Grey-Box Cryptography: Physical Unclonable Functions

Abstract

Cryptography is a fundamental component of any information security infrastructure. It allows two parties, a sender and a receiver, to exchange messages in a secure and authentic way. For this goal the parties use a publicly known algorithm that depends on a secret key. The main assumption in cryptography is that the honest parties have some secure hardware containing the secret key. This is the so-called black-box model. Within this model, cryptography has developed many useful secure algorithms and protocols. The security level of these algorithms is well understood. It can for instance be guaranteed that mathematical attacks are very difficult. This difficulty is even made precise in terms of a security parameter. When the black-box assumption does not hold however, the security guarantees provided by cryptography do not hold anymore.