Vapor

VAPOR is a peer-to-peer crypto off-ramp that lets people convert stablecoins (like USDT) into fiat without relying on exchanges or custodians. The system is non-custodial and permissionless, built on smart contracts, staking, and cryptoeconomic incentives. • Fillers provide fiat liquidity and lock stablecoins into escrow. • Relayers send fiat to Receivers and stake collateral; if they fail, they are slashed. • Receivers off-ramp into fiat once payouts are verified. • App Builders maintain contracts and matching logic but never touch funds.

Verification is handled through unique reference codes, attestations, and dispute resolution, not bank APIs. Protection comes from escrow, slashing, reputation, and optional insurance pools, ensuring fairness without licenses or intermediaries.

The vision is to create an alternative financial rail: verifiable, anonymous, and censorship-resistant.

We built this off-ramp as a permissionless protocol combining smart contracts, staking, and off-chain verification to enforce trust without banks or APIs. At the core, Solidity contracts manage escrow for Fillers’ stablecoins and slash Relayers’ stakes if payouts fail. Each fiat transfer is tied to a unique job reference, and Relayers must post collateral equal to their promised payout. Reputation logic allows reliable Relayers to handle larger amounts over time.

Since bank APIs aren’t available, we developed alternative verification methods. These include parsing DKIM-signed bank emails, hashing redacted statements on-chain, and staked multi-attestors who confirm receipt. The contracts only release funds once the required proofs are posted.

The frontend is a React/TypeScript app with wallet integration, while a lightweight Node.js matching engine pairs Fillers, Relayers, and Receivers. Supporting tools like IPFS for storing artifacts, Chainlink VRF for attestor selection, and OpenZeppelin libraries for escrow/staking strengthen the stack.

Notable hacks include embedding random reference codes in fiat memos to bind transfers to jobs, a two-step settlement flow that releases most funds immediately but holds back a portion during recall windows, and modular evidence weighting that accepts combinations of weaker proofs. We also explored zero-knowledge commitments for Relayer reputation, allowing them to prove track records without revealing full histories.