Group communication in multicast environment has been a growing importance in ad hoc networks, and providing secure communication in the group is essential in many ad hoc applications. A common way of securing multicast group is to establish a cryptographic key known only to the group members. To maintain security, the group key must be updated whenever the group membership changes. A group key distribution scheme provides algorithms to establish and maintain the group key. In this paper, we propose a reliable and ubiquitous group key distribution scheme that is suitable for ad hoc networks. The scheme has self-initialisation and self-securing features. The former feature allows a cooperation of an arbitrary number of nodes to initialise the system, and it also allows node admission to be performed in a decentralised fashion. The latter feature allows a group member to determine the group key remotely while maintaining the system security. We also consider a decentralised solution of ...