Cryptology ePrint Archive: Report 2002/134

Asynchronous Verifiable Secret Sharing and Proactive Cryptosystems

Christian Cachin and Klaus Kursawe and Anna Lysyanskaya and Reto Strobl

Abstract: Verifiable secret sharing is an important primitive in distributed cryptography. With the growing interest in the deployment of threshold cryptosystems in practice, the traditional assumption of a synchronous network has to be reconsidered and generalized to an asynchronous model. This paper proposes the first \emph{practical} verifiable secret sharing protocol for asynchronous networks. The protocol creates a discrete logarithm-based sharing and uses only a quadratic number of messages in the number of participating servers. It yields the first asynchronous Byzantine agreement protocol in the standard model whose efficiency makes it suitable for use in practice. Proactive cryptosystems are another important application of verifiable secret sharing. The second part of this paper introduces proactive cryptosystems in asynchronous networks and presents an efficient protocol for refreshing the shares of a secret key for discrete logarithm-based sharings.

Category / Keywords: cryptographic protocols / threshold cryptography, byzantine agreement

Publication Info: Extended abstract appears in ACM CCS-9.

Date: received 29 Aug 2002

Contact author: cachin at acm org

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Version: 20020829:163209 (All versions of this report)

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