Development and implementation of an one-way hybrid key distribution scheme for broadcast transmission

In broadcast communications, the schemes are used to transmit messages from a source to multiple users where the encryption methods are employed within the schemes. The schemes can be either tree based or have different topologies. There are three types of tree-based scheme categories: centralized, distributed and hybrid schemes. In this work, centralized, distributed and hybrid techniques which are widely used nowadays are investigated. The centralized techniques considered in this work are as follows: Logical Key Hierarchy (LKH), One-way Function Tree (OFT) and One-way Function Chain (OFC). The distributed techniques can be given as: Tree-based Group Diffie Hellman (TGDH), Distributed Scalable sEcure Communication (DISEG) and Skinny Tree (STR). The hybrid technique can be given as: The Logical Ring Based Secure Group Communication Scheme (RISeG). A new binary tree-based broadcast encryption schemes, both centralized and distributed, named One-way Hybrid Key Distribution (OHKD) have been proposed. Both a symmetric encryption and an asymmetric key distribution protocol are used in the OHKD scheme. In key updates, the left or right half of the symmetric keys are transmitted from the user nodes to the root node. This ensures that the total key size transmitted is reduced. The centralized model of the OHKD scheme includes a Group Manager. The role of Group Manager is undertaken by a consensus structure between users in the distributed model of the OHKD scheme. The OHKD scheme is compared with the existing schemes in terms of number of key transmissions, number of operations, number of user keys, size of user keys and size of key transmission in user adding-removing and batch user adding-removing operations. The results are shown graphically.