Hash
Security
Fixed-size digest produced by a cryptographic hash function.
A hash is a fixed length digest of some input. Secure hash functions are one way and collision resistant, which lets systems check integrity and build structures like Merkle trees.
Frequently asked questions
What makes a good hash function?
Preimage resistance, collision resistance, and fast computation. Popular choices include SHA-256 and Keccak.How are hashes used on blockchains?
To link blocks, build Merkle trees, and verify data integrity without sharing the whole dataset.Can two inputs share the same hash?
Collisions are theoretically possible but impractical with secure functions at typical sizes.