Glossary
Digest (Hash Value)
A digest is the fixed-size output of a hash function — also called a hash value, hash, or message digest. The same input always produces the same digest.
A digest is the output of a hash function — also called a hash value, hash, or message digest. Whatever the size of the input, the digest has a fixed length determined by the algorithm: 128 bits for MD5, 256 bits for SHA-256, 512 bits for SHA-512, and so on.
Key properties of a digest from a good cryptographic hash:
- Deterministic — the same input always yields the same digest.
- Fixed size — independent of input length.
- Avalanche — a one-bit input change produces a completely different digest (see the avalanche effect).
- One-way — you cannot recover the input from the digest (see preimage resistance).
Digests are usually shown as hexadecimal, but the underlying value is just bytes. Generate digests for any text or file in your browser, or read how cryptographic hashing works.