Imagine you have a top-secret code that opens a mysterious door in a cave. You want to sell the code to your friend, but you also want to prove to them that you have the code without revealing it in any way. Is that even possible? Yes, it is through a cryptographic method called zero knowledge proof. In this article, we will explain what zero knowledge proof is and how it works.
What is Zero Knowledge Proof?
Zero knowledge proof is a method of authentication that proves something is known without revealing the information. This concept was developed by mathematicians in the 1980s and has been used by various cryptocurrencies such as Zcash to provide financial privacy through shielded addresses.
Example of Zero Knowledge Proof
Suppose you have a code that opens the door in the cave, and you want to prove to your friend that you have it. In this scenario, you are known as the prover, and your friend is known as the verifier. Imagine two different entrances to the cave, connected by a path and a door. This provides the perfect environment for you to prove to your friend that you have the code without revealing it.
Your friend goes to one entrance of the cave and waits outside to give you instructions. You enter at random through one of the entrances while your friend waits outside to tell you which path to exit through. If you have the code, you would be able to exit through the path that your friend wants every single time by using the door. However, mathematically, you would have a 50% chance of picking the right entrance and path from the start. To reduce the chance of luck involved, you can run the test multiple times.
From this example, you're able to use the same proofs to verify that you have the code by opening the door and coming out through your friend's requested path multiple times. In this sense, your proof system aims to achieve statistical soundness, completeness, and most importantly, zero knowledge.
Criteria for Zero Knowledge Proof
A zero knowledge proof method must satisfy three main criteria:
Soundness - If the information provided by the prover is false, then a zero knowledge proof method must allow the verifier to refute that the prover is telling the truth.
Statistical completeness - If the information provided by the prover is true, then a zero knowledge proof method must enable the verifier to verify that the prover is telling the truth.
Zero knowledge - The method must reveal to the verifier nothing else than whether the prover is telling the truth or not.
Types of Zero Knowledge Proof
There are two types of zero knowledge proof: interactive and non-interactive. Interactive zero knowledge proof requires several interactions between the prover and the verifier until the verifier is convinced. Non-interactive zero knowledge proof allows proof to be delivered offline without direct communication to the verifier.
Advantages of Zero Knowledge Proof
Zero knowledge proof has several advantages, including simplicity, reinforcement of system security and privacy, and the strengthening of the security of information.
Disadvantages of Zero Knowledge Proof
Zero knowledge proof also has its drawbacks, including the need for a large amount of computing power in interactive zero knowledge proofs, making them unsuitable for slow devices. Furthermore, zero knowledge proof does not give a 100% guarantee that the provers' information is true mathematically speaking.
Applications of Zero Knowledge Proof
Zero knowledge proof has been applied in many industries, including crypto. Zcash uses a type of zero knowledge cryptographic method to introduce more privacy to its blockchain. Apart from its application in cryptocurrency, zero knowledge proof has potential applications across various industries, including:
Authentication and Identity Verification Voting Cybersecurity Supply Chain Management Cloud Computing Online Privacy Smart Contracts
Conclusion
Zero knowledge proof is a powerful cryptographic tool that can be used to prove the authenticity of information without revealing sensitive details. It has been successfully applied in cryptocurrency to provide financial privacy, and it has potential applications in various industries, including authentication, voting, cybersecurity, supply chain management, cloud computing, online privacy, and smart contracts. The applications of zero knowledge proof are only limited by our imagination, and it has the potential to revolutionize the way we think about privacy and security.
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