eth4estate

Eth4Estate is a Web3 real estate platform targeting the Czech market, built as a two-DApp system on Ethereum (Sepolia testnet). DApp 1 handles user verification. Users input a property address and a secret client-side. A ZKP (Zero-Knowledge Proof) is generated, proving knowledge of these inputs which hash to a public commitment, without revealing the inputs on-chain. Successful ZKP verification by an on-chain verifier (leveraging vlayer for ZK verification infrastructure) allows minting of an Eth4Estate SBT (Soulbound Token). This SBT is non-transferable and acts as an access key for DApp 2. DApp 2 is the marketplace. SBT holders can list tokenized properties (standard ERC721 PropertyNFTs) for sale or rent. Key features:

Sale listings escrow the PropertyNFT. Buyer funds (ERC20) are locked and deposited into Aave V3 pools for yield. An off-chain intermediary approves the sale on-chain, triggering fund transfer (principal + Aave yield) to the seller and PropertyNFT transfer to the buyer. Rental listings require ERC20 collateral, also deposited into Aave V3 for yield. An intermediary handles dispute resolution. Collateral (+ Aave yield) is returned post-lease if no issues. The goal is to increase transparency and efficiency in real estate using on-chain logic for core transaction steps, while integrating intermediaries for necessary off-chain processes.

We built Eth4Estate using Scaffold-ETH 2 (Hardhat) as our boilerplate, which significantly sped up frontend and smart contract setup. Core Tech:

Smart Contracts: Solidity for Eth4EstateSBT, PropertyNFT, PropertyListing, and the ZK Verifier. Deployed on Sepolia. We're architecting for future deployment on Flow, Hedera, Rootstock, and World Chain. ZKP: Circom for circuits, snarkjs (Groth16) for client-side proof generation. vlayer is utilized as part of our ZK proof verification pipeline. The on-chain Verifier.sol (from snarkjs) validates proofs. DeFi Integration: Aave V3 on Sepolia. The PropertyListing contract directly interacts with Aave pools (IPool interface) to supply and withdraw ERC20 tokens (buyer funds/rental collateral), capturing yield for the benefit of the end-user (seller/tenant). Oracles & Collateral (Future Work): We're researching Pyth Network for price feeds and using Blockscout for token data to support diverse ERC20 collateral types. This is not yet fully implemented. Frontend: React/Next.js (from Scaffold-ETH 2). Deployment: Vercel for frontend. Hardhat for smart contracts