Indivisible State Mirroring in Cross-Chain Atomic Swap across Heterogeneous Blockchains

Abstract

The significance of interoperability has intensified with the continuous expansion of blockchain applications. However, the heterogeneous architecture of distinct blockchain networks exacerbates the complexities during seamless cross-chain communication. Furthermore, the lack of a global clock, shared memory, or universal knowledge complicates synchronized state updates, and coherent transaction sequencing in distributed and asynchronous communication. Atomic cross-chain swap is a distributed coordination task enabling interoperability through digital asset exchange across multiple blockchains without intermediaries. Previous attempts at atomic cross-chain swap largely overlooked the complexity posed by the heterogeneity and asynchronicity of cross-chain communication leading to suboptimal (platform-dependent) solutions. Therefore, this work develops a novel, platform-agnostic, state machine-based atomic swap written in a smart contract which shows a paradigm shift by theoretically and experimentally addressing the diversity of blockchains and the distributed nature of cross-chain communication. States are mirrored by implementing on-chain state updates to ensure synchronization and swap advancement with a safe rollback mechanism without any underlying assumption. Furthermore, real-time network traffic is represented utilizing a gamma distribution model across heterogeneous permissionless blockchains. The model pro- vides a systematic way of quantifying, comparing, and evaluating different types of variability to understand how heterogeneity impacts the swap performance. Performance is evaluated in delay and cost across distinct networks, and a successful Ethereum-Polygon cross-chain swap. Moreover, we formally validate our protocol’s correctness, ensuring consistency, liveness, no race conditions, deadlocks, and sustained atomicity.