Zero-knowledge proof (ZKP) is a cryptographic technology that allows the truth of information (or parts of it) to be verified without revealing the information itself. It is increasingly important in the blockchain, cryptocurrency, and decentralized finance (DeFi) space because it improves privacy and security.
Many DeFi projects are already using ZKP technology to provide greater privacy to users of services such as lending, borrowing, and trading. A number of layer-one blockchains are implementing rollups based on ZKP or zkEVM. As the technology becomes more widespread, zero-knowledge proofs are expected to be increasingly used in blockchains and Web3.
1. How Zero-Knowledge Proof Works
Zero-knowledge proof is a cryptographic technique that enables one party (the prover) to demonstrate the truth of a statement to another party (the verifier) without disclosing any underlying information. It is particularly useful for verifying sensitive data while maintaining confidentiality.
The prover provides a unique and self-generated mathematical proof, and the verifier uses this proof to verify the truth of the statement. Neither party can use the proof to reconstruct or view the original information.
1.1 Example of Zero-Knowledge Proof
Imagine a tunnel with two entrances, A and an exit B. The only way from A to B is blocked by a locked door with a secret code, preventing people from passing through the tunnel from one end to the other. You have the secret code and want to sell it to user X, who needs to pass through the tunnel.
User X is willing to pay to reveal the code, but first, you must prove that you actually have the code. In this example, it would be enough for him to see you enter the tunnel through entrance A and exit through exit B to verify that you have the real code.
2. Advantages of Zero-Knowledge Proof
The popularity of zero-knowledge proof in blockchain and cryptocurrency is due to the growing demand for privacy and security in digital transactions. With the development of blockchain technology and the cryptocurrency industry, there is also a need for a reliable method of verifying transactions without revealing sensitive information—this is exactly what ZKP does.
Zero-knowledge proofs have gained increased interest in recent years, with many ZKP-enabled protocols launched and major blockchains developing zero-knowledge rollups. The popularity of zero-knowledge proofs is also evidenced by the fact that over 20% of all talks at DevCon 2022 were devoted to this technology.
3. Main Developments in Zero-Knowledge Proof
One of the key advances in zero-knowledge proofs is the increased adoption of a special type of ZKP called zk-SNARKs (zero-knowledge short non-interactive argument of knowledge). The use of zk-SNARKs has become widespread in various DeFi applications, such as private token transactions and hidden-value lending and borrowing.
Another important development in zero-knowledge proof technology is the pursuit of increased scalability and performance through zk rollups.
3.1 zk-SNARK
A short-cut non-interactive zero-knowledge argument of knowledge (zk-SNARK) is a special type of zero-knowledge proof that allows one to verify a statement without revealing any information about the statement itself.
zk-SNARKs have already been used in applications such as Zcash and the JP Morgan Chase blockchain-based payment system. zk-SNARKs are also used to securely authenticate clients to servers.
3.2 zk-Rollups
ZK rollups are a scaling solution for blockchain networks that make it easier to combine multiple transactions into one, larger transaction, which is then recorded on the blockchain.
For example, in 2022, BNB Chain launched the zkBNB testnet, which is built on the ZK rollup architecture. zkBNB can aggregate hundreds of transactions into a single off-chain batch and generate a cryptographic proof to confirm the validity of all transactions. ZK rollups provide a balance between scalability and security and are suitable for large-scale, low-latency systems.
4. Applications of Zero-Knowledge Proof
Zero-knowledge proofs can be used for a variety of different purposes, with some use cases already implemented and others coming soon.
4.1 Digital Identification
Zero-knowledge proofs can be used to verify the identity of users without revealing any sensitive personal data. This feature may be necessary, for example, in digital voting systems that require identity verification while preserving the anonymity of users.
4.2 Confidential Transactions
One of the key goals of zero-knowledge proofs is to enable transactions while preserving privacy.
For example, Manta Network’s decentralized application (DApp), MantaPay, uses ZKP to allow users to transact on a decentralized exchange (DEX) without revealing their identity or transaction details. In this way, users can use the platform to transact while maintaining privacy.
4.3 Private Transactions
Zcash is a cryptocurrency that uses zero-knowledge proof to make private transactions. In such transactions, the sender and recipient addresses, as well as the transaction amounts, are hidden from the public blockchain, providing additional privacy for users.
4.4 Tokenization and Ownership Verification
Zero-knowledge proofs can also be used to tokenize assets and verify ownership.
For example, a property owner could tokenize it and provide proof of ownership to another party without revealing any other information publicly.
4.5 Regulatory Compliance
Some countries have strict laws regarding the collection and exchange of financial information, which are difficult to comply with on decentralized platforms. Zero-knowledge proofs can be used to transmit the necessary information to regulators in a confidential manner.
This allows for a connection between decentralized platforms and traditional financial institutions, facilitating regulatory compliance in the DeFi space.
5. Prospects of ZKP Technology in Blockchain
Zero-knowledge proof technology is likely to lead to new technological innovations in the future. Here are a few ZKP-related developments to watch:
5.1 Cross-Chain Privacy Layers
As blockchain ecosystems and DeFi continue to evolve, the need for interoperability between different blockchain networks is rapidly growing. Cross-chain privacy layers allow transactions to take place across different blockchain networks while maintaining the privacy of the parties involved.
5.2 zk-STARK
Another interesting development is the active distribution of zk-STARK (scalable zero-knowledge transparent argument of knowledge), a new type of zero-knowledge proof that is considered more efficient and secure than zk-SNARK.
Another advantage of zk-STARK over zk-SNARK is that it can be verified quickly without the need for a third-party trust setup.
5.3 A Set of Convenient Tools
Zero-knowledge proof is a fairly complex technology, and not every development team has experience in this particular area of cryptography. Easy-to-use ZKP toolkits will make it easier for developers of all skill levels to use the technology.
6. Limitations of Zero-Knowledge Proofs
Zero-knowledge proofs are a unique method of verifying the truth of information while preserving privacy, but the technology is not 100% guaranteed.
While the probability of a prover fooling a verifier is extremely low, users should be aware that ZKPs can be hacked too. In addition, zero-knowledge proof algorithms are computationally expensive. Some types of ZKPs require intensive computations, requiring a large number of interactions between verifiers and provers, which could potentially limit their use.
Conclusion
Zero-knowledge proofs are rapidly gaining popularity due to their unique properties: privacy preservation and scalability potential. The wider application of this technology in blockchain, cryptocurrency, and DeFi will likely give us more innovative and useful services.
Zero-knowledge proofs are expected to play a crucial role in creating an ecosystem of decentralized applications (DApps) that are more secure, private, and efficient.
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