Hardware/software co-design of physical unclonable function based authentications on FPGAs

Physical Unclonable Functions (PUFs) enable the generation of device-unique, on-chip, and digital identifiers by exploiting the manufacturing process variation. The past decade has seen an extensive effort in PUF design. Yet, most PUF constructions are regarded as stand-alone hardware building blocks. In contrast, we propose PUF constructions that are tightly integrated into the design of a micro-processor. The proposed PUFs are essentially a collection of time-to-digital converters that are integrated into the custom instruction or memory-mapped interface of a processor. Therefore, the processor can issue the PUF challenges and collect the associated responses using instruction executions. This integration enables practical, run-time physical authentication and it allows flexible post-processing mechanisms using software. In this article, we describe the design, implementation, and the performance analysis details of such hardware/software co-designed authentication mechanisms on FPGAs. We propose two variants of the PUF architecture: a synchronous module that requires minimal place and route constraints utilizing the common clock of the SoC, and an asynchronous alternative that is independent of the clock but realized with a controlled placement. We implemented the synchronous architecture on the Altera Cyclone-IV FPGAs and performed a large-scale characterization on 55 boards. The asynchronous design is realized on the Xilinx Virtex-5 FPGAs and tested on 100 boards. Measurements reveal that the proposed solutions can authenticate trillions of devices and provide better performance than the ring oscillator based alternative. (C) 2015 Elsevier B.V. All rights reserved.