The reason why I did it this way with a certificate: To have a *proof* of ownership and option that it is me who did that and the blockchain helps to undermine that, because at the timestamping service I am registered and log in there via Gmail. My pub key in the certified document is stored on a YubiKey for additional security and can be uses with rage, the Rust version of age, because age currently does not have this option. Two other things about my certificate. The identicon graphic represents a visual representation of my public key ASCII string and the QR-Code contains a Hashcash token, created from my pub key and De-Mail adress. Regards Stefan ---------- Original Message ---------- On Sat, February 19, 2022 at 4:19 PM, Stefan Claas<stefan@ctemplar.com> wrote: Hi Karl, the certified document's hash is in three blockchains, Bitcoin, ETH and Aion, which you can easily verify. And I did not payed any cent for the transactions. Regards Stefan