An Inter-blockchain Escrow Approach for Fast Bitcoin Payment

In recent years, the Bitcoin (BTC) payment is increasingly popular in retailers and service providers. A BTC transaction (tx) needs six confirmations (one hour) to be validated, making it not suitable for fast-pay scenarios. Theoretically, a shorter waiting time period increases the success possibility of a double-spending attack. To address this problem, we propose BTCFast scheme to support fast BTC tx. BTCFast is a novel, decentralized, escrow-based scheme on top of the programmable smart contract (PSC)-enabled blockchains (e.g. Ethereum, EOS). We develop a smart contract (PayJudger) to work as a trusted payment judger, which guarantees the tx fairness. In addition, we devise a proof-of-work (PoW)-based payment judgment mechanism for PayJudger to resolve a BTC payment dispute. Our theoretical and experimental results show that BTCFast can reduce the waiting time to be less than 1 second with comparable security as the current approach (i.e., waiting for six confirmations) with no extra operation fee.