‘No Miracles’ in Security Protocol Analysis

Dynamic Epistemic Logic (DEL) and Epistemic Temporal Logic (ETL), from epistemic logic, have been proposed as frameworks well-suited to the analysis of security protocols. DEL offers a succinct representation of higher-order epistemic facts, while ETL lends itself to representing a sequence of epistemic actions. It is known that DEL cannot represent all of the protocols which ETL can; in particular, DEL can only represent protocols which satisfy the No Miracles principle. However, a recent generalization of DEL, Action-Epistemic Logic, promises to overcome this limitation; we summarize this result in this short paper.