Hardware intrinsic security based on SRAM PUFs: Tales from the industry

Physical Unclonable Functions originate in intrinsic properties extracted from devices and objects for the purpose of identification. They can take many forms among which the most common ones are optical PUFs, paper PUFs, coating PUFs and silicon PUFs. In order to identify silicon devices, further variants include PUFs based on delays in a silicon circuitry such as arbiter PUFs and ring-oscillator PUFs, and PUFs based on the start-up behavior of memory cells such as SRAM PUFs, butterfly PUFs and flip-flop PUFs.