Multicast Open Shortest Path First (MOSPF) is an en hancement to unicast routing protocol OSPF. It has been widely used in many multicast applications for years. How ever, its security is still a major concern in some applica tions. Much work has been done on data protection, but only a few works have been done on member access con trol mechanisms. In this paper, we present a new secure multicast architecture and protocol for MOSPF from the perspective of member access control. Our new model in cludes a variant of previous access control mechanism and a novel distributed encryption scheme. This architecture in particular meets the access control security needs of dense multicast routing protocol in MOSPF, simplifies the access control process, and increases scalability and flexibility in revocation and reauthorization.