Seedy: Trustless On-Chain Randomness via VDF

On-chain VDF verifier enabling trustless, tamper-resistant randomness on EVM.

Problem

Secure and fair randomness on-chain is hard. Block variables are manipulable, and oracles introduce external trust assumptions and costs.

Solution: Seedy VDF

Seedy uses Verifiable Delay Functions (VDFs) based on the Pietrzak scheme to provide:

1. Tamper Resistance: A mandatory time delay (T) prevents predicting/biasing the output randomness (y) after a seed x is known.
2. Trustless On-Chain Verification: A cryptographic proof (pi) allows our SeedyVerifier.sol contract to mathematically validate the VDF computation directly on-chain.

The final randomness is keccak256(y). This approach offers enhanced security guarantees compared to alternatives by verifying the computation proof trustlessly on-chain.

Architecture

• /contracts: Solidity contracts (SeedyVerifier, SeedyCoordinator, Raffle example).
• /experiments: TypeScript implementation for off-chain VDF proving (generateProof) and testing.
• /frontend: React/Next.js frontend for the Raffle example.

How it Works (Flow)

1. Request: Commit to a seed source (future blockhashes) via SeedyCoordinator.
2. Compute: Off-chain prover calculates VDF output y and proof pi over time T.
3. Finalize: Prover submits x, y, pi to SeedyCoordinator.
4. Verify: SeedyCoordinator calls SeedyVerifier.verify() for on-chain validation.
5. Result: Coordinator provides keccak256(y) as the final random output.

Getting Started & Running Locally

• Prerequisites: Node.js, npm, Foundry.
• Contracts: cd contracts && forge build && forge test
• Experiments (Prover/Test Script): cd experiments && npm install && node ./dist/index.js
• Frontend Demo: cd frontend && npm install && npm run dev

Deployed Contracts (Base Sepolia Testnet)

• SeedyVerifier: 0xd4ee61b3CB112747B534876E4c5F7e60b36E2893
• SeedyCoordinator: 0xf25469bdf21c06aff3f4236b8e0ca1b51c9e5ec6
• Raffle: 0xF918db551C9C9bd8c960582676657b32DcD19b4a

Future Work

• Dvelop a robust BigNumber library for Solidity.
• Debug and scale the off-chain prover for large T & target delays.
• Explore gas optimizations (e.g., zk-VDF).
• Develop more RNG use cases.

License

MIT