Supported Payment Methods

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Overview

• Payment Method Hash: Unique identifier for the payment platform
• Supported Currencies: List of fiat currencies accepted
• Verification Method: EIP-712 signed attestations from off-chain services
• Timestamp Buffer: Maximum time allowance for L2 flexibility (up to 48 hours)

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Supported Platforms

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Venmo

• USD

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PayPal

• USD

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Wise (TransferWise)

• USD, EUR, GBP, CNY
• AUD, NZD, CAD, CHF
• AED, SGD, HKD, JPY
• ZAR, ILS, PLN, TRY
• IDR, KES, MYR, MXN
• THB, VND, UGX, CZK
• DKK, HUF, INR, NOK
• PHP, RON, SEK

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Zelle

• Citibank (Zelle Citi)
• Chase Bank (Zelle Chase)
• Bank of America (Zelle BofA)

• USD (all variants)

• Zelle Citi: See deployments/verifiers/zelle.ts
• Zelle Chase: See deployments/verifiers/zelle.ts
• Zelle BofA: See deployments/verifiers/zelle.ts

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CashApp

• USD

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Revolut

• USD, EUR, GBP, SGD
• NZD, AUD, CAD, JPY
• HKD, MXN, SAR, AED
• THB, TRY, PLN, CHF
• ZAR, CNY, CZK, DKK
• HUF, NOK, RON, SEK

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MercadoPago

• See deployments/verifiers/mercadopago.ts for supported currencies

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Monzo

• GBP, EUR, USD

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Additional Payment Methods

• N26: European mobile bank
• Alipay: Chinese payment platform
• Luxon: Regional payment service
• Chime: US mobile banking

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Verification Architecture

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UnifiedPaymentVerifier

1. Validates EIP-712 Attestations: Verifies cryptographically signed payment attestations
2. Checks Intent Snapshots: Ensures payment details match the on-chain intent
3. Prevents Double-Spending: Nullifies payment IDs in the NullifierRegistry
4. Enforces Timestamp Buffers: Allows flexibility for L2 transaction timing (max 48 hours)
5. Emits Payment Events: Records verified payment details for off-chain reconciliation

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Payment Attestation Structure

struct PaymentAttestation {
    bytes32 intentHash;       // Binds payment to on-chain intent
    uint256 releaseAmount;    // Final token amount after FX conversion
    bytes32 dataHash;         // Hash of payment details for integrity
    bytes[] signatures;       // Witness signatures
    bytes data;               // Encoded payment and intent data
    bytes metadata;           // Additional unsigned metadata
}

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Payment Details

struct PaymentDetails {
    bytes32 method;           // Payment method hash (e.g., "venmo")
    bytes32 payeeId;          // Hashed recipient ID (privacy-preserving)
    uint256 amount;           // Amount in smallest currency unit (cents)
    bytes32 currency;         // Currency hash (e.g., "USD")
    uint256 timestamp;        // Payment timestamp (UTC milliseconds)
    bytes32 paymentId;        // Hashed payment identifier
}

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Adding New Payment Methods

1. Create Verifier Configuration: Add a new file in deployments/verifiers/
2. Define Payment Method Hash: Use calculatePaymentMethodHash("method-name")
3. Specify Supported Currencies: List all supported Currency enum values
4. Create Deployment Script: Add script in deploy/ directory
5. Register with UnifiedVerifier: Call addPaymentMethod() on UnifiedPaymentVerifier
6. Register with PaymentVerifierRegistry: Call addPaymentMethod() with currencies

import { calculatePaymentMethodHash, Currency } from "@utils/protocolUtils";

export const VENMO_PAYMENT_METHOD_HASH = calculatePaymentMethodHash("venmo");

export const VENMO_CURRENCIES: any = [
  Currency.USD,
];

export const VENMO_PROVIDER_CONFIG = {
  paymentMethodHash: VENMO_PAYMENT_METHOD_HASH,
  currencies: VENMO_CURRENCIES
};

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Payment Method Registry

• Mapping of payment method hashes to verifier contracts
• Supported currencies for each payment method
• Active/inactive status for each method

const verifier = await paymentVerifierRegistry.getVerifier(paymentMethodHash);
const currencies = await paymentVerifierRegistry.getCurrencies(paymentMethodHash);

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Security Considerations

bytes32 nullifier = keccak256(abi.encodePacked(paymentMethod, paymentId));

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Network Deployment Status

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Related Resources

• UnifiedPaymentVerifier Contract
• PaymentVerifierRegistry Contract
• Orchestrator Integration
• Troubleshooting Guide