A Comparative Analysis of Proof-of-Authority Consensus Algorithms: Aura vs Clique

Proof-of-authority (PoA) has become a popular consensus algorithm for permissioned blockchains, in which a group of trusted entities governs the networks. This algorithm provides fast consensus while requiring less computational resources and energy. Aura and Clique are two major implementations of PoA, which have their own set of advantages and disadvantages. In this paper, we evaluate the performance of both algorithms in terms of consistency, availability, partition tolerance, security, block time, and transaction throughput. The algorithms were implemented in Python, and experiments were conducted by connecting six consensus nodes having different computing power. The experimental results were comprehensively analyzed. It was observed that Clique provides higher availability and transaction throughput but lower security and consistency than Aura. The blockchains in the Aura network are immediately consistent while the blockchains stored by individual Clique authorities become eventually consistent. Permissioned blockchain practitioners will find this paper useful in choosing the most appropriate PoA implementation based on their requirements.