README.md

📄 Drand Oracle Smart Contract

🔎 Overview

The DrandOracle smart contract serves as an on-chain source of randomness by storing values from the drand network.

📚 Core Contracts

🎲 DrandOracle.sol

The main contract responsible for storing and managing randomness from the drand network.

🛠️ Usage

• getRandomnessFromRound(uint64 _round) external view returns (Random memory)
  • Retrieves the complete randomness data for a specific round
  • Parameters:
    • _round: The round number to query
  • Returns:
    • Random memory: The Random struct containing the round's data
• getRandomnessFromTimestamp(uint64 _timestamp) external view returns (Random memory)
  • Retrieves the complete randomness data for a specific timestamp, or the latest timestamp prior to the given timestamp if no exact match is found
  • Parameters:
    • _timestamp: The timestamp to query
  • Returns:
    • Random memory: The Random struct containing the timestamp's data

🔒 Access Control

The contract implements a simple single-updater access control pattern:

• Only the designated updater address can submit new randomness
• Updater address is set during contract deployment
• Updater can be updated by the owner

⚠️ Limitations

1. The randomness stored in the contract is verifiable off-chain but not on-chain. This is due to BLS signatures used by Drand network are not yet supported on EVM.
2. Reliance on trusted updater.

🧪 Testing

Run tests with:

forge test

💻 Run Locally

1. Start local anvil chain

anvil

2. Deploy the contract

forge build
make deploy-anvil

🚀 Deploy

Edit the .env file to set the correct environment variables for the chain you want to deploy to. Then run:

FOUNDRY_PROFILE=deploy forge script ./script/deploy/DrandOracle.s.sol:DrandOracleScript --broadcast --verify --verifier blockscout

Note that for some testnets, --gas-estimate-multiplier x is required to avoid out-of-gas errors.

🌍 Deployments

• Gravity Alpha Testnet Sepolia - 0x8d180A75fAc0De59BB1e833fc3838EE026a53aC5