AlphaBlock: An evaluation framework for blockchain consensus algorithms

Abstract

Consensus algorithm is the core of blockchain and it plays a crucial role in the performance of the blockchain. In general, there are two types of blockchain consensus algorithms: the Bitcoin-like Nakamoto consensus (NC) algorithms and the Byzantine fault tolerance (BFT) consensus algorithms. These two types of consensus algorithms are fundamentally different in forms and hard to be compared. However, currently, they are often used interchangeably for similar blockchains, which naturally raises a question of "given a network, which consensus would have the best performance in practice''. In this paper, we propose AlphaBlock, a theoretical framework for the performance comparison of blockchain consensus algorithms, in particular, NC algorithms and BFT algorithms. To make fair comparisons, AlphaBlock captures the most important advantages and disadvantages of both categories. Moreover, we incorporate some of the key features of the practical blockchain networks. The results show that BFT algorithms have a superior performance over NC algorithms in most cases in both throughput and latency, expect for the low latency region in large networks, where the NC algorithms show strong competence to the best BFT algorithms.