Cryptology ePrint Archive: Report 2011/575

Exclusive Key Based Group Rekeying Protocols

Jing Liu and Changji Wang

Abstract: In this paper, we first clarify the meaning of research on 1-resilient group rekeying protocols by showing that they are actually building blocks for constructing hybrid group rekeying protocols with tunable collusion-bandwidth tradeoffs. We then construct secure and efficient 1-resilient group rekeying protocols based on the idea of exclusive key. Given a group of users, an exclusive key for a user i is a key shared by all users in this group except i, and thus can be used to exclude i from this group effectively. We first present three personal key assignment algorithms based on this idea. The first is based on independent exclusive keys, and thus has a great storage requirement. The other two are based on functionally-dependent exclusive keys, and thus greatly reduce the storage requirement. Employing each personal key assignment algorithm, we propose both a stateful group rekeying protocol and a stateless one. We prove that all six protocols are secure against single-user attacks (i.e., 1-resilient) in a symbolic security model. Performance comparisons between our protocols and related ones show that either of the proposed Protocol III and Protocol IIIí is the best in its own class.

Category / Keywords: multicast key distribution, group rekeying, 1-resilient, collusion attack

Date: received 25 Oct 2011, last revised 5 Sep 2012

Contact author: liujing3 at mail sysu edu cn

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Version: 20120906:012954 (All versions of this report)

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