  Physical unclonable functions (PUFs), as hardware security primitives,
exploit manufacturing randomness to extract hardware instance-specific secrets.
One of most popular structures is time-delay based Arbiter PUF attributing to
large number of challenge response pairs (CRPs) yielded and its compact
realization. However, modeling building attacks threaten most variants of APUFs
that are usually employed for strong PUF-oriented application---lightweight
authentication---without reliance on the securely stored digital secrets based
standard cryptographic protocols. In this paper, we investigate a
reconfigurable latent obfuscation technique endowed PUF construction, coined as
OB-PUF, to maintain the security of elementary PUF CRPs enabled authentication
where a CRP is never used more than once. The obfuscation---determined by said
random patterns---conceals and distorts the relationship between
challenge-response pairs capable of thwarting a model building adversary
needing to know the exact relationship between challenges and responses. A bit
further, the obfuscation is hidden and reconfigured on demand, in other words,
the patterns are not only invisible but also act as one-time pads that are only
employed once per authentication around and then discarded. As a consequence,
the OB-PUF demonstrates significant resistance to the recent revealed powerful
Evaluation Strategy (ES) based modeling attacks where the direct relationship
between challenge and response is even not a must. The OB-PUF's uniqueness and
reliability metrics are also systematically studied followed by formal
authentication capability evaluations.
