ERC-6147: Analysis of the Semi-Mandatory NFT Property Separation Standard

The Ethereum Improvement Proposal ERC-6147 was officially finalized on March 7, 2023. This standard is an extension of ERC-721, aimed at separating the ownership and transfer rights of NFTs and SBTs, and introduces a new "guardian" (Guard) role. This innovation makes applications such as NFT anti-theft, lending, leasing, and SBTs more flexible.

Background

One of the main challenges facing the NFT field is insufficient liquidity. This issue arises not only from the NFT protocols themselves but, more importantly, from how to give NFTs actual use value, rather than relying solely on market speculation. The existing problems with NFT protocols include:

1. Property coupling: High-value NFTs tend to be safe havens, leading to inconvenience in use.

2. When borrowing NFT, the owner loses the right to use it.

3. SBT is bound to the Ethereum address, and it is difficult to recover if the private key is lost.

ERC-6147 Operating Mechanism

Guard role

ERC-6147 defines the Guard( Guardian) role, which includes the guardian address and expiration time. Only the current owner of the NFT or an address with withholding permissions can set the Guard. There are the following restrictions when setting the Guard:

• Guard cannot be set to the 0 address
• Only Guard can modify itself
• Only NFT owners or authorized persons can set the Guard

Guard information can be queried through the guardInfo method and will automatically expire after the due date.

Guard permissions

1. Forced Transfer Rights: After setting the Guard, only the Guard can transfer the NFT.

2. The original holder retains only the holding rights and loses the transfer rights.

3. Signatures on the trading platform remain valid but cannot be transferred in practice.

4. The Guard can use the transferAndRemove method to clear Guard information after the transfer.

5. The Guard can transfer the guard power through the changeGuard method.

Guard limit

1. Guard cannot set up automatic deduction authorization.

2. Guard cannot set Approve to prevent abuse after transferring the return rights.

Summary

Compared to ERC-4907, ERC-6147 has been optimized in terms of compatibility:

• No active support from the project is required, as long as the owner is recognized, it can be used.
• Propose the concepts of "manageable SBT" and "effective SBT", balancing the non-transferable characteristics and management needs.

ERC-6147 provides a semi-mandatory solution for the separation of NFT ownership rights, which is expected to play an important role in scenarios such as theft prevention, lending, and leasing.