Based on a true story.

I had to renew my passport, expiration was close, I hadn’t any trip planned so I wans’t too worried about it. I went to the official government web, booked a slot on the calendar a couple weeks ahead, all good. At checkout, I got a confirmation message saying my appointment was succesfully created, green checkmark included, of course.

A week before the appointment, I went back to the website to double check the details, but to my surprise, it didn’t exist. No appointment had been created, so I had to take a new one and wait a few more weeks.

What if I had a way to verify that my appointment was actually created?

I’ve been doing some research on ZKVMs during the last few days and saw this line on the Jolt paper

As an example, the prover could be a cloud service provider running an expensive computation on behalf of its client who acts as the verifier. A SNARK gives the verifier confidence that the prover ran the computation honestly

And that brought back memories of my failed passport appointment. What if, alongside the green checkmark on the confirmation page, I also had a proof I could verify? That way, I’d known for certain that the goverment server had actually made the computation of taking my appointment and record it in the appointments database.