🪂 Airdrop Token System with EIP-712 & Merkle Tree Whitelisting

A secure, gas-optimized airdrop smart contract built with Solidity that uses EIP-712 for off-chain signature verification and Merkle Trees for scalable whitelisting.

---

📸 Demo Flow (Architecture)

---

📦 Features

• ✅ EIP-712 typed structured signatures for off-chain whitelisting
• 🌲 Merkle Tree proof verification for scalable claims (O(log N))
• 🔒 Signature replay protection
• 🔄 One-time claim enforcement
• ⛽ Gas-optimized design

---

📚 Tech Stack

• Solidity for smart contracts

• Foundry for testing and deployment

• Merkle Tree JS utilities for generating proofs

• EIP-712 Typed Data Signatures

---

📂 Project Structure

├── contracts
│   └── Airdrop.sol
├── scripts
│   └── DeployMerkleAirDrop.s.sol / Interact.s.sol
├── test
│   └── MerkleAirDrop.t.sol
├── assets
│   └── airdrop.png
└── README.md

---

🚀 How It Works

1. Off-chain, a list of eligible addresses and airdrop amounts is created.
2. A Merkle Tree is generated using this list.
3. Each user signs a claim message using EIP-712.
4. The user sends a transaction with:
   • Their address and claim amount
   • EIP-712 signature
   • Merkle proof
5. The smart contract verifies:
   • The Merkle proof is valid
   • The signature matches the typed data
   • The user hasn’t claimed before
6. Tokens are transferred securely 🎉

---

🔧 Setup Instructions

1. Clone the repo:

   git clone https://github.com/DakshMane/AirDropContract
   cd merkle-airdrop

2. Install dependencies:

   npm install

3. Compile contracts:

   forge build

4. Run tests:

        forge test

---

📄 Example Claim Function

function claim(address account, uint256 amount, bytes calldata sig, bytes32[] calldata merkleProof) external {
    require(!claimed[account], "Already claimed");

    // Verify Merkle proof
    bytes32 node = keccak256(abi.encodePacked(account, amount));
    require(MerkleProof.verify(merkleProof, merkleRoot, node), "Invalid proof");

    // Verify EIP-712 signature
    require(verifySignature(account, amount, sig), "Invalid signature");

    claimed[account] = true;
    token.transfer(account, amount);
}

---

🤝 Contributing

PRs and feedback welcome! If you found this useful or learned something, feel free to give it a ⭐

---

🧠 Learn More

• EIP-712 Documentation
• Merkle Trees in Ethereum
• Gas Optimization in Smart Contracts

---

📬 Contact

Made with ❤️ by Daksh Mane
Open to feedback, collaborations, and Web3 conversations!