A Privacy-Preserving ID-Based Group Key Agreement Scheme Applied in VPAN

In 2008, Wan et al. presented an anonymous ID-based group key agreement scheme for wireless networks, for which they claim that it ensures anonymity and unlinkability of the group members, as well as forward and backward secrecy of the group session key. In this paper, we show that forward and backward secrecy do not hold for the protocol. We propose a correction that introduces a shielding factor that protects each member’s input to the group key. we also introduce a new feature that assures the correctness of the key as computed by all group members. This results in an increased computation cost, due to extra public key operations, and a similar communication cost. We also show in which practical setting the protocol can be deployed.