Physical XMR coin

XMR allow a view key which show what came in but not what came out. So it's not sufficient to prove that the coin contain what has been announced and sold ? However it has been already fixed whith the reserve proofs (get_reserve_proof / check_reserve_proof in the CLI wallet). The proof is generated once when the coin is loaded, and anyone can check it against the chain later without any keys. If the funds ever move, that same proof shows them as spent. So here is the idea: - each coin has a serial number and a QR code linking to a signed certificate (address, view key, reserve proof) - certificates are public, with a page showing the status of every coin in the series - the private key is sealed inside the coin, tamper evident If you buy one second hand, you scan it and check in a minute that it’s still loaded and unspent, no need to trust the seller. And since every coin’s status is public, if the maker (me) ever kept a key and swept a coin, everyone would see it right away. Pretty good incen