Theoretical Limits of Helperless Stabilizers for Physically Unclonable Constants

Physically unclonable constants (PUCs) have recently been proposed for private ID generation. Because in most of the proposed PUC schemes the generated value is not stable (i.e., it can change at different turn-ons), a postprocessing with a stabilizer is usually required. Most of the proposed stabilizer schemes use auxiliary data (helper data) to overcome the inherent randomness of the generation process. However, this complicates the structure of the scheme and poses additional security problems (e.g., helper data can be vectors for attacks), so that there is some interest in stabilizers that do not use helpers (helperless stabilizers). In this paper, we begin the study of the theoretical limits of helperless stabilizers. We show three main results: 1) perfect stability is unachievable; 2) we can make as small as desired the probability that a PUC has low stability; and 3) we can reliably recognize the bad devices at production time and discard them. The proofs of the latter two results are constructive.