Smart Contract-Based Checkpoint for Initial PoW Network Security

Abstract

Proof of Work (PoW) is the most widely adopted consensus mechanism on public blockchains. The PoW blockchain network achieves consensus by solving computational problems. If a network participant owns more than 50% of the total computational power in the network, they can forge the blockchain. Hence, initial PoW blockchain networks with low computing power are vulnerable to block forgery attacks. We propose a smart contract-based checkpoint method to improve security vulnerabilities in the initial blockchain networks. In our method, participants periodically record block headers in an Ethereum smart contract. The recorded checkpoint block header validates the blockchain. Participants reject blocks with blocks that differ from the recorded checkpoints. Our method ensures the integrity of blocks until the height of the most recently created checkpoint, reducing the risk of double-spending. We optimize checkpoint costs by overlapping multiple checkpoint processes in a single transaction. The interval of our checkpoint method grows with the growth of the network, making the network less dependent on checkpoints. We analyze the performance of checkpoints in mitigating attacks and demonstrate that they significantly decrease the success probability of attacks in the network.