An automated technique for protocol development is discussed along with its application to the specification, verification, and semiautomatic implementation of an authentication protocol for computer networks. An overview is given of the specification language, implementation method, and software tools used with this technique. The authentication protocol is described, along with an example of its operation. The reachability analysis technique for the verification of some protocol properties is discussed, and protocol verification software that uses this technique is described. The results of mechanical verification of some properties of this protocol are presented with a partial implementation generated automatically from the protocol specification.