Cryptology ePrint Archive: Report 2005/395

Secure Group Key Establishment Revisited

Jens-Matthias Bohli and Maria Isabel Gonzalez Vasco and Rainer Steinwandt

Abstract: We examine the popular proof models for group key establishment of Bresson et al. and point out missing security properties that are present in some models for two-party key establishment. These properties are actually of more importance in group key establishments due to the possibility of malicious insiders. We show that established group key establishment schemes from CRYPTO 2003 and ASIACRYPT 2004 do not fully meet these new requirements. Next to giving a formal definition of these extended security properties, we prove a variant of the explored proposal from ASIACRYPT 2004 secure in this stricter sense.

Category / Keywords: cryptographic protocols / group key establishment, provable security, malicious insiders

Date: received 2 Nov 2005, last revised 15 Sep 2006

Contact author: bohli at ira uka de

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Version: 20060915:132333 (All versions of this report)

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