PI 제어를 통한 FPGA 기반 TRNG에 대한 재고

At the CHES2011 conference, a new method of generating random numbers by inducing metastability using PDL(Programmable Delay Line) and PI(proportional-Integral) control has been proposed. During our confirmatory experiment, we found that their method to build a Programmable Delay Line using FPGA LUT was wrong. Moreover, even after we correct the scheme and re-implemented the TRNG what they suggested, we could not verify such a high randomness they provided. In this paper, we present experimental methods and results to prove that the TRNG they suggested cannot serve high entropy.