Assume that someone who ordered a physical coin from smoothie either:

  1. Lost the funding instructions
  2. Received the instructions but wants to verify them in case they were replaced in a MITM attack before delivery

What are the instructions to securely fund a physical coin?

1 Answer 1


You cannot “fund a physical coin” with Monero, because Monero exists only as data on a distributed ledger. These so-called “physical coins” are just arbitrary objects on which seed-phrases can be stuck or engraved (and in this case apparently hidden behind a sticker).

A physical coin could function as a back-up of your seed phrase, but it has no real advantages over a seed-phrase written on any other object. A sticker might not even be waterproof, let alone fireproof. An engraved seed-phrase would be tougher, but brass has to be protected from corrosion, and it melts at 900–940°C. As a transferable bearer-bond, it's useless, because the bearer has no way of knowing whether or not a previous bearer wrote down the seed-phrase before handing over the coin.

If you really want to use one of these things to store your seed phrase, and you have nimble fingers, then perhaps you could engrave it. Or you could convert your seed-phrase into a tiny QR-code, print it on sticky paper and stick it to the coin. Your question specified “securely”, which would mean using a non-networked computer to generate the seed-phrase (& convert it to QR code) and a directly connected printer (a low-tech printer so your funds can't be compromised by printer malware). But why would you want to?

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