SightCVC: An Efficient and Compatible Multi-Chain Transaction Protocol in Heterogeneous Blockchain Systems

With the popularity of cross-chain transactions in heterogeneous blockchain systems, scalability has become a critical challenge. To overcome this, researchers propose to establish virtual channels, which move cross-chain transactions off the blockchain, enabling instant transaction confirmation between users and improving the system throughput. However, existing off-chain cross-chain transaction schemes encounter the following issues: (i) they are incompatible with non-Turing complete blockchain systems; (ii) they are incapable of accessing authentic information from blockchain systems. These issues have a dual impact on the cross-chain transaction, affecting its compatibility and dispute resolutions among mutually distrustful users. To alleviate these issues, this paper introduces SightCVC, a novel cross-chain payment protocol. The core of SightCVC is a new smart contract, which facilitates unrestricted off-chain transactions among mutually distrustful users in heterogeneous blockchain systems. It only requires off-chain protocol of the blockchain system involved in the transactions to support a Turing complete scripting language, which resolves the compatibility issue. Meanwhile, it can securely retrieve the real information from the blockchain systems, significantly improving the effectiveness of dispute resolution and enforcing the privacy of cross-chain transactions. We conduct a thorough security analysis within the Universal Composability framework to validate that SightCVC can achieve consensus at each stage. We implement and deploy SightCVC on the experimental networks of Ripple and Ethereum. Comprehensive evaluations demonstrate that SightCVC is able to effectively handle the disputes and reduce the system costs by approximately 64% compared to existing solutions. Its superiority becomes more evidence when the number of transactions increases.