PBKDF2 Key Generator
Derive a key from a passphrase with PBKDF2 and the iterations you choose. Free, and runs entirely in your browser — nothing is uploaded.
About Key Derivation
A passphrase is not a key: it is short, guessable and drawn from a small alphabet. A key derivation function turns one into key material by being deliberately expensive — so an attacker who steals the stored result has to pay that cost again for every guess.
Four functions, and the choice matters more than the parameters. Argon2id is the current recommendation: it costs both time and memory, which is what defeats a machine built for cracking. scrypt is the older memory-hard option and a good answer where Argon2 is unavailable. PBKDF2 is what standards and compliance regimes still name, and it resists a faster processor but not a wider one — a GPU runs thousands of copies in parallel. HKDF is the odd one out: it expands a secret that is already unguessable, and must never be handed a password.
The time the derivation took in this browser is reported, because that is the number that matters: it is roughly what one guess costs an attacker with similar hardware. The findings underneath say whether the settings meet the guidance of the day — 600,000 iterations for PBKDF2-SHA256, 19 MiB and two passes for Argon2id.
Everything happens in this tab: the passphrase is never sent anywhere, and neither is the key that comes out.
Where it helps
- Argon2id, scrypt, PBKDF2 and HKDF in one place, with the parameters each one actually takes.
- Reports how long the derivation took here, which is the honest measure of how costly a guess is.
- Checks the settings against current guidance and says plainly when they fall short.
- Accepts a salt as text, hex or Base64, so an existing stored salt can be reproduced exactly.
- Runs locally: neither the passphrase nor the derived key leaves the browser.
Limits
- A browser is slower than a server and far slower than a cracking rig, so the timing is a lower bound on your own cost and an upper bound on nobody's.
- Argon2id and scrypt hold their memory in this tab; very large settings will make the page pause while they run.
- It derives keys — it does not store them, rotate them or wrap them for you.
- HKDF is offered for completeness and is the wrong answer for a password, which the findings say each time.
Frequently asked questions
Which function should I choose?
Argon2id unless something stops you, then scrypt. PBKDF2 only when a standard or a platform requires it — and then with 600,000 iterations or more of SHA-256.
What is the salt for?
It makes each derivation unique, so one table of pre-computed hashes cannot cover every user. It is not a secret: store it alongside the result, but use a different one for every secret.
Why is HKDF here if it is not a password hash?
Because deriving several keys from one strong secret — a session key and a MAC key from the same shared secret, say — is a real and separate job, and HKDF is what does it.
Can I use this to check a stored password?
Only if you can reproduce the exact function, salt and parameters it was stored with. Reproduce them here and the derived key will match byte for byte.
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