ESPuF – Enabling SRAM PUFs on Commodity Hardware

Physically unclonable functions (PUFs) are a promising way of introducing hardware-based security primitives into widely used digital systems such as Internet of Things (IoT) devices or Industry 4.0 production plants. Former research attempts focused on conceptually evaluating SRAM PUFs in particular, thus forming the theoretical basis for this paper. The real-world applicability of the proposed SRAM PUFs has hardly been shown before. Therefore, this paper contributes an SRAM PUF implementation based on commodity off-the-shelf (CoTS) hardware, in particular an ESP32 microcontroller. Most notably, the proposed concept does not require any additional hardware. This is a decisive factor for the overall applicability in real-world scenarios since it can be executed on every general-purpose ESP32 microcontroller. Furthermore, this paper provides a detailed PUF algorithm overview which has also been implemented in soft- and hardware. To support the various theoretical benefits of the proposed system, a statistical evaluation of the robustness and overall performance of the PUF concept is also part of this paper. The results show, that the ESP32 SRAM PUF concept allows for a secure on-device authentication based on nanoscale hardware variations during the manufacturing of the ESP32 SRAM cells.