A Self-Timed Ring based PUF
Grégoire Gimenez, Abdelkarim Cherkaoui, Laurent Fesquet · 2020
A new type of physical unclonable function (PUF) is presented in this paper. It leverages the sub-gate-delay phase resolution of self-timed ring oscillators to efficiently extract the randomness due to the chip manufacturing process. The main advantage of the presented technique is its ability to fine tune the measurement resolution in order to find the best trade-off between the PUF stability and its uniqueness. We show that on-the-fly evaluation of the propagation time through delay elements can be achieved, enabling the extraction of a unique identifier per chip. This approach can efficiently replace the methods based on time-consuming frequency estimations. The first results, based on an FPGA implementation, are given. They show decent and configurable stability, uniqueness and randomness properties while outperforming the response latency of the traditional ring oscillator PUF.