Fast and robust speckle pattern authentication by scale invariant feature transform algorithm in physical unclonable functions

Nowadays, due to the growing phenomenon of forgery in many fields, the interest in developing new anti-counterfeiting devices and cryptography keys based on the Physical Unclonable Functions (PUFs) paradigm has increased widely. PUFs are physical hardware with an intrinsic, irreproducible disorder that allows for on-demand cryptographic key extraction. Among them, optical PUFs are characterized by a large number of degrees of freedom resulting in higher security and higher sensitivity to environmental conditions. While these promising features led to the growth of advanced fabrication strategies and materials for new PUF devices, their combination with robust recognition algorithms remains largely unexplored. In this work, we present a metric-independent authentication approach that leverages the Scale Invariant Feature Transform (SIFT) algorithm to extract unique and invariant features from the speckle patterns generated by optical PUFs. The application of SIFT to the challenge response pairs protocol allows us to correctly authenticate a client while denying any other fraudulent access. In this way, the authentication process is highly reliable even in the presence of response rotation, zooming, and cropping that may occur in consecutive PUF interrogations and to which other postprocessing algorithms are highly sensitive. These characteristics, together with the speed of the method (tens of microseconds for each operation), broaden the applicability and reliability of PUF to practical high-security authentication or merchandise anti-counterfeiting.