Table 1: E-newspaper subscription service Access Relation Sports Financial Stock Top News Weather

In group communication, users often have different access rights to multiple data streams. Based on the access relation of users and data streams, users can form partially ordered relation, and data streams can form partially ordered relation. In this paper, we propose a key management scheme for hierarchical access control, which considers both partially ordered user relations and partially ordered data stream relations. We also propose an algorithm for constructing a logical key graph, which is suitable even when users and data streams have complex relations. Simulation results show that our scheme can significantl