Optics

Physics

Authentication (law)

Encryption

Embedded system

Lens (geology)

Power (physics)

Cryptography

Physical security

SILK

Computer security

Computer science

Reliability (semiconductor)

Quantum mechanics

Telecommunications

Physical unclonable function

Computer hardware

Nature Communications

For modern security, devices, individuals, and communications require unprecedentedly unique identifiers and cryptographic keys. One emerging method for guaranteeing digital security is to take advantage of a physical unclonable function. Surprisingly, native silk, which has been commonly utilized in everyday life as textiles, can be applied as a unique tag material, thereby removing the necessary apparatus for optical physical unclonable functions, such as an objective lens or a coherent light source. Randomly distributed fibers in silk generate spatially chaotic diffractions, forming self-focused spots on the millimeter scale. The silk-based physical unclonable function has a self-focusing, low-cost, and&nbsp;eco-friendly&nbsp;feature&nbsp;without relying on pre-/post-process for security&nbsp;tag creation. Using these properties, we implement a lens-free, optical, and portable physical unclonable function with silk identification&nbsp;cards&nbsp;and study its characteristics and&nbsp;reliability in a systemic manner. We further&nbsp;demonstrate&nbsp;the feasibility of the physical unclonable functions in two modes: authentication and data encryption. Although conventional optical physical unclonable functions (PUFs) are attractive for security applications, existing optical PUFs have inherent complexity. Here, the authors report a low-cost, lens-free and compact optical PUF that uses&nbsp;silk microfiber-based stochastic diffraction.

Revisiting silk: a lens-free optical physical unclonable function