ZoneProof

ZoneProof is a decentralized land registry and due diligence protocol that aggregates county-level zoning data through a Chainlink CRE oracle network and anchors every petition and parcel change on Hedera. Web3 lenders and land tokenizers like RealT, Propy, Maple Finance, and Centrifuge currently pay $12,000 to $20,000 to third-party vendors just to gather fragmented zoning records before minting a token or underwriting a loan. ZoneProof eliminates that process.

Three Chainlink CRE nodes independently scrape Wake County's open GIS data, reach BFT consensus on a SHA-256 Merkle root, and commit it to a smart contract on Hedera EVM. Every time a user pays for a due diligence report via the x402 protocol (0.05 HBAR), the oracle signs the report with its zoneproof.eth ECDSA key, logs an immutable entry to a Hedera HCS topic, and mints a ZPR NFT receipt on Hedera Token Service with no Solidity and pure Hedera SDK. AI agents can also autonomously request reports through an MCP server that detects the 402, pays HBAR via Hedera SDK, and retries with no human action required. The downloaded PDF embeds the cryptographic seal and a QR code so any counterparty can scan it and verify authenticity against the oracle's ENS name in under 5 seconds.

The backend is a FastAPI Python oracle that serves 434,000 Wake County parcels and 2,000+ rezoning petitions loaded from Supabase. The frontend is React with Vite, Mapbox GL JS for parcel polygon rendering, and jsPDF for generating the due diligence PDF with an embedded QR code.

The Chainlink CRE layer runs three independent scraper nodes that pull from Wake County's ArcGIS REST API, each computing a SHA-256 Merkle tree over the petition dataset. Two of three nodes must agree on the same root before it is committed to RezoningOracle.sol deployed on Hedera EVM, making the oracle Byzantine fault tolerant.

For Hedera we built a lightweight Node.js Express sidecar (port 8002) that wraps the Hedera JS SDK. The Python oracle calls it via httpx after every report is generated, triggering a TopicMessageSubmitTransaction to the HCS audit topic and a TokenMintTransaction to mint a ZPR NFT receipt on HTS, all with zero Solidity. x402 payment middleware intercepts requests, returns HTTP 402 with HBAR payment instructions, then verifies the transaction on the Hedera Mirror Node with five retry attempts to handle the indexing lag.

The hackiest part is the oracle signing. Hedera accounts use secp256k1 keys, which are identical to Ethereum keys, so we reuse the Hedera private key directly in Python's eth_account library to produce EIP-191 personal_sign signatures. The same key that controls zoneproof.eth on Sepolia ENS also signs every report, so anyone can resolve zoneproof.eth, recover the signer from the ECDSA signature, and confirm the report is genuine without trusting ZoneProof at all. The MCP server exposes parcel tools to AI agents and autonomously pays HBAR via TransferTransaction when it receives a 402, making the entire due diligence flow completable by an AI with no human action.