Design And Implementation Of A Stateful Group Key Management Scheme With Tunable Collusion Resistance

With the development of information technology,applications based on the multicast technology have been flourishing,Then there brings the question of multicast security,that is,guaranteeing both the confidentiality and integrity of multicast communication data.The confidentiality of multicast communication data can be enforced by using Group Key(GK)to encrypt the group data.When there are changes in group membership(join or leave),the Group Controller(GC)needs to update the GK to ensure group forward secrecy and group backward secrecy.The current research has proved that O(log2 n)is the lower bound on the communication complexity of generic collusion-resistant stateful group rekeying protocols.However,some cost-sensitive applications or resource-constrained environments still require a much lower communication complexity.This lower bounds suggest that it is impossible to achieve a lower communication overhead without trading off some degree of collusion resistance.This paper focuses on the Logical Key Hierarchy(LKH)protocol and the Stateful Exclusive Complete Subtree(SECS)protocol.The communication cost of the LKH protocol is O(log2 n)and it is folly collusion-resistant.SECS protocol requires O(1)messages for rekeying but in which any two receivers can collude to recover the new group key.In this paper,we designed and implemented a Hybrid Stateful Exclusive Complete Subtree(H-SECS)protocol,which achieves tunable collusion-bandwidth tradeoffs.This paper describes the H-SECS protocol from the member initialization,member join and member departure.The theoretically analyzes the algorithm complexity and security of H-SECS protocol.Finally,with the Visual C++ and OpenSSL cryptographic library,we implement the H-SECS protocol and do some performance experiments.We compare the SECS protocol,LKH protocol and H-SECS protocol with respect to communication cost,collusion resistance,computational overhead and storage overhead.