A Key Recovery Mechanism for Reliable Group Key Management

Abstract

Secret group communication can be achieved by encryption messages with a group key. Dynamic groups face the problem of changing the group key whenever members join or leave. One of the solutions to this problem is to send the updated group key to members via rekey messages in a secure manner. The recovery of lost keys consequently becomes important because a member cannot decrypt the group data if he loses these messages. Saving messages and resending them by KDC (Key Distribution Center) not only requires large saving space, but also causes the transmission and decryption of unnecessary keys. Furthermore, the keys in the unsaved messages cannot be recovered. This paper proposes an efficient method for recovering group keys. The group key generation method presented in this paper is simple, enabling us to recover group keys without storing and eliminating the transmission and decryption of useless auxiliary keys.