Intensifying Challenge Obfuscation by Cascading FPGA RO-PUFs for Random Number Generation
Arjun Singh Chauhan, Vineet Sahula, Ankita Mandal, Abhigyan Dutta · 2020
Physical unclonable function (PUF) is a digital circuit, utilized as the random number generator (RNG) by exploiting device manufacturing/process variations. The physical unclonable functions based RNG can be used in security, communication, statistics, gaming applications, etc. ROPUF is considered weak PUF, since, the number of the challenge-response pairs (CRP), generated is comparatively smaller. We have proposed a cascaded ROPUF (C-ROPUF) design, which is able to produce a random number by employing reliability enhancing features of the ROPUF and a linear feedback shift register (LFSR). The proposed C-ROPUF design utilizes a novel obfuscation cell, leading to (i) a large reduction in the correlation between challenges and responses, (ii) generation of a larger number of CRP, and (iii) greatly enhanced the length of response sequence, of the order of a Million. These sequences have successfully passed the NIST statistical test for randomness. The inter-chip hamming distance and obfuscated hamming distance statistical mean values are the same as theoretical value, whereas their variance approaches to zero. Moreover, the mean intra-chip hamming distance is approximately 0.0001% at ambient condition, evaluated on the Xilinx-7 Series FPGA in 28 nm technology.