SodsBC: Stream of Distributed Secrets for Quantum-safe Blockchain

Abstract

SodsBC is the first asynchronous blockchain consensus utilizing the concurrent preprocessing model to achieve high performance and quantum-safety. Each participant proposes one block part by a reliable broadcast (RBC), and n parallel RBCs are finalized by n parallel binary Byzantine agreement (BBA) instances, rendering a consistent block part union. Each asynchronous and randomized BBA will consume common random coins to keep livenessIn a preprocessing stage, SodsBC continuously produces a stream of distributed secrets shared by a novel quantum-safe and asynchronous weak secret sharing (AWSS) scheme. The finished secret shares are ordered in the same asynchronous consensus architecture and combined to form coins for future online stages. In an online stage (simultaneously as a preprocessing stage), SodsBC makes a consensus block for transactions which consumes the agreed one-time used coins (generated in previous preprocessing stages) to support the BBA usage. SodsBC demonstrates the possibility to support the preprocessing activity by the agreement capabilities of the online activity. Ongoing concurrent preprocessing and online activities are continuously executed in a producer-consumer fashion to support the quantum-safe coin-flipping protocol. AWSS also helps to distribute the keys of a symmetric encryption scheme which encrypts the proposed block parts to avoid transaction censorshipAfter deploying the concurrent preprocessing model and equipping our quantum-safe building blocks, the SodsBC implementation shows a better throughput rate than VISA in a four-node-LAN network, i.e., a typical consortium blockchain. SodsBC also outperforms the open-source asynchronous blockchain, Honeybadger, when we deploy worldwide 100 AWS t2.medium nodes to construct a global WAN network.