Enhanced Strict Binary Logical Key Hierarchy Algorithm for Secure Group Communication

Abstract

Logical Key Hierarchy is a scalable and efficient method to achieve logarithmic rekeying cost in secure group communication. In applications like pay per view, video conferencing with multiple rekeying operations, the key tree will be unbalanced and will generate worst-case rekeying cost. With each join, leave operation we change the group key as well as update all keys along the key path of join/leave user. Key aspect in secure group communication is maintaining a balanced key tree and achieving logarithmic rekeying cost. In this paper, a new Strict Binary Logical Key Hierarchy rekeying algorithm is proposed. SBLKH (Strict Binary Logical Key Hierarchy) with proposed Join user algorithm and leave user algorithm maintains the balance of tree and always achieves logarithmic rekeying cost. Our experimental result shows the achieved improvement in rekeying cost of SBLKH join and leave operations compared to original LKH (Logical Key Hierarchy) join and leave operations. Rekeying cost of LKH join/leave is O(log N) and proposed SBLKH join/leave algorithm cost is O(log d), where d is the depth of tree and N is the number of users.