Paper 2019/263

Monoxide: Scale Out Blockchain with Asynchronous Consensus Zones

Jiaping Wang and Hao Wang

Abstract

Cryptocurrencies have provided a promising infrastructure for pseudonymous online payments. However, low throughput has significantly hindered the scalability and usability of cryptocurrency systems for increasing numbers of users and transactions. Another obstacle to achieving scalability is the requirement for every node to duplicate the communication, storage, and state representation of the entire network. In this paper, we introduce the Asynchronous Consensus Zones, which scales blockchain system linearly without compromising decentralization or security. We achieve this by running multiple independent and parallel instances of single-chain consensus systems termed as zones. The consensus happens independently within each zone with minimized communication, which partitions the workload of the entire network and ensures a moderate burden for each individual node as the network grows. We propose eventual atomicity to ensure transaction atomicity across zones, which achieves the efficient completion of transactions without the overhead of a two-phase commit protocol. Additionally, we propose Chu-ko-nu mining to ensure the effective mining power in each zone to be at the same level of the entire network, making an attack on any individual zone as hard as that on the full network. Our experimental results show the effectiveness of our work: on a testbed including 1,200 virtual machines worldwide to support 48,000 nodes, our system delivers 1,000x throughput and 2,000x capacity over the Bitcoin and Ethereum networks.