title: Verify user is owner of an NFT via MetaMask connection? Make sure connected users public eth address is the same as of the NFT?
body: <p>I need to verify on my own domain/server the user which has connected his MetaMask wallet is the owner of a specific NFT in order to allow him special functions? Basically, I want to give the user access to an area that only the owner of this NFS would have.</p>
  <p>My original NFT is sold in opensea but I can't use the opensea hidden-area option to just give the user a hidden password since the next owner (after reselling) and the old owner would have the same password and old owners could still access like this. But I need that only the current owner has access.</p>
  <p>My user/visiter can already connect with MetaMask at my own domain and I get the public ETH address of the active account but since this is only javascript and my backend is PHP I can't just post the MetaMask info to my PHP backend since this would be easy to trick/hack.</p>
  <p>How can I make sure the current connected MetaMask Account is the same as the NFT owner (which I know) and allow to access a URL only for this user?</p>
  <p>My current state is that the user connects his MetaMask and I use opensea API to check who is currently the owner of the NFT. I can compare both eth addresses but the flaw in this is obviously that I use ajax to send the MetaMask public address to my backend which is only for testing since this is of course zero save!</p>
  <p>Thank you in advance for any idea, help, tip I can get.</p>
  <p>PS: My backend is PHP</p>