Paper 2024/1463

Asynchronous Distributed Key Generation with Flexible Threshold and Batched Key Derivation

Abstract

Distributed Key Generation (DKG) is a vital security foundation for decentralized technologies like blockchain and threshold signatures. However, existing asynchronous DKG (ADKG) protocols face bottlenecks in rigid configuration, limited throughput, and poor scalability, failing to meet the dynamic security management demands of large-scale services.In this paper, we propose an efficient suite of ADKG protocols that support flexible threshold configurations. First, we design a Flexible-Threshold Asynchronous Complete Secret Sharing (FT-ACSS) protocol using bivariate polynomials and zero-knowledge proofs. In an $n \ge 3f+1$ network, FT-ACSS enables dealers to freely configure the threshold $t \in [f, n-f)$, surpassing the limitations of traditional fixed $f$ or $2f$ thresholds. Furthermore, FT-ACSS implements a batch processing mechanism to share up to $t$ secrets simultaneously with $O(\lambda n^2)$ communication cost. We additionally extend the Schnorr protocol into $m$-Schnorr to support multi-secret commitments, significantly reducing amortized resource overhead.Combined with RBC and ABA, these components form a complete FT-ADKG protocol. Theoretical and experimental evaluations demonstrate that our scheme offers superior flexibility and efficiency compared to state-of-the-art protocols, providing a practical security management solution for large-scale asynchronous distributed systems.