Enhanced challenge-response set and secure usage scenarios for ordering-based ring oscillator-physical unclonable functions

The number of applicable challenge–response pairs (CRPs) in physical unclonable functions (PUFs) is critical especially for authentication protocols in security systems. Ideally, full read-out of all CRPs should be infeasible and CRPs should be independent from each other for a highly secure system. CRP concept is not defined in ordering-based ring oscillator (RO) PUFs presented in the literature. In this paper, the authors propose two methods for enhanced CRP set in ordering-based RO-PUFs and analyse their performance in terms of uniqueness and area efficiency. Next, they propose three secure usage scenarios based on enhanced CRP set methods, preventing the CRPs from leaking information about each other. With the proposed systems, 100% robust, area and power efficient and secure PUF structures with exponential number of CRPs become possible that are very convenient especially for authentication protocols.