Literature Survey of Physical Unclonable Functions on FPGAs

Physical Unclonable Functions A Physical Unclonable Function, or PUF as they are generally referred to, is a function with certain desirable properties. First of all, the function must be embodied in a physical structure. This may seem obvious, but it’s important to clarify that PUF only refers to the function of a physical unit and not something like a software implementation. Secondly, a PUF must be easy to evaluate, but hard (“impossible”) to predict. It is similar in this way to a mathematical one-way function. A given input should repeatedly lead to the same output, but it should be impossible to predict the output of a given input without previously observing it. Finally, a PUF should be easy to make, but “impossible” to duplicate. It’s necessary that it be easy to make, or it would not be economically reasonable. It must be “impossible” to duplicate, otherwise it wouldn’t really serve any purpose at all. An attacker could just manufacture or purpose a duplicate, provide the same input, and generate the same output. The response of such a PUF would basically prove nothing at all.