# Zero knowledge proof in smart parking managment systems

I read this paper on protecting user privacy in smart parking management system. It talks about using zero knowledge proofs to protect privacy but I am not certain how they do it. My assumption is that the Verifier has the public key of the User and sends the User challenges that the User needs to complete with its private key. Would be great if someone could clarify this to me.

• The authors aren't doing signing or encryption. There is secret information $x$ (encoded as an integer mod n) that the prover wants to prove they know (in zero knowledge), and nothing more in this scheme. I'd just keep the notions separate for clarity. Re-read the steps of the protocol in 5.2 and 5.3 and you'll plainly see that the prover does indeed transmit $x\cdot P$. In other contexts, that's a public key. But we just don't care about those semantics here. – Michael Nov 10 '18 at 16:20