Tree Based Scalable Secure Group Communication

In order to establish a group communication, a common key must be available with all the members of the group. The group key can be used for encrypting data between the group members or restricting access to the resources intended for group members only. Each member in a group has a unique key referred as member key, used for decrypting data in a group. The group key is distributed by group key server, which changes the group key time to time called as group rekeying. It is mandatory that the group key changes after a new user has joined and an existing user departed periodically. The existing system analyse the Bursty behaviour and operation. Burstiness is an important behavior in Secure Group Communication (SGC). Performing bursty operation, which may accumulate the simultaneous leave and join as a single operation, thus reduces the frequency of key distribution and reduces time complexity. But in the existing system the aggregate operation will occur only in rare condition so it may not perform the key reduction in all cases as well as it perform less scalability and security. To achieve better scalability, security and key reduction a new group key management protocol based on the Chinese Remainder Theorem and a hierarchical tree is proposed, in which each node contains a key and a modulus. The Keys and modulus are constructed as a tree and maintained by the key server. The key server shares the keys with each member on the path from its leaf to the root. The keys on its path from the leaf to the root need to be updated in the protocol, when a member joins or leaves the group but all modulus must be kept fixed. To update the keys on the tree, the key server generates a new key for each update node and encrypts it with its children keys on its path from the leaf to the root. Thus the new scalable protocol increases the security, scalability issues when the group size goes up to millions of members and reduces the key.