NCKC: Non-Code-aided Key Calculation for group Key Management

Key Management protocol is one of the most important mechanisms for communication security, whereas its security analysis is critical to evaluate the information security. In this paper, we study a kind of group key management schemes which use key calculation in rekeying. At first, the security vulnerability in Code for Key Calculation (CKC) is analyzed. The codes in the key tree can be exposed to the user who should not get them. Thus, the user can get additional key information in group key updating process. Moreover, the user can continue to get the communication contents after he/she leaves the group. Sequentially, we construct two effective attacks and discuss the condition of successful attack. We analyze similar problems in other schemes. Finally, we propose an improved scheme to CKC, named Non-Code-aided Key Calculation (NCKC). Performance analysis and simulation results show that NCKC can fulfill forward and backward security at the cost of a little increase in communication overhead.