Paper 2021/1244

IvyCross: A Trustworthy and Privacy-preserving Framework for Blockchain Interoperability

Ming Li and Jian Weng and Yi Li and Yongdong Wu and Jiasi Weng and Dingcheng Li and Robert Deng

Abstract

Blockchain interoperability is essential for the long-envisioned cross-chain decentralized applications. Existing hardware-based approaches demand several Trusted Execution Environments (TEEs) and large storage on the storage-limited TEEs. This paper presents a TEE-based privacy-preserving blockchain interoperability framework, calls as IvyCross, which decreases the requirement of TEE numbers and TEE's storage sizes by enforcing honest behaviors of TEE hosts with economic incentives. Specifically, IvyCross runs privacy-preserving cross-chain smart contracts atop two distributed TEE-powered hosts, and utilizes a sequential game between rational hosts to guarantee the correctness of contracts execution. IvyCross enables arbitrarily complex smart contracts execution across heterogenous blockchains at low costs. We formally prove the security of IvyCross in the Universal Composability framework. We also implement a prototype of IvyCross atop Bitcoin, Ethereum, and FISCO BOCS. The experiments indicate that (i) IvyCross is able to support privacy-preserving and multiple-round smart contracts for cross-chain communication; (ii) IvyCross successfully decreases the off-chain costs on storage and communication of a TEE without using complex cryptographic primitives; and (iii) the on-chain transaction fees in cross-chain communication are relatively low.