Unified Payment Verifier

Overview

UnifiedPaymentVerifier verifies standardized off‑chain attestations produced by the Attestation Service. It validates EIP‑712 signatures via a pluggable AttestationVerifier, enforces snapshot consistency with on‑chain intent state, prevents replay via nullifiers, and caps the release amount to the signaled intent amount.

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Typed Data

• Primary type: PaymentAttestation(bytes32 intentHash,uint256 releaseAmount,bytes32 dataHash)
• Domain (EIP‑712):
  • name = "UnifiedPaymentVerifier"
  • version = "1"
  • chainId = block.chainid
  • verifyingContract = address(this)

Attestation struct passed on‑chain

struct PaymentAttestation {
  bytes32 intentHash;      // binds to on-chain intent
  uint256 releaseAmount;   // token amount to release (pre-fees)
  bytes32 dataHash;        // keccak256(data)
  bytes[] signatures;      // witness signatures
  bytes data;              // abi.encode(PaymentDetails, IntentSnapshot)
  bytes metadata;          // optional; not signed
}

Data payload

struct PaymentDetails {
  bytes32 method;     // payment method (bytes32)
  bytes32 payeeId;    // hashed off-chain recipient id
  uint256 amount;     // smallest fiat unit (e.g., cents)
  bytes32 currency;   // fiat code hash
  uint256 timestamp;  // ms epoch
  bytes32 paymentId;  // hashed provider transaction id
}

struct IntentSnapshot {
  bytes32 intentHash;
  uint256 amount;           // signaled token amount
  bytes32 paymentMethod;    // bytes32
  bytes32 fiatCurrency;     // bytes32
  bytes32 payeeDetails;     // bytes32 (must match PaymentDetails.payeeId)
  uint256 conversionRate;   // 1e18
  uint256 signalTimestamp;  // seconds
  uint256 timestampBuffer;  // ms/seconds window
}

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Verification Flow

1. Compute struct hash for (intentHash, releaseAmount, dataHash).
2. Compute domain‑bound digest and verify witness signatures via AttestationVerifier.
3. Check keccak256(attestation.data) == dataHash.
4. Decode (PaymentDetails, IntentSnapshot) and validate snapshot against on‑chain Orchestrator.getIntent(intentHash) (amount, method, currency, conversionRate, signalTimestamp) and Escrow.getDepositPaymentMethodData(...).payeeDetails.
5. Nullify the payment: keccak256(paymentMethod || paymentId); revert if already used.
6. Cap releaseAmount to intent.amount.

Returns PaymentVerificationResult { success, intentHash, releaseAmount } to the Orchestrator.

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Governance & Config

Provided by BaseUnifiedPaymentVerifier:

• getPaymentMethods() — list of supported methods (bytes32).
• addPaymentMethod(method) / removePaymentMethod(method) — owner‑only.
• setAttestationVerifier(address) — update the witness verifier; emits AttestationVerifierUpdated.