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Definition

What is Hash Function?

A hash function maps any input — a password, a file, a message — to a fixed-length string that acts as a fingerprint of the original.

Also called: cryptographic hash · MD5 · SHA-256

Good cryptographic hashes (SHA-256, SHA-3, BLAKE3) are one-way: given the digest, you can't recover the input. They're also collision-resistant — finding two different inputs with the same hash should be computationally infeasible.

Hashes power password storage (with a salt and a slow function like bcrypt or Argon2), file-integrity checks, Git commit IDs, blockchain proofs, and HMAC signatures.

Older algorithms like MD5 and SHA-1 are broken for security use. They still work for non-adversarial checksums, but never for anything that could be attacked.

Try a tool that uses Hash Function

Hash Generator

Compute SHA-1, SHA-256, SHA-384, and SHA-512 hashes.

Password Generator

Create strong random passwords with custom rules.

JWT Decoder

Decode JWT header and payload claims safely in your browser.

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