Weight-Based batch rekeying scheme for dynamic multi-privileged group communications

Abstract

In multi-privileged group communications, the group users have different access privileges to multiple data resources. The influence on the system is different between the users when membership changes in the group. In batch rekeying, when the keys are not updated promptly, the more access privileges the users change, the more related resources are exposed to the malicious users. Unfortunately, in those existing batch rekeying schemes, the group users are treated equally. So in this paper, we propose a weight-based batch rekeying scheme for multi-privileged group communications to decrease the exposure of data resources in a batch. A weight is assigned for each membership change of the users. Then, rekeying is performed in batch when the sum of collected weights is larger than a predetermined threshold. In the operation of batch rekeying, a marking algorithm is devised to process a batch of joining/leaving/switching requests, and the related keys are updated according to the corresponding marks. We give some analysis on our scheme to show that our scheme can provide hierarchical access control, as well as backward security and weak forward security. It also shows that our scheme can save server cost substantially. At last, extensive simulation results show our scheme can improve the security to a certain extent.