What Is Zero-knowledge Proof and How Does It Impact Blockchain?

Binance Academy · 2023-01-20T14:15:15.000Z

This article is a community submission. The author is Kenny Li, co-founder of Manta Network, a programmable privacy Layer 1 protocol powered by zero-knowledge proof technology. Views in this article are of the contributor/author and do not necessarily reflect those of Binance Academy. TL;DR Zero-knowledge proof (ZKP) is a cryptographic technology that allows the truth of a piece of information to be verified without revealing the information itself. It’s become an increasingly important technology in blockchain, cryptocurrency, and decentralized finance (DeFi) for enhancing privacy and security. Many DeFi projects are already using ZKPs to provide users with better privacy and security for services such as lending, borrowing, and trading. A number of Layer 1 blockchains are adding ZKP-based roll-ups or zkEVMs. Zero-knowledge proofs are expected to play an increasingly crucial role in the world of blockchain and Web3 as their applications are expected to become more widely adopted. How Does Zero-Knowledge Proof Work? Zero-knowledge proof is a method by which one party (the prover) can prove to another party (the verifier) that a statement is true without revealing any additional information. This is particularly useful when the information is sensitive and the prover doesn’t want the verifier to have access to it. The prover provides a mathematical proof only they can generate and the verifier can use this proof to verify the truth of the statement. However, they cannot use the proof to reconstruct the original information. Imagine a tunnel with two entrances, A and B. There is a locked door with a secret code blocking the only path and preventing people from walking through the tunnel from one end to another (A to B). You know the secret code and want to sell it to Mrs. X, who wants to access the tunnel. You want her to pay upfront before you reveal the code to her but she first wants you to prove you really know the code. In this case, she can do so by standing in front of the tunnel and watching you walk into one of the entrances and come out of the other. This way, she will be satisfied that you really know the secret code. Advanced Zero-Knowledge Proof Example Imagine you have a friend who cannot distinguish between red and blue colors. You have two balls on display: one red and one blue. Your friend doesn’t believe, however, that the balls can be distinguished from one another. You want to prove they are different colors without revealing that you have a red and a blue ball. In fact, you don’t want to disclose any information about how you distinguish between them at all. So how do we prove they can be distinguished while revealing zero knowledge about the identification process or defining features? The answer is simple. You ask your friend to hold the two balls behind their back before displaying one. They will then place the ball behind their back and randomly pick (50/50) one of the two to show again. Note that your friend will always know if they have switched the ball. Your friend will then ask you, “Has the ball switched?” before confirming the validity of your answer. After giving your correct answer, your friend may be suspicious that you have guessed. They ask you to do it five additional times, meaning the chance of you having guessed correctly every time in the experiment would be: The chances look slim! To be sure, you and your friend repeat the process 15 times. The chances then of you correctly guessing would be: You would be almost certain the proof is correct at this point. If you and the friend repeat the experiment an infinite amount of times, the chance you would correctly guess every time tends to zero. You have therefore proved to your friend that the balls are distinguishable with zero knowledge on your friend’s side of how this is done. He can, however, accept the finding with confidence. Why Use Zero-Knowledge Proofs? The popularity of zero-knowledge proofs in blockchain and crypto is driven by the increasing demand for privacy and security in digital transactions. With the rise of blockchain technology and cryptocurrency, there is a growing need for a way to verify transactions without revealing sensitive information — a need ZKPs can meet. Zero-knowledge proofs have attracted greater attention and interest in recent years, with many protocols utilizing ZKPs having been launched and major blockchains having built zero-knowledge roll-ups. A clear sign of zero-knowledge proofs’ popularity was seen at the DevCon 2022 conference, where over 20% of all talks were about this technology. Key Developments One key development in zero-knowledge proofs is the increased use of zk-SNARKs, a specific type of ZKP. zk-SNARKs have been widely adopted in various DeFi applications, such as private token transactions and shielded lending and borrowing. Another major development in zero-knowledge proofs is the increased focus on scalability and performance via zk-rollups. zk-SNARKs Zero-knowledge succinct non-interactive argument of knowledge (zk-SNARKs) is a specific type of zero-knowledge proof that allows a statement to be verified without revealing any information about the statement itself. zk-SNARKs have been already used on applications such as Zcash and JP Morgan Chase’s blockchain-based payment system. It’s also been used as a way to securely authenticate clients to servers. Zk-Rollups Zk-rollups are a scaling solution for blockchain networks that facilitates the batching of multiple transactions into a single, larger transaction that is then recorded on the blockchain. For example, BNB Chain launched its zkBNB testnet built on zk-rollup architecture in 2022. zkBNB can bundle hundreds of transactions into a single batch off-chain and generate a cryptographic proof to prove the validity of all the transactions. zk-rollups provide a balance between scalability and security and are suitable for high-scale, low-latency settings. Use Cases For Zero-Knowledge Proofs Zero-knowledge proofs have many use cases, some of which have already been realized; others are expected to become a reality in the future. Some major ZKP use cases include: Digital identity verification Zero-knowledge proofs can be used to verify the identities of users without revealing any sensitive personal information. This can be useful in applications such as digital voting systems, where the identities of voters must be verified without compromising their anonymity. Privacy-preserving transactions One of the most popular use cases for zero-knowledge proofs in crypto is to enable privacy-preserving transactions. For example, Manta Network’s MantaPay decentralized application (DApp) uses ZKPs to enable users to make transactions on the decentralized exchange (DEX) without revealing their identities or transaction details. This allows users to maintain their privacy while still being able to use the platform for transactions. Shielded transactions Zcash is a cryptocurrency that uses zero-knowledge proofs to enable shielded transactions. In such transactions, sender and recipient addresses, as well as transaction amounts, are obscured from the public blockchain, providing added privacy for users. Tokenization and ownership verification Zero-knowledge proofs can also be used to tokenize assets and verify their proof of ownership. For example, a property can be tokenized and any party can verify its ownership without publicly revealing any other information. Global compliance Some countries have strict regulations regarding the collection and sharing of financial information, which can be difficult for decentralized platforms to comply with. Zero-knowledge proofs can be used to share the required information with regulators while keeping it private from other parties. This can help bridge the gap between decentralized platforms and traditional financial institutions, making it easier for DeFi to comply with regulations in various jurisdictions. The Future of Zero-Knowledge Proofs in Blockchain Zero-knowledge proofs are likely to bring about new technological innovations in future. Some ZKP-related future developments worth paying attention to include: Cross-chain privacy layers As the blockchain and DeFi ecosystems continue to grow and evolve, there is an increasing need for interoperability across different blockchain networks. Cross-chain privacy layers will allow transactions to be conducted on different blockchain networks while preserving the privacy of the parties involved. zk-STARKs Another area to watch out for is the increased use of zk-STARKs (zero-knowledge scalable transparent argument of knowledge), a newer type of zero-knowledge proof that is considered more efficient and secure than zk-SNARKs. Another advantage of zk-STARKs over zk-SNARKs is that the former are faster to verify and do not require a trusted set-up. User-friendly toolkits Zero-knowledge proof technology can be complex, and not every development team has expertise in this particular area of cryptography. User-friendly ZKP toolkits can help bridge this gap and make it easier for developers of different backgrounds to use the technology. Limitations of Zero-Knowledge Proofs Zero-knowledge proofs represent a unique method of verifying the truth of information while preserving privacy, but they don’t provide a 100% guarantee. While the probability of verification when the prover is lying is negligible, users should be aware that ZKPs are not bullet-proof. In addition, algorithms used by zero-knowledge proofs need intense computational resources. In some types of ZKPs, intensive computing is necessary because they require many interactions between verifiers and provers. In others, the algorithms are extremely computationally intense, which could potentially limit ZKPs’ applications. Closing Thoughts Zero-knowledge proofs are rapidly gaining attention because of their unique properties of privacy preservation and scaling potential. The increasing application of this technology in blockchain, cryptocurrency, and DeFi will likely bring more innovative services that greatly benefit users. Zero-knowledge proofs are expected to play a crucial role in creating DApp ecosystems that are more secure, private, and efficient. Further Reading zk-SNARKs and zk-STARKs Explained Blockchain Layer 1 vs. Layer 2 Scaling Solutions

本文是社区提交的文章。作者是 Kenny Li，Manta Network 的联合创始人，Manta Network 是一种由零知识证明技术支持的可编程隐私第一层协议。
本文中的观点属于贡献者/作者，并不一定反映币安学院的观点。
长话短说
零知识证明（ZKP）是一种密码技术，可以在不泄露信息本身的情况下验证一条信息的真实性。它已成为区块链、加密货币和去中心化金融（DeFi）领域日益重要的技术，用于增强隐私和安全性。
许多 DeFi 项目已经在使用 ZKP 为用户的借贷和交易等服务提供更好的隐私和安全性。许多第 1 层区块链正在添加基于 ZKP 的汇总或 zkEVM。零知识证明预计将在区块链和 Web3 领域发挥越来越重要的作用，因为它们的应用预计将得到更广泛的采用。
零知识证明如何工作？零知识证明是一种方法，通过该方法，一方（证明者）可以向另一方（验证者）证明某个陈述是真实的，而无需透露任何附加信息。当信息敏感并且证明者不希望验证者访问它时，这特别有用。
证明者提供只有他们才能生成的数学证明，验证者可以使用该证明来验证陈述的真实性。然而，他们无法使用证据来重建原始信息。
想象一条有两个入口 A 和 B 的隧道。有一扇上锁的门，上面有密码，封锁了唯一的路径，阻止人们从隧道的一端走到另一端（A 到 B）。您知道密码并想将其卖给想要进入隧道的 X 女士。
您希望她在向她透露代码之前先付款，但她首先希望您证明您确实知道该代码。在这种情况下，她可以站在隧道前，看着你走进一个入口并从另一个入口出来。这样，她就会对你确实知道密码感到满意。
高级零知识证明示例想象一下你有一个朋友无法区分红色和蓝色。您展示了两个球：一红一蓝。然而，你的朋友不相信这些球可以彼此区分。您想要证明它们是不同的颜色，而又不想透露您有一个红色和一个蓝色的球。事实上，您根本不想透露任何有关如何区分它们的信息。
那么，我们如何证明它们可以被区分，同时揭示有关识别过程或定义特征的零知识呢？答案很简单。您要求您的朋友在展示其中一个之前将两个球放在背后。然后，他们会将球放在背后，并随机选择 (50/50) 两个球之一再次展示。请注意，您的朋友将始终知道他们是否换了球。
然后你的朋友会问你：“球换了吗？”在确认您的答案的有效性之前。在给出正确答案后，你的朋友可能会怀疑你猜对了。他们要求你再做五次，这意味着你在实验中每次都猜对的机会是：
机会看起来很渺茫！可以肯定的是，您和您的朋友重复这个过程 15 次。那么你猜对的机会是：
此时，你几乎可以肯定证明是正确的。如果你和朋友重复实验无数次，你每次猜对的几率就会趋于零。
因此，你已经向你的朋友证明，这些球是可以区分的，而你的朋友对此的了解为零。然而，他可以自信地接受这一发现。
为什么使用零知识证明？数字交易中对隐私和安全的需求不断增长，推动了区块链和加密货币中零知识证明的流行。随着区块链技术和加密货币的兴起，人们越来越需要一种在不泄露敏感信息的情况下验证交易的方法——ZKP 可以满足这一需求。
近年来，零知识证明引起了越来越多的关注和兴趣，许多使用 ZKP 的协议已经推出，主要区块链也构建了零知识汇总。在 DevCon 2022 大会上，零知识证明的受欢迎程度得到了明显体现，超过 20% 的演讲都是关于这项技术的。
主要进展零知识证明的一个关键发展是 zk-SNARK（ZKP 的一种特定类型）的使用增加。 zk-SNARK 已广泛应用于各种 DeFi 应用中，例如私人代币交易和屏蔽借贷。零知识证明的另一个重大发展是通过 zk-rollups 更加关注可扩展性和性能。
zk-SNARK零知识简洁非交互式知识论证（zk-SNARKs）是一种特定类型的零知识证明，它允许在不透露有关陈述本身的任何信息的情况下验证陈述。
zk-SNARK 已用于 Zcash 和摩根大通基于区块链的支付系统等应用程序。它还被用作向服务器安全地验证客户端身份的一种方法。
Zk-RollupsZk-rollups 是区块链网络的扩展解决方案，有助于将多个交易批处理为单个更大的交易，然后记录在区块链上。例如，BNB Chain于2022年推出了基于zk-rollup架构的zkBNB测试网。
zkBNB 可以将数百笔交易捆绑到单批链下交易中，并生成密码证明来证明所有交易的有效性。 zk-rollups 在可扩展性和安全性之间提供了平衡，适合高规模、低延迟的设置。
零知识证明的用例零知识证明有很多用例，其中一些已经实现；其他的预计将在未来成为现实。一些主要的 ZKP 用例包括：
数字身份验证零知识证明可用于验证用户身份，而无需泄露任何敏感个人信息。这在数字投票系统等应用中非常有用，因为这些系统必须验证选民的身份，而又不损害他们的匿名性。
保护隐私的交易加密领域零知识证明最流行的用例之一是支持隐私保护交易。例如，Manta Network 的 MantaPay 去中心化应用程序 (DApp) 使用 ZKP 使用户能够在去中心化交易所 (DEX) 上进行交易，而无需透露其身份或交易详细信息。这允许用户维护自己的隐私，同时仍然能够使用该平台进行交易。
屏蔽交易Zcash 是一种使用零知识证明来实现屏蔽交易的加密货币。在此类交易中，发送者和接收者地址以及交易金额在公共区块链中是模糊的，从而为用户提供了更多的隐私。
标记化和所有权验证零知识证明还可用于对资产进行代币化并验证其所有权证明。例如，财产可以被标记化，任何一方都可以验证其所有权，而无需公开透露任何其他信息。
全球合规性一些国家对金融信息的收集和共享有严格的规定，这对于去中心化平台来说可能很难遵守。零知识证明可用于与监管机构共享所需信息，同时对其他方保密。
这有助于弥合去中心化平台和传统金融机构之间的差距，使 DeFi 更容易遵守各个司法管辖区的法规。
区块链零知识证明的未来零知识证明未来很可能带来新的技术创新。一些值得关注的 ZKP 相关未来发展包括：
跨链隐私层随着区块链和 DeFi 生态系统的不断发展和演变，不同区块链网络之间的互操作性需求日益增加。跨链隐私层将允许在不同的区块链网络上进行交易，同时保护相关方的隐私。
零知识证明另一个需要注意的领域是 zk-STARK（零知识可扩展透明知识论证）的使用增加，这是一种新型的零知识证明，被认为比 zk-SNARK 更高效、更安全。 zk-STARKs 相对于 zk-SNARKs 的另一个优点是前者验证速度更快，并且不需要可信设置。
用户友好的工具包零知识证明技术可能很复杂，并不是每个开发团队都拥有这一特定密码学领域的专业知识。用户友好的 ZKP 工具包可以帮助弥合这一差距，并使不同背景的开发人员更轻松地使用该技术。
零知识证明的局限性零知识证明是一种独特的方法，可以在保护隐私的同时验证信息的真实性，但并不能提供 100% 的保证。虽然当证明者撒谎时，验证成功的概率可以忽略不计，但用户应该意识到 ZKP 并非万无一失。
此外，零知识证明使用的算法需要大量的计算资源。在某些类型的 ZKP 中，密集计算是必要的，因为它们需要验证者和证明者之间的大量交互。在其他情况下，算法的计算量非常大，这可能会限制 ZKP 的应用。
结束语零知识证明因其独特的隐私保护和扩展潜力而迅速受到关注。该技术在区块链、加密货币和 DeFi 中的应用越来越多，可能会带来更多创新服务，让用户受益匪浅。零知识证明有望在创建更安全、私密和高效的 DApp 生态系统中发挥至关重要的作用。
进一步阅读zk-SNARK 和 zk-STARK 解释
区块链第 1 层与第 2 层扩展解决方案