NOTICE: This project eventually became the basis for Uniswap's Permit2, which supercedes this project in scope. Unless you need a really a lean/gas-optimized implementation provided by this solution, you'll probably want to use Permit2 👈

PermitEverywhere

PermitEverywhere is a set of contracts that enable permit style approvals for all ERC20 and ERC721 tokens, regardless of whether they implement EIP2612 or not.

Users simply need set an allowance on the ERC20PermitEverywhere contract (for ERC20 assets) or the ERC721PermitEverywhere contract (for ERC721 assets). Afterwards, protocols can accept a signed permit message from the user, which they can pass into a PermitEverywhere contract to securely transfer funds without an explicit allowance set on their own contracts.

Addresses

• ERC20PermitEverywhere is deployed at 0xeee20efDe3b7222561CB29b03aa62d3f1368fba2 on Ethereum, Polygon, Optimism, Arbitrum, Rinkeby, and Ropsten.
• ERC721PermitEverywhere is deployed at 0xEEe721c6f50d0223D4c19CA30Cf9F448E5B17426 on Ethereum, Polygon, Optimism, Arbitrum, Rinkeby, and Ropsten.
• (ERC1155 coming soon).

Permit Messages

Permit messages are implemented EIP712 so they can be signed in a human readable fashion through popular web3 wallets.

ERC20PermitEverywhere Permit Spec

The EIP712Domain fields for ERC20PermitEverywhere messages are as follows:

    EIP712Domain({
        name: 'ERC20PermitEverywhere',
        version: '1.0.0',
        chainId: TARGET_CHAIN_ID,
        verifyingContract: 0xeee20efDe3b7222561CB29b03aa62d3f1368fba2
    })

The permit message itself is defined as:

struct PermitTransferFrom {
    // The token to transfer.
    address token;
    // Who can execute this permit.
    address spender;
    // Maximum amount of tokens to move.
    uint256 maxAmount;
    // Timestamp after which this permit is no longer valid.
    uint256 deadline;
    // The nonce for the signer of this permit.
    // The current nonce can be retrieved through ERC20PermitEverywhere.currentNonce().
    uint256 nonce;
}

ERC721PermitEverywhere Permit Spec

The EIP712Domain fields for ERC20PermitEverywhere messages are as follows:

    EIP712Domain({
        name: 'ERC721PermitEverywhere',
        version: '1.0.0',
        chainId: TARGET_CHAIN_ID,
        verifyingContract: 0xEEe721c6f50d0223D4c19CA30Cf9F448E5B17426
    })

The permit message itself is defined as:

struct PermitTransferFrom {
    // The token to transfer.
    address token;
    // Who can execute this permit.
    address spender;
    // The NFT token ID that can be moved. Ignored if allowAnyTokenId is true.
    uint256 tokenId;
    // If true, any token ID can be moved by spender.
    bool allowAnyTokenId;
    // Timestamp after which this permit is no longer valid.
    uint256 deadline;
    // The nonce for the signer of this permit.
    // The current nonce can be retrieved through ERC721PermitEverywhere.currentNonce().
    uint256 nonce;
}

Executing Permit Messages

For ERC20 permits, protocols can burn a user's permit message and execute an eligible transfer by calling ERC20PermitEverywhere.executePermitTransferFrom(), which is declared as follows:

    function executePermitTransferFrom(
        address from,
        address to,
        uint256 amount,
        PermitTransferFrom calldata permit,
        Signature calldata sig
    )
        external;

For ERC721 permits, protocols can burn a user's permit message and execute an eligible transfer by calling either ERC721PermitEverywhere.executePermitTransferFrom() or ERC721PermitEverywhere.executePermitSafeTransferFrom(), which are declared as follows:

    function executePermitTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        PermitTransferFrom calldata permit,
        Signature calldata sig
    )
        external

    function executePermitSafeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data,
        PermitTransferFrom calldata permit,
        Signature calldata sig
    )
        external;