An approach for establishing secure multicast communication among multiple multicast proxy service nodes is disclosed. The multicast proxy service nodes, which can be distributed throughout an enterprise domain, are organized in a logical tree that mimics the logical tree arrangement of domains in a directory server system. The attributes of the multicast proxy service nodes include the group session keys that are members of the secure multicast or broadcast groups. Because keys as well as key version information are housed in the directory, multicast security can be achieved over any number of network domains across the entire enterprise. Key information is stored in, and the logical tree is supported by, a directory service. Replication of the directory accomplishes distribution of keys. Multicast proxy service nodes may obtain current key information from a local copy of the replicated directory.