Zero-knowledge proof is an encryption technology, which is short for “Zero-Knowledge Succinct Non-Interactive Argument of Knowledge”. It allows “proof providers” to mathematically prove to “verifiers” the accuracy of information without revealing anything other than its authenticity and integrity.
Filecoin is currently the largest zero-knowledge proof network. How does it use zero-knowledge proof? Verifying storage on Filecoin involves two proofs: Proof of Replication (PoRep) and Proof of Spacetime (PoSt).
In Proof of Replication, the storage providers need to certify that they are storing a unique copy of a piece of data or information. Proof-of-replication only happens once when a storage transaction occurs between a client and a provider, and the data is stored by a miner for the first time. Each on-chain proof-of-replication consists of 10 individual SNARKs (Succinct Non-Interactive Argument of Knowledge) that collectively prove that the process is correctly done through a probabilistic challenge.
However, Proof-of-Spacetime is used to prove that the original data continues to be stored by the storage provider over time, without being manipulated or corrupted in the meantime. When a storage provider first agrees to store data for a client, they must stake FIL as collateral. If providers fail to provide Proof of Spacetime at any time during the agreement, they will be penalized and may lose all or part of their staked FIL.
Proof of Replication and Proof of Spacetime take up a large amount of network bandwidth and bring high operational costs for storage providers and miners. But now, storage providers can use zero-knowledge proofs to reduce costs, which can generate a small size of proof packets and increase verification speed. Proofs that typically require hundreds of KB to verify can be compressed to just 192 bytes using zero-knowledge proofs. So, each Proof of Replication contains 10 SNARKs, which is 1920 bytes (10192 bytes). In this way, Filecoin can continuously maintain the block generation time at 30 seconds.
Zero-knowledge proof is an important tool that has been used since the Filecoin mainnet was launched. It has been a part of the Filecoin network and plays a vital role in the future development of an efficient, economical, and secure network. It changed the rules of the Filecoin network, greatly shortened the verification process, and ensured that the Filecoin network is trusted by users.