ERC721 permit2

ERC721Permit2 applies the ideas from ERC20 Permit2 to NFT contract, introducing a low-overhead, next-generation NFT approval/meta-tx system to make NFT approvals easier, more secure, and more consistent across applications.

Features

• Signature Based Approvals: Any ERC721 token, can now use permit style approvals. This allows applications to have a single transaction flow by sending a permit signature along with the transaction data when using ERC721Permit2 integrated contracts.
• Batched Token Approvals: Set permissions on different tokens to different spenders with one signature.
• Signature Based Token Transfers: Owners can sign messages to transfer tokens directly to signed spenders, bypassing setting any allowance. This means that approvals aren't necessary for applications to receive tokens and that there will never be hanging approvals when using this method. The signature is valid only for the duration of the transaction in which it is spent.
• Batched Token Transfers: Transfer different tokens to different recipients with one signature.
• Signature Verification for Contracts: All signature verification supports EIP-1271 so contracts can approve tokens and transfer tokens through signatures.
• Non-monotonic Replay Protection: Signature based transfers use unordered, non-monotonic nonces so that signed permits do not need to be transacted in any particular order.
• Expiring Approvals: Approvals can be time-bound, removing security concerns around hanging approvals on a wallet’s entire token balance. This also means that revoking approvals do not necessarily have to be a new transaction since an approval that expires will no longer be valid.
• Batch Revoke Allowances: Remove allowances on any number of tokens and spenders in one transaction.

Integrating with Permit2

Before integrating, contracts can request users’ tokens through ERC721Permit2, users must approve the ERC721Permit2 contract through the specific token contract. There's no tech docs, but being a derivation from Uniswap's Permit2, you should get a very good idea by looking at Uniswap's documentation site.

Deployed addresses

The contract is deployed at 0x6b210f49C0f0c8A008A1a4DC25df2E4473D97D85 currently on Ethereum, Arbtitrum, Base, Optimism, Gnosis, & Polygon. Get in touch if you'd like to see it in other chains

Contributing

You will need a copy of Foundry installed before proceeding. See the installation guide for details.

Setup

git clone https://github.com/contango-xyz/erc721-permit2.git
cd erc721-permit2
forge install

Lint

forge fmt [--check]

Run Tests

# unit
forge test

Deploy

Run the command below. Remove --broadcast, ---rpc-url, --private-key and --verify options to test locally

forge script --broadcast --rpc-url <RPC-URL> --private-key <PRIVATE_KEY> --verify script/Deploy.s.sol

Acknowledgments

Inspired by ERC20 Permit2.

Audits

Audited by Offbeat Security, report can be found in the audits folder or here