Group key distribution with full-healing property

Abstract

A new type of group key distribution, called 'Full-Healing' Group Key Distribution (F-GKD), is proposed in this paper which can help new-added members to recover the historical session keys. It is specially designed to support practical (but not confidential and critical) applications (such as Chat and Instant Messaging Systems (CIMS), Massively Multiplayer Online Games (MMOG)) with requirement of 'Historical Session Recovery', in which later-added members can recover the content in the conversations among earlier members. The property of 'full-healing' is not only focused on registered-session recovery as most self-healing or mutual-healing group key distribution schemes, it enables an authorized group member to recover entire key chain for the historical sessions. We give a formal definition of the 'full-healing' and introduce technical details and properties of the F-GKD schemes. Moreover, we propose a basic F-GKD scheme by using a one-way hash function and Shamir's secret sharing. Analysis proves that the proposed scheme has the following advantages: it is efficient in key recovery without additional transmissions from group manager or other neighboring members; it is collusion-resistant and information theoretically secure; it is communication efficient and flexible to member addition/revocation; it guarantees forward secrecy due to the one-way hash operations.