Argon2-hash og -verifikation

(Dokumentation på engelsk)

What it does

The Argon2

HashHashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

& Verify tool hashes passwords with Argon2id — the winner of the 2015 Password

HashingHashingA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

Competition and the modern replacement for bcrypt and PBKDF2 — and verifies existing Argon2 hashes. You control the three cost parameters: memory (default 64 MiB), iterations (default 3 passes), and parallelism (lanes). Everything runs in your browser via WebAssembly: passwords never leave your device.

The output is a self-contained PHC string you can store directly in a database:

$argon2id$v=19$m=65536,t=3,p=1$<salt>$<hash>

It embeds the algorithm, version, all cost parameters, the random

saltsaltRandom data mixed into each password before hashing, so identical passwords produce different digests and precomputed tables become useless.

, and the digest — so verification needs nothing but the string and the password.

How to use it

1. Pick

   HashHashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

   , enter the password, and optionally tune memory / iterations / parallelism /

   hashhashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

   length.
2. Press

   HashHashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

   — copy the encoded PHC string (what you store) or the raw hex digest.
3. To check a password against a stored

   hashhashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

   , switch to Verify, paste the $argon2id$… string, and press Verify — the tool also shows the parameters parsed out of the string.

Examples

• New user signup (server-side analogy): argon2Hash(password) → store the encoded string in your users row. On login, argon2Verify(encoded, password) decides the match.
• Cross-implementation check: password / somesalt, m=65536, t=2, p=4, 32-byte digest → 1a9677b0afe81fda… — identical to golang.org/x/crypto/argon2 with the same inputs.
• Tuning: m=19456 (19 MiB), t=2, p=1 is the OWASP minimum acceptable profile; m=65536, t=3, p=1 (this tool’s default) is the recommended one.

Good to know

• Why memory-hardness matters: bcrypt and PBKDF2 cost only CPU time. Argon2id’s cost is set by RAM — an attacker must dedicate 64 MiB of memory per guess, so GPUs (fast cores, scarce memory per core) and ASICs lose their advantage. A laptop and a GPU farm pay roughly the same per guess.
• Argon2id specifically: Argon2i is side-channel resistant (data-independent memory access, for running on servers); Argon2d is GPU-attack resistant. Argon2id is the hybrid recommended for password storage.
• Store the encoded string, not the hex digest — the PHC string carries the parameters and

  saltsaltRandom data mixed into each password before hashing, so identical passwords produce different digests and precomputed tables become useless.

  , so future logins don’t depend on today’s configuration.
• Verify any variant: the tool auto-detects argon2d / argon2i / argon2id from the string itself.
• Private:

  hashinghashingA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

  runs 100% client-side in WASM (reference Argon2 v1.0.2) — safe for real passwords.
• Related tools: Password Generator, Passphrase Generator, Password Strength Analyser,

  HMACHMACA construction that combines a hash function with a secret key to prove a message is intact and came from someone holding the key.

  Generator.