.In the process of quantum key distribution, the Eve can also obtain information from the channel, so it is not safe. Security enhancement can eliminate the information leakage in the transmission, and can improve the security of the final generated key. In this part, we mainly used the Toeplitz matrix and fast Fourier transform(FFT). Firstly, this process is implemented on CPU, then FFT is used to improve the algorithm, finally, GPU is used to speed up the process, and the effect is very significantly.