Innovative Dynamic SRAM PUF Authentication for Trusted Internet of Things

This paper presents innovative dynamic SRAM PUF (Physical Unclonable Function) authentication for microcontroller units (MCU) embedding static RAM. We introduce a low cost PUF extractor, designed to monitor the MCU power-up and to read SRAM content. Some SRAM cells, referred as flipping-bits, have a fix content dependant on the voltage rising time. Experiments, using double ramp power-up waveform, show that these cells switch at low voltage values (below 500mV) according to a distribution, which seems to be linear. Because the digital part of the MCU is not working when flipping-bits switch, we propose a simple SRAM dynamic authentication protocol, based on slope and square power-up waveform, whose goal is to detect cloned MCUs.