A device having a physical unclonable function includes an integrated circuit and a phase change memory embedded in the integrated circuit and including a plurality of cells, where the phase change memory is set in a manner that creates a phase variation over the plurality of cells, and where the phase variation comprises the physical unclonable function. In another embodiment, a device having a physical unclonable function includes a phase change memory embedded in the device and comprising a plurality of cells, where the phase change memory is set in a manner that creates a phase variation over the plurality of cells, and where the phase variation comprises the physical unclonable function, and a measurement circuit for extracting the physical unclonable function from the phase change memory.