Asynchronous Verifiable Secret-Sharing Protocols on a Good Day

07/10/2018

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by   Soumya Basu, et al.

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Asynchronous verifiable secret sharing (AVSS) is a cornerstone primitive in secure multi-party computation and Byzantine fault tolerance. AVSS requires a dealer to share a secret with a set of replicas, of which some may be faulty. In prior AVSS schemes, the dealer paid for the possibility of replica failures up front, thus incurring quadratic or worse communication complexity. However, in practice, there would typically be at most a few replica failures in each sharing. This paper introduces an optimistic AVSS protocol that only pays for the number of failures that actually occur, rather than the maximum allowed number of failures. By doing so, we bring the cost of AVSS down to typically linear on a good day, specifically with only linear communication cost for the dealer.