jm x;ÏZÞXÄø°· ¥%\JÔ¬Ù|:dkÑL«a blockchain (this is why Hashgraph claim to be "safe")
But I've not read satoshis.place code so I might be wrong and it might be slow enough to be be done on a blockchain
https://whatsonchain.com/tx/0eafd12c01cb90b86375ca4cf2a64753ad6de7e92cd204e74267b1ed913c8844