Method, system, and terminal for hierarchical management of group keys of broadband cluster system

A method, system, and terminal for hierarchical management of group keys of a broadband cluster system. The method comprises: a system side generates a group root key for a group and issues the group root key to terminals in the group; when establishing a group call, the system side generates a group call security parameter, generates a non-access stratum key and an access stratum key on the basis of the group root key and of the group call security parameter, and issues the group call security parameter to a listening user terminal in the group; and, the system side protects a group call shared channel of the group call on the basis of the non-access stratum key and of the access stratum key.