Cryptographic Protocol (CP) analysis is a topic of intense research. Meadows describes four approaches for CP verification under investigation in [MEA92] and several authors have categorized protocols based on types of errors they are subject to [BIRD92], [SYV93a],[SYV93b]. This paper addresses the weakness injected into protocols when information is passed in the clear or encrypted only under the private key of a public/private key pair. We also propose a method for logically analyzing protocols based on action list analysis of valid and compromised protocol runs and of valid protocol runs interleaved with action lists of intruders conducting known attacks. Note: Abstract extracted from PDF file via OCR