Photonic physically unclonable functions using randomly positioned aluminum nanoholes

Abstract

With the advancement of the Internet of Things, the volume of information and communication has significantly increased, highlighting the critical need for enhanced data security. Physically unclonable functions (PUFs), which generate encryption keys through nondeterministic and replication-resistant methods, have been proposed as a solution. Among the various types of PUFs, optical-based PUFs are gaining attention owing to their ability to leverage light for rapid measurements and their superior resistance and complexity to replication compared to other methods. In this study, we proposed a photonic PUF based on an aluminum film structure with randomly positioned nanoholes on a substrate. Light transmission through this structure resulted in scattering owing to localized and propagating surface plasmon resonances. The resulting image was digitized to generate an encryption key. Our tests involved adjusting the filling factor (FF) and pixel size, yielding a high randomness of 49.87% and a high bit density of 1.6 × 10⁷ bits/cm². The independent bits produced a total of 258 bits, closely matching the actual bit count of 256 bits. Furthermore, applying a Gaussian distribution to the hole sizes, assuming a more realistic scenario, yielded favorable results. This structure is cost-effective owing to the simplicity of its materials, production method, and design. Additionally, its compact size of 40 μm × 40 μm makes it ideal for miniaturization and integration into various applications.