What does a digital signature actually look like in real life?
You’ve seen the stamp at the bottom of a signed PDF. But what is it — a picture, a seal, a password? Imagine building it out of real things: a note in a glass box that anyone can read, a key that only locks — one copy, never shared — and a key that only opens, handed to everyone. Follow one note from Marko to Boris twice, once in an open box and once in a locked one, and you’ll know what the stamp proves, what it doesn’t, and why “signed” is not “secret”. One page, one diagram, no jargon — and the PDF is itself signed, so you can click the stamp and check the story against the real thing.
Download the signed PDF — open it in a PDF reader that checks signatures (a browser only shows the picture) and click the stamp.
This is a picture of the page — as the page says, a browser only shows the picture. Download the PDF to open the box.