Silicon PUFs in Practice

Abstract

Low cost computing devices have become a key enabler of the digital economy, supporting everyday activities such as banking, access control, and travel. These devices often present highly resource constrained environments which impede the introduction of technologies that can improve the safety of the transactions performed on them. Several approaches have been proposed which strive to enhance the security of the user application without significantly increasing the associated cost, for example foregoing the use of higher grade smart cards supporting efficient public-key cryptography. In high volume scenarios the cost saving associated with such a decision can be compelling and security is invariably compromised as a result. This paper proposes realistic scenarios for the use of silicon PUFs (Physically Unclonable Functions) to enable lower cost and more secure implementations of smartcards and similar technologies. Silicon PUFs leverage the unique manufacturing variation present on all ICs to support authentication that is conceptually similar to biometric functionality as well as the generation of cryptographic key material. We recognize that significant improvements in PUF implementation will need to be achieved in order to make the technology commercially deployable. With these improvements, we can anticipate the potential applicability of PUFs to meeting the authentication, confidentiality and integrity requirements of many everyday transactions. In addition, the volatility of PUF-based secrets offers an attractive alternative to storing cryptographic keys in non-volatile memory.