Cryptology ePrint Archive: Report 2005/185

Security properties of two provably secure conference key agreement protocols

Qiang Tang and Chris J. Mitchell

Abstract: In this paper we analyse the security of two authenticated group key agreement schemes based on the group key agreement protocol of Burmester and Desmedt. One scheme was proposed by Burmester and Desmedt, and uses a separate authentication scheme to achieve authentication among the participants. We show that this scheme suffers from a number of security vulnerabilities. The other scheme was generated using the general protocol compiler of Katz and Yung. We show that in some circumstances, even if key confirmation is implemented, this scheme still suffers from insider attacks (which are not covered by the security model used by Katz and Yung).

Category / Keywords: authentication, group key agreement

Date: received 17 Jun 2005, last revised 26 Jun 2005

Contact author: qiang tang at rhul ac uk

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Version: 20050626:200802 (All versions of this report)

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