Polynomial-based key management for secure intra-group and inter-group communication

Secure group communication has become an important issue in many applications. Both intra-group and inter-group multicast traffic must be protected by shared secret keys. In order to communicate securely in the same group and among different groups, we employed a polynomial $P$ to achieve efficient intra-group key refreshment and generated a polynomial $H\left(x\right)$ to create an inter-group key. Proposed polynomial-based key management schemes have the following advantages: (1) Group members and the group controller can share the intra-group key without any encryption/decryption. (2) When the members of the group get changed, the group controller needs to update and distribute the renewed group keys. The proposed mechanism can reduce the number of re-keying messages. (3) The proposed mechanism lessens the storage overhead of group members and the group controller by adopting a polynomial-based key management scheme. (4) As compared with previous approaches, the group controller does not need to broadcast heavy messages which are necessary for creating an inter-group key. Hence, it introduces only a small amount of broadcast traffic to the group members. The analysis of the proposed mechanism is conducted to demonstrate the improvements.