Physical vulnerabilities of Physically Unclonable Functions

In recent years one of the most popular areas of research in hardware security has been Physically Unclonable Functions (PUF). PUFs provide primitives for implementing tamper detection, encryption and device fingerprinting. One particularly common application is replacing Non-volatile Memory (NVM) as key storage in embedded devices like smart cards and secure microcontrollers. Though a wide array of PUF have been demonstrated in the academic literature, vendors have only begun to roll out PUFs in their end-user products. Moreover, the improvement to overall system security provided by PUFs is still the subject of much debate. This work reviews the state of the art of PUFs in general, and as a replacement for key storage in particular. We review also techniques and methodologies which make the physical response characterization and physical/digital cloning of PUFs possible.