A Lightweight and Efficiently Verified Assets Cross-Chain Transfer Method for Multi-Level Blockchains Architecture

The multi-level blockchains architecture is an architecture that organizes multiple blockchains into a tree, where each blockchain can control and manage part of the functions and on-chain data of the next level of the blockchains to which it is connected by cross-chain technology. However, the cross-chain transfer of assets under this architecture is a multi-hop cross-chain problem, where the evidence of successful execution of a cross-chain transaction needs to be transmitted and verified in multiple hops on the path from the source chain to the target chain, resulting in longer execution latency of the cross-chain transaction, higher evidence transmission overhead and verification overhead. Therefore, this paper proposes a lightweight and efficiently verified assets cross-chain transfer method for multi-level blockchains architecture, which introduces a top-level witness chain connecting each multi-level architecture and deploys a witness contract on each chain, so that the parent chains of the source and target chains in a cross-chain transaction act as witness chains to drive the completion of the cross-chain transaction. This paper also introduces a cross-chain transaction verification evidence based on Verkle tree, the method organizes the cross-chain transaction information to be processed in the same block in a Verkle tree employing KZG polynomial commitment, and adds the KZG commitment and the proof data into the evidence, and proves the execution state of the cross-chain transaction by verifying the evidence, so as to optimize the transmission and verification of the evidence. Theoretical analysis and experiments on the prototype of the method prove that the method reduces the execution latency of the cross-chain transaction and reduces the evidence verification overhead compared to the scheme using SPV without increasing the evidence transmission overhead, which is lightweight and efficiently verified.