Verifiable secret sharing in a total of three rounds

Verifiable secret sharing (VSS) is an important building block in the design of secure multi-party protocols, when some of the parties are under the control of a malicious adversary. Henceforth, its round complexity has been the subject of intense study. The best known unconditionally secure protocol takes 3 rounds in sharing phase, which is known to be optimal, and 1 round in reconstruction. Recently, by introducing a negligible probability of error in the definition of VSS, Patra et al. [CRYPTO 2009] have designed a novel protocol which takes only 2 rounds in sharing phase. However, the drawback of their protocol is that it takes 2 rounds in reconstruction as well. Hence, the total number of rounds required for VSS remains the same.In this paper, we present a VSS protocol which takes a total of 3 rounds only—2 rounds in sharing and 1 round in reconstruction.

► We study unconditionally secure verifiable secret sharing.
► We focus on the round optimality aspect.
► We give the first protocol which takes only 3 rounds overall.