A Lightweight Prepositioned Secret Sharing Tree for Multicast Key Management

Secure group communications are increasingly used in the continuous growth of the Internet applications. In a secure multicast environment, an identical data can be efficiently delivered from a source to multiple receivers within a dynamic group. A simple solution is to encrypt the transmitted data using a symmetric key. However, scalable group rekeying is the main challenge for large and dynamic groups. The key tree-based scheme is widely used to achieve logarithmic computational and transmitted costs in the rekeying process. Nevertheless, the key tree-based schemes use the fixed secret key to encrypt confidential messages until every membership changes, which is lack of security in protecting the high-value content. On the other hand, the key tree-based scheme may result in difficult problems in maintaining synchronization due to the interdependencies among rekeying messages. In this paper, we shall propose a key management scheme based on the secret sharing, in which we apply a new lightweight prepositioned secret sharing tree-based scheme to solve the problem in the key tree-based scheme. Furthermore, we eliminate the encryption/decryption processes during every membership and periodic key changes which can dynamically change the secret key frequently.