SGKMP: A scalable group key management protocol

The Online Social Network (OSN) has changed the ways of communication among users from one-to-one toward the group communication. The users of a particular group are interested in communicating securely among the group members using secure group key. Although the data remains secure during the transmission when it is encrypted with the group key, however, the group key management and generation is a challenge while using the insecure channel and untrusted server. The contributory key management is a solution in such situations, but the creation process of the group key, among the group members itself, is a challenge. In the literature, the contributory key generation requires at least n rounds to accomplish the group key generation process. Modification in a group requires the re-keying process for backward and forward security, and it also needs the same number of rounds again. In this paper, a scalable group key management protocol (SGKMP) is proposed, which requires only two rounds to complete the group key generation process, irrespective of group size and it is secure from the eavesdropper in the middle. The backward and forward secrecy is maintained when any user joins or leaves the group while doing a single activity by the group leader. The proposed protocol is implemented using Java as a programming language in order to validate the applicability of the protocol.