A calculus to detect guessing attacks

Abstract

We present a calculus for detecting guessing attacks, based on oracles that instantiate cryptographic functions. Adversaries can observe oracles, or control them either on-line or off-line. These relations can be established by protocol analysis in the presence of a Dolev-Yao intruder, and the derived guessing rules can be used together with standard intruder deductions. Our rules also handle partial verifiers that fit more than one secret. We show how to derive a known weakness in the Anderson-Lomas protocol, and new vulnerabilities for a known faulty ATM system. © 2009 Springer Berlin Heidelberg.