What is evidence with zero disclosure (Zero-Knowledge Proof)?

Proof of zero disclosure is a cryptographic protocol, which allows one side (proving) to confirm the truth of approval by the other side (verifier), while not revealing any additional information about it (neither content nor the source from which the proving learned about veracity).Such a definition was first proposed by researchers from the Massachusetts Institute of Technology (MIT) Shafi Goldvasser, Silvio Mikali and Charles Rakoff in the scientific article “The complexity of evidence in interactive systems” (1985).

How it works?

Imagine that you are in a room with a person who blindfolded. On the table in front of you are two balls – white and black. You need to prove to the second person (verifier) ​​that the balls of really different colors, without revealing which exactly.To do this, you must ask him to hide both balls under the table. After that, ask to get only one so that you can see him. Further, the ball is hiding again and the next time the verifier can again show either white or black. However, you can prove the statement, because you know exactly if he changed them under the table.

Nevertheless, the verifier in the truth of the fact will not be sure of the completely fully, because luck or deception could take place. This problem is solved by repeating the experiment N number of times. With each round, the chance to accidentally be reduced by the right one will double: after five repetitions, the probability of deception will be 1 to 32, after 10 rounds – 1 to 1024, and after 20 rounds – about 1 to 1,000,000.

Thanks to repetitions, the desired level of reliability of evidence can be achieved, but it is impossible to achieve absolute confidence.

Why use proof with zero disclosure?

One of the obvious applications of evidence with zero disclosure in cryptocurrencies can be called a test of the user of funds for transaction, without disclosing the network to the network, who is this user and how much money he has in the account.

This protocol can also be used in areas where it is necessary to ensure the safety of data (for example, personal information) or conduct a financial transaction.

Proof of Yuga Labs has earned zero disclosure can play the role of a tool that provides data and users verification, providing privileged access and establishing trusted formations.

What are the types of evidence with zero disclosure?

• interactive (the verifier independently interviews the proving in real time);
• non -interactive (does not require direct communication between the verifier and the proving; the first can check the authenticity of the approval of the post -fact).

Evidence with zero disclosure can also be divided into two groups, based on the presence or absence of a phase of fixation of the authenticity of the approval by several verifiers – the so -called trusted installation [Trusted Setup] using a pinpoint function.

For some protocols, such as ZK-Snarks (Zero-Knowledge Succint non -intractive Argument of Knowledge), this is a prerequisite. Verifiers generate a special secret, which is destroyed immediately after the trusted installation. If the secret continues to exist, then the data on the network can be faked, thereby leveling the advantages of using the protocol.

There are protocols that do not require a trusted installation (for example, ZK-Stark (Zero-KnowLeDge Scalable Transparents of Knowledge).

What are the advantages of evidence with zero disclosure?

• increasing the privacy of users in public blockchains and other networks;
• strengthening information security by replacing ineffective methods of authentication and verification;
  increasing blockchain throughput and improving scalability.

What are the shortcomings of evidence with zero disclosure?

• require significant computing power;
• the possibility of compromising during trusted installation;
• potential vulnerability before quantum calculations.

What projects use evidence with zero disclosure?

Zcash, focused on increased privacy of cryptocurrency users, uses a modified ZK-Snarks protocol. The same protocol was partially implicated on the Ethereum network as part of the BYZantium hard fork. At the moment, the business developers are considering additional opportunities for the use of this technology.

The Qedit startup has developed SDK (Software Development Kit), which allows you to implement evidence with zero disclosure into existing blockchains to increase the privacy of transactions while maintaining the possibility of their validation with nodes. It should be noted that the project has already been awarded the quality of the European Commission, and among its partners such well -known companies as VMware, Ant Financial and Deloitte.

Starkware has created solutions based on ZK-Starks, which can also be implemented in existing networks. The project has already attracted funding from Vitalik Buterin, Pantera Capital, Intel Capital, Sequoia Capital and other investors.

The Dutch bank Ing has issued a modified version of the evidence with zero disclosure-Zero-KnowLeDge Range Proof (ZKRP). This protocol may prove that the client has a wage in the range necessary for obtaining a mortgage, while without disclosing the amount itself.

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