Research On FPGA Physical Fingerprint Optimization Method Based On Ring Oscillator

At present,with the continuous development of integrated circuits,Field Programmable Gate Array(FPGA)has been widely used,but traditional key storage methods are vulnerable to be attacked,which poses new challenges to the security authentication of FPGAs.Physical Unclonable Function(PUF),as a promising solution,can generate safe and reliable physical fingerprints for FPGAs.Ring oscillator(RO)PUF has been widely used due to its advantage of not requiring symmetrical design on FPGA.As an authentication key,the reliability and security of ROPUF have always been the focus and hotspot of research.This thesis uses Xilinx Artix7 XC7A100 T as the experimental chip.The main work carried out and the research results obtained are as follows:(1)In order to ensure the reliability of ROPUF,the influence of the number of inverters in the ROstructure on the frequency is analyzed,and the hard macros of 3-stage,5-stage,and 7-stage ROs are designed.The experimental test analyzes the frequency uniqueness of 3-stage,5-stage,and 7-stage ROs in two SLICEs,and have confirmed that the 3 stages ROfrequency has the highest uniqueness characteristics.(2)The randomness optimization method based on polynomial fitting frequency reconstruction is studied.Based on the 3-stage ROfrequency obtained by the FPGA Xilinx Artix7 XC7A100 T experimental test,the ROfrequency distribution law is analyzed,and the distribution law is enhanced by polynomial fitting frequency reconstruction,effectively solves the problem of low ROPUF entropy density,thereby improving the randomness of ROPUF.(3)The ROPUF stability enhancement method of the quaternion comparison strategy is designed,providing three matching schemes in each closely adjacent 3-stage ROs quaternion,using the frequency difference to flexibly select the optimal output.On the basis of maximizing the use of hardware resources,the stability of ROPUF is effectively enhanced.(4)In order to make physical fingerprints applicable to engineering,the ROPUF response is encrypted again with a hash function,and one-way transformation and data testing are carried out for 10,000 groups of high-digit(128bit)ROPUF responses,and the randomness of the response processed by the hash function can pass the authoritative randomness test standard for cryptography applications,indicating that the method has engineering applicability.