266 lines
10 KiB
Markdown
266 lines
10 KiB
Markdown
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---
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eip: 5635
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title: NFT Licensing Agreements
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description: An oracle for retrieving NFT licensing agreements
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author: Timi (@0xTimi), 0xTriple7 (@ysqi)
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discussions-to: https://ethereum-magicians.org/t/eip-5635-discussion-nft-licensing-agreement-standard/10779
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status: Draft
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type: Standards Track
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category: ERC
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created: 2022-08-10
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requires: 165, 721, 1155, 2981
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---
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## Abstract
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This EIP standardizes an NFT licensing oracle to store (register) and retrieve (discover) granted licensing agreements for non-fungible token (NFT) derivative works, which are also NFTs but are created using properties of some other underlying NFTs.
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In this standard, an NFT derivative work is referred to as a **dNFT**, while the original underlying NFT is referred to as an **oNFT**.
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The NFT owner, known as the `licensor`, may authorize another creator, known as the `licensee`, to create a derivative works (dNFTs), in exchange for an agreed payment, known as a `Royalty`. A licensing agreement outlines terms and conditions related to the deal between the licensor and licensee.
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## Specification
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.
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In general, there are three important roles in this standard:
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- oNFT: An original underlying NFT. The holder of an oNFT is a licensor. An oNFT can be any NFT.
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- dNFT: A derivative work based on one or more oNFTs. The holder of a dNFT is a licensee.
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- Registry: A trusted smart contract able to verify whether a credential is signed or released by the holder of oNFT.
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Every **dNFT** contract must implement the `IERC5635NFT` and `IERC165` inferfaces.
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```solidity
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pragma solidity ^0.6.0;
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import "./IERC165.sol";
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///
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/// @notice Interface of NFT derivatives (dNFT) for the NFT Licensing Standard
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/// @dev The ERC-165 identifier for this interface is 0xd584841c.
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interface IERC5635DNFT is IERC165 {
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/// ERC165 bytes to add to interface array - set in parent contract
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/// implementing this standard
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///
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/// bytes4(keccak256("IERC5635DNFT{}")) == 0xd584841c
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/// bytes4 private constant _INTERFACE_ID_IERC5635DNFT = 0xd584841c;
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/// _registerInterface(_INTERFACE_ID_IERC5635XDNFT);
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/// @notice Get the number of credentials.
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/// @param _tokenId - ID of the dNFT asset queried
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/// @return _number - the number of credentials
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function numberOfCredentials(
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uint256 _tokenId
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) external view returns (
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uint256 _number
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);
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/// @notice Called with the sale price to determine how much royalty is owed and to whom.
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/// @param _tokenId - ID of the dNFT asset queried
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/// @param _credentialId - ID of the licensing agreement credential, the max id is numberOfCredentials(_tokenId)-1
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/// @return _oNFT - the oNFT address where the licensing from
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/// @return _tokenID - the oNFT ID where the licensing from
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/// @return _registry - the address of registry which can verify this credential
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function authorizedBy(
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uint256 _tokenId,
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uint256 _credentialId
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) external view returns (
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address _oNFT,
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uint256 _tokenId,
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address _registry
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);
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}
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interface IERC165 {
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/// @notice Query if a contract implements an interface
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/// @param interfaceID The interface identifier, as specified in ERC-165
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/// @dev Interface identification is specified in ERC-165. This function
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/// uses less than 30,000 gas.
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/// @return `true` if the contract implements `interfaceID` and
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/// `interfaceID` is not 0xffffffff, `false` otherwise
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function supportsInterface(bytes4 interfaceID) external view returns (bool);
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}
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```
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Every **Registry** contract must implement the `IERC5635Registry` and `IERC165` inferfaces.
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```solidity
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pragma solidity ^0.6.0;
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import "./IERC165.sol";
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///
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/// @dev Interface of NFT derivatives (dNFT) for the NFT Licensing Standard
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/// Note: the ERC-165 identifier for this interface is 0xb5065e9f
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interface IERC5635Registry is IERC165 {
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/// ERC165 bytes to add to interface array - set in parent contract
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/// implementing this standard
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///
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/// bytes4(keccak256("IERC5635Registry{}")) == 0xb5065e9f
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/// bytes4 private constant _INTERFACE_ID_IERC5635Registry = 0xb5065e9f;
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/// _registerInterface(_INTERFACE_ID_IERC5635Registry);
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// TODO: Is the syntax correct?
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enum LicensingAgreementType {
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NonExclusive,
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Exclusive,
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Sole
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}
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/// @notice
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/// @param _dNFT -
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/// @param _dNFT_Id -
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/// @param _oNFT -
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/// @param _oNFT_Id -
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/// @return _licensed -
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/// @return _tokenID - the oNFT ID where the licensing from
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/// @return _registry - the address of registry which can verify this credential
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function isLicensed(
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address _dNFT,
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uint256 _dNFT_Id,
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address _oNFT,
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uint256 _oNFT_Id
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) external view returns (
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bool _licensed
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);
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/// @return _licenseIdentifier - the identifier, e.g. `MIT` or `Apache`, similar to `SPDX-License-Identifier: MIT` in SPDX.
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function licensingInfo(
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address _dNFT,
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uint256 _dNFT_Id,
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address _oNFT,
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uint256 _oNFT_Id
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) external view returns (
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bool _licensed,
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address _licensor,
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uint64 _timeOfSignature,
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uint64 _expiryTime,
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LicensingAgreementType _type,
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string _licenseName,
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string _licenseUri //
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);
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function royaltyRate(
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address _dNFT,
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uint256 _dNFT_Id,
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address _oNFT,
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uint256 _oNFT_Id
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) external view returns (
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address beneficiary,
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uint256 rate // The decimals is 9, means to divide the rate by 1,000,000,000
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);
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}
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```
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The **Registry** contract MAY implement the `IERC5635Licensing` and `IERC165` inferfaces.
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```solidity
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pragma solidity ^0.6.0;
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import "./IERC165.sol";
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///
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///
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interface IERC5635Licensing is IERC165, IERC5635Registry {
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event Licence(address indexed _oNFT, uint256 indexed _oNFT_Id, address indexed _dNFT, uint256 indexed _dNFT_Id, uint64 _expiryTime, LicensingAgreementType _type, string _licenseName, string _licenseUri);
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event Approval(address indexed _oNFT, address indexed _owner, address indexed _approved, uint256 indexed _tokenId);
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event ApprovalForAll(address indexed _oNFT, address indexed _owner, address indexed _operator, bool _approved);
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function licence(address indexed _oNFT, uint256 indexed _oNFT_Id, address indexed _dNFT, uint256 indexed _dNFT_Id, uint64 _expiryTime, LicensingAgreementType _type, string _licenseName, string _licenseUri) external payable; //TODO: mortgages or not?
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function approve(address indexed _oNFT, address _approved, uint256 _tokenId) external payable; //TODO: why payable?
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function setApprovalForAll(address indexed _oNFT, address _operator, bool _approved) external;
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function getApproved(address indexed _oNFT, uint256 _tokenId) external view returns (address);
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function isApprovedForAll(address indexed _oNFT, address _owner, address _operator) external view returns (bool);
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}
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```
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## Rationale
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Licensing credentials from a dNFT's contract can be retrieved with `authorizedBy`, which specifies the details of a licensing agreement, which may include the oNFT. Those credentials may be verified with a `registry` service.
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Anyone can retrieve licensing royalty information with `licensingRoyalty` via the registry. While it is not possible to enforce the rules set out in this EIP on-chain, just like [EIP-2981](./eip-2981.md), we encourages NFT marketplaces to follow this EIP.
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### Two stages: Licensing and Discovery
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Taking the moment when the dNFT is minted as the cut-off point, the stage before is called the **Licensing** stage, and the subsequent stage is called the **Discovery** stage. The interface `IERC5635Licensing` is for the **Licensing** stage, and the interfaces `IERC5635DNFT` and `IERC5635Registry` are for the **Discovery** stage.
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### Design decision: beneficiary of licensing agreement
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As soon as someone sells their NFT, the full licensed rights are passed along to the new owner without any encumbrances, so that the beneficiary should be the new owner.
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### Difference between CantBeEvil Licenses and Licensing Agreements.
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CantBeEvil licenses are creator-holder licenses which indicate what rights the NFTs' holder are granted from the creator. Meanwhile, licensing agreements is a contract between a licensor and licensee. So, CantBeEvil licenses cannot be used as a licensing agreement.
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### Design decision: Relationship between different approval levels
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The approved address can `license()` the licensing agreement to **dNFT** on behalf of the holder of an **oNFT**. We define two levels of approval like that:
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1. `approve` will lead to approval for one NFT related to an id.
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2. `setApprovalForAll` will lead to approval of all NFTs owned by `msg.sender`.
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## Backwards Compatibility
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This standard is compatible with [EIP-721](./eip-721.md), [EIP-1155](./eip-1155.md), and [EIP-2981](./eip-2981.md).
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## Reference Implementation
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### Examples
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#### Deploying an [EIP-721](./eip-721.md) NFT and signaling support for dNFT
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```solidity
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constructor (string memory name, string memory symbol, string memory baseURI) {
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_name = name;
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_symbol = symbol;
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_setBaseURI(baseURI);
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// register the supported interfaces to conform to ERC721 via ERC165
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_registerInterface(_INTERFACE_ID_ERC721);
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_registerInterface(_INTERFACE_ID_ERC721_METADATA);
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_registerInterface(_INTERFACE_ID_ERC721_ENUMERABLE);
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// dNFT interface
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_registerInterface(_INTERFACE_ID_IERC5635DNFT);
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}
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```
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#### Checking if the NFT being sold on your marketplace is a dNFT
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```solidity
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bytes4 private constant _INTERFACE_ID_IERC5635DNFT = 0xd584841c;
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function checkDNFT(address _contract) internal returns (bool) {
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(bool success) = IERC165(_contract).supportsInterface(_INTERFACE_ID_IERC5635DNFT);
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return success;
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}
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```
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#### Checking if an address is a Registry
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```solidity
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bytes4 private constant _INTERFACE_ID_IERC5635Registry = 0xb5065e9f;
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function checkLARegistry(address _contract) internal returns (bool) {
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(bool success) = IERC165(_contract).supportsInterface(_INTERFACE_ID_IERC5635Registry);
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return success;
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}
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```
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## Security Considerations
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Needs discussion.
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## Copyright
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Copyright and related rights waived via [CC0](../LICENSE.md).
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