FPGA Implemented RO-Based PUFs for User Authentication in the Metaverse

Protecting resources/services in the metaverse from unauthorized access, corruption, and misuse is of primary importance. A widely adopted strategy for users' authentication is to generate a user's signature by a physical unclonable function (PUF) based approach. For metaverse applications, the implementation of PUFs using Field Programmable Gate Arrays (FPGAs) is considered promising, mainly due to FPGAs' low cost and flexibility. When implemented on FPGAs, PUFs are typically of the Ring Oscillators (ROs)-based kind. FPGA implemented RO-based PUFs proposed so far in the literature have been designed using either manual place-and-route, or manual placement (with no provided details on the adopted routing strategy). However, manual place-and-route, as well as manual placement only, may significantly decrease the cost and flexibility benefits of FPGA implementations. In this paper, we investigate the adoption of automatic place-and-route to design FPGA implemented RO-based PUFs, considering a different number of ROs' inverting stages. Moreover, as a term of comparison, we design FPGA implemented RO-based PUFs also using manual placement and automatic routing. Uniqueness, uniformity, steadiness and reliability of our designed PUFs are evaluated by means of experimental measurements. We compare our PUF designed using automatic place-and-route with alternate PUFs proposed so far in the literature, and with our PUF designed using manual placement and automatic routing, from the point of view of the provided uniqueness, uniformity, steadiness and reliability. We show that our PUF designed using automatic place-and-route constitutes an acceptable, low cost alternative to PUFs designed using manual place and route, or manual placement and automatic routing, thus being promising especially for metaverse applications, for which cost and flexibility may play a relevant role.