ZK facts & stats

Question 1

In 'ZK proof', what does ZK stand for?

Accepted Answer

Zero-knowledge. ZK is short for zero-knowledge.

Question 2

In a zero-knowledge proof, what is the party trying to convince the other called?

Accepted Answer

The prover. The prover shows a claim is true; the verifier checks it.

Question 3

In the classic 'Ali Baba cave' story, what does the prover show without revealing it?

Accepted Answer

That they know the secret word to open a door inside the cave. The prover exits from whichever side the verifier calls out, which is only reliably possible by opening the magic door.

Question 4

In a proof system, what does 'soundness' mean?

Accepted Answer

A cheater can't prove a false claim, except by rare luck. Soundness guarantees false statements are rejected with high probability.

Question 5

In the term zk-SNARK, what does the 'N' stand for?

Accepted Answer

Non-interactive. zk-SNARK means zero-knowledge Succinct Non-interactive ARgument of Knowledge.

Question 6

In which decade were zero-knowledge proofs first introduced in a research paper?

Accepted Answer

The 1980s. The idea was introduced in the paper 'The Knowledge Complexity of Interactive Proof Systems', published in 1985.

Question 7

Zero-knowledge proofs exist for graph 3-coloring. Why is that important?

Accepted Answer

3-coloring is NP-complete, so the method extends to all NP problems. Because every NP problem reduces to 3-coloring, a ZK proof for it gives ZK proofs for all NP statements, under standard assumptions.

ZK facts & stats

The basics