Lucid (https://www.writelucid.cc/ https://www.writelucid.cc/) has a similar feature, though not for proving authorship, just for history. I don't know if you ca

Lucid (https://www.writelucid.cc/ https://www.writelucid.cc/) has a similar feature, though not for proving authorship, just for history. I don't know if you can definitively prove human authorship somehow.