Abstract: Method and apparatus for authenticating analog mixed-signal integrated circuits using process-specific functions (PSF) comprising: presenting wafer having plurality of dies, each die having circuit with identical design but having inherent physical differences due to process variation in their manufacture, each circuit designed to enhance the effects of the inherent differences; defining selected number of inputs/stimuli for authenticating and identifying each integrated circuit; defining expected response for each circuit, wherein the expected response for each circuit is the same due to the identical design; defining statistical window for analog response by the circuit to the inputs/stimuli; applying the inputs/stimuli to each circuit; receiving analog response corresponding to the applied inputs/stimuli, wherein the analog response falls outside statistical window when there are functional or physical changes to the circuit; separating from plurality of dies each die providing a response outside the stati