A Discussion on the Properties of Physically Unclonable Functions

The increasing interest in physically unclonable functions or PUFs and in PUF-based security applications desires a concrete and as formal as possible description of what a PUF is and which properties can be naturally expected. However, the wide and growing variety of different PUF and PUF-like proposals makes such a formalization attempt a nontrivial task. In this work we provide a starting point by developing a concrete, though still informal, description of the minimal requirements a construction needs to meet in order to be called a PUF. Additionally, this study gives an insight into attainable and/or desirable PUF properties and reveals some interesting research directions for future investigation.