Formal Analysis of IBC Protocol

Qiuyang Wei, Xufeng Zhao, Xue-Yang Zhu, Wenhui Zhang

Abstract: Since the inception of Bitcoin in 2008, blockchain technology has had a significant impact on many fields. The lack of effective communication between heterogeneous and isolated blockchains, however, restricts the promotion and ecological development of blockchain industry. In this context, crosschain technology has rapidly developed and become a new research hotspot. Due to the decentralized nature of blockchain and the complexity of crosschain scenarios, crosschain technology faces huge security risks. In this paper, we propose formal analysis of the IBC protocol, one of the most popular crosschain communication protocols, aiming to help developers design and implement crosschain technologies more securely. We formalize three main components of the IBC protocol with TLA+, a temporal logic specification language, and verify some important requirements with model checking tool TLC. The verification results are analyzed comprehensively. Issues found through our formal analysis have been reported to the community, most of which have been acknowledged. We also propose some recommendations for removing potential risks.