Paper 2020/106 Original: eprint.iacr.org/2020/106 ↗

Relaxed freshness in component authentication

Abstract

We suggests a relaxed freshness paradigm for challenge-response authentication for each field of application where challenger and responder are tightly coupled and authentication takes place in a friendly environment. Replay attacks are not feasible under this premise, and freshness can be relaxed to relative freshness: no refresh is required as long as all previously tested responders were authentic. One field of application is anti-counterfeiting of electronic device components. The main contribution is a formal security proof of an authentication scheme with choked refresh. A practical implication is the lifetime increase of stored challenge-response-pairs. This is a considerable advantage for solutions based on hardware intrinsic security. For solutions based on symmetric keys, it opens the possibility to use challenge-response-pairs instead of secret keys by the challenger – a cheap way to reduce the risk of key disclosure.