SmartSync: Cross-Blockchain Smart Contract Interaction and Synchronization

TL;DR

SmartSync introduces a novel cross-blockchain communication method enabling synchronized smart contracts with verifiable state updates, reducing trust assumptions and supporting seamless interactions across diverse blockchain networks.

Contribution

It proposes a new approach for cross-chain smart contract synchronization using Merkle proofs and transition confirmations, with a prototype on EVM-compatible blockchains.

Findings

Verifiable state updates without trusted intermediaries

Sub-linear scaling of execution costs with updates

Prototype demonstrates practical cross-chain contract interactions

Abstract

Cross-Blockchain communication has gained traction due to the increasing fragmentation of blockchain networks and scalability solutions such as side-chaining and sharding. With SmartSync, we propose a novel concept for cross-blockchain smart contract interactions that creates client contracts on arbitrary blockchain networks supporting the same execution environment. Client contracts mirror the logic and state of the original instance and enable seamless on-chain function executions providing recent states. Synchronized contracts supply instant read-only function calls to other applications hosted on the target blockchain. Hereby, current limitations in cross-chain communication are alleviated and new forms of contract interactions are enabled. State updates are transmitted in a verifiable manner using Merkle proofs and do not require trusted intermediaries. To permit lightweight synchronizations, we introduce transition confirmations that facilitate the application of verifiable state transitions without re-executing transactions of the source blockchain. We prove the concept's soundness by providing a prototypical implementation that enables smart contract forks, state synchronizations, and on-chain validation on EVM-compatible blockchains. Our evaluation demonstrates SmartSync's applicability for presented use cases providing access to recent states to third-party contracts on the target blockchain. Execution costs scale sub-linearly with the number of value updates and depend on the depth and index of corresponding Merkle proofs.