Quality metric evaluation of a physical unclonable function derived from an IC's power distribution system

The level of security provided by digital rights management functions and cryptographic protocols depend heavily on the security of an embedded secret key. The current practice of embedding the key as digital data in the integrated circuit (IC) weakens these security protocols because the keys can be learned through attacks. Physical unclonable functions (PUFs) are a recent alternative to storing digital keys on the IC. A PUF leverages the inherent manufacturing variations of an IC to define a random function. Given environmental variations such as temperature and supply noise, PUF quality criteria such as reproducibility and the level of randomness in the responses may be difficult to achieve for a given PUF circuit architecture. In this paper, we evaluate a PUF derived from the power distribution system of an IC with regard to a set of quality metrics including single-bit and collision probability and entropy. The analysis is carried out using data obtained from 36 chips fabricated in IBM's 65 nm SOI technology.