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ZKP2P Protocol V3 — Overview

ZKP2P V3 makes the protocol faster, more flexible, and easier to integrate by moving proof verification off-chain into a standardized Attestation Service, and by consolidating on-chain verification logic into a single Unified Payment Verifier. The protocol remains fully non-custodial: contracts only move funds, while verification and orchestration are modular and replaceable.

What’s new vs V2​

  • Off-chain verification: the Attestation Service validates provider proofs (e.g., Reclaim/TLSNotary), normalizes them, and signs an EIP‑712 PaymentAttestation used on-chain.
  • Single on-chain verifier: UnifiedPaymentVerifier validates the EIP‑712 signature and enforces protocol rules (intent bounds, nullifiers, release capping).
  • Cleaner intent path: the gating service signs intents with richer context (payment method, fiat currency, conversion rate, orchestrator/escrow addresses) to reduce round trips.
  • Extensible: adding providers is purely off-chain (transformers) with a stable on-chain attestation format.

Flow​

  • Buyer (on‑ramper): pays off-chain and receives on-chain tokens.
  • Seller (off‑ramper): supplies token liquidity in Escrow and receives off-chain fiat.
  • Gating Service (Curator): authorizes intent creation for sellers, returns payee details and a signature.
  • Attestation Service: verifies provider proofs and issues PaymentAttestations.
  • On-chain: Escrow, Orchestrator, UnifiedPaymentVerifier, AttestationVerifier (witness set).

###High‑level flow

  1. Quote: client fetches quotes (developer docs cover API).
  2. Intent signing: client calls the gating API (Curator v2 endpoint) to obtain gatingServiceSignature tied to deposit/payment method/fiat.
  3. Signal Intent (on-chain): call Orchestrator.signalIntent(...) with depositId, amount, to, paymentMethod, fiatCurrency, conversionRate, gatingServiceSignature.
  4. Pay off‑chain: buyer pays seller’s off-chain identifier (hashed on-chain as payeeDetails).
  5. Generate proof: via PeerAuth; send proof + intent details to Attestation Service.
  6. Attestation: Attestation Service returns a PaymentAttestation EIP‑712 signature and an ABI-encoded payload.
  7. Fulfill (on‑chain): call Orchestrator.fulfillIntent({ paymentProof: abi.encode(PaymentAttestation), intentHash, ... }). Orchestrator routes to UnifiedPaymentVerifier to check the attestation, then unlocks and transfers tokens.

Trust model​

  • Off-chain witnesses: Attestation Service signatures are verified on-chain by AttestationVerifier (e.g., SimpleAttestationVerifier with a witness key). Witness rotation is on-chain governed.
  • Intent integrity: snapshot values in the attestation are checked against on-chain intent state; nullifiers prevent double-spend; release amount is capped to the signaled amount.