Brief Note: Asynchronous Verifiable Secret Sharing with Optimal Resilience and Linear Amortized Overhead

TL;DR

This paper introduces hbAVSS, an asynchronous verifiable secret sharing protocol that achieves optimal resilience and linear amortized communication overhead without relying on optimistic assumptions or sacrificing security.

Contribution

The paper presents hbAVSS, the first AVSS protocol with optimal resilience and linear overhead in the worst case, using a novel encrypt-and-disperse approach.

Findings

Achieves linear amortized communication in worst-case scenarios.

Maintains security under static computationally bounded Byzantine adversaries.

Closes the gap between resilience and communication efficiency in AVSS protocols.

Abstract

In this work we present hbAVSS, the Honey Badger of Asynchronous Verifiable Secret Sharing (AVSS) protocols - an AVSS protocol that guarantees linear amortized communication overhead even in the worst case. The best prior work can achieve linear overhead only at a suboptimal resilience level (t < n/4) or by relying on optimism (falling back to quadratic overhead in case of network asynchrony or Byzantine faults). Our protocol therefore closes this gap, showing that linear communication overhead is possible without these compromises. The main idea behind our protocol is what we call the encrypt-and-disperse paradigm: by first applying ordinary public key encryption to the secret shares, we can make use of highly efficient (but not confidentiality preserving) information dispersal primitives. We prove our protocol is secure under a static computationally bounded Byzantine adversary model.