Security Model and Threat Analysis for ML Bridge Platform

ZK Proof Implementation

// Zero-knowledge proof for computation verification
circuit ComputationVerifier {
    // Public inputs
    signal input modelHash;
    signal input inputHash;
    signal input outputHash;
    
    // Private inputs (witness)
    signal private input modelParameters;
    signal private input inputData;
    signal private input computationSteps;
    
    // Constraints
    component modelVerifier = ModelHashVerifier();
    modelVerifier.parameters <== modelParameters;
    modelVerifier.hash <== modelHash;
    
    component computationVerifier = MLComputationVerifier();
    computationVerifier.model <== modelParameters;
    computationVerifier.input <== inputData;
    computationVerifier.steps <== computationSteps;
    computationVerifier.output <== outputHash;
    
    // Verify input hash
    component inputHasher = Poseidon(1);
    inputHasher.inputs[0] <== inputData;
    inputHasher.out === inputHash;
}

// SMPC protocol for privacy-preserving ML
class SMPCProtocol {
    constructor(parties, threshold) {
        this.parties = parties;
        this.threshold = threshold;
        this.secretShares = new Map();
    }
    
    // Secret sharing of model parameters
    shareModel(model) {
        const shares = shamirSecretSharing(model, this.parties.length, this.threshold);
        return shares.map((share, index) => ({
            party: this.parties[index],
            share: share
        }));
    }
    
    // Secure computation on shared data
    async computeSecurely(inputShares) {
        const computationShares = await Promise.all(
            this.parties.map(party => party.computeOnShare(inputShares[party.id]))
        );
        
        // Reconstruct result from shares
        return reconstructSecret(computationShares, this.threshold);
    }
}

// Role-based access control implementation
contract AccessControl {
    mapping(bytes32 => mapping(address => bool)) private _roles;
    
    bytes32 public constant ADMIN_ROLE = keccak256("ADMIN_ROLE");
    bytes32 public constant PROVIDER_ROLE = keccak256("PROVIDER_ROLE");
    bytes32 public constant VERIFIER_ROLE = keccak256("VERIFIER_ROLE");
    
    modifier onlyRole(bytes32 role) {
        require(hasRole(role, msg.sender), "AccessControl: unauthorized");
        _;
    }
    
    function grantRole(bytes32 role, address account) 
        external onlyRole(ADMIN_ROLE) {
        _roles[role][account] = true;
        emit RoleGranted(role, account, msg.sender);
    }
    
    function revokeRole(bytes32 role, address account) 
        external onlyRole(ADMIN_ROLE) {
        _roles[role][account] = false;
        emit RoleRevoked(role, account, msg.sender);
    }
}

// Comprehensive reentrancy protection
contract ReentrancyGuard {
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;
    uint256 private _status;
    
    constructor() {
        _status = _NOT_ENTERED;
    }
    
    modifier nonReentrant() {
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
        _status = _ENTERED;
        _;
        _status = _NOT_ENTERED;
    }
    
    // Additional protection for external calls
    modifier noExternalCalls() {
        require(tx.origin == msg.sender, "External calls not allowed");
        _;
    }
}

Economic Security Implementation

// Staking and slashing mechanism
contract StakingManager {
    struct Stake {
        uint256 amount;
        uint256 lockTime;
        uint256 reputation;
        bool slashed;
    }
    
    mapping(address => Stake) public stakes;
    uint256 public constant MIN_STAKE = 50000 * 10**18; // 50k MLB
    uint256 public constant SLASH_COOLDOWN = 7 days;
    
    function stake(uint256 amount) external {
        require(amount >= MIN_STAKE, "Insufficient stake amount");
        require(token.transferFrom(msg.sender, address(this), amount), "Transfer failed");
        
        stakes[msg.sender].amount += amount;
        stakes[msg.sender].lockTime = block.timestamp + SLASH_COOLDOWN;
        
        emit Staked(msg.sender, amount);
    }
    
    function slash(address provider, uint256 percentage, string calldata reason) 
        external onlyRole(SLASHER_ROLE) {
        require(percentage <= 100, "Invalid percentage");
        
        Stake storage providerStake = stakes[provider];
        uint256 slashAmount = (providerStake.amount * percentage) / 100;
        
        providerStake.amount -= slashAmount;
        providerStake.reputation = providerStake.reputation / 2; // Reputation penalty
        
        // Burn slashed tokens
        token.burn(slashAmount);
        
        emit Slashed(provider, slashAmount, reason);
    }
}

// Reputation management system
contract ReputationManager {
    struct Reputation {
        uint256 score;           // 0-1000 reputation score
        uint256 totalTasks;      // Total tasks completed
        uint256 successfulTasks; // Successfully completed tasks
        uint256 lastUpdate;      // Last reputation update
        bool penalized;          // Currently under penalty
    }
    
    mapping(address => Reputation) public reputations;
    
    function updateReputation(address provider, bool success, uint256 taskComplexity) 
        external onlyRole(REPUTATION_UPDATER_ROLE) {
        Reputation storage rep = reputations[provider];
        
        rep.totalTasks++;
        if (success) {
            rep.successfulTasks++;
            // Increase reputation based on task complexity
            uint256 increase = taskComplexity * 2;
            rep.score = Math.min(1000, rep.score + increase);
        } else {
            // Decrease reputation for failures
            uint256 decrease = taskComplexity * 5;
            rep.score = rep.score > decrease ? rep.score - decrease : 0;
        }
        
        rep.lastUpdate = block.timestamp;
        emit ReputationUpdated(provider, rep.score, success);
    }
    
    function getReputationMultiplier(address provider) external view returns (uint256) {
        uint256 score = reputations[provider].score;
        if (score >= 900) return 120; // 20% bonus for excellent reputation
        if (score >= 700) return 110; // 10% bonus for good reputation
        if (score >= 500) return 100; // No bonus/penalty for average reputation
        if (score >= 300) return 90;  // 10% penalty for poor reputation
        return 80; // 20% penalty for very poor reputation
    }
}

// Dispute resolution system
contract DisputeResolver {
    enum DisputeStatus { Open, UnderReview, Resolved, Escalated }
    
    struct Dispute {
        bytes32 taskId;
        address challenger;
        address[] defendants;
        bytes evidence;
        DisputeStatus status;
        uint256 createdAt;
        uint256 resolvedAt;
    }
    
    mapping(bytes32 => Dispute) public disputes;
    
    function createDispute(
        bytes32 taskId,
        address[] calldata defendants,
        bytes calldata evidence
    ) external payable {
        require(msg.value >= DISPUTE_FEE, "Insufficient dispute fee");
        require(disputes[taskId].status == DisputeStatus.Open, "Dispute already exists");
        
        disputes[taskId] = Dispute({
            taskId: taskId,
            challenger: msg.sender,
            defendants: defendants,
            evidence: evidence,
            status: DisputeStatus.UnderReview,
            createdAt: block.timestamp,
            resolvedAt: 0
        });
        
        emit DisputeCreated(taskId, msg.sender, defendants);
    }
    
    function resolveDispute(bytes32 taskId, bool challengerWins) 
        external onlyRole(ARBITRATOR_ROLE) {
        Dispute storage dispute = disputes[taskId];
        require(dispute.status == DisputeStatus.UnderReview, "Invalid dispute status");
        
        if (challengerWins) {
            // Slash defendants and reward challenger
            for (uint i = 0; i < dispute.defendants.length; i++) {
                stakingManager.slash(dispute.defendants[i], 25, "Lost dispute");
            }
            payable(dispute.challenger).transfer(DISPUTE_FEE * 2);
        } else {
            // Challenger loses dispute fee
            // Defendants receive compensation
        }
        
        dispute.status = DisputeStatus.Resolved;
        dispute.resolvedAt = block.timestamp;
        
        emit DisputeResolved(taskId, challengerWins);
    }
}

// Differential privacy implementation
class DifferentialPrivacy {
    constructor(epsilon, delta) {
        this.epsilon = epsilon; // Privacy budget
        this.delta = delta;     // Failure probability
    }
    
    // Add Laplace noise for differential privacy
    addLaplaceNoise(value, sensitivity) {
        const scale = sensitivity / this.epsilon;
        const noise = this.sampleLaplace(scale);
        return value + noise;
    }
    
    // Sample from Laplace distribution
    sampleLaplace(scale) {
        const u = Math.random() - 0.5;
        return -scale * Math.sign(u) * Math.log(1 - 2 * Math.abs(u));
    }
    
    // Add Gaussian noise for differential privacy
    addGaussianNoise(value, sensitivity) {
        const sigma = Math.sqrt(2 * Math.log(1.25 / this.delta)) * sensitivity / this.epsilon;
        const noise = this.sampleGaussian(0, sigma);
        return value + noise;
    }
}

// Homomorphic encryption for ML computations
class HomomorphicML {
    constructor(publicKey, privateKey) {
        this.publicKey = publicKey;
        this.privateKey = privateKey;
    }
    
    // Encrypt training data
    encryptData(data) {
        return data.map(value => this.encrypt(value));
    }
    
    // Perform encrypted computation
    computeEncrypted(encryptedData, model) {
        let result = this.encrypt(0);
        
        for (let i = 0; i < encryptedData.length; i++) {
            const weightedInput = this.multiply(encryptedData[i], model.weights[i]);
            result = this.add(result, weightedInput);
        }
        
        return result;
    }
    
    // Decrypt final result
    decryptResult(encryptedResult) {
        return this.decrypt(encryptedResult);
    }
}

// Node authentication protocol
class NodeAuthentication {
    constructor(nodeId, privateKey) {
        this.nodeId = nodeId;
        this.privateKey = privateKey;
        this.certificate = null;
    }
    
    // Generate authentication challenge
    generateChallenge() {
        const timestamp = Date.now();
        const nonce = crypto.randomBytes(32);
        const challenge = {
            nodeId: this.nodeId,
            timestamp,
            nonce: nonce.toString('hex')
        };
        
        return challenge;
    }
    
    // Sign authentication response
    signResponse(challenge) {
        const message = JSON.stringify(challenge);
        const signature = crypto.sign('sha256', Buffer.from(message), this.privateKey);
        
        return {
            challenge,
            signature: signature.toString('hex'),
            certificate: this.certificate
        };
    }
    
    // Verify node authentication
    verifyAuthentication(response, publicKey) {
        const message = JSON.stringify(response.challenge);
        const signature = Buffer.from(response.signature, 'hex');
        
        return crypto.verify('sha256', Buffer.from(message), publicKey, signature);
    }
}

// Incident response automation
class IncidentResponse {
    constructor(alertingSystem, emergencyContacts) {
        this.alerting = alertingSystem;
        this.contacts = emergencyContacts;
        this.procedures = new Map();
    }
    
    // Automated incident detection
    detectIncident(metrics) {
        const anomalies = this.analyzeMetrics(metrics);
        
        if (anomalies.severity >= 'HIGH') {
            this.triggerEmergencyResponse(anomalies);
        } else if (anomalies.severity >= 'MEDIUM') {
            this.escalateToSecurityTeam(anomalies);
        }
        
        return anomalies;
    }
    
    // Emergency response procedures
    triggerEmergencyResponse(incident) {
        // Immediate actions
        this.pauseSystemIfNecessary(incident);
        this.notifyEmergencyContacts(incident);
        this.activateIncidentRoom(incident);
        
        // Documentation
        this.createIncidentReport(incident);
        this.startTimelineTracking(incident);
        
        return incident.id;
    }
    
    // System pause mechanism
    pauseSystemIfNecessary(incident) {
        if (incident.requiresPause) {
            this.emergencyPause();
            this.logEmergencyAction('SYSTEM_PAUSED', incident.id);
        }
    }
}