On Learning zk-SNARK
Recently I am picking up the knowledge necessary to understand what is going on in zk-SNARK. For those who are not familiar with this term, "zk" stands for zero-knowledge, and "SNARK" stands for succinct, non-interactive, argument of knowledge. What this term means is:
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zero-knowledge: this is a way for a prover proving "something" to a verifier in such a way that the verifer will not gain any additional knowledge than before the interaction. We will elaborate the "something" in the following bullet points.
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succinct: the proof is going to be short compared to the actual knowledge, and the verifier will be able to perform the verification quite fast. To be more concrete, if the knowledge m has a length of |m|, the proof may probably be O(log |m|) or even shorter.
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non-interactive: there won't be rounds of back and forth interactions between the prover and verifier. The prover will only send a single message to the verifier.
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Argument of Knowledge: This is the "something" mentioned in the first bullet point. Notice that this is not the knowledge itself, but a proof that demonstrate that the prover indeed knows the knowledge.