Paper 2025/1946 Original: eprint.iacr.org/2025/1946 ↗

Robust and Scalable Lattice-Based Distributed Key Generation for Asynchronous Networks

Abstract

Distributed Key Generation (DKG) is essential for secure, decentralized cryptographic systems, enabling collaborative key pair generation without a trusted authority. This capability underpins critical applications such as threshold signatures and blockchain-based protocols. To achieve post-quantum security, existing robust lattice-based DKG protocols, tailored for synchronous networks, rely on complaint-based Verifiable Secret Sharing (VSS). However, these protocols lack public verifiability and compatibility with asynchronous environments, constraining their use in Byzantine fault-tolerant settings. This paper presents LADKG, the first Lattice-Based Asynchronous Distributed Key Generation protocol designed for post-quantum secure and scalable distributed systems. LADKG integrates Asynchronous Verifiable Short Secret Sharing (AV3S) with an Approximate Asynchronous Common Subset (AACS) protocol to achieve efficient key generation. By deferring verification and leveraging deterministic approximate agreement, LADKG reduces computational and communication overhead while maintaining security and robustness. Evaluations on geo-distributed AWS EC2 clusters demonstrate that LADKG is comparable or better than classical Asynchronous Distributed Key Generation (ADKG) schemes in scalability and efficiency. Under optimistic conditions with $n=121$ nodes, completion is achieved in 45 seconds, ensuring robust key generation for post-quantum secure applications.