Scalable Rekeying Using Linked LKH Algorithm for Secure Multicast Communication

Introduction

Group Communication among valid users is a powerful Message exchange Model. Group communication applications include content distribution over large-scale networks, smart wireless networks, software updates, Video Conferencing, and many more (He Niedermeier & Meer 2013). Key management security should have basic requirements like authenticity, integrity, and confidentiality. The factors that affect any group key management process's performance are scalability, 1 affects n problem, delays bandwidth for efficient group key distribution. Scalability refers to the network's ability to handle large dynamic groups, i.e., if the number of users becomes large, the key management scheme should handle without degrading its performance. 1-affects n problem relates with new key generation after a leave or joins processes during a rekeying. Quality of service should also be maintained during a rekeying process, such as control packets, storing keys, and delay induced during encryption and decryption. Key management is very important in group communication restricting access control (Duma, Shahmehri, lambrix 2003). Key management establishes and maintains the secret keying relationships between valid parties according to a policy. It includes member identification and authentication. in this regard, authentication plays a significant role. Once a new member joins, it has to be validated (Zhu, Jajodia 2003). It is also essential to change or update the group key at regular intervals to effectively maintain a communicated message's security. Also, key independence has to be properly maintained in which each key is independent of another key. It means the method of generating a new group key should be independent of the previous key generation. It also enhances the security of the overall system. Combinatorial optimization of group key is given in (Eltoweissy, Heydari, Morales, Sudborough, 2004). Any Participant can become a part of Group Communication by becoming a group member explicitly. A group member holds a secretly shared cryptographic Group key and used the same for exchanging the messages. When a participant becomes a group member, it is required to maintain backward secrecy, i.e., the participant cannot decipher the messages exchanged before it’s joined.

Similarly, whenever the group member leaves the group, Group communication must maintain the forward secrecy. After the group leaves, it must prevent the node from accessing the messages. To achieve the forward secrecy and backward secrecy, group rekeying is performed, which ensures a new and different key among the group members when a node leaves or joins the group. However, group rekeying doesn’t play an effective role if we could ensure the group's structure by defining the members through the pre-registration of members (Panda, Thool 2016). Group key management can be classified into three classes: centralized, decentralized, and distributed key management. In centralized schemes, a single entity generates, distributes, and management of the group key.

Hence a single entity controls the entire group. Minimization of storage, computational power, and bandwidth are the key challenges in this scheme. In decentralized schemes, the process of management of group keys is divided among different group members. Hence a single point of failure is not a problem in this scheme.

In distributed group key management, No key server is explicitly declared. In this scheme, group members perform the key generation function. It can be contributory or done by individual members. Maintaining security in every group communication protocol is a critical issue.