Decentralized Identity DeFi: Self-Sovereign Yield Strategies That Actually Work

// Example: Age-verified liquidity pool
contract AgeVerifiedPool {
    mapping(address => bool) public verifiedUsers;
    uint256 public standardAPY = 8e18; // 8%
    uint256 public verifiedAPY = 15e18; // 15%
    
    function verifyAge(bytes32 credentialHash) external {
        // Zero-knowledge proof verification
        require(zkVerifier.verifyAge(credentialHash, msg.sender), "Invalid age proof");
        verifiedUsers[msg.sender] = true;
    }
    
    function getAPY(address user) external view returns (uint256) {
        return verifiedUsers[user] ? verifiedAPY : standardAPY;
    }
}

// Reputation calculation for DID-based lending
class ReputationLender {
    calculateCreditScore(did, credentials) {
        let score = 0;
        
        // Professional credentials (+20 points)
        if (credentials.includes('employment_verified')) {
            score += 20;
        }
        
        // Education verification (+15 points)
        if (credentials.includes('degree_verified')) {
            score += 15;
        }
        
        // Transaction history (+30 points max)
        const txScore = this.analyzeTxHistory(did);
        score += Math.min(txScore, 30);
        
        return Math.min(score, 100);
    }
    
    getLendingTerms(score) {
        if (score >= 80) return { maxLoan: 100000, apr: 5.5 };
        if (score >= 60) return { maxLoan: 50000, apr: 7.2 };
        return { maxLoan: 10000, apr: 12.0 };
    }
}

# Cross-chain yield optimization
class CrossChainYieldManager:
    def __init__(self, did_resolver):
        self.did_resolver = did_resolver
        self.chains = ['ethereum', 'polygon', 'arbitrum', 'optimism']
    
    def find_best_yields(self, did, amount):
        opportunities = []
        
        for chain in self.chains:
            # Get verified credentials for this chain
            credentials = self.did_resolver.get_credentials(did, chain)
            
            # Find available pools
            pools = self.get_eligible_pools(chain, credentials)
            
            for pool in pools:
                yield_data = {
                    'chain': chain,
                    'pool': pool['address'],
                    'apy': pool['apy'],
                    'max_deposit': pool['max_deposit'],
                    'gas_cost': self.estimate_gas(chain, amount)
                }
                opportunities.append(yield_data)
        
        # Sort by net APY after gas costs
        return sorted(opportunities, 
                     key=lambda x: x['apy'] - x['gas_cost'], 
                     reverse=True)

// Creating a DID with ION (Bitcoin-anchored)
import { IonDidResolver, IonMethod } from '@decentralized-identity/ion-tools';

async function createDID() {
    // Generate key pairs
    const keyPair = await IonMethod.generateKeyPair();
    
    // Create DID document
    const didDocument = {
        publicKeys: [{
            id: 'key-1',
            type: 'EcdsaSecp256k1VerificationKey2019',
            publicKeyJwk: keyPair.publicJwk
        }],
        services: [{
            id: 'defi-profile',
            type: 'DeFiCredentialService',
            serviceEndpoint: 'https://your-credential-service.com'
        }]
    };
    
    // Anchor to Bitcoin
    const anchorRequest = await IonMethod.createAnchorRequest(didDocument);
    return anchorRequest;
}

// Requesting employment verification
interface EmploymentCredential {
    id: string;
    type: ['VerifiableCredential', 'EmploymentCredential'];
    issuer: string;
    credentialSubject: {
        id: string; // Your DID
        employmentStatus: 'employed';
        verifiedDate: string;
        // Note: No personal details like company name or salary
    };
}

async function requestEmploymentVerification(did: string) {
    const credentialRequest = {
        did: did,
        credentialType: 'employment',
        verificationMethod: 'payroll_integration' // Automated verification
    };
    
    // Submit to credential issuer
    const response = await fetch('https://credential-issuer.com/verify', {
        method: 'POST',
        body: JSON.stringify(credentialRequest)
    });
    
    return await response.json();
}

// Interacting with credential-gated pools
contract YieldFarmer {
    IDIDResolver public didResolver;
    
    function enterVerifiedPool(
        string memory did,
        bytes32 credentialProof,
        uint256 amount
    ) external {
        // Verify the credential without revealing contents
        require(
            didResolver.verifyCredential(did, credentialProof, "employment"),
            "Invalid employment credential"
        );
        
        // Higher yield for verified users
        uint256 boostedAmount = amount * 115 / 100; // 15% boost
        
        _stake(msg.sender, boostedAmount);
        emit VerifiedStake(msg.sender, did, amount, boostedAmount);
    }
}

# Automated yield optimization
class DIDYieldOptimizer:
    def __init__(self, wallet, did_manager):
        self.wallet = wallet
        self.did_manager = did_manager
        
    async def optimize_yields(self):
        # Get current positions
        positions = await self.get_current_positions()
        
        # Find better opportunities
        opportunities = await self.scan_yield_opportunities()
        
        for position in positions:
            best_opportunity = self.find_best_migration(position, opportunities)
            
            if best_opportunity['apy'] > position['apy'] * 1.05:  # 5% improvement threshold
                await self.migrate_position(position, best_opportunity)
                
    async def migrate_position(self, current, target):
        # Withdraw from current pool
        tx1 = await self.wallet.withdraw(current['pool'], current['amount'])
        
        # Present credentials to new pool
        credential_proof = await self.did_manager.generate_proof(
            target['required_credentials']
        )
        
        # Deposit to new pool with verification
        tx2 = await self.wallet.deposit_verified(
            target['pool'], 
            current['amount'],
            credential_proof
        )
        
        return [tx1, tx2]

// Example: Proving age without revealing birthdate
const circomlib = require('circomlib');

class AgeProofGenerator {
    generateProof(birthdate, minimumAge) {
        const currentDate = new Date();
        const age = this.calculateAge(birthdate, currentDate);
        
        // Create zero-knowledge circuit
        const circuit = {
            age: age,
            minimumAge: minimumAge,
            isValid: age >= minimumAge ? 1 : 0
        };
        
        // Generate proof that age >= minimumAge without revealing actual age
        return circomlib.groth16.prove(circuit);
    }
}

interface CredentialRotationSchedule {
    employment: 90; // days  
    education: 365; // days
    reputation: 30; // days
}

class CredentialManager {
    async rotateCredentials(did: string, schedule: CredentialRotationSchedule) {
        const credentials = await this.getCredentials(did);
        
        for (const [type, maxAge] of Object.entries(schedule)) {
            const credential = credentials.find(c => c.type === type);
            
            if (this.isExpired(credential, maxAge)) {
                await this.renewCredential(did, type);
            }
        }
    }
}

contract StackedYieldPool {
    struct YieldMultiplier {
        uint256 base;           // 100 = 1x
        uint256 employment;     // +20%
        uint256 education;      // +15%
        uint256 reputation;     // +25%
        uint256 governance;     // +10%
    }
    
    function calculateYield(
        address user,
        bytes32[] memory credentialProofs
    ) external view returns (uint256) {
        YieldMultiplier memory multiplier = YieldMultiplier(100, 0, 0, 0, 0);
        
        for (uint i = 0; i < credentialProofs.length; i++) {
            bytes32 credType = getCredentialType(credentialProofs[i]);
            
            if (credType == "employment") multiplier.employment = 20;
            if (credType == "education") multiplier.education = 15;
            if (credType == "reputation") multiplier.reputation = 25;
            if (credType == "governance") multiplier.governance = 10;
        }
        
        uint256 totalMultiplier = multiplier.base + 
                                  multiplier.employment + 
                                  multiplier.education + 
                                  multiplier.reputation + 
                                  multiplier.governance;
        
        return baseAPY * totalMultiplier / 100;
    }
}

# Credential access marketplace
class CredentialAccessMarket:
    def __init__(self):
        self.access_requests = {}
        self.credential_holders = {}
    
    def request_pool_access(self, pool_address, required_credentials, fee_offered):
        """Request temporary access to credential-gated pool"""
        request_id = self.generate_request_id()
        
        self.access_requests[request_id] = {
            'pool': pool_address,
            'credentials': required_credentials,
            'fee': fee_offered,
            'requester': msg.sender
        }
        
        return request_id
    
    def provide_access(self, request_id, credential_proof):
        """Provide access using your credentials for a fee"""
        request = self.access_requests[request_id]
        
        # Verify credential holder can access the pool
        if self.verify_pool_access(request['pool'], credential_proof):
            # Create temporary delegation
            delegation_token = self.create_delegation(
                credential_proof, 
                request['requester'],
                duration=3600  # 1 hour access
            )
            
            # Transfer fee to credential holder
            self.transfer_fee(request['fee'], msg.sender)
            
            return delegation_token

// Portfolio tracking dashboard
class DIDPortfolioTracker {
    constructor(did, web3Provider) {
        this.did = did;
        this.web3 = web3Provider;
        this.positions = new Map();
    }
    
    async trackPerformance() {
        const summary = {
            totalValue: 0,
            totalYield: 0,
            averageAPY: 0,
            privacyScore: 0
        };
        
        for (const [pool, position] of this.positions) {
            const currentValue = await this.getCurrentValue(pool, position);
            const yieldEarned = await this.getYieldEarned(pool, position);
            
            summary.totalValue += currentValue;
            summary.totalYield += yieldEarned;
        }
        
        summary.averageAPY = this.calculateWeightedAPY();
        summary.privacyScore = this.calculatePrivacyScore();
        
        return summary;
    }
    
    calculatePrivacyScore() {
        // Score based on credential usage vs. direct identity exposure
        let score = 100;
        
        for (const [pool, position] of this.positions) {
            if (position.usesDirectIdentity) score -= 20;
            if (position.hasKYC) score -= 30;
            if (position.usesZKProofs) score += 10;
        }
        
        return Math.max(0, score);
    }
}

// Debug credential verification
async function debugCredentialIssue(did, credential, targetPool) {
    const checks = {
        didResolution: await checkDIDResolution(did),
        credentialFormat: await validateCredentialFormat(credential),
        issuerTrust: await checkIssuerTrusted(credential.issuer, targetPool),
        expirationStatus: credential.expirationDate > new Date(),
        proofValidity: await verifyCredentialProof(credential)
    };
    
    console.log('Credential Debug Report:', checks);
    
    // Suggest fixes
    if (!checks.didResolution) {
        console.log('Fix: Re-anchor your DID to the blockchain');
    }
    if (!checks.issuerTrust) {
        console.log('Fix: Use credentials from trusted issuers only');
    }
    
    return checks;
}

// Batch credential verification
contract BatchCredentialVerifier {
    function verifyMultipleCredentials(
        bytes32[] memory credentialHashes,
        address[] memory pools
    ) external {
        require(credentialHashes.length == pools.length, "Array length mismatch");
        
        for (uint i = 0; i < credentialHashes.length; i++) {
            _verifyAndStore(credentialHashes[i], pools[i], msg.sender);
        }
        
        emit BatchVerificationComplete(msg.sender, credentialHashes.length);
    }
}

# Risk evaluation model
class DIDDeFiRiskAssessment:
    def evaluate_protocol_risk(self, protocol_data):
        risks = {
            'smart_contract': self.audit_score(protocol_data['audits']),
            'credential_privacy': self.privacy_score(protocol_data['verification_method']),
            'yield_sustainability': self.tokenomics_score(protocol_data['token_model']),
            'regulatory_compliance': self.compliance_score(protocol_data['jurisdiction'])
        }
        
        # Weight the risks
        weights = {'smart_contract': 0.4, 'credential_privacy': 0.3, 
                  'yield_sustainability': 0.2, 'regulatory_compliance': 0.1}
        
        total_risk = sum(risks[key] * weights[key] for key in risks)
        return min(100, max(0, total_risk))

// Universal credential adapter
interface UniversalCredential {
    did: string;
    credentialType: string;
    issuer: string;
    proofFormat: 'zk-snark' | 'zk-stark' | 'bulletproof';
    chainCompatibility: string[];
}

class CredentialPortabilityManager {
    async adaptCredential(
        credential: UniversalCredential, 
        targetProtocol: string
    ): Promise<any> {
        const adapter = this.getProtocolAdapter(targetProtocol);
        return await adapter.convertCredential(credential);
    }
}