Privacy amplification (PA) is a vital procedure in quantum key distribution (QKD) to shrink the eavesdropper's information about the final key almost to zero. With the increase of repeat frequency of discrete variable QKD (DV-QKD) system, PA processing speed has become the bottleneck in many highspeed DV-QKD systems. In this paper, a high-speed adaptive field-programmable gate array (FPGA)-based PA scheme using a fast Fourier transform (FFT) is presented. To decrease the computation complexity, a modified 2-D FFT-based Toeplitz PA scheme is designed. To increase the processing speed of the scheme on the constraint of limited resources, a real-value oriented FFT acceleration method and a fast read/write balanced matrix transposition method are designed and implemented in our scheme. The experimental results on a Xilinx Virtex-6 FPGA demonstrate that the throughput is nearly double of the latest FPGA based Toeplitz PA scheme according to the literature. Besides, this scheme owns not only the good adaptivity to compression ratio but also the compression ratio independent resource consumption. Therefore, this scheme can fit many high-speed QKD applications.
INDEX TERMSQuantum key distribution, privacy amplification, fast Fourier transform, field-programmable gate array.
Privacy amplification (PA) is the art of distilling a highly secret key from a partially secure string by public discussion. It is a vital procedure in quantum key distribution (QKD) to produce a theoretically unconditional secure key. The throughput of PA has become the bottleneck of most high-speed discrete variable QKD (DV-QKD) systems. Although some Toeplitz-hash PA schemes can meet the demand of throughput, their high throughput extremely depends on the high cost platform, such as MIC or GPU. From the comprehensive view of development cost, integration level and power consumption, CPU is a general low cost platform. However, the throughput of CPU based PA scheme is not satisfactory so far, mainly due to the conflict between the intrinsic serial characteristic of CPU and the parallel requirement of high throughput Toeplitz-hash PA scheme. In this paper, a high throughput modular arithmetic hash PA scheme using GNU multiple precision arithmetic library (GMP) based on CPU platform is proposed. The experimental results show that the throughput of our scheme is nearly an order of magnitude higher than the comparative scheme on the similar CPU platform, which is 135 Mbps and 69 Mbps at the block sizes of 10 6 and 10 8 on Intel i3-2120 CPU respectively. Moreover, our scheme can provide the best throughput among DV-QKD PA schemes, which is 260 Mbps and 140 Mbps at the block sizes of 10 6 and 10 8 on Intel i9-9900k CPU respectively.
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