Early bitcoin NFTs were not immutable.
In November 2015, XCPCARDS.com solved this for several cards, ZAIFCARD included.
This was achieved by including the following text in a bitcoin transaction:
xcpcards.com/ZAIFCARD YaQuBWUG
The identifier YaQuBWUG is the jpeg's checksum which proves the card's design. Since this text is engraved on the blockchain, the proof can never be tampered with, nor can the timestamp be disputed.
This makes ZAIFCARD one of the first real crypto cards!
The file's full sha-256 hash in hex and base64 encodings:61a42e056506dd10b2f51dc4fbe0f68b4ee79539444a31a075a5c787d46bbbe0
YaQuBWUG3RCy9R3E++D2i07nlTlESjGgdaXHh9Rru+A=
The identifier is a 48 bit truncated hash.
This is sufficiently strong, yet short enough to have the text fit inside a Bitcoin op_return message.
The below cards were notarized by XCPCARDs.com
Most are from the Spells of Genesis project.
Click a card to view its details.