A Practical Heartbeat-based Defense Scheme Against Cloning Attacks in PoA Blockchain

Consensus mechanism, as the soul-building-block of decentralized settings, enables a series of blockchain applications, such as Bitcoin and Ethereum. For better security and soundness, more and more blockchain systems tend to adopt proof-of-authority (PoA) to avoid or alleviate the various security risks caused by their peer-to-peer (P2P) networks. However, the PoA protocol is also vulnerable to cloning attack (CA), which provides a potential pathway for double-spending attack and has not been well solved. In this paper, we propose a heartbeat-based defense scheme to achieve an effective CA detection in PoA blockchians. To this end, we first analyze two PoA algorithms, Aura and Clique, along with their CA. On this basis, we propose a heartbeat-based defense scheme that can detect CA effectively regardless of the underlying consensus algorithm of the blockchain. Then, to avoid the potential efficiency reduction caused by the increase of sealers, we further design an enhanced hierarchical node selection algorithm, in which sealers can challenge partial nodes selected randomly according our strategy to detect CA in an efficient manner. Finally, we theoretically estimate the precision rate model of our scheme and then establish a prototype PoA blockchain system to test the performance of our scheme. As expected, the experiment results are consistent with our theoretical analysis, which powerfully demonstrates the efficiency and practicability of the proposed scheme.