Early bitcoin NFTs were not immutable.
In November 2015, XCPCARDS.com solved this for several cards, BEARWHALECD included.
This was achieved by including the following text in a bitcoin transaction:
xcpcards.com/BEARWHALECD bab7ad233d2d
The identifier bab7ad233d2d 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 BEARWHALECD one of the first real crypto cards!
The file's full sha-256 hash in hex and base64 encodings:bab7ad233d2d52d1336fce478d690055135533c957e21279a8e4dbbee981b68d
uretIz0tUtEzb85HjWkAVRNVM8lX4hJ5qOTbvumBto0=
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.