Protecting SRAM PUF from BTI Aging-based Cloning Attack

Abstract

SRAM Physical Unclonable Function (PUF) is currently one of the most popular PUFs, practically adopted in IC productions, to perform security primitives like encryption. However, previous works suggest responses of an SRAM PUF may be changeable due to one of the CMOS aging effects, Bias Temperature Instability (BTI). A physical counterfeit is thereby able to be produced by using BTI to change its responses, based on those of a target PUF. To prevent the BTI-based physical cloning attack, we propose a scheme without any modifications on the current SRAM PUF circuit, which is to pre-charge a challenged cell before it is powered up, so that its response can be affected by those transistors that cannot be precisely aged in the cloning process. We also show security and reliability metrics of SRAM PUFs are not affected by the extra pre-charge phase.