Manchmal ist Kryptographie ganz einfach. Gerfried Fuchs:

On a small side-note, the job change also required me to switch my mobile phone number because the old one was a company's number. I now have a private one that I don't fear of losing anymore. If you subtract the number 3933309527644 from my old one you have my new one.

Ok, es ist kein richtiges OTP, aber wenn ich das grad richtig überblicke, genau so sicher.