The safest place for your crypto assets (NFTs and coins) is in a cold wallet (i.e. ledger) that is not connected to anything, other than your own transfers in/out of the wallet.
The problem is that you can't easily use the utility of NFTs in a cold wallet without connecting it to the site providing the utility.
The Fizzy has created and is using a simple standard called NFT Wallet Link to enables use of your Broker NFTs stored in a cold wallet, without linking that cold wallet to this website.
The NFT Wallet Link standard works like this:
Create a new address/account in your existing wallet (i.e Metamask).
- This will be your hot wallet.
- Call it something like "Broker Connect" so you can remember what it is for.
- Do not store any NFTs or significant coin in this wallet.
Create a standard transaction (send) from your cold wallet to the new hot wallet address.
- Amount for transfer can be 0 ETH.
- Add the hex code 763D6E66743120616C6C to the transaction.
- In Metamask you can enable addition of hex codes to transactions in Settings/Advanced.
An application can then look for a transaction in this format
- The app can find address of the cold wallet.
- The app can then look for NFTs in the cold wallet instead of the hot wallet.
There is no security issue with doing this. It is a standard transaction, nothing else. It does not give away any access to your cold wallet.
It does provide a way to connect to websites that support this standard and use your NFTs for utility without putting them at risk.
If you ever want to undo this, create a new transaction from the cold wallet to the hot wallet with the hex code 763D6E667431206E6F6E65. See my blog post for full details on how this all works at a technical level.
If you have stored your Brokers in a cold wallet, follow the instructions above to gain full access to all the features of The Fizzy.