# Zero Knowledge Proof - Offline Data

I've been reading about Zero Knowledge Proofs with some interest, but I'm still unclear if it can be used to solve my real-life problem.

I'm wondering if someone can help me understand a little better how they work - intuitively it seems possible.

Let's assume I have 3 bank accounts with different balances, 1 balance is known, as read-only credentials to access the account are made public, but the second and third accounts are private, with the credentials kept secret.

Would it be possible to use a Zero Knowledge Proof to conclusively prove that the balances of the second and third accounts are what I say they are?

Including a brief description of what a ZKP is (quoting the ZKP article at Wikipedia):

In cryptography, a zero-knowledge proof or zero-knowledge protocol is a method by which one party (the prover) can prove to another party (the verifier) that a given statement is true, without conveying any information apart from the fact that the statement is indeed true.

So, extending this definition, the statement in my example would be: the balance of account A = X. Which the verifier would require the prover to prove is true.

• Can you ask the bank to just sign a statement saying that the balance of account A is X? What would the verifier do with the information? What are you trying to conceal from whom with a zero-knowledge proof? Aug 8, 2017 at 19:27
• I must not understand your scenario, because something seems or trivial, or impossible. There is a third, trusted party, the bank holding accounts A, B and C, that has authority over what's the balance of these accounts. For your account A, people trust that what you say about it is true, because there's public read access on the bank's site. However, the only way to verify the private amounts on B and C is to show that account to the person you need to prove it, give them a certificate from the bank, or to have them ask the bank, no ? What am I missing ? Dec 7, 2017 at 5:40