💎Understanding EIP-2981: NFT Royalty Standard

The EIP-2981 defines a standard way for NFT contracts to communicate royalty information to marketplaces and platforms. This allows for consistent enforcement of royalty payments whenever an NFT is sold on secondary markets. Implementing this standard ensures that the creator automatically receives a portion of the sales proceeds.

The key function introduced by EIP-2981 is:

function royaltyInfo(uint256 tokenId, uint256 salePrice) external view returns (address receiver, uint256 royaltyAmount);

This function returns the royalty recipient’s address and the royalty amount based on the sale price of the NFT.

In addition, EIP-165 must also be implemented to enable marketplace contracts to detect whether an NFT supports the EIP-2981 standard. Without implementing EIP-165, marketplaces may be unable to verify that an NFT includes royalties, leading to missed payments for the creator.

---

Vulnerability: Missing EIP-2981 Implementation

If the NFT contract does not implement EIP-2981 properly or fails to include the necessary interface detection through EIP-165, the NFT will not signal its royalty information to marketplaces. As a result, platforms that support EIP-2981-compliant NFTs may assume that royalties are not applicable, resulting in no royalties being paid to the creator when an NFT is resold.

Impact

1. Loss of Creator Royalties: Without a properly implemented royalty mechanism, creators will miss out on their entitled share of secondary sales, undermining the economic value of their work.

2. Marketplace Incompatibility: Marketplaces may not enforce royalties for NFTs that lack EIP-2981 support, leading to inconsistencies across platforms and confusion among buyers and sellers.

Implementing EIP-2981 Properly

To prevent this issue and ensure that royalties are paid correctly, both EIP-2981 and EIP-165 must be implemented in the contract. Below is a step-by-step guide for adding the necessary functionality.

Step 1: Implement EIP-2981 Royalty Logic

First, add the royalty logic to your NFT contract. Here’s an example implementation of how to manage royalties for different tokens:

Step 2: Implement EIP-165 for Interface Detection

Next, implement EIP-165 to allow marketplaces to detect that the contract supports EIP-2981. Without this, the marketplace will not be able to verify whether royalties apply to your NFTs.