A stochastic all-digital weak physically unclonable function for analog/mixed-signal applications

Abstract

Physically Unclonable Functions (PUFs) are a promising security technique which utilize the random process variation in silicon fabrication in order to create unique identifiers and other security features that are impossible to recreate exactly. This paper builds upon and evaluates a weak PUF which employs dynamic latched comparators and their random input offset voltages to create a chip-specific identifier. The proposed PUF can be used in analog/mixed-signal (AMS) chips due to the analog characteristics of the comparators employed. Because comparators are a fundamental block in AMS applications, the proposed PUF can reuse comparators in an AMS chip to generate unique identifiers with minimal hardware overhead. Additionally, the comparators tested in this work can be created with digital components, making this PUF suitable for use in digital chips as well. The proposed PUF is fabricated using a 0.13 μm CMOS process. Measurements show that the PUF achieves a normalized intra-Hamming Distance (HD) of less than 0.15% and 0.96% across 0°C–80°C and 0.8V–1.4 V, respectively. The normalized inter-HD is 48.5% for a 64-bit PUF output key. The power consumption of the PUF is 1.5 nJ/bit with a throughput of 4Mb/s.