A technology that allows someone to prove something is true without revealing any details about it. It's used to make transactions more private.
zk-SNARKs stands for "Zero-Knowledge Succinct Non-Interactive Argument of Knowledge." It is a type of cryptographic proof that allows one party to prove they possess certain information without revealing that information.
To understand zk-SNARKs, imagine a puzzle that you have the solution to. A regular proof would require you to show someone the solution to prove you have it. A zero-knowledge proof would allow you to prove that you have the solution without revealing what the solution is. The other party would be convinced that you have the solution without learning anything about it.
A zk-SNARK is a specific, highly efficient type of zero-knowledge proof.5 It is "succinct," meaning the proof is small and can be verified quickly.6 It is "non-interactive," meaning the proof can be generated once and verified by anyone without a back-and-forth dialogue.7 This makes it ideal for use on a blockchain. The "argument of knowledge" part means that it is computationally sound and that a malicious actor cannot create a fake proof without having the secret information.
zk-SNARKs have a variety of uses in cryptocurrency and Web3, most notably in a ZK-Rollup and in privacy coins like Zcash. In a ZK-Rollup, the zk-SNARK is the "validity proof" that ensures all the off-chain transactions are legitimate without having to post all of the transaction data to the main chain. This dramatically reduces fees and increases speed.
In privacy coins, zk-SNARKs allow a user to prove they have the funds for a transaction without revealing the sender, the recipient, or the amount of the transaction.8 The proof is used to show that a transaction is valid and that the user has the funds, but all the sensitive information is hidden from the public.9
zk-SNARKs are a foundational technology for a new era of privacy and scalability in the digital world. By allowing for the validation of information without revealing any sensitive data, they have unlocked the potential for a more secure, efficient, and private internet.