How your files are protected.
Plain words first. The technical details are at the end, for experts to check.
Encrypted on your phone
Everything is encrypted before it's saved. Even names, folders and dates.
Only on your phone
Keys come from your pattern plus your phone's secure hardware. Copies can't be opened anywhere else.
We can't see in
No account and no server holding your files. We can't open a vault, so we can't be made to.
9 recovery words
Your way back in if you forget your pattern. Nobody else can recover a vault for you.
Hidden vaults
Every pattern opens its own vault. The app keeps no list of vaults and stores them among random cover files, so the number of files doesn't give away how many vaults exist. A pattern that opens nothing just offers to make a new vault, exactly like one you've never used.
If someone forces you to open it
You can make one vault a duress vault. Opening it looks normal, and at that moment every other vault on the phone is destroyed: their keys are wiped from the phone's secure hardware, so their files can never be decrypted again, even from a copy taken earlier. A fingerprint never opens the duress vault.
Locking
The app locks when you leave it (straight away or after a delay you choose), when the screen turns off, when you lay the phone face down or shake it, or with the Quick lock button. Screenshots, screen recording and the recent-apps preview are blocked.
Backups and new phones
Backups go to your own Google Drive, a folder in OneDrive, Dropbox or Nextcloud, a file, or your computer. They're encrypted the same way and open only with that vault's recovery words, so a stolen backup is useless without them.
Fingerprint is your choice
You can let your fingerprint open one vault. We say plainly what that means: anyone who can force your finger onto the sensor can open it. For anything truly private, keep the pattern only.
What Vault This can't protect against
- An open vault is open. If someone takes the phone while a vault is open, they can see it until it locks. Short timers and quick-lock help.
- A compromised phone. Spyware could watch you draw your pattern. Keep Android up to date and install apps only from trusted places.
- Someone watching. Turn on "Hide my pattern as I draw", or use a passphrase.
- Forgetting both the pattern and the recovery words means the vault is gone for good.
- Copies outside the vault. Anything you save out or share to another app is no longer protected.
- Vault This hasn't had an independent security audit yet. The design is written up below so experts can check it.
Technical details
- Encryption: AES-256-GCM in 1 MiB chunks, each with its own random 96-bit nonce and the chunk number and file id as associated data. Thumbnails, names, folders, dates and the index use the same scheme. Files are padded so exact sizes aren't revealed.
- Opening a vault: your pattern or passphrase goes through Argon2id (64 MiB, 3 passes) with a per-phone salt, mixed with an HMAC from a key held in StrongBox or the TEE that never leaves the hardware. Every guess needs the phone.
- Duress: each vault's index is wrapped by one of 64 hardware keys made up front, so the number of keys says nothing about the number of vaults. Duress deletes the other vaults' keys, then their files.
- Recovery words: 9 words from the BIP-39 English list, through Argon2id, open an envelope holding the vault key. Backups use keys from the words only.
- Sharing: a read-only encrypted copy opened by a separate share phrase that never reaches our server.
- No trackers: no analytics or advertising code. Photo labels for search are worked out by a model inside the app.
Take back your privacy.
Free to download. No account. Your files never leave your phone unless you choose.