NFToken — EIP-712 Signature-Based NFT Mint

An ERC-721 contract that supports gasless minting via EIP-712 typed-data signatures. The holder signs an off-chain Mint message; an authorized minter submits the signature on-chain to mint the NFT to the holder.

Quick start

Compile & deploy

The contract targets Remix IDE.

1. Open Remix
2. Paste contracts/NFToken.sol
3. Compile with Solidity ^0.8.27
4. Deploy with constructor (minter, name, symbol)

Generate a Mint signature

pip install -r requirements.txt
cp .env.example .env   # fill in PRIVATE_KEY, CHAIN_ID, VERIFYING_CONTRACT, URI
python test_signature.py

Output is a hex signature you can pass to sigMint() from the minter account.

Flow

User (off-chain)                  Minter (on-chain)
  │                                    │
  │ 1. signTypedData(Mint{to, uri,     │
  │                  nonce, deadline}) │
  │ ─────────────────────────────────▶ │
  │                                    │
  │                              2. sigMint(...) verifies:
  │                                    - msg.sender == minter
  │                                    - block.timestamp ≤ deadline
  │                                    - nonce == nonces[to]
  │                                    - ECDSA.recover(digest, sig) == to
  │                                    - mint NFT to `to` with `uri`

• Replay protection via per-to nonces[]
• Deadline guards against stale signatures
• Minter role is single-address and transferable (transferMintership / renounceMinter)

Layout

contracts/NFToken.sol           ERC-721 + EIP-712 contract
scripts/deploy_with_ethers.ts   Remix deployment entry point
scripts/ethers-lib.ts           Deployment helper using ethers.js
test_signature.py               EIP-712 signature generator (Python)
.env.example                    Template for the signature script
prettierrc.json                 Solidity formatting rules
remix.config.json               Remix workspace settings

Dependencies

• OpenZeppelin Contracts ^5.4.0 (ERC721, EIP712, ECDSA)
• Python (test script): eth-abi, eth-keys, eth-utils

License

MIT