FPGA implementation of Toeplitz hashing extractor for real time post-processing of raw random numbers

Abstract

Random numbers are widely used in many fields. However, most existing random number generators cannot directly generate ideal random bits without post-processing. With the development of generation techniques, the generation rate of raw random data has reached Gbps magnitude and the speed of existing post-processing cannot satisfy the growth of demand. To solve this issue, we propose a concurrent pipeline algorithm based on Toeplitz matrix hashing and implement it in a resource limited field-programmable gate array (FPGA). By taking advantage of the concurrent computation features of FPGA instead of common computer serial computation, the post-processing speed is improved by three orders of magnitudes to above 3.36 Gbps, which is suited for Gbps real time post-processing of raw random numbers. After post-processing, the final extracted random bits can well pass the standard randomness tests. To implement the scheme, a printed circuit board (PCB) is designed for raw data acquisition, real time post-processing and final extracted random data transmission. On the PCB, the random signal is sampled and digitalized as raw random data and then the data are fed into a FPGA for real time post-processing. At the same time, three different transmission interfaces including a small form-factor pluggable (SFP) fiber transceiver, a universal serial bus (USB) 2.0 port and a Gigabit Ethernet port are designed for different scenarios. An optional DDR3 memory module is also provided for testing purpose.