Enhancement of cell-based decentralized Key Management in vehicular communication networks

Cell-based Decentralized Key Management (CDKM) was proposed to manage a group key for secure multicast in mobile cellular networks efficiently. It achieves better performance with less management overhead than other currently available schemes by dividing a group into the cell-based multiple subgroups and delegating key management functions to each base station governing each subgroup. However, room for improvement still remains in the subgroup size affecting the rekeying overhead directly. This paper proposes the enhanced CDKM which improves the rekeying performance through the reduction of the size of the subgroup, and adopts this scheme to group key management in vehicular communication networks. The proposed scheme further splits the cell-based subgroups into several segments, which is simple but very efficient way to reduce the rekeying overhead. We prove mathematically that the additional split enhances the performance, and show the proposed scheme can improve the rekeying performance by up to 15% over the original CDKM and by at least 80% over the existing schemes.