# Understanding zkSync: What are Zero Knowledge Proofs? By [spacesmutje](https://paragraph.com/@spacesmutje) ยท 2024-06-03 --- Zero-knowledge proofs (ZKPs) are cryptographic methods that allow one party (the prover) to prove to another party (the verifier) that a statement is true without revealing any additional information beyond the validity of the statement itself. This concept was first introduced in a 1985 paper by Shafi Goldwasser, Silvio Micali, and Charles Rackoff\[11\]\[19\]. ### Key Properties of Zero-Knowledge Proofs 1. **Completeness**: * If the statement is true, an honest verifier will be convinced by an honest prover that the statement is true\[11\]\[13\]\[16\]. 2. **Soundness**: * If the statement is false, no dishonest prover can convince an honest verifier that it is true, except with some small probability\[11\]\[13\]\[16\]. 3. **Zero-Knowledge**: * If the statement is true, the verifier learns nothing other than the fact that the statement is true. This ensures that no additional information about the statement is revealed\[11\]\[13\]\[16\]. ### Types of Zero-Knowledge Proofs 1. **Interactive Zero-Knowledge Proofs**: * These require multiple rounds of interaction between the prover and the verifier. The verifier sends challenges to the prover, who responds with proofs. This process continues until the verifier is convinced of the prover's knowledge\[7\]\[13\]\[18\]. 2. **Non-Interactive Zero-Knowledge Proofs (zk-SNARKs)**: * These do not require ongoing interaction between the prover and verifier. The prover generates a proof that can be verified by the verifier in a single step. zk-SNARKs are known for their succinctness and efficiency but often require a trusted setup\[7\]\[13\]\[14\]. 3. **zk-STARKs**: * These are similar to zk-SNARKs but do not require a trusted setup and are resistant to quantum computing attacks. They tend to produce larger proofs but offer enhanced security\[12\]\[14\]. ### Applications of Zero-Knowledge Proofs 1. **Blockchain and Cryptocurrencies**: * ZKPs are used to enhance privacy and scalability in blockchain networks. For example, Zcash uses zk-SNARKs to enable shielded transactions, where transaction details are hidden while still being verified as valid\[5\]\[13\]\[17\]. 2. **Identity Verification**: * ZKPs allow individuals to prove their identity or certain attributes (e.g., age, citizenship) without revealing sensitive personal information. This is useful for compliance with regulations like KYC (Know Your Customer) and AML (Anti-Money Laundering)\[3\]\[7\]\[17\]. 3. **Secure Authentication**: * ZKPs can be used in authentication systems to verify user credentials without transmitting passwords or other sensitive data. This reduces the risk of data breaches and identity theft\[2\]\[7\]\[15\]. 4. **Privacy-Preserving Computation**: * ZKPs enable secure data sharing and computation on private data without revealing the data itself. This is valuable in scenarios like secure voting systems, confidential financial transactions, and privacy-preserving data analysis\[7\]\[12\]\[20\]. ### How Zero-Knowledge Proofs Work A zero-knowledge proof typically involves the following steps: 1. **Commitment**: * The prover commits to a secret value without revealing it to the verifier. 2. **Challenge**: * The verifier sends a random challenge to the prover. 3. **Response**: * The prover computes a response based on the challenge and the secret information. 4. **Verification**: * The verifier checks if the response is consistent with the commitment and challenge without learning any information about the secret itself\[7\]\[9\]\[16\]. In summary, zero-knowledge proofs are powerful cryptographic tools that enable the verification of information without revealing the information itself. They have broad applications in enhancing privacy, security, and efficiency across various digital systems, particularly in blockchain and Web3 technologies. [Subscribe](null) Citations: \[1\] [https://chain.link/education-hub/zero-knowledge-proof-projects](https://chain.link/education-hub/zero-knowledge-proof-projects) \[2\] [https://info.cs.st-andrews.ac.uk/student-handbook/files/project-library/cs4796/gf45-Final\_Report.pdf](https://info.cs.st-andrews.ac.uk/student-handbook/files/project-library/cs4796/gf45-Final_Report.pdf) \[3\] [https://www.coindesk.com/consensus-magazine/2024/01/11/what-are-zero-knowledge-proofs/](https://www.coindesk.com/consensus-magazine/2024/01/11/what-are-zero-knowledge-proofs/) \[4\] [https://eprint.iacr.org/2024/050.pdf](https://eprint.iacr.org/2024/050.pdf) \[5\] [https://koinly.io/de/crypto-glossary/zero-knowledge-proof/](https://koinly.io/de/crypto-glossary/zero-knowledge-proof/) \[6\] [https://crypto.stackexchange.com/questions/10595/when-would-one-prefer-a-proof-of-knowledge-instead-of-a-zero-knowledge-proof](https://crypto.stackexchange.com/questions/10595/when-would-one-prefer-a-proof-of-knowledge-instead-of-a-zero-knowledge-proof) \[7\] [https://www.hypersign.id/blogs/tpost/oyeti7uia1-zero-knowledge-proof-types-advantages-us](https://www.hypersign.id/blogs/tpost/oyeti7uia1-zero-knowledge-proof-types-advantages-us) \[8\] [https://www.cryptoblogs.io/zero-knowledge-proofs/](https://www.cryptoblogs.io/zero-knowledge-proofs/) \[9\] [https://ethereum.org/en/zero-knowledge-proofs/](https://ethereum.org/en/zero-knowledge-proofs/) \[10\] [https://www.circularise.com/blogs/zero-knowledge-proofs-explained-in-3-examples](https://www.circularise.com/blogs/zero-knowledge-proofs-explained-in-3-examples) \[11\] [https://en.wikipedia.org/wiki/Zero-knowledge\_proof](https://en.wikipedia.org/wiki/Zero-knowledge_proof) \[12\] [https://cointelegraph.com/learn/zero-knowledge-proofs-vs-transparent-blockchain](https://cointelegraph.com/learn/zero-knowledge-proofs-vs-transparent-blockchain) \[13\] [https://cointelegraph.com/explained/zero-knowledge-proofs-explained](https://cointelegraph.com/explained/zero-knowledge-proofs-explained) \[14\] [https://hacken.io/discover/zero-knowledge-proof/](https://hacken.io/discover/zero-knowledge-proof/) \[15\] [https://research.aimultiple.com/zero-knowledge-proofs/](https://research.aimultiple.com/zero-knowledge-proofs/) \[16\] [https://chain.link/education/zero-knowledge-proof-zkp](https://chain.link/education/zero-knowledge-proof-zkp) \[17\] [https://chain.link/education-hub/zero-knowledge-proof-use-cases](https://chain.link/education-hub/zero-knowledge-proof-use-cases) \[18\] [https://www.geeksforgeeks.org/zero-knowledge-proof/](https://www.geeksforgeeks.org/zero-knowledge-proof/) \[19\] [https://www.forbes.com/sites/forbestechcouncil/2023/02/07/what-are-zero-knowledge-proofs/](https://www.forbes.com/sites/forbestechcouncil/2023/02/07/what-are-zero-knowledge-proofs/) \[20\] [https://www.zeeve.io/blog/practical-use-cases-of-zero-knowledge-proofs/](https://www.zeeve.io/blog/practical-use-cases-of-zero-knowledge-proofs/) --- *Originally published on [spacesmutje](https://paragraph.com/@spacesmutje/understanding-zksync-what-are-zero-knowledge-proofs)*