MEV Protection Strategies: Defending Against Maximal Extractable Value Attacks

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// Sophisticated sandwich attack implementation
class SandwichAttackBot {
    constructor(web3, flashloanProvider, targetAMM) {
        this.web3 = web3;
        this.flashloanProvider = flashloanProvider;
        this.targetAMM = targetAMM;
        this.mempool = new MempoolMonitor();
        this.gasTracker = new GasTracker();
    }
    
    async monitorMempool() {
        this.mempool.on('pendingTransaction', async (tx) => {
            const opportunity = await this.analyzeTxForMEV(tx);
            
            if (opportunity.profitable) {
                await this.executeSandwichAttack(tx, opportunity);
            }
        });
    }
    
    async analyzeTxForMEV(victimTx) {
        // Decode transaction to understand the swap
        const swapData = await this.decodeSwapTransaction(victimTx);
        
        if (!swapData) return { profitable: false };
        
        // Calculate price impact
        const priceImpact = await this.calculatePriceImpact(
            swapData.tokenIn,
            swapData.tokenOut,
            swapData.amountIn
        );
        
        // Estimate frontrun profit
        const frontrunAmount = await this.calculateOptimalFrontrunAmount(
            swapData,
            priceImpact
        );
        
        // Factor in gas costs and slippage
        const gasPrice = await this.gasTracker.getOptimalGasPrice(victimTx.gasPrice);
        const totalGasCost = gasPrice * (21000 * 2 + 100000); // Front + back transactions
        
        const estimatedProfit = frontrunAmount.profit - totalGasCost;
        
        return {
            profitable: estimatedProfit > 0.01 * 10**18, // Minimum 0.01 ETH profit
            frontrunAmount: frontrunAmount.amount,
            backrunAmount: frontrunAmount.amount,
            estimatedProfit: estimatedProfit,
            gasPrice: gasPrice
        };
    }
    
    async calculateOptimalFrontrunAmount(swapData, priceImpact) {
        // Use Uniswap V2 constant product formula
        const reserveIn = await this.getReserve(swapData.tokenIn);
        const reserveOut = await this.getReserve(swapData.tokenOut);
        
        // Calculate optimal frontrun amount using calculus
        // Maximize: profit = backrun_output - frontrun_input - gas_costs
        const k = reserveIn * reserveOut;
        const victimAmountIn = swapData.amountIn;
        
        // Optimal frontrun amount (simplified calculation)
        const optimalAmount = Math.sqrt(k * victimAmountIn) - reserveIn;
        
        // Calculate expected profit
        const frontrunOutput = this.getAmountOut(optimalAmount, reserveIn, reserveOut);
        const newReserveIn = reserveIn + optimalAmount;
        const newReserveOut = reserveOut - frontrunOutput;
        
        // After victim transaction
        const finalReserveIn = newReserveIn + victimAmountIn;
        const finalReserveOut = newReserveOut - this.getAmountOut(
            victimAmountIn, newReserveIn, newReserveOut
        );
        
        // Backrun transaction
        const backrunInput = frontrunOutput;
        const backrunOutput = this.getAmountOut(
            backrunInput, finalReserveOut, finalReserveIn
        );
        
        const profit = backrunOutput - optimalAmount;
        
        return {
            amount: optimalAmount,
            profit: profit
        };
    }
    
    async executeSandwichAttack(victimTx, opportunity) {
        try {
            // Step 1: Frontrun transaction
            const frontrunTx = await this.buildFrontrunTransaction(
                opportunity.frontrunAmount,
                opportunity.gasPrice + 1 // Slightly higher gas price
            );
            
            const frontrunHash = await this.web3.eth.sendTransaction(frontrunTx);
            
            // Step 2: Wait for victim transaction to be included
            await this.waitForTxInclusion(victimTx.hash);
            
            // Step 3: Backrun transaction
            const backrunTx = await this.buildBackrunTransaction(
                opportunity.backrunAmount,
                opportunity.gasPrice
            );
            
            const backrunHash = await this.web3.eth.sendTransaction(backrunTx);
            
            console.log(`Sandwich attack executed: ${frontrunHash} -> ${victimTx.hash} -> ${backrunHash}`);
            
        } catch (error) {
            console.error('Sandwich attack failed:', error);
        }
    }
    
    getAmountOut(amountIn, reserveIn, reserveOut) {
        const amountInWithFee = amountIn * 997;
        const numerator = amountInWithFee * reserveOut;
        const denominator = reserveIn * 1000 + amountInWithFee;
        return numerator / denominator;
    }
}

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// Sophisticated commit-reveal swap protection
pragma solidity ^0.8.19;

contract MEVProtectedSwap {
    struct Commitment {
        bytes32 commitment;
        uint256 revealDeadline;
        address committer;
        bool revealed;
        bool executed;
    }
    
    mapping(bytes32 => Commitment) public commitments;
    mapping(address => uint256) public nonces;
    
    uint256 public constant REVEAL_WINDOW = 15 minutes;
    uint256 public constant EXECUTION_WINDOW = 5 minutes;
    
    event CommitmentMade(bytes32 indexed commitmentHash, address committer);
    event TransactionRevealed(bytes32 indexed commitmentHash, bytes32 txHash);
    event TransactionExecuted(bytes32 indexed commitmentHash);
    
    function commitTransaction(bytes32 _commitment) external {
        bytes32 commitmentHash = keccak256(abi.encodePacked(
            _commitment,
            msg.sender,
            nonces[msg.sender]++
        ));
        
        require(commitments[commitmentHash].committer == address(0), "Commitment exists");
        
        commitments[commitmentHash] = Commitment({
            commitment: _commitment,
            revealDeadline: block.timestamp + REVEAL_WINDOW,
            committer: msg.sender,
            revealed: false,
            executed: false
        });
        
        emit CommitmentMade(commitmentHash, msg.sender);
    }
    
    function revealAndExecute(
        bytes32 _commitmentHash,
        address _tokenIn,
        address _tokenOut,
        uint256 _amountIn,
        uint256 _minAmountOut,
        uint256 _deadline,
        uint256 _salt
    ) external {
        Commitment storage commitment = commitments[_commitmentHash];
        
        require(commitment.committer == msg.sender, "Not committer");
        require(!commitment.revealed, "Already revealed");
        require(block.timestamp <= commitment.revealDeadline, "Reveal period expired");
        
        // Verify commitment
        bytes32 expectedCommitment = keccak256(abi.encodePacked(
            _tokenIn,
            _tokenOut,
            _amountIn,
            _minAmountOut,
            _deadline,
            _salt
        ));
        
        require(commitment.commitment == expectedCommitment, "Invalid reveal");
        
        commitment.revealed = true;
        
        // Add randomized delay to prevent timing attacks
        uint256 executionDelay = _generateRandomDelay(_commitmentHash);
        
        if (block.timestamp + executionDelay <= _deadline) {
            // Execute with delay
            _scheduleExecution(_commitmentHash, executionDelay);
        } else {
            // Execute immediately if deadline pressure
            _executeSwap(_tokenIn, _tokenOut, _amountIn, _minAmountOut, msg.sender);
            commitment.executed = true;
        }
        
        emit TransactionRevealed(_commitmentHash, keccak256(abi.encodePacked(
            _tokenIn, _tokenOut, _amountIn, _minAmountOut
        )));
    }
    
    function _generateRandomDelay(bytes32 _commitmentHash) internal view returns (uint256) {
        // Use commitment hash and block data for pseudo-randomness
        uint256 random = uint256(keccak256(abi.encodePacked(
            _commitmentHash,
            block.timestamp,
            block.difficulty
        )));
        
        // Random delay between 1-5 blocks
        return (random % 5 + 1) * 12; // Assuming 12 second block times
    }
    
    function _scheduleExecution(bytes32 _commitmentHash, uint256 _delay) internal {
        // In practice, this would use a decentralized scheduler or keeper network
        // For demonstration, we'll use a simplified approach
        
        // Store execution parameters for later execution
        // Implementation would integrate with Chainlink Keepers or similar
    }
    
    function _executeSwap(
        address _tokenIn,
        address _tokenOut,
        uint256 _amountIn,
        uint256 _minAmountOut,
        address _recipient
    ) internal {
        // Implement actual swap logic here
        // This would interact with your preferred DEX
        
        IERC20(_tokenIn).transferFrom(_recipient, address(this), _amountIn);
        
        // Perform swap through DEX
        uint256 amountOut = _performDEXSwap(_tokenIn, _tokenOut, _amountIn);
        
        require(amountOut >= _minAmountOut, "Insufficient output");
        
        IERC20(_tokenOut).transfer(_recipient, amountOut);
    }
    
    function _performDEXSwap(
        address _tokenIn,
        address _tokenOut,
        uint256 _amountIn
    ) internal returns (uint256) {
        // Simplified DEX interaction
        // Real implementation would use router contracts
        return _amountIn * 99 / 100; // Simplified 1% slippage
    }
}

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// Submarine send implementation for MEV protection
pragma solidity ^0.8.19;

contract SubmarineSend {
    struct SubmarineCommit {
        bytes32 commitHash;
        uint256 revealBlock;
        uint256 gasPrice;
        uint256 gasLimit;
        address sender;
        bool revealed;
    }
    
    mapping(bytes32 => SubmarineCommit) public commits;
    mapping(address => uint256) public balances;
    
    uint256 public constant REVEAL_DELAY_BLOCKS = 5;
    
    event SubmarineCommitment(bytes32 indexed commitHash, uint256 revealBlock);
    event SubmarineReveal(bytes32 indexed commitHash, address recipient, uint256 amount);
    
    function commitSubmarineSend(
        bytes32 _commitHash,
        uint256 _gasPrice,
        uint256 _gasLimit
    ) external payable {
        require(msg.value > 0, "Must send ETH");
        require(commits[_commitHash].sender == address(0), "Commit exists");
        
        commits[_commitHash] = SubmarineCommit({
            commitHash: _commitHash,
            revealBlock: block.number + REVEAL_DELAY_BLOCKS,
            gasPrice: _gasPrice,
            gasLimit: _gasLimit,
            sender: msg.sender,
            revealed: false
        });
        
        balances[msg.sender] += msg.value;
        
        emit SubmarineCommitment(_commitHash, block.number + REVEAL_DELAY_BLOCKS);
    }
    
    function revealSubmarineSend(
        address _recipient,
        uint256 _amount,
        uint256 _nonce,
        bytes32 _salt
    ) external {
        bytes32 commitHash = keccak256(abi.encodePacked(
            _recipient,
            _amount,
            _nonce,
            _salt,
            msg.sender
        ));
        
        SubmarineCommit storage commit = commits[commitHash];
        
        require(commit.sender == msg.sender, "Not sender");
        require(!commit.revealed, "Already revealed");
        require(block.number >= commit.revealBlock, "Too early to reveal");
        require(balances[msg.sender] >= _amount, "Insufficient balance");
        
        commit.revealed = true;
        balances[msg.sender] -= _amount;
        
        // Execute the hidden transaction
        payable(_recipient).transfer(_amount);
        
        emit SubmarineReveal(commitHash, _recipient, _amount);
    }
    
    function cancelCommit(bytes32 _commitHash) external {
        SubmarineCommit storage commit = commits[_commitHash];
        
        require(commit.sender == msg.sender, "Not sender");
        require(!commit.revealed, "Already revealed");
        require(block.number >= commit.revealBlock + 100, "Reveal window still open");
        
        // Refund the committed amount
        uint256 refundAmount = balances[msg.sender];
        balances[msg.sender] = 0;
        
        payable(msg.sender).transfer(refundAmount);
    }
}

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// MEV-resistant TWAP oracle with manipulation detection
pragma solidity ^0.8.19;

contract MEVResistantTWAP {
    struct PriceObservation {
        uint256 timestamp;
        uint256 price;
        uint256 volume;
        uint256 blockNumber;
    }
    
    struct TWAPConfig {
        uint256 windowSize;
        uint256 minObservations;
        uint256 maxDeviation;
        bool manipulationDetected;
    }
    
    mapping(address => PriceObservation[]) public priceHistory;
    mapping(address => TWAPConfig) public twapConfigs;
    mapping(address => uint256) public lastUpdateBlock;
    
    uint256 public constant MAX_PRICE_DEVIATION = 500; // 5%
    uint256 public constant MIN_UPDATE_INTERVAL = 4; // blocks
    
    event PriceUpdated(address indexed token, uint256 price, uint256 volume);
    event ManipulationDetected(address indexed token, uint256 suspiciousPrice);
    event TWAPConfigUpdated(address indexed token, TWAPConfig config);
    
    function updatePrice(
        address _token,
        uint256 _price,
        uint256 _volume
    ) external {
        require(
            block.number >= lastUpdateBlock[_token] + MIN_UPDATE_INTERVAL,
            "Too frequent updates"
        );
        
        // Check for price manipulation
        if (_detectPriceManipulation(_token, _price)) {
            twapConfigs[_token].manipulationDetected = true;
            emit ManipulationDetected(_token, _price);
            return; // Reject suspicious price updates
        }
        
        PriceObservation memory observation = PriceObservation({
            timestamp: block.timestamp,
            price: _price,
            volume: _volume,
            blockNumber: block.number
        });
        
        priceHistory[_token].push(observation);
        lastUpdateBlock[_token] = block.number;
        
        // Maintain sliding window
        _maintainWindow(_token);
        
        emit PriceUpdated(_token, _price, _volume);
    }
    
    function getTWAP(address _token, uint256 _period) external view returns (uint256) {
        PriceObservation[] memory observations = priceHistory[_token];
        require(observations.length > 0, "No price data");
        
        uint256 cutoff = block.timestamp - _period;
        uint256 weightedSum = 0;
        uint256 totalWeight = 0;
        
        for (uint i = observations.length; i > 0; i--) {
            PriceObservation memory obs = observations[i - 1];
            
            if (obs.timestamp < cutoff) break;
            
            // Weight by volume and time
            uint256 timeWeight = block.timestamp - obs.timestamp;
            uint256 volumeWeight = obs.volume;
            uint256 totalObsWeight = timeWeight * volumeWeight;
            
            weightedSum += obs.price * totalObsWeight;
            totalWeight += totalObsWeight;
        }
        
        require(totalWeight > 0, "No valid observations");
        return weightedSum / totalWeight;
    }
    
    function _detectPriceManipulation(
        address _token,
        uint256 _newPrice
    ) internal view returns (bool) {
        PriceObservation[] memory observations = priceHistory[_token];
        
        if (observations.length == 0) return false;
        
        // Get recent TWAP
        uint256 recentTWAP = _calculateRecentTWAP(_token, 5 minutes);
        
        // Check for excessive deviation
        uint256 deviation = _newPrice > recentTWAP
            ? (_newPrice - recentTWAP) * 10000 / recentTWAP
            : (recentTWAP - _newPrice) * 10000 / recentTWAP;
        
        if (deviation > MAX_PRICE_DEVIATION) {
            return true;
        }
        
        // Check for flash loan attack patterns
        return _detectFlashLoanPattern(_token, _newPrice);
    }
    
    function _detectFlashLoanPattern(
        address _token,
        uint256 _newPrice
    ) internal view returns (bool) {
        PriceObservation[] memory observations = priceHistory[_token];
        
        if (observations.length < 3) return false;
        
        // Look for rapid price swings within same block
        uint256 currentBlock = block.number;
        uint256 pricesThisBlock = 0;
        uint256 maxPriceThisBlock = 0;
        uint256 minPriceThisBlock = type(uint256).max;
        
        for (uint i = observations.length; i > 0; i--) {
            if (observations[i - 1].blockNumber != currentBlock) break;
            
            pricesThisBlock++;
            if (observations[i - 1].price > maxPriceThisBlock) {
                maxPriceThisBlock = observations[i - 1].price;
            }
            if (observations[i - 1].price < minPriceThisBlock) {
                minPriceThisBlock = observations[i - 1].price;
            }
        }
        
        // Multiple price updates in same block with high volatility
        if (pricesThisBlock > 2) {
            uint256 intraBlockVolatility = maxPriceThisBlock > minPriceThisBlock
                ? (maxPriceThisBlock - minPriceThisBlock) * 10000 / minPriceThisBlock
                : 0;
            
            return intraBlockVolatility > 1000; // 10% intra-block volatility threshold
        }
        
        return false;
    }
    
    function _calculateRecentTWAP(
        address _token,
        uint256 _period
    ) internal view returns (uint256) {
        PriceObservation[] memory observations = priceHistory[_token];
        uint256 cutoff = block.timestamp - _period;
        
        uint256 sum = 0;
        uint256 count = 0;
        
        for (uint i = observations.length; i > 0; i--) {
            if (observations[i - 1].timestamp < cutoff) break;
            
            sum += observations[i - 1].price;
            count++;
        }
        
        return count > 0 ? sum / count : 0;
    }
    
    function _maintainWindow(address _token) internal {
        TWAPConfig memory config = twapConfigs[_token];
        PriceObservation[] storage observations = priceHistory[_token];
        
        uint256 cutoff = block.timestamp - config.windowSize;
        
        // Remove old observations
        while (observations.length > 0 && observations[0].timestamp < cutoff) {
            // Shift array left (expensive but necessary for demonstration)
            for (uint i = 0; i < observations.length - 1; i++) {
                observations[i] = observations[i + 1];
            }
            observations.pop();
        }
    }
}

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// Batch auction system for MEV protection
pragma solidity ^0.8.19;

contract BatchAuction {
    struct Order {
        address trader;
        address tokenIn;
        address tokenOut;
        uint256 amountIn;
        uint256 minAmountOut;
        uint256 deadline;
        bool filled;
    }
    
    struct Batch {
        uint256 batchId;
        uint256 submissionDeadline;
        uint256 executionTime;
        Order[] orders;
        bool executed;
        mapping(address => uint256) clearingPrices;
    }
    
    mapping(uint256 => Batch) public batches;
    uint256 public currentBatchId;
    uint256 public constant BATCH_DURATION = 30 seconds;
    
    event OrderSubmitted(uint256 indexed batchId, address trader, uint256 orderId);
    event BatchExecuted(uint256 indexed batchId, uint256 totalOrders);
    event OrderFilled(uint256 indexed batchId, uint256 orderId, uint256 executionPrice);
    
    function submitOrder(
        address _tokenIn,
        address _tokenOut,
        uint256 _amountIn,
        uint256 _minAmountOut,
        uint256 _deadline
    ) external {
        require(_amountIn > 0, "Invalid amount");
        require(_deadline > block.timestamp, "Invalid deadline");
        
        // Get or create current batch
        if (batches[currentBatchId].submissionDeadline <= block.timestamp) {
            _createNewBatch();
        }
        
        Batch storage batch = batches[currentBatchId];
        
        Order memory order = Order({
            trader: msg.sender,
            tokenIn: _tokenIn,
            tokenOut: _tokenOut,
            amountIn: _amountIn,
            minAmountOut: _minAmountOut,
            deadline: _deadline,
            filled: false
        });
        
        batch.orders.push(order);
        
        // Transfer tokens to auction contract
        IERC20(_tokenIn).transferFrom(msg.sender, address(this), _amountIn);
        
        emit OrderSubmitted(currentBatchId, msg.sender, batch.orders.length - 1);
    }
    
    function executeBatch(uint256 _batchId) external {
        Batch storage batch = batches[_batchId];
        
        require(!batch.executed, "Batch already executed");
        require(block.timestamp >= batch.executionTime, "Execution time not reached");
        
        // Calculate clearing prices using uniform price auction
        _calculateClearingPrices(_batchId);
        
        // Execute all orders at clearing prices
        for (uint i = 0; i < batch.orders.length; i++) {
            _executeOrder(_batchId, i);
        }
        
        batch.executed = true;
        emit BatchExecuted(_batchId, batch.orders.length);
    }
    
    function _createNewBatch() internal {
        currentBatchId++;
        
        Batch storage newBatch = batches[currentBatchId];
        newBatch.batchId = currentBatchId;
        newBatch.submissionDeadline = block.timestamp + BATCH_DURATION;
        newBatch.executionTime = block.timestamp + BATCH_DURATION + 60; // 1 minute buffer
        newBatch.executed = false;
    }
    
    function _calculateClearingPrices(uint256 _batchId) internal {
        Batch storage batch = batches[_batchId];
        
        // Group orders by token pair
        mapping(bytes32 => Order[]) storage ordersByPair;
        
        for (uint i = 0; i < batch.orders.length; i++) {
            Order memory order = batch.orders[i];
            bytes32 pairKey = keccak256(abi.encodePacked(order.tokenIn, order.tokenOut));
            
            // In a real implementation, this would require more sophisticated data structures
            // For demonstration, we'll use a simplified clearing price calculation
        }
        
        // Simplified clearing price calculation
        // Real implementation would use sophisticated matching algorithms
        _setUniformClearingPrices(_batchId);
    }
    
    function _setUniformClearingPrices(uint256 _batchId) internal {
        Batch storage batch = batches[_batchId];
        
        // Simplified: use current market prices as clearing prices
        // Real implementation would calculate supply/demand equilibrium
        
        for (uint i = 0; i < batch.orders.length; i++) {
            Order memory order = batch.orders[i];
            
            // Get market price from external oracle
            uint256 marketPrice = _getMarketPrice(order.tokenIn, order.tokenOut);
            
            batch.clearingPrices[order.tokenIn] = marketPrice;
        }
    }
    
    function _executeOrder(uint256 _batchId, uint256 _orderId) internal {
        Batch storage batch = batches[_batchId];
        Order storage order = batch.orders[_orderId];
        
        if (order.deadline < block.timestamp) {
            // Refund expired order
            IERC20(order.tokenIn).transfer(order.trader, order.amountIn);
            return;
        }
        
        uint256 clearingPrice = batch.clearingPrices[order.tokenIn];
        uint256 amountOut = order.amountIn * clearingPrice / 1e18;
        
        if (amountOut >= order.minAmountOut) {
            // Fill order
            IERC20(order.tokenOut).transfer(order.trader, amountOut);
            order.filled = true;
            
            emit OrderFilled(_batchId, _orderId, clearingPrice);
        } else {
            // Refund unfillable order
            IERC20(order.tokenIn).transfer(order.trader, order.amountIn);
        }
    }
    
    function _getMarketPrice(address _tokenIn, address _tokenOut) internal view returns (uint256) {
        // Simplified price oracle call
        // Real implementation would use Chainlink or other reliable oracles
        return 1e18; // 1:1 price for demonstration
    }
    
    function getBatchInfo(uint256 _batchId) external view returns (
        uint256 submissionDeadline,
        uint256 executionTime,
        uint256 orderCount,
        bool executed
    ) {
        Batch storage batch = batches[_batchId];
        return (
            batch.submissionDeadline,
            batch.executionTime,
            batch.orders.length,
            batch.executed
        );
    }
}

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// Flashbots integration for MEV protection
const { FlashbotsBundleProvider } = require('@flashbots/ethers-provider-bundle');
const { ethers } = require('ethers');

class FlashbotsProtectedSwap {
    constructor(provider, signer, flashbotsRelay) {
        this.provider = provider;
        this.signer = signer;
        this.flashbotsProvider = FlashbotsBundleProvider.create(
            provider,
            signer,
            flashbotsRelay
        );
    }
    
    async submitPrivateTransaction(transaction) {
        const blockNumber = await this.provider.getBlockNumber();
        const targetBlock = blockNumber + 1;
        
        // Create bundle with our transaction
        const bundle = [{
            transaction: {
                to: transaction.to,
                value: transaction.value,
                data: transaction.data,
                gasLimit: transaction.gasLimit,
                gasPrice: transaction.gasPrice
            },
            signer: this.signer
        }];
        
        // Submit bundle to Flashbots
        const bundleSubmission = await this.flashbotsProvider.sendBundle(
            bundle,
            targetBlock
        );
        
        console.log('Bundle submitted:', bundleSubmission.bundleHash);
        
        // Wait for inclusion
        const receipt = await bundleSubmission.wait();
        
        if (receipt === FlashbotsBundleResolution.BundleIncluded) {
            console.log('Bundle included in block');
            return bundleSubmission.bundleHash;
        } else if (receipt === FlashbotsBundleResolution.BlockPassedWithoutInclusion) {
            console.log('Bundle not included, retrying...');
            return this.submitPrivateTransaction(transaction);
        } else {
            throw new Error('Bundle submission failed');
        }
    }
    
    async submitMultiTransactionBundle(transactions) {
        const blockNumber = await this.provider.getBlockNumber();
        const targetBlock = blockNumber + 1;
        
        // Create bundle with multiple transactions
        const bundle = transactions.map(tx => ({
            transaction: tx,
            signer: this.signer
        }));
        
        // Add MEV protection by bundling user tx with protection transactions
        const protectionBundle = await this.addMEVProtection(bundle);
        
        const bundleSubmission = await this.flashbotsProvider.sendBundle(
            protectionBundle,
            targetBlock
        );
        
        return bundleSubmission;
    }
    
    async addMEVProtection(userBundle) {
        // Add front-protection and back-protection transactions
        const protectedBundle = [];
        
        // Front-protection: transaction that makes sandwich attacks unprofitable
        const frontProtection = await this.createFrontProtection(userBundle[0]);
        if (frontProtection) {
            protectedBundle.push(frontProtection);
        }
        
        // Add user transactions
        protectedBundle.push(...userBundle);
        
        // Back-protection: transaction that captures any remaining MEV
        const backProtection = await this.createBackProtection(userBundle);
        if (backProtection) {
            protectedBundle.push(backProtection);
        }
        
        return protectedBundle;
    }
    
    async createFrontProtection(userTransaction) {
        // Analyze user transaction to determine protection strategy
        const txData = this.parseTransactionData(userTransaction);
        
        if (txData.type === 'swap') {
            // Create a small opposite swap to reduce price impact
            return this.createAntiSandwichTransaction(txData);
        }
        
        return null;
    }
    
    async createBackProtection(userBundle) {
        // Create transaction that captures any MEV created by user transactions
        // This ensures users get the value instead of external searchers
        
        return {
            transaction: {
                to: '0x...', // MEV recapture contract
                data: '0x...', // Encoded function call
                gasLimit: 100000,
                gasPrice: userBundle[0].transaction.gasPrice
            },
            signer: this.signer
        };
    }
    
    parseTransactionData(transaction) {
        // Parse transaction data to understand the operation
        // This would decode function calls to determine transaction type
        
        return {
            type: 'swap',
            tokenIn: '0x...',
            tokenOut: '0x...',
            amountIn: ethers.BigNumber.from('1000000000000000000')
        };
    }
    
    async createAntiSandwichTransaction(swapData) {
        // Create a small trade in the opposite direction
        // This reduces the profitability of sandwich attacks
        
        const protectionAmount = swapData.amountIn.div(100); // 1% of user trade
        
        return {
            transaction: {
                to: swapData.router,
                data: this.encodeSwapData(
                    swapData.tokenOut,
                    swapData.tokenIn,
                    protectionAmount
                ),
                gasLimit: 200000,
                gasPrice: swapData.gasPrice.add(1000000000) // Slightly higher gas
            },
            signer: this.signer
        };
    }
    
    encodeSwapData(tokenIn, tokenOut, amount) {
        // Encode swap function call
        const iface = new ethers.utils.Interface([
            'function swapExactTokensForTokens(uint256,uint256,address[],address,uint256)'
        ]);
        
        return iface.encodeFunctionData('swapExactTokensForTokens', [
            amount,
            0, // Min amount out (for protection tx)
            [tokenIn, tokenOut],
            this.signer.address,
            Math.floor(Date.now() / 1000) + 300 // 5 minute deadline
        ]);
    }
}

// Usage example
const provider = new ethers.providers.JsonRpcProvider('https://mainnet.infura.io/v3/YOUR_KEY');
const signer = new ethers.Wallet('YOUR_PRIVATE_KEY', provider);
const flashbotsRelay = 'https://relay.flashbots.net';

const protectedSwap = new FlashbotsProtectedSwap(provider, signer, flashbotsRelay);

// Submit protected swap
const transaction = {
    to: '0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D', // Uniswap router
    data: '0x...', // Encoded swap call
    value: 0,
    gasLimit: 200000,
    gasPrice: ethers.utils.parseUnits('50', 'gwei')
};

protectedSwap.submitPrivateTransaction(transaction)
    .then(bundleHash => console.log('Protected transaction submitted:', bundleHash))
    .catch(error => console.error('Error:', error));