ioPUF: A PUF-based IoT Node Identification Utilizing Pull-Up/Down Resistors on IO Pins

This paper introduces ioPUF, a novel Physical Unclonable Function (PUF), for uniquely identifying Integrated Circuits (IC) and the IoT nodes encompassing them. The PUF generates unique device identifiers utilizing the pull-up/down resistors on the Input-Output (IO) pins of the ICs. The method relies on the fact that the pull-up/down resistor values on IO pins differ from the designed value due to manufacturing variations. The variations in these resistor values across ICs are significantly higher than those within the IC. Since pull-up/down resistors are present in the IOs of many ICs, ioPUF implementation does not demand custom circuits or ICs. Also, unlike PUFs that demand dedicated resources, ioPUF does not require reserving resources such as IO pins throughout the device’s operation. It uses IO pins only when a device identifier is generated. For these reasons, ioPUF is well-suited for cost-sensitive embedded systems built from Commercial off-the-shelf (COTS) components. Simulation studies of the PUF, specifically on inter-device and intra-device hamming distances, indicate near-to-ideal performances with intra-device hamming distances centred around zero and well separated from inter-hamming distances. Experimental evaluations using the commercial IC, PSoC-5, from Infineon affirms the PUF’s feasibility.