Zero-knowledge proofs (ZK-proofs) are cryptographic protocols that allow one party (the prover) to prove the truth of a statement to another party (the verifier) without revealing any additional information beyond the validity of the statement itself. In other words, a zero-knowledge proof demonstrates knowledge or possession of certain information without revealing the information itself. The key features of zero-knowledge proofs are:
- Completeness: If the statement is true, an honest prover can convince an honest verifier of its truth with overwhelming probability.
- Soundness: If the statement is false, no prover, even if malicious, can convince a verifier of its truth, except with negligible probability.
- Zero-knowledge: The proof should not reveal any information beyond the statement's validity. Even after interacting with the prover and receiving the proof, the verifier should not gain additional knowledge about the underlying witness or secret information.
Despite being decades old, zero-knowledge proofs have only recently become practical for real-world use in finance. The implications of the technology are enormous: ZKPs can maintain blockchains’ accuracy and make scalability possible with ease and precision. Users can also know with complete clarity how their data is utilized, while only needing to share what’s absolutely necessary for a given transaction.
Zero-knowledge proofs have various applications, including:
- Authentication and identification: Zero-knowledge proofs can allow users to authenticate or identify themselves to a party without revealing any personally identifiable information.
- Privacy-Preserving transactions: Zero-knowledge proofs can be used to prove the correctness of a transaction or computation without revealing the inputs or intermediate values involved.
- Secure Multi-Party Computation (MPC): Zero-knowledge proofs can enable multiple parties to perform joint computations on their private inputs without revealing the inputs to each other.
- Blockchain and cryptocurrencies: Zero-knowledge proofs are widely used in blockchain and cryptocurrency systems to enhance privacy, improve scalability, and verify the correctness of transactions without exposing sensitive information. Zero-knowledge proofs provide potent tools for cryptographic protocols, allowing for secure and private interactions between parties while maintaining confidentiality and integrity. With ZKPs, users no longer need to re-execute every transaction in a ledger, as they can instead check a succinct proof.