A study on solutions of cross-ledger intercommunication : Classification, analysis and comparison of crosschain projects

Sammanfattning: The phenomenon of isolated value in each blockchain system has become adistinct issue of the blockchain field. To address this problem, the demandof cross-chain intercommunication came up. In a narrow sense, cross-chainrefers to the process of asset interoperability between relatively independentblockchains. In this thesis, we mainly analyze the design principles, technicaldifficulties, and solutions of cross-chain intercommunication in this narrowsense. With the introduction of distributed ledger technology(DLT), we describethe interaction with other ledgers as the fundamental problem of currentblockchain technology.The implementation of cross-chain is mainly manifested as asset swap and assettransfer. So far, there are many existing application scenarios and projectsadopted from these manifestation. This paper will focus on these two implementations,illustrate their principles, locate the realization difficulties, andput forward corresponding possible solutions. Then we elaborated on eightpopular cross-chain projects underlying mechanism listed with three maincategories. A detailed comparison according to their interoperability level,consensus algorithm and application scenarios of the overall overview of 20cross-chain projects is presented as a table in the Appendix A.During the implementation process, we performed a simple atomic swap crosschainframework based on Hash Time Lock Contract between Bitshares andEthereum, then compare the performance with a wallet application presentby Ripple using Interledger Protocol. These two applications are representedthe two different use case of cross-chain realization.With limited number of projects to test out, our conclusion was reached aftera discussion with the relative merits of the two approaches. Interledger protocolhas a better solution from the aspects of the decentralization, scalability,and whether it supports traditional ledgers.