Zero-Knowledge Proof (ZKP) Applications: How and Where?

Zero-Knowledge Proof (ZKP) is widely used in the modern digital world as it unlocks unique opportunities for privacy, security, and verification. We previously covered ZKP and its mechanisms. 

Now let’s dig deeper into the practical application of ZKP and look at the areas where it’s already being actively used, as well as some successful blockchain projects based on ZKP.

Cryptocurrencies 

ZKP technologies are most frequently used in cryptocurrency projects with a high level of privacy. Some of them are:

• Zcash (ZEC). Established in 2016, this project was designed to ensure the full privacy of transactions on the blockchain. Zcash is based on the Zerocash protocol, which utilizes the ZKP technology. Due to it, transactions with ZEC can be completely hidden from prying eyes while still being subject to verification by the network to guarantee security and consensus compliance.
• Monero (XMR). This crypto project relies on the Ring Confidential Transactions (RingCT) cryptographic protocol based on ZKP, which can hide the identities of a sender and a recipient and the number of transactions. ZKP in this project allows for the creation of “ring signature” transactions, where multiple random addresses can be combined to become the senders of a transaction. This makes it impossible to determine exactly which address initiated the transaction, thus ensuring anonymity.
• Beam (BEAM). This crypto project is based on the Mimblewimble protocol, which utilizes ZKP to provide complete confidentiality of transactions. Thanks to ZKP, the addresses and amounts of transactions using BEAM can be hidden, and the blockchain has a compact size.

Verge (XVG). This crypto project is built on several different privacy protocols at once. Verge uses TOR (The Onion Router), I2P (Invisible Internet Project), and ZKP protocols to provide the highest level of anonymity and protection of user privacy. ZKP within this project allows users to choose between public and private transactions.

DeFi Protocols

ZKP is used to secure the confidentiality of financial transactions. For example, a user can prove that they have enough funds for a certain transaction without disclosing their exact balance. This can be applied to verify the solvency of a creditor, the authenticity of online payments, or audits of financial transactions.

A prime example of such a platform is Pasha Funding, which uses ZKP to verify a creditor’s solvency and allows users to securely and discreetly transfer funds without disclosing the amount or source of money.

“This technology helps to ensure that our users’ data is secure and private and that their transactions are safe and secure,” assures Julia Mathers, Head of Marketing at Pasha Funding. 

ZKP technologies are also particularly in demand in the financial sector as part of the development of decentralized applications and platforms. Here are some examples:

• ZKSwap. A Layer 2 protocol for Ethereum that allows users to remain completely anonymous thanks to ZKP and solves the problems of high fees and slow transaction processing on the network.
• Aztec. A protocol for conducting sensitive financial transactions on the Ethereum network. Aztec enables the creation of “secure” tokens — zkAssets, the transfer of which is verified by ZKP without disclosing the exact amounts or addresses of senders and recipients.
• Tornado Cash. A decentralized crypto mixer that uses ZKP to mix funds from different users before making transactions. The technology ensures that once funds are sent to the project’s smart contracts, their origin is virtually untraceable.

Medicine 

ZKP technologies are widely used to keep patients’ medical data confidential. For instance, a patient can prove the presence of a certain disease without revealing all the details of their medical record. This can be helpful when conducting research and sharing medical data between doctors or insurance companies.

Examples of projects that use ZKP to provide medical data privacy:

• MedCo. A project for medical research that uses ZKP to ensure a high level of privacy and security for patient data involved in research. The project enables data analytics without disclosing the personal information of individuals participating in the study.
• MediLedger. A blockchain initiative designed to optimize and provide transparency in the pharmaceutical industry. The project utilizes ZKP to enable the exchange of information about medical products between various participants in the pharmaceutical supply chain. ZKP also provides mechanisms for data verification like supply history, the origin of medical products, the authenticity of their manufacturers, and other important details without disclosing personal information or trade secrets.
• Medicalchain. A blockchain project for sharing medical data between patients and healthcare providers. With ZKP, patients can store their medical data in encrypted form and share it only with selected institutions and doctors.
• ProCredEx. A platform for medical data exchange and accreditation management in the medical industry.

Identification Systems

ZKP ensures identity verification and authentication in digital identification systems. For example, ZKP can prove that a person is of legal age when registering on a website or confirm their identity when interacting with government services with no need to disclose personal data or identification documents.

Here are some examples of projects that use ZKP in identification systems:

• Civic. The project provides users with a digital identification for the blockchain space that, thanks to ZKP technologies, eliminates the need to undergo KYC or authenticate one’s identity. 
• iden3. A project that develops private identification and authentication systems and other digital privacy solutions powered by the ZKProofs protocol based on ZKP.
• Serto. A digital identification platform based on the Ethereum blockchain network. Users have full control over their personal data and can authenticate to various services without centralized intermediaries.
• SelfKey. A decentralized identification platform that allows users to perform authentication without revealing full personal information.
• Ontology. A platform for creating decentralized identity solutions that uses ZKP to provide secure and reliable authentication for users without having to disclose personal information.
• FNZ. A ZKP-based digital identity solution through which users can prove their identity in online services by disclosing only the necessary information for verification.
• Sovrin. An open identification network based on ZKP technologies, thanks to which users have full control over their personal data.

Data Exchange

ZKP is not only used to enable confidential data sharing on blockchain networks but also serves as an effective means of scaling them by reducing the amount of data that needs to be transferred and stored. George Smith, Digital Marketing and PR Executive at DuoCall MSP and InfiSIM, said:

“ZKPs can drastically minimize the amount of data that needs to be transferred between shards in protocols like sharding, where transactions are processed in parallel across numerous shards.”

These are several examples of projects using ZKP to enable confidential data exchange on blockchain networks:

• Oasis Labs. A cloud computing blockchain platform that utilizes ZKP to protect data privacy and enable secure information sharing between participants, making it possible to create dApps with a high level of privacy.
• Aleo. A service that allows users to use ZKP-based smart contracts for data exchange without disclosing their contents and developers to create fully anonymous blockchain apps.
• Incognito. With the use of ZKP, users can anonymously transfer assets between different blockchains without revealing their personal information.
• RAILGUN. A protocol for confidential data exchange, the essence of which is to build parallel networks for transactions using zero-proof principles.

Voting and Elections

ZKP ensures anonymity and security in electronic voting systems. A participant can prove that they’re eligible to vote and vote correctly without revealing their identity or the candidates chosen. This helps to prevent manipulation and ensure the integrity of the vote.

Here are some examples of such platforms:

• Horizon State. A platform for anonymous voting and collective decision-making, where ZKP ensures the anonymity of votes and authenticity of results.
• Follow My Vote. A platform for anonymous and transparent elections that uses ZKP protocols to ensure voter anonymity and authenticate results.
• Agora. A blockchain platform for anonymous online voting that uses ZKP to confirm data integrity.
• SecureVote. A platform that encrypts voter data and authenticates it, after which it can remain completely anonymous.
• Voatz. An electronic voting platform that uses ZKP to protect the privacy of voter information.
• Helios Voting. An electronic voting system that uses ZKP to encrypt votes so that voter personal information remains private, however, the data can be verified.

Online Auctions

ZKP protects the privacy of bidders and auction results. Participants can prove their ability to pay the winning bid without revealing their actual bid or personal data. This ensures anonymity and protection from possible manipulation.

The following are examples of projects that use ZKP to secure the privacy of participants and auction results:

• Bounce Finance. A decentralized blockchain auction platform.
• OpenSea. A major NFT marketplace that uses ZKP to protect participant information and auction results, ensuring privacy and security in the trading process.

Access to Databases

ZKP provides privacy for database requests. Users can prove they have the right to access certain data without revealing the data itself or their identity.

For example, the Seven Marketing project uses ZKP to perform complex data analysis, protecting the data on the one hand and building trust in the information on the other. 

“Our ZKP integration empowers secure and confidential data sharing across international e-commerce partners, large-scale software firms, and renowned sports entities, all while upholding the highest privacy standards,” assures Chris Stott, Director of Seven Marketing.

Another example of a platform that utilizes ZKP to ensure the privacy of database requests is EY OpsChain. The project’s ZKP technologies manage supply chains and other tokenization-enabled business processes.

Recommendation Systems

ZKP is used to protect user personal preferences on online platforms where personalized recommendation of content or products is performed. Users can prove that they match certain characteristics or preferences without revealing details about their personal interests.

Here are some examples of projects and recommendation systems that can utilize zero-knowledge proof (ZKP) technology:

• AdEx. A decentralized advertising platform that applies ZKP for anonymous analytics and ads tailored to users’ interests.
• Recombee. An AI-based personalized recommendation system.

Machine Learning Systems

When processing data in machine learning systems, ZKP ensures that privacy is respected. For example, ZKP allows users to verify the correctness of model training without revealing the data on which the training is performed.

For example, IBM Research is actively testing this technology as part of its research on homomorphic encryption and its application in machine learning. The experiments involve analysts testing computations using data encrypted with ZKP.

The MPC Alliance, a global community working on multi-party computation (MPC) protocols in machine learning, is also actively using ZKP technologies for privacy.

Another example of ZKP being used in such systems is PySyft, a library for secure and privacy-preserving distributed machine learning developed by the OpenMined community. ZKP within the project provides data and model security.

To sum up, it’s worth noting that the scope of the practical application of ZKP technologies goes beyond the given examples and projects as their potential opens up a huge variety of use cases for developers. In fact, any ecosystem that requires privacy can successfully implement ZKP and secure its users.