Hash generator (MD5, SHA-256 and more)

What is a hash?

A hash function turns any text into a fingerprint of fixed length. The same text always gives the same hash, but change one character and the hash is completely different. You can't turn a hash back into the text. Hashes are used to check that a download or message hasn't changed, or to compare data without storing it.

Every space and line break counts: "hello" and "hello " give different hashes. The text is hashed as UTF-8, just like sha256sum or PHP's hash().

Which algorithm?

• SHA-256 is the standard for checksums, APIs and blockchains.
• SHA-384 and SHA-512 are longer members of the same family.
• MD5 and SHA-1 are still fine for spotting a corrupted file, but they are no longer safe against deliberate forgery. Don't use them for passwords or signatures.

Passwords should never be stored with a plain hash anyway, but with a slow function such as bcrypt or Argon2.

HMAC with a key

With HMAC, a secret key is mixed into the hash. Only someone who knows the key can produce the same code; that is how webhooks from payment providers prove a message really came from them. Hash each line separately gives one hash per line, handy for a list of e-mail addresses or IDs.