Paper 2021/537

SoK: Exploring Blockchains Interoperability

Gang Wang

Abstract

Distributed ledger technologies like blockchain have gained great attention in both academia and industry. Blockchain as a potentially disruptive technology can advance many different fields, e.g., cryptocurrencies, supply chains, and the industrial Internet of Things. The next-generation blockchain ecosystem is expected to consist of various homogeneous and heterogeneous distributed ledgers. These ledger systems will inevitably require a certain level of proper cooperation of multiple blockchains to enrich advanced functionalities and enhance interoperable capabilities for future applications. The interoperability among blockchains will definitely revolutionize current blockchain design principles, like the emergence of Internet. The development of cross-blockchain applications involves much complexity regarding the variety of underlying cross-blockchain communication. The way to effectively enable interoperability across multiple blockchains is thus essential and expecting to confront various unprecedented challenges. For instance, due to different transaction structures, ensuring the properties of ACID (Atomicity, Consistency, Isolation, Durability) in transactions processing and verification processes across diverse blockchain systems remains a challenging task in both academia and industry. This paper provides a systematic and comprehensive review of the current progress of blockchain interoperability. We explore both general principles and practical schemes to achieve interoperable blockchain systems. We then survey and compare the state-of-the-art solutions to deal with the interoperability of blockchains in detail. Finally, we discuss several critical challenges and some potential research directions to advance the research on exploring blockchain interoperability.