Original article: "How to achieve cross-chain NFT on the Aptos chain?"

Author: Aptos Global

Currently, NFT on the Aptos chain can be cross-chain with other chains through Wormhole. How is this achieved? For ordinary users, how should it be operated?

Mo Shaikh, co-founder and CEO of Aptos, said, "With the Aptos NFT Bridge, Wormhole has taken Aptos' network interoperability to a new level, and Aptos will welcome millions of NFT assets and thousands of creators and artists accessed through the bridge."

How is the NFT cross-chain bridge implemented?

The NFT Bridge supports transferring NFTs back and forth between any supported chains while preserving their metadata. When an NFT is transferred out of its origin chain, this is what happens:

1) NFT is locked in the NFT Bridge smart contract;

2) An equivalent wrapped NFT is minted into the corresponding collection on the target chain;

3) This wrapped NFT has the same name, looks the same as the original, and behaves exactly the same as other NFTs on the chain. On the EVM chain, wrapped NFTs are ERC721 tokens, on Solana, they are SPL tokens with Metaplex metadata, and on Aptos, they are instances of the Aptos token standard.

Aside from the name and appearance, what makes wrapped NFTs unique is the ability to send them back to the originating chain and unlock the original NFT. This means, for example, an NFT originating from Aptos can be bridged to Ethereum, subsequently sold on Opensea, and then transferred back to Aptos by the new owner.

Which chains currently support NFT cross-chain to Aptos?

Users can currently bridge NFTs from Arbitrum, Aurora, Avalanche, BSC, Celo, Ethereum, Fantom, Karura, Klaytn, Moonbeam, Oasis, Optimsm, Polygon, and Solana to Aptos, and vice versa.

In the past, some premium NFTs, such as dozens of Cryptopunks and a Beeple, have been cross-chained to Aptos via Wormhole.

What is Wormhole?

Wormhole is an interoperability protocol that allows projects to build on top of its universal messaging layer, which links multiple chains including Ethereum, Solana, Binance Smart Chain, Polygon, Avalanche, Algorand, Fantom, Karura, Celo, Acala, Aptos, and Arbitrum.

Wormhole does this by sending messages from one chain to another, which are observed and verified by a network of guardian nodes, which then submit the message to the target chain for processing. This simple messaging primitive enables xChain functionality, where users interact with xDapps (xChain decentralized applications) to transfer xAssets (cross-chain assets) between networks or access their xData (xChain data) to provide services to them on their current network.

Wormhole's current total transaction volume has exceeded $35B, hundreds of millions of messages have been successfully transmitted, millions of messages are submitted every day, and more than 60 protocols are built on Wormhole's universal messaging layer.

How to operate cross-chain NFT on Aptos chain?

1) Click on the link

https://www.portalbridge.com/#/nft

You can see that there are multiple chains of NFTs to choose from, such as choosing NFTs on Arbitrum for cross-chain;

2) Select an NFT to be transferred across chains, click it and confirm it with the signature of the wallet;

3) Click “redeem” to transfer the packaged NFT back across the chain.