sAVSS: Scalable Asynchronous Verifiable Secret Sharing in BFT Protocols

TL;DR

This paper presents sAVSS, a framework that transforms any verifiable secret sharing scheme into an asynchronous version with constant overhead, enhancing BFT protocols with privacy guarantees and efficient secret sharing.

Contribution

The paper introduces sAVSS, a novel framework enabling any VSS scheme to operate asynchronously with constant overhead, and demonstrates its integration with Kate et al.'s scheme for efficient BFT-based secret sharing.

Findings

Asynchronous VSS with constant overhead achieved.

Key-value store supports secret sharing with 30-50% throughput overhead.

Request latency remains below 35 milliseconds.

Abstract

This paper introduces a new way to incorporate verifiable secret sharing (VSS) schemes into Byzantine Fault Tolerance (BFT) protocols. This technique extends the threshold guarantee of classical Byzantine Fault Tolerant algorithms to include privacy as well. This provides applications with a powerful primitive: a threshold trusted third party, which simplifies many difficult problems such as a fair exchange. In order to incorporate VSS into BFT, we introduced sAVSS, a framework that transforms any VSS scheme into an asynchronous VSS scheme with constant overhead. By incorporating Kate et al.'s scheme into our framework, we obtain an asynchronous VSS that has constant overhead on each replica -- the first of its kind. We show that a key-value store built using BFT replication and sAVSS supports writing secret-shared values with about a 30% - 50% throughput overhead with less than 35 millisecond request latencies.