⚠️ This EIP is not recommended for general use or implementation as it is likely to change.

EIP-5298: ENS Trust to hold NFTs under ENS name Source

An interface for a smart contract acting as a "trust" that holds tokens by ENS name.

AuthorZainan Victor Zhou
Discussions-Tohttps://ethereum-magicians.org/t/erc-eip-5198-ens-as-token-holder/10374
StatusDraft
TypeStandards Track
CategoryERC
Created2022-07-12
Requires 137, 721, 1155

Abstract

This EIP standardizes an interface for smart contracts to hold of EIP-721 and EIP-1155 tokens on behalf of ENS domains.

Motivation

Currently, if someone wants to receive a token, they have to set up a wallet address. This EIP decouples NFT ownership from wallet addresses.

Specification

  1. Compliant contracts MUST implement ERC721TokenReceiver, as defined in EIP-721.
  2. Compliant contracts implement the following interface:
interface IERC_ENS_TRUST is ERC721Receiver, ERC1155Receiver {
    function claimTo(address to, bytes32 ensNode, address operator, uint256 tokenId) payable external;
}
  1. claimTo MUST check if msg.sender is the owner of the ENS node (and/or approved by the domain in implementation-specific ways). The compliant contract then MUST make a call to the safeTransferFrom function of EIP-721 or EIP-1155.

Rationale

  1. ENS was chosen because it is a well-established scoped ownership namespace. This is nonetheless compatible with other scoped ownership namespaces.

Backwards Compatibility

No backward compatibility issues were found.

Test Cases

import { loadFixture } from "@nomicfoundation/hardhat-network-helpers";
import { expect } from "chai";
import { ethers } from "hardhat";

describe("FirstENSBankAndTrust", function () {

    describe("Receive and Claim Token", function () {

        it("Should ACCEPT/REJECT claimTo based on if ENS owner is msg.sender", async function () {
            ...
            // Steps of testing:
            // mint to charlie
            // charlie send to ENSTrust and recorded under bob.xinbenlvethsf.eth
            // bob try to claimTo alice, first time it should be rejected
            // bob then set the ENS record
            // bob claim to alice, second time it should be accepted

            // mint to charlie
            await erc721ForTesting.mint(charlie.address, fakeTokenId);

            // charlie send to ENSTrust and recorded under bob.xinbenlvethsf.eth
            await erc721ForTesting.connect(charlie)["safeTransferFrom(address,address,uint256,bytes)"](
                charlie.address, firstENSBankAndTrust.address,
                fakeTokenId,
                fakeReceiverENSNamehash
            );

            // bob try to claimTo alice, first time it should be rejected
            await expect(firstENSBankAndTrust.connect(bob).claimTo(
                alice.address,
                fakeReceiverENSNamehash,
                firstENSBankAndTrust.address,
                fakeTokenId
                ))
                .to.be.rejectedWith("ENSTokenHolder: node not owned by sender");

            // bob then set the ENS record
            await ensForTesting.setOwner(
                fakeReceiverENSNamehash, bob.address
            );

            // bob claim to alice, second time it should be accepted
            await expect(firstENSBankAndTrust.connect(bob).claimTo(
                alice.address,
                fakeReceiverENSNamehash,
                erc721ForTesting.address,
                fakeTokenId
            ));
        });
    });
});

Reference Implementation

pragma solidity ^0.8.9;

contract FirstENSBankAndTrust is IERC721Receiver, Ownable {
    function getENS() public view returns (ENS) {
        return ENS(ensAddress);
    }

    function setENS(address newENSAddress) public onlyOwner {
        ensAddress = newENSAddress;
    }

    // @dev This function is called by the owner of the token to approve the transfer of the token
    // @param data MUST BE the ENS node of the intended token receiver this ENSHoldingServiceForNFT is holding on behalf of.
    function onERC721Received(
        address operator,
        address /*from*/,
        uint256 tokenId,
        bytes calldata data
    ) external override returns (bytes4) {
        require(data.length == 32, "ENSTokenHolder: last data field must be ENS node.");
        // --- START WARNING ---
        // DO NOT USE THIS IN PROD
        // this is just a demo purpose of using extraData for node information
        // In prod, you should use a struct to store the data. struct should clearly identify the data is for ENS
        // rather than anything else.
        bytes32 ensNode = bytes32(data[0:32]);
        // --- END OF WARNING ---

        addToHolding(ensNode, operator, tokenId); // conduct the book keeping
        return ERC721_RECEIVER_MAGICWORD;
    }

    function claimTo(address to, bytes32 ensNode, address tokenContract uint256 tokenId) public {
        require(getENS().owner(ensNode) == msg.sender, "ENSTokenHolder: node not owned by sender");
        removeFromHolding(ensNode, tokenContract, tokenId);
        IERC721(tokenContract).safeTransferFrom(address(this), to, tokenId);
    }
}

Security Considerations

Needs discussion.

Copyright and related rights waived via CC0.

Citation

Please cite this document as:

Zainan Victor Zhou, "EIP-5298: ENS Trust to hold NFTs under ENS name [DRAFT]," Ethereum Improvement Proposals, no. 5298, July 2022. [Online serial]. Available: https://eips.ethereum.org/EIPS/eip-5298.