Optimizing protocol rewrite rules of CIL specifications

For purposes of security analysis, cryptographic protocols can be translated from a high-level message-list language such as CAPSL into a multiset rewriting (MSR) rule language such as CIL. The natural translation creates two rules per message or computational action. We show how to optimize the natural rule set by about 50% into a form similar to the result of hand encoding, and prove that the transformation is sound because it is attack-preserving, and unique because it is terminating and confluent. The optimization has been implemented in Java.