Cross-Chain Verification

Ensures data consistency across multiple blockchain networks through:

Data Aggregation

• Cross-chain state verification

• Bridge transaction validation

• Asset movement tracking

• Protocol state consistency

Technical Parameters:

• Verification latency: <200ms

• Chain support: All major EVM networks

• Proof composition: Automatic

• State sync interval: Real-time

// // Cross-chain verification for DA3N
import { Web3 } from 'web3';
import { ethers } from 'ethers';
import { ZkSyncProvider } from 'zksync';
import { StarknetProvider } from 'starknet';

interface ChainState {
   chainId: number; 
   blockNumber: number;
   stateRoot: string;
   timestamp: number;
}

interface CrossChainProof {
   sourceState: ChainState;
   targetState: ChainState;
   proof: Uint8Array;
   signature: string;
}

class CrossChainVerifier {
   private providers: Map<number, any>;
   private bridgeContracts: Map<number, string>;

   constructor() {
       // Initialize providers for different chains
       this.providers = new Map([
           [1, new Web3('ETH_RPC_URL')], // Ethereum
           [137, new Web3('POLYGON_RPC_URL')], // Polygon
           [324, new ZkSyncProvider('ZKSYNC_RPC_URL')], // zkSync
           [5, new StarknetProvider('STARKNET_RPC_URL')] // StarkNet
       ]);

       // Bridge contract addresses
       this.bridgeContracts = new Map([
           [1, 'ETH_BRIDGE_ADDRESS'],
           [137, 'POLYGON_BRIDGE_ADDRESS'],
           [324, 'ZKSYNC_BRIDGE_ADDRESS'],
           [5, 'STARKNET_BRIDGE_ADDRESS']
       ]);
   }

   async verifyStateTransition(
       sourceChainId: number,
       targetChainId: number,
       txHash: string
   ): Promise<CrossChainProof> {
       const sourceProvider = this.providers.get(sourceChainId);
       const targetProvider = this.providers.get(targetChainId);

       // Get source chain state
       const sourceTx = await sourceProvider.eth.getTransaction(txHash);
       const sourceBlock = await sourceProvider.eth.getBlock(sourceTx.blockNumber);
       const sourceState = {
           chainId: sourceChainId,
           blockNumber: sourceTx.blockNumber,
           stateRoot: sourceBlock.stateRoot,
           timestamp: sourceBlock.timestamp
       };

       // Get target chain state
       const targetBlock = await targetProvider.eth.getBlock('latest');
       const targetState = {
           chainId: targetChainId,
           blockNumber: targetBlock.number,
           stateRoot: targetBlock.stateRoot,
           timestamp: targetBlock.timestamp
       };

       // Generate cross-chain proof
       const proof = await this.generateStateProof(
           sourceState,
           targetState,
           txHash
       );

       // Sign proof with validator key
       const signature = await this.signProof(proof);

       return {
           sourceState,
           targetState,
           proof,
           signature
       };
   }

   private async generateStateProof(
       sourceState: ChainState,
       targetState: ChainState,
       txHash: string
   ): Promise<Uint8Array> {
       // Get bridge contract for source chain
       const bridgeAddress = this.bridgeContracts.get(sourceState.chainId);
       const sourceProvider = this.providers.get(sourceState.chainId);
       const bridge = new sourceProvider.eth.Contract(
           BRIDGE_ABI,
           bridgeAddress
       );

       // Get proof inputs from bridge
       const proofInputs = await bridge.methods
           .generateProofInputs(
               sourceState.stateRoot,
               targetState.stateRoot,
               txHash
           )
           .call();

       // Generate ZK proof using circuit
       return await this.prover.generateProof(proofInputs);
   }

   private async signProof(proof: Uint8Array): Promise<string> {
       // Sign proof with validator key
       const message = ethers.utils.keccak256(proof);
       return await this.wallet.signMessage(message);
   }

   async verifyProof(crossChainProof: CrossChainProof): Promise<boolean> {
       // Verify proof and signature
       const isValidProof = await this.verifier.verifyProof(
           crossChainProof.proof,
           crossChainProof.sourceState,
           crossChainProof.targetState
       );

       const signer = ethers.utils.verifyMessage(
           crossChainProof.proof,
           crossChainProof.signature  
       );

       return isValidProof && this.isValidValidator(signer);
   }
}

The system maintains sub-second verification while ensuring data integrity across protocols and chains.