Blockchain Privacy

Zero-knowledge proofs, privacy coins, confidential transactions, and privacy solutions.

Overview

Privacy solutions protect transaction data on public blockchains.

Privacy Techniques

Zero-Knowledge Proof

// Simplified ZKP verification
contract ZKPVerifier {
    function verifyProof(
        uint[2] calldata a,
        uint[2][2] calldata b,
        uint[2] calldata c,
        uint[2] calldata publicInputs
    ) public view returns (bool) {
        // Pairing check
        return pairingCheck(a, b, c, publicInputs);
    }
}

Confidential Transaction

class ConfidentialTransaction:
    def __init__(self):
        self.amount = None
        self.blinding_factor = None
    
    def create_commitment(self, amount):
        # Pedersen commitment
        self.amount = amount
        self.blinding_factor = generate_random()
        
        commitment = hash(amount, self.blinding_factor)
        return commitment
    
    def verify_range(self, commitment, min_val, max_val):
        # Range proof
        return min_val <= commitment.amount <= max_val

Privacy Coins

Privacy Smart Contracts

// Commit-reveal scheme
contract PrivacyGame {
    mapping(address => bytes32) public commitments;
    
    function commit(bytes32 hash) public {
        commitments[msg.sender] = hash;
    }
    
    function reveal(uint256 value, bytes32 salt) public {
        require(keccak256(abi.encodePacked(value, salt)) == commitments[msg.sender]);
        
        // Process revealed value
    }
}

Best Practices

1. Layer 2 privacy — Avoid on-chain exposure
2. Mixing services — Break links
3. New addresses — Prevent tracking
4. Metadata protection — Network privacy

Practice

Implement a commit-reveal voting system.