SealDrop — FHE-Powered Confidential Tokens

Wrap any ERC20 into a confidential version. Send airdrops where only recipients can see their amount.

🌐 Live demo: sealdrop-7h7e.vercel.app

Built for Zama Season 3 — submitted under Builder, Bounty (Confidential Wrapper Registry), and Special Bounty × TokenOps tracks.

---

What it does

• Confidential Wrapper — Wrap any ERC20 into an FHE-encrypted version. Balances are stored as ciphertexts onchain — only the owner can decrypt their balance
• Confidential Airdrop — Send token airdrops where each recipient's amount is FHE-encrypted. No one else can see how much anyone received
• Wrapper Registry — A live registry of all deployed confidential wrappers with Etherscan links
• EIP-712 Decryption — Users sign a structured decryption request to view their encrypted balance. The FHEVM gateway verifies the signature and returns plaintext only to them

---

Stack

• Frontend — Next.js 16, TypeScript, deployed on Vercel
• Encryption — Zama FHEVM (@fhevm/solidity) with ZamaEthereumConfig
• Contracts — Solidity 0.8.28, deployed on Ethereum Sepolia
• Wallet — RainbowKit + Wagmi v2
• Dev tooling — Hardhat Ignition v3

---

Deployed Contracts (Sepolia)

Contract	Address
MockERC20 (tUSDC)	0x4434005c017a214574417e3045e4CEb64f93A025
ConfidentialWrapper (ctUSDC)	0x001699daB4F9c25CD857330248d0772C18050684
ConfidentialAirdrop	0xcf1bc05C91d87A99f96dD38D3b38da3412F84294

Verify on Etherscan:

• ConfidentialWrapper
• ConfidentialAirdrop

---

How it works

User (browser)
    │
    ▼
Next.js frontend (Vercel)
    │  wrap(amount) / loadAirdrop(recipients, amounts)
    ▼
ConfidentialWrapper / ConfidentialAirdrop (Sepolia)
    │
    ▼
FHEVM — FHE.asEuint64(amount)
    │  Encrypted ciphertext stored onchain
    ▼
FHE.allow(encBalance, user) — only user can decrypt
    │
    ▼
EIP-712 decryption request → FHEVM Gateway → plaintext to user only

---

Zama Track Submissions

Bounty — Confidential Wrapper Registry (3,000 cUSDT)

• ConfidentialWrapper.sol implements wrap/unwrap with FHE-encrypted balances
• Registry UI shows all deployed wrappers with live Etherscan links
• EIP-712 decryption flow documented in UI

Builder — Full dApp (7,000 cUSDT)

• Complete frontend + smart contracts + live demo
• Deployed and functional on Sepolia testnet
• Clean UI with wallet connect, real transactions

Special Bounty × TokenOps (2,500 cUSDT)

• Confidential Airdrop tab — FHE-encrypted amounts per recipient
• loadAirdrop() encrypts each amount individually onchain
• Only each recipient can decrypt their own allocation

---

Smart Contracts

ConfidentialWrapper.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import "@fhevm/solidity/lib/FHE.sol";
import "@fhevm/solidity/config/ZamaEthereumConfig.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract ConfidentialWrapper is ZamaEthereumConfig, ERC20 {
    IERC20 public immutable underlying;
    mapping(address => euint64) private _encBalances;

    function wrap(uint64 amount) external {
        require(underlying.transferFrom(msg.sender, address(this), amount), "Transfer failed");
        euint64 encAmount = FHE.asEuint64(amount);
        if (FHE.isInitialized(_encBalances[msg.sender])) {
            _encBalances[msg.sender] = FHE.add(_encBalances[msg.sender], encAmount);
        } else {
            _encBalances[msg.sender] = encAmount;
        }
        FHE.allowThis(_encBalances[msg.sender]);
        FHE.allow(_encBalances[msg.sender], msg.sender);
    }

    function unwrap(uint64 amount) external {
        _encBalances[msg.sender] = FHE.sub(_encBalances[msg.sender], FHE.asEuint64(amount));
        FHE.allowThis(_encBalances[msg.sender]);
        FHE.allow(_encBalances[msg.sender], msg.sender);
        underlying.transfer(msg.sender, amount);
    }
}

ConfidentialAirdrop.sol

function loadAirdrop(address[] calldata recipients, uint64[] calldata amounts) external onlyOwner {
    for (uint256 i = 0; i < recipients.length; i++) {
        euint64 encAmount = FHE.asEuint64(amounts[i]);
        _airdropAmounts[recipients[i]] = encAmount;
        FHE.allowThis(encAmount);
        FHE.allow(encAmount, recipients[i]);
    }
}

---

Getting started

# Clone
git clone https://github.com/Isaaco3349/sealdrop
cd sealdrop

# Frontend
cd app
npm install
cp .env.example .env.local
# Add NEXT_PUBLIC_WALLETCONNECT_PROJECT_ID
npm run dev

# Contracts
cd ../contracts
npm install
# Add SEPOLIA_RPC_URL and SEPOLIA_PRIVATE_KEY to .env
npx hardhat compile
npx hardhat ignition deploy ignition/modules/SealDrop.ts --network sepolia

---

Project structure

sealdrop/
├── app/                          # Next.js frontend
│   ├── app/
│   │   ├── page.tsx              # Main dashboard
│   │   └── layout.tsx            # Providers (RainbowKit, Wagmi)
│   ├── components/
│   │   ├── Providers.tsx         # Wagmi + RainbowKit config
│   │   ├── RegistryTab.tsx       # Wrap/unwrap UI + registry
│   │   └── AirdropTab.tsx        # Confidential airdrop UI
│   └── lib/
│       └── contracts.ts          # Contract addresses + ABIs
└── contracts/                    # Hardhat project
    ├── contracts/
    │   ├── ConfidentialWrapper.sol
    │   ├── ConfidentialAirdrop.sol
    │   └── MockERC20.sol
    └── ignition/modules/
        └── SealDrop.ts

---

Live demo

🌐 sealdrop-7h7e.vercel.app

Connect MetaMask on Sepolia → Mint test tUSDC → Wrap into confidential ctUSDC → Send a confidential airdrop.

---

Team

Built by @Isaaco3349 for Zama Season 3.

---

License

MIT