What is Zero-Knowledge Proof?

Zero-Knowledge Proof (ZKP) is a cryptographic method that allows a prover to convince a verifier that a statement is true, without revealing any information beyond the truth of that statement.

Picture a familiar situation. A citizen needs to prove they are at least 18 to access an online public service. The traditional way is to present an ID card, which exposes their full name, date of birth, identity number, and address. ZKP lets the system confirm that the citizen is over 18 without knowing the exact date of birth, storing the ID number, or accessing any other data field.

The concept of ZKP was introduced in 1985 by researchers Shafi Goldwasser, Silvio Micali, and Charles Rackoff in the paper “The Knowledge Complexity of Interactive Proof Systems”. Over nearly four decades, ZKP evolved from academic theory into a practical engineering tool, and blockchain became the environment that brought ZKP into large-scale use.

🔑 Read more: What is a Layer 1 blockchain? How it works and its key role in the blockchain ecosystem

The three conditions of a valid Zero-Knowledge Proof

Every ZKP protocol must simultaneously satisfy three foundational properties.

Completeness: if the statement is true, an honest prover always convinces the verifier. The system never rejects a valid proof.

Soundness: if the statement is false, no cheating prover can trick the verifier into accepting it. The probability of successful fraud approaches zero.

Zero-Knowledge: the verifier gains no information beyond the true-or-false conclusion. The entire proving process reveals none of the underlying data.

These three conditions form the mathematical foundation for blockchain security when ZKP is integrated, ensuring data is verified accurately without being exposed.

zk-SNARKs and zk-STARKs: The two main branches of ZKP

In practical deployment on Layer 1 blockchains, the two most common ZKP variants are zk-SNARKs and zk-STARKs.

zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge)

zk-SNARKs produce very small proofs, just a few hundred bytes, and verify extremely fast, making them suitable for high-throughput systems. However, zk-SNARKs require an initial trusted setup. If that step is compromised, the entire system can be threatened.

zk-STARKs (Zero-Knowledge Scalable Transparent Arguments of Knowledge)

zk-STARKs eliminate the trusted setup and replace it with full transparency. Their proofs are larger than zk-SNARKs but are quantum-resistant, a strategic advantage for a platform that must operate for decades. For national Layer 1 infrastructure, zk-STARKs are often preferred for their transparency and long-term security.

How does ZKP work on a Layer 1 blockchain?

On a Layer 1 blockchain, ZKP is integrated at the protocol layer rather than the application layer. This means every transaction and every on-chain verification is protected by ZKP without each application having to implement it separately. The process has four steps.

Commitment: the original data is encoded into a hash commitment stored on-chain. The real data never appears on the blockchain.

Proof generation: the prover uses a ZKP algorithm to create a mathematical proof that the data meets the required condition, without revealing its content.

On-chain verification: a smart contract verifies the proof. This is fast and lightweight because it only checks the math, not the underlying data.

State update: the verification result, valid or invalid, is written to the distributed ledger, immutable and auditable.

This model fully resolves the paradox between transparency and privacy on blockchain: the ledger remains transparent and auditable, while sensitive data stays fully protected.

Applications of ZKP on Layer 1 blockchain

Digital Identity Verification

This is the highest-impact application. With ZKP, a Decentralized Identity (DID) system can verify personal information without storing personal data on-chain. The self-sovereign identity solution NDAKey in the ecosystem is one example of combining DID and ZKP to give users control over their data.

A concrete example: a company needs to verify that an employee holds a valid university degree. Instead of sending a copy of the diploma, the employee presents a Verifiable Credential together with a ZKP proof. The system confirms the degree is valid without the company knowing which school issued it, the GPA, or the graduation year.

🔑 Read more: What is W3C DID? Why the Internet needs a decentralized identity standard

🔑 Read more: What are Verifiable Credentials (VC)?

Data verification and legal compliance

Under Vietnam's Personal Data Protection Law 2025 and Data Law 2024, organizations must ensure data integrity and traceability while protecting privacy. ZKP on a Layer 1 blockchain meets both requirements at once: data is verified for integrity and traced on-chain, while its content stays hidden, protected by ZKP.

Trust is a real business problem. According to PwC's 29th Global CEO Survey, 66% of CEOs said their company experienced stakeholder trust concerns over the past year, on topics such as AI safety, data privacy, and transparency (PwC, 2026). ZKP rebuilds trust through a mathematical mechanism, without relying on the promises or ethical commitments of a third party.

Supply chain traceability

In a supply chain, each participant has data to protect: manufacturers do not want to reveal formulas, distributors do not want to reveal purchase prices, retailers do not want to reveal margins. ZKP lets each party prove a product meets standards for origin, storage temperature, or organic certification without disclosing business data. The traceability platform NDATrace applies this principle to increase supply chain transparency while protecting a company's trade secrets.

On a Layer 1 blockchain, these proofs are recorded immutably, and end consumers can check a product's full journey without any party exposing its trade secrets.

International case studies: ZKP in blockchain infrastructure

EBSI and eIDAS 2.0

The European Union integrates cryptographic-proof principles into digital identity verification under the eIDAS 2.0 standard, Regulation (EU) 2024/1183, in force since May 2024 (EUR-Lex). European citizens use the European Digital Identity Wallet to present verifiable credentials, disclosing only the necessary attributes such as being of age, EU nationality, or a valid driver's license, without revealing their entire personal record. All 27 member states must provide citizens with an identity wallet, running on permissioned blockchain infrastructure and using no digital assets of any kind.

🔑 Read more: What is EBSI? The role of EBSI in Europe's digital infrastructure

🔑 Read more: EUDI Wallet: Is Europe leading the shift to self-sovereign identity?

Estonia: X-Road and Blockchain

Estonia integrated blockchain into its X-Road system in 2012, using cryptographic proofs to protect the integrity of citizen data. Estonia's KSI blockchain proof model demonstrates that national infrastructure can operate blockchain security without storing personal data on-chain, a principle similar to ZKP.

🔑 Read more: Estonia X-Road and KSI: the national blockchain model behind 99% of digitized public services

NDAChain and Zero-Knowledge Proof: digital trust infrastructure for Vietnam

Resolution 57-NQ/TW identifies developing digital infrastructure as a national strategic task. NDAChain, Vietnam's Layer 1 blockchain infrastructure, is designed with ZKP as a core security layer, serving the goals of protecting national data and data sovereignty.

Technical architecture supporting ZKP

NDAChain runs on the PoA-qBFT consensus mechanism with a throughput of about 1,200 transactions per second and is EVM-compatible, with enough capacity to handle large volumes of ZKP verification without congestion. This architecture delivers three advantages.

Fast proof verification: PoA-qBFT finalizes blocks in seconds, ensuring near real-time ZKP responses.

Low verification cost: no volatile gas fees like public blockchains, so costs are predictable and stable.

Ecosystem compatibility: EVM compatibility means ZKP libraries such as Circom, SnarkJS, and Halo2 can be deployed directly on NDAChain.

🔑 Read more: What is PoA-qBFT? The consensus mechanism of NDAChain Layer 1 blockchain

The did:nda identity system and Verifiable Credentials

NDAChain implements the did:nda decentralized identity method, registered in the W3C DID Registry. Combined with ZKP, the system lets individuals present verifiable credentials to prove attributes without exposing raw data, organizations verify information about partners, employees, and suppliers without directly accessing personal databases, and regulators audit compliance without centrally collecting and storing sensitive data.

This model complies with the Personal Data Protection Law 2025: personal data never leaves its source, and only cryptographic proofs are verified on-chain. This is the national data protection principle that NDAChain implements at the protocol layer.

🔑 Read more: Vietnam leads Southeast Asia in international DID interoperability under the W3C standard

ZKP for enterprises on NDAChain

For enterprises, ZKP on NDAChain opens three strategic possibilities.

Non-intrusive compliance: prove compliance with tax, environmental, or origin regulations without exposing internal financial data.

Trustless collaboration: multiple enterprises in a supply chain verify data together without needing to trust one another, because ZKP guarantees correctness mathematically.

Trade-secret protection: join a shared data network without trading away competitive advantage.

The future: ZKP and digital trust infrastructure

ZKP is not just a cryptographic technology, it is the foundation for a new model of trust in the digital economy. Instead of trust based on reputation or institutional power, ZKP builds trust on mathematics: anyone can verify, and no one has to trust blindly.

The Data Law 2024 requires data integrity and traceability. The Personal Data Protection Law 2025 requires privacy protection. NDAChain, with ZKP integrated at the protocol layer, is infrastructure that meets both requirements at once, creating a digital trust foundation on which public services, e-commerce, healthcare, education, and supply chains can operate safely.

🔑 Read more: Decentralized identity: a global trend in the digital era

🔑 Read more: How does Zero-Knowledge Proof (ZKP) work in self-sovereign identity?

NDAChain is ready to accompany agencies, organizations, and enterprises that want to apply Zero-Knowledge Proof to balance transparency, security, and legal compliance. Visit ndachain.vn to discuss the technical architecture and an implementation roadmap that fits your organization.