We present a hybrid group key management protocol that incorporates both a centralized and a contributory scheme for key management, and a tree-based Elliptic Curve Diffie-Hellman technique for group key updates. It combines the advantage of the centralized approach's efficiency and the contributory scheme's fault tolerance. In addition, our rekeying algorithm updates the group key in the presence of any sequence of node failures, node restorations, and membership changes. Furthermore, our scheme incorporates a reliable and authenticated rekeying message transport method. Performance analysis indicates that our protocol reduces computational costs and communication overhead as compared to other popular protocols.