Privacy Transfer (UNO)

// Shield 1000 TOS
ShieldTransfer {
    amount: 1000_00000000,  // Public amount
    asset: TOS_ASSET,
}
// Result: 1000 TOS now in encrypted balance

UnoTransfer {
    privacy_level: PrivacyLevel::AmountHidden,
    sender: my_address,
    receiver: recipient,
    encrypted_amount: encrypt(amount),
    zk_proof: generate_proof(),
    nullifier: generate_nullifier(),
}

UnshieldTransfer {
    encrypted_amount: my_encrypted_balance,
    zk_proof: generate_unshield_proof(),
    nullifier: generate_nullifier(),
}
// Result: Amount appears in public balance

pub enum FeeType {
    TOS = 0,    // Public fee
    Energy = 1, // Gas-free
    UNO = 2,    // Private (burned)
}

/// Nullifier mechanism
/// Each output can only be spent once
fn check_nullifier(nullifier: Hash) -> bool {
    if nullifier_set.contains(nullifier) {
        return false; // Already spent
    }
    nullifier_set.insert(nullifier);
    true
}

/// Optional compliance proof
pub struct ComplianceProof {
    /// Prove AML compliance
    pub aml_proof: ZKProof,
 
    /// Prove identity verified (without revealing identity)
    pub kyc_proof: ZKProof,
 
    /// Prove amount within limits
    pub limit_proof: ZKProof,
}

Problem: All salaries visible on public blockchain
Solution: AmountHidden transfers

- HR knows payment was made (sender visible)
- Employees can't see each other's pay
- Auditors can verify with ZK proofs

Problem: Other players copy bet sizes
Solution: AmountHidden betting

- Game sees deposit occurred
- Bet amount is encrypted
- Prevents copy-trading

Problem: Large transfers attract attention
Solution: FullPrivate transfers

- Only sender identity public
- Amount and recipient encrypted
- Reduces targeting risk