# CrossDeFi: A Novel Cross-Chain Communication Protocol
## 2 Literature Survey
### Cross-Chain Interoperability Solutions  
The realm of cross-chain interoperability has various projects addressing the limitations inherent in blockchain technologies. The Metronome project [25] offers a solution limited to blockchains that support smart contracts, excluding those without this capability, and does not tackle issues related to transfer finality and confirmation. Conversely, KyberNetwork [26] provides instant trading and redemption services for digital assets on Ethereum blockchains. Further extending this concept, another project [27] leverages BTCRelay technology to facilitate cross-chain confirmations but lacks support for multi-currency transactions. Wanchain [32] is a pioneering project in blockchain cross-chain technology using intermediate chains to facilitate transactions.  
Recent advancements include a blockchain scaling solution [33] focusing on computational scalability. A multi-public chain cross-chain project [34] introduces a distance-based consensus eliminating the verifier role to achieve true power decentralization. The Plasma blockchain scaling model [35] aims to regulate blockchain entities through designated rewards and penalties. Peer-to-peer heterogeneous cross-chain mechanisms are explored [36], employing the oracle machine concept to improve interoperability. BrokerFi [37] represents a significant advancement by designing a decentralized application (dApp) that enables users to manage their digital assets effectively and monetize their participation within the BrokerFi ecosystem.  
Platforms like BitXHub [38], the cross-chain technology platform of Hyperchain, and WeCross [39], the cross-chain platform of WeBank, have been open-sourced, significantly advancing the development of China's domestic, independent cross-chain technology platforms. These platforms focus on interoperability of ledgers between heterogeneous consortium chains and tackle key issues in transaction capture, transmission, and verification [40]. BitXHub has achieved autonomy in consortium cross-chain interactions and supports services like unified identity management, permission control for cross-chain activities, node management, and information auditing.  
In [41], the introduction of the first cross-chain Polkadot bridge enabled EVM smart contracts on Polkadot, allowing developers from Ethereum, Wanchain, and other blockchains to integrate DOT into their applications using Wanchain's decentralized blockchain interoperability solution. Moreover, Interlay launched the wrapped Bitcoin token, InterBTC (iBTC), on the Polkadot network, providing users the option to keep BTC in their Polkadot wallet [22]. The MyWish platform [42] facilitates the construction of smart contracts on the blockchain without requiring written code, supporting various blockchains like Ethereum [43] and Binance [44], and fostering high interest among users in learning about token transfers through the Wish Swap cross-chain token exchange.  
However, some solutions like Cosmos [45] and wrapped bitcoin on Ethereum [46] still face challenges in providing effective bridging solutions. The work in [47] discusses multiple standards for cross-chain communication but lacks a discussion on interoperability standards compatible with different types of tokens. Additionally, a rotary group-based cross-chain mechanism in [48] achieves improved interoperability across different blockchains through effective notary selection. Another approach [49] uses sidechains for fast cross-chain transfers across multiple chains but faces performance challenges as the number of chains increases.