How Zero-Trust protects your data
Your data is encrypted on your phone before it goes anywhere. Here is what that means in practice.
Encrypted before it leaves your phone
Every note, task, contact, event, workout, bookmark, time entry and attached file is encrypted on your phone with AES-256-GCM. Our servers store and sync only the encrypted result. Someone who got a copy of our database, including us, would see random bytes.
Your password never reaches us
When you sign in, the app runs your password through PBKDF2 on your phone, then splits the result with HKDF into two unrelated keys: one to prove it's you when you sign in, and one to unlock your data. Only the first one is ever sent, and the server can't work backwards from it to your password or your data key.
Keys only you hold
- Your data is encrypted with a random data key. We store that key only in encrypted form, locked by your password, and a second copy locked by your recovery key.
- Each app's data is encrypted under its own key, derived from your data key on your phone.
- Each change is signed (Ed25519), so the app can tell if stored data was tampered with.
On your phone
- The apps keep an encrypted local database (SQLCipher), so they work offline.
- Fingerprint or face unlock keeps a key in your phone's secure hardware. Your password isn't stored.
- The apps lock themselves after a period of inactivity.
On our servers
- Hosted by Supabase in the EU (Frankfurt). Every row is protected by database rules so an account can only reach its own data.
- Attached files are stored encrypted in a private storage bucket, in a folder per account.
- We see only what's needed to run the service: your email, and when your encrypted items changed and how big they are. See the Privacy Policy.
What this means for you
- Keep your recovery key. If you forget your password, it's the only way back in. We can't reset access to your data.
- Encryption protects your data on our servers and in transit. It can't protect a phone that is unlocked in someone else's hands, so keep a screen lock on.
Check our work
The encryption code is open source in Zero-Trust-Core ↗, with test vectors you can reproduce. If you find a security problem, please tell us privately via Support.
Last updated 10 November 2026