Sensor array for reading a magnetic PUF

A magnetic sensor array device is described that is constructed with multiple single sensor die, diced out of a wafer as a group and packaged in a wafer level package (WLP). The device comprises an array of multi-axis magnetic sensors that can measure the multi-dimensional magnetic field of an arbitrary sized two-dimensional region with high spatial resolution, reduced sensing distance, higher measurement throughput, tolerance to motion, improved temperature measurement, and improved yield when placed on a circuit card comprises part of an authentication system including a physical unclonable function ("PUF"), a substrate, a plurality of magnetized particles randomly dispersed in the substrate, and a PUF reader constructed using one or more of the magnetic sensor array devices wherein the PUF reader measures the magnetic field 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.