Token with Metadata | Ethereum Improvement Proposals

Abstract

This standard extends the ERC-20 standard to include a metadata function interface and a JSON schema for metadata.

Motivation

Memecoins have demonstrated the value of associating tokens with visual metadata. By standardizing a way to include metadata in ERC-20 tokens, developers can create more engaging and interactive tokens, fostering community engagement.

Specification

The keywords “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “NOT RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in RFC 2119 and RFC 8174.

Every compliant contract must implement the IERC7729, and ERC20 interfaces.

This standard includes the following interface:

pragma solidity ^0.8.0;

interface IERC20Metadata is IERC20 {
    /// @dev Returns the metadata URI associated with the token.
    ///  The URI may point to a JSON file that conforms to the "ERCX Metadata JSON Schema".
    function metadata() external view returns (string memory);
}

This is the “ERC-7729 Metadata JSON Schema” referenced above.

{
    "title": "Token Metadata",
    "type": "object",
    "properties": {
        "name": {
            "type": "string",
            "description": "Identifies the asset to which this token represents"
        },
        "description": {
            "type": "string",
            "description": "Describes the asset to which this token represents"
        },
        "image": {
            "type": "string",
            "description": "A URI pointing to a resource with mime type image/* representing the asset to which this token represents."
        }
    }
}

Rationale

The metadata function was chosen based on existing implementations in standards and applications.

Backwards Compatibility

This standard is backward compatible with the ERC-20 as it extends the existing functionality with new interfaces.

Reference Implementation

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

interface IERC7729 is IERC20 {
    function metadata() external view returns (string memory);
}

contract ERC7729 is ERC20, IERCX {
    string _metadata = "ipfs://QmakTsyRRmvihYwiAstYPYAeHBfaPYz3v9z2mkA1tYLA4w";

    function metadata() external view returns (string memory) {
        return _metadata;
    }
}

Security Considerations

The metadata URI could be manipulated to point to malicious content or phishing sites. Off-chain indexers should perform validation checks to ensure the security and integrity of the metadata URIs for users.