Novel Strong PUF based on Nonlinearity of MOSFET Subthreshold Operation

Many strong silicon physical unclonable functions (PUFs) are known to be vulnerable to machine-learning attacks due to linear separability of the output function. This significantly lim-its their potential as reliable security primitives. We introduce a novel strong silicon PUF based on the exponential current-voltage behavior in subthreshold region of FET operation which injects strong nonlinearity into the response of the PUF. The PUF, which we term subthreshold current array (SCA) PUF, is implemented as a pair of two-dimensional n × k transistor arrays with all devices subject to stochastic variability operating in subthreshold region. Our PUF is fundamentally different from earlier attempts to inject nonlinearity via digital control techniques, which could also be used with SCA-PUF. Voltages produced by nominally identical arrays are compared to produc