# CrossDeFi: A Novel Cross-Chain Communication Protocol
## 5 Proposed Work Overview
### Miner and Bridge Selection (MBS)  
Bridges in DeFi systems support various types of digital assets and are critical in managing the diverse transaction fees, liquidity depths, and user capacities that characterize different blockchain environments. Effective bridge and miner selection tailored to the specific needs of a DeFi application enhances cross-chain interoperability substantially. Miner and bridge selection is crucial for ensuring secure, fast, and cost-efficient multi-asset transfer support in the CrossDeFi framework. The selection begins within a consensus pool, hosting a spectrum of miners differentiated by their transaction fee structures, liquidity provisions, network congestion handling, and reliability. Choosing the optimal miner from this pool can significantly enhance user experience by optimizing transaction costs and boosting system trustworthiness.  
Traditional blockchain architectures typically restrict message transmission to a unidirectional flow. This limitation is a significant hurdle in verifying the successful receipt of assets, as the destination DeFi system cannot send confirmation back through the same channel. Addressing this, CrossDeFi implements a two-way interaction strategy that not only fortifies trust across different blockchain networks but also bridges fundamental gaps observed in traditional cross-chain communication protocols. Here, cross-chain bridges serve a dual function: they facilitate asset transfers and enable reciprocal transfer confirmation communications, thereby assuring transaction finality--a feature absent in other cross-chain components like dexes, aggregators, wrapped tokens, and oracles.  
The proposed model employs a bridge-centric approach designed to boost performance across DeFi cross-chains. Selecting the right bridge is crucial; inappropriate choices could delay transactions and height vulnerability to attacks. CrossDeFi tackles these challenges by adopting a unique selection strategy that leverages multi-criteria evaluations of both miners and bridges, thus enhancing the robustness and reliability of the DeFi ecosystem.  
Figure 2: Design process of CrossDeFi protocol.  
The best miner selection (BMS) algorithm in CrossDeFi leverages the underlying consensus algorithms of the DeFi systems involved to ensure robust and efficient miner selection. For example, miners operating under a proof-of-work (PoW) system, like DeFi X, are selected based on different criteria than those under a proof-of-stake (PoS) system, such as DeFi Y.  
Step 1: The BMS algorithm efficiently selects the most suitable miners, \(BMiX\) and \(BMiY\), from the mining pools of DeFi X and Y, respectively. This selection process is designed to ensure high integrity and trust within the network.  
Step 2: The selection algorithm considers a network of \(k\) nodes \(N=\{N1,N2,\ldots,Nk\}\), each responsible for generating blocks \(B=\{B1,B2,\ldots,Bk\}\) linked in sequence. The miner for the next transaction, \(Nk-1\), is chosen based on its ability to maintain the security and reliability of the chain:  
\[BMi\_Score=w1\cdot R_{i}+w2\cdot TF_{i}+w3\cdot Lq_{i}+w4\cdot SL_{i} \tag{5}\]  
where \(R_{i}\), \(TF_{i}\), \(Lq_{i}\), and \(SL_{i}\) represent the reliability, transaction fee, liquidity, and security level of node \(i\), respectively. Weights \(w1\), \(w2\), \(w3\), and \(w4\) prioritize these factors based on current DeFi requirements, ensuring an optimal selection.  
Step 3: Upon selection, a token representing the transaction details (Token X = createToken(F_ID, T, F_H)) is generated, encapsulating the identity, timestamp, and hash value of the transaction. This token is sent by \(BMiX\) to \(BMiY\), initiating the asset transfer process.  
This multi-step BMS algorithm, synchronized across both the source (DeFi X) and the destination (DeFi Y), enhances security, reduces costs, and improves the efficiency of cross-chain asset transfers by aligning mining operations with the specific needs and operational parameters of each involved blockchain system.