A Clockless Sequential PUF with Autonomous Majority Voting

Abstract

Physical unclonable functions (PUFs) leverage minute silicon process variations to produce device-tied secret keys. The energy and area costs of creating keys from PUFs can far exceed the costs of the basic PUF circuits alone. Minimizing the end-to-end cost of reliable key generation is critical to enable broader adoption of PUFs. In this work, we introduce a new style of PUF that employs autonomous majority voting to improve reliability. The novelty of this design, and the source of its efficiency, is that the inherently sequential majority voting procedure is carried out by a self-timed circuit without orchestration by a global clock. We use circuit simulation to evaluate the energy versus reliability tradeoffs achieved by different parameterizations of the design, to show that the design performs well across a range of supply voltages, and to quantify the robustness of the design across a broad range of operating temperatures.