The article discusses the use of coherent multiple scattering from inhomogeneous structures to implement one-way functions, which are essential for secure authentication systems. The authors demonstrate that this approach can be used over classical communication channels, unlike quantum cryptography. They describe how laser speckle fluctuations, which are sensitive to the structure of inhomogeneous media, can be used to create authentication systems. The physical one-way function (POWF) is based on the idea that any changes in the microstructure of a disordered medium cause significant changes in its speckle pattern, providing a fixed-length key that hashes the 3D spatial distribution of scatterers. The authors experimentally validate the POWF by producing physical tokens with glass spheres and recording their speckle patterns at multiple angles. They use a Gabor transform to generate a 2400-bit key, which is shown to have high entropy and low correlation between bits. The security of the system is demonstrated by showing that tampering with the token results in a significant increase in the Hamming distance between keys, making it infeasible to forge new keys. The article also discusses the infeasibility of copying or duplicating the token due to the vast number of possible illumination-key pairs. The system can be used for authentication and key distribution in a distributed cryptographic system, where the physical interaction is part of a larger computation. The authors conclude that this approach offers a secure and efficient method for authentication and key distribution, particularly in scenarios where conventional semiconductor technology is not feasible.The article discusses the use of coherent multiple scattering from inhomogeneous structures to implement one-way functions, which are essential for secure authentication systems. The authors demonstrate that this approach can be used over classical communication channels, unlike quantum cryptography. They describe how laser speckle fluctuations, which are sensitive to the structure of inhomogeneous media, can be used to create authentication systems. The physical one-way function (POWF) is based on the idea that any changes in the microstructure of a disordered medium cause significant changes in its speckle pattern, providing a fixed-length key that hashes the 3D spatial distribution of scatterers. The authors experimentally validate the POWF by producing physical tokens with glass spheres and recording their speckle patterns at multiple angles. They use a Gabor transform to generate a 2400-bit key, which is shown to have high entropy and low correlation between bits. The security of the system is demonstrated by showing that tampering with the token results in a significant increase in the Hamming distance between keys, making it infeasible to forge new keys. The article also discusses the infeasibility of copying or duplicating the token due to the vast number of possible illumination-key pairs. The system can be used for authentication and key distribution in a distributed cryptographic system, where the physical interaction is part of a larger computation. The authors conclude that this approach offers a secure and efficient method for authentication and key distribution, particularly in scenarios where conventional semiconductor technology is not feasible.