Physically unclonable camouflage structure and methods for fabricating same

An application specific integrated circuit (ASIC) and a method for its design and fabrication is disclosed. In one embodiment, the camouflaged application specific integrated circuit (ASIC), comprises a plurality of interconnected functional logic cells that together perform one or more ASIC logical functions, wherein the functional logic cells comprise a camouflage cell including: a source region of a first conductivity type, a drain region of the first conductivity type, and a camouflage region of a second conductivity type disposed between the source region and the drain region. The camouflage region renders the camouflage cell always off in a first camouflage cell configuration and always on in a second camouflage cell configuration having a planar layout substantially indistinguishable from the first configuration.