Blockchain-Empowered Privacy-Preserving Digital Object Trading in the Metaverse

The metaverse is an advanced digital world where users can have interactive and immersive experiences. Users enter the metaverse through digital objects created by extended reality and digital twin technologies. The ownership issue regarding these digital objects can be solved by the blockchain-based nonfungible token (NFT), which is of vital importance for the economics of the metaverse. Users can utilize NFTs to engage in various social and economic activities. However, current NFT protocols expose the owner's information to the public, which may contradict with the privacy requirement. In this article, we propose a protocol, NFTPrivate, that can realize anonymous and confidential trading of digital objects. The key idea is to utilize cryptographic commitments to hide users' addresses. By constructing proper zero-knowledge proofs, the owner can initiate privacy-preserving yet publicly verifiable transactions. Illustrative results show that the proposed protocol has higher computation and storage overhead than traditional NFT protocols. We think this is an acceptable compromise for privacy protection.