Entropy Analysis of RO-based Physically Unclonable Functions

Abstract:
In this paper we estimate the probability distribution of a ring oscillator based PUF (RO-PUF) operating under different digitization schemes (topologies) of compensated measuring, and we quantify their performance and security properties by means of the entropy and entropy-related metrics: entropy per bit ratio, entropy per oscillator ratio and the product of both. We have studied the most common digitization schemes for this type of systems, and we propose a new construction designed to overcome some flaws found in these. Each topology has been tested with a large set of frequencies obtained from an array of three-stages oscillators implemented in FPGA.