Guide
Passphrase, PIN or Face ID: What Actually Protects a Vault?
Published November 11, 2026
Short answer
Face ID is a convenient way to open the app. The passphrase is what the encryption is built on. A short PIN is quick to guess if someone can copy the stored data and try millions of combinations, while a long passphrase plus a deliberately slow key-derivation method makes each guess expensive.
What each one does
- Passphrase: the secret your encryption key is derived from. This is the part that matters most.
- Face ID or Touch ID: an optional shortcut to unlock on your own phone. It does not replace the passphrase.
- PIN: a short number, easy to type and easy to guess in bulk if nothing slows guessing down.
Why slow guessing matters
Sealed hardens your passphrase with Argon2id, set to 3 passes and 64 MiB of memory. In plain terms, Argon2id is a password-hashing method designed to make each guess take real time and real memory, so an attacker cannot try guesses at the speed of a fast computer.
The vault key also depends on a secret held in this iPhone's Keychain, so a copied vault file cannot be attacked on another device. None of this makes a weak passphrase strong. It raises the cost for the attacker, and your passphrase sets how high.
Choose a passphrase you can remember
- Use four or more unrelated words rather than one word with a number on the end.
- Do not reuse a passphrase from another account.
- Do not use your iPhone passcode. Sealed has its own passphrase on purpose, so the number a stranger watched you type does not open your vault.
- Make sure you can type it quickly with one hand, since you will use it often.
Where Face ID fits
Turn on Face ID if you want fast access on your own phone. Keep the passphrase as the real key, and keep the recovery key somewhere safe in case you ever need it. See what happens if you forget a passphrase.