A group-oriented cipher communication method is developed and implemented on a WWW-based (World Wide Web) network system. In this method, a group key common to all entities of the group is generated based on the group name or the identities of entities belonging to the group. The group key, in turn, is used for encrypting the data being shared among the group via the WWW server. The data theft at the WWW cache sites on the intermediate communication line is prevented, establishing a unified feature of the good WWW cache performance and security. A prototype of our method proved the feasibility and the efficiency.