Early bitcoin NFTs were not immutable.
In November 2015, XCPCARDS.com solved this for several cards, LTBCARD included.
This was achieved by including the following text in a bitcoin transaction:
xcpcards.com/LTBCARD MVWuimMK
The identifier MVWuimMK 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 LTBCARD one of the first real crypto cards!
The file's full sha-256 hash in hex and base64 encodings:3155ae8a630a32aaec2b1e03b789d038a109668003d20f4504e5d0cb2eb9db2c
MVWuimMKMqrsKx4Dt4nQOKEJZoAD0g9FBOXQyy652yw=
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.