Skip to main content

Hash

cryptography
security

A fixed-size digest produced by a one-way function, used for data integrity, identifiers, signatures, and proof-of-work.

Also known as
cryptographic hash
digest
message digest
1
concept

A cryptographic hash function maps any input to a fixed-size output called a hash or digest. The same input always produces the same hash, while a tiny input change should produce an unrelated-looking result.

2
properties

Useful hash functions are preimage-resistant, second-preimage-resistant, collision-resistant, fast to verify, and well distributed. Hashing is not encryption: a hash is designed for verification, not recovery of the original message.

3
uses

Blockchains use hashes to link blocks, summarize transaction sets, derive identifiers, and define proof-of-work targets. Wallet software also hashes transaction data before signing it.

Conceptual links

Related terms

3 linked

Explore connected entries beyond the alphabetical index.

All terms and definitions may update as the Cryptionary improves.