...by Daniel Szego
"On a long enough timeline we will all become Satoshi Nakamoto.."
Daniel Szego

Sunday, March 19, 2023

Zero knowledge proof (ZKP)


Zero knowledge proof (ZKP) is a cryptographic protocol that allows one party to prove to another party that a particular statement is true, without revealing any other information apart from the fact that the statement is indeed true. In other words, it is a method of demonstrating knowledge of a secret without revealing the secret itself.

ZKP involves three parties: the prover, the verifier, and a trusted setup (depending on the ZKP there might be non-trsuted setups as well). The prover wishes to prove a statement to the verifier, without revealing any additional information beyond the truth of the statement. The trusted setup is responsible for generating a set of parameters that the prover and verifier will use to perform the proof.

ZKP is used in many applications, including password authentication, digital signatures, and privacy-preserving systems such as anonymous cryptocurrencies. For example, in a cryptocurrency like Zcash, ZKP is used to prove that a transaction is valid without revealing the details of the transaction, such as the amount or the sender's identity.

One common example of a ZKP is the "graph isomorphism problem," which involves two graphs and proving that they are the same without revealing any information about the graphs themselves. Another example is proving that you know a password without actually revealing the password itself.

Overall, ZKP is a powerful tool in cryptography that enables secure and private communication between parties while preserving confidentiality.

Zero knowledge proofs (ZKP) are increasingly being used in blockchains for various purposes, such as enhancing privacy, scalability, and security. Here are some of the ways ZKP is used in blockchains:

  • Privacy-Preserving Transactions: One of the most popular use cases of ZKP in blockchains is for privacy-preserving transactions. In some blockchains, such as Zcash and Monero, ZKP is used to prove that a transaction is valid without revealing any sensitive information, such as the sender's identity or the transaction amount. This helps to preserve the privacy of the users while still maintaining the integrity of the blockchain.
  • Scalability: Another application of ZKP in blockchains is to improve scalability. One of the challenges with blockchains is that the more data they contain, the slower they become. With ZKP, it is possible to prove that certain transactions are valid without including all the details in the blockchain. This reduces the size of the blockchain and makes it faster.
  • Access Control: ZKP can also be used for access control in blockchains. For example, in a permissioned blockchain, only certain users may have access to certain parts of the network. With ZKP, it is possible to prove that you have the right to access a certain part of the network without revealing any sensitive information.
  • Auditing: ZKP can also be used for auditing purposes. For instance, it is possible to prove that certain transactions have occurred without revealing the identities of the parties involved. This can be useful for auditing purposes, particularly in industries such as finance, where transparency is critical.

Overall, ZKP is a powerful tool for enhancing the privacy, scalability, security, and auditability of blockchains. As such, it is likely to become even more prevalent in the future development of blockchain technology.