SCAN-PUF: A low overhead Physically Unclonable Function from scan chain power-up states

Physically Unclonable Functions (PUFs) are structures with many applications, including device authentication, identification, and cryptographic key generation. In this paper we propose a new PUF, called SCAN-PUF, based on scan-chain power-up states. We argue that scan chains have multiple characteristics that make them uniquely suited as a low-cost PUF. We present results from test chips fabricated in a 65nm bulk CMOS process in support of these claims. While approximately 20% of the total population of scan elements are unreliable across temperature variations, we find that simple unanimous selection schemes can result in mean error rates of less than 0.1% for the selected populations across all measurements collected.