Dual-space visible light authentication toward high security physical unclonable function.

Random pattern generation by nondeterministic self-assembly offers physical unclonable function (PUF) for hardware-based information security system. However, authenticating intricate signals from randomized disordered structures is challenging without time-consuming, expensive characterization. Here, we present easily authenticatable, highly secure self-assembly-based PUF system enabled by synergistic authentication mechanism exploiting dual-space visible signals. Polycrystalline monolayer morphology of colloidal self-assembled pattern, consisting of a virtual 3D space defined by 2D spatial coordinates and crystal orientation, can be effectively authenticated by combining real-space Bragg reflection and reciprocal-space diffraction signals in visible wavelength regime. Notably, polycrystalline patterned structures composed of hexagonal close-packed colloidal grains are highly beneficial for practical PUF labels, while providing unpredictable reciprocal lattice information with a high degree of freedom for easy authentication with a vast number of encryption keys. Our PUF solely based on structural information can serve for versatile templates for mechanically flexible, renewable, concealable, medium-independent, and biocompatible purposes.