In e-commerce protocols, malicious participantsmisbehave on their benefits. There is some work in analysisthe application-protocols but little similar work about thefoundation-protocols. To fill the gap we use semi-regularentities to denote the entities different from penetrators thatparticipate in the protocol on behalf of themselves such ascustomers in e-commerce. A method in strand space model isalso presented. After descriptions of hash and Diffie-Hellmanexchange, semi-regular strand and semi-regular node areadded into the model, finally is an attack on the Internet KeyExchange (IKE) protocol as a case.