A system for use in authentication processes is described comprising a physical unclonable function (“PUF”), a substrate, a plurality of magnetized particles randomly dispersed in the substrate, a PUF reader constructed using multiple discrete magnetometer chips that have magnetic field sensors, placed on a circuit card in an array with a sufficient center to center spacing between sensing elements of adjacent magnetometer chips, wherein the PUF reader measures the magnetic field data at multiple locations in close proximity to the magnetized particles. The measured magnetic field data may be compared to previously enrolled data to assess authenticity.