International Association
for Cryptologic Research

Analysis of advanced Physical Unclonable Function (PUF) applications and protocols rely on assuming that a PUF behaves like a random oracle, that is, upon receiving a challenge, a uniform random response with replacement is selected, measurement noise is added, and the resulting response is returned. In order to justify such an assumption, we need to rely on digital interface computation that into some extent remains confidential -- otherwise, information about PUF challenge response pairs leak with which the adversary can train a prediction model for the PUF.

We introduce a theoretical framework that allows the adversary to have a prediction model (with typical accuracy of 75% for predicting response bits for state-of-the-art silicon PUF designs). We do not require any confidential digital computing or digital secrets while we can still prove rigorous statements about the bit security of a system that interfaces with the PUF. In particular, we prove the bit security of a PUF based random oracle construction; this merges the PUF framework with fuzzy extractors.