Confidentiality and Integrity are realized by the group key in secure group communications.Adapt to the limited computation and communication resources

the group key management protocol in MANET environment should have less computation and less complexity.The necessary property that the group key management protocol should have is analyzed.A new ID-based group key agreement protocol CEAGKP is put forward by introducing the key tree of STR protocol that has minimum traffic in fixed network environment combined with the ID-based public key cryptography.The protocol has strong security and scalability at less traffic and well suits the requirement of MANET.The simulation proves that CEAGKP scales well in MANET.