The Synchronize Choice Petri net, a subclass of Petri nets that is constructed based on special structural objects, can improve analytical power to make solving the behavioral problems of Petri nets practically possible. The fact that proving liveness and verifying reachability of a Synchronize Choice Petri net are feasible may lead to several applications. This thesis contributes to one of the applications: building a dynamic key exchange mechanism embedded in Virtual Private Network products by applying Synchronize Choice Petri nets. 　　Based on modern symmetric-key algorithms, such as DES, the dynamic key exchange mechanism enables two communicating sides to use the changing keys to encrypt or decrypt messages correctly without requiring any key transmission during the communication session after the initiation. A proper use of the mechanism is to be integrated with Virtual Private Network products to make the information transmitting between two peers more confidential.