# How Unifile protects your data
Unifile is built so that **we cannot read what you store**. Your notes, photos, videos, audio, files, places and links are encrypted on your phone before they leave it. What reaches our servers is scrambled data that only your devices can open. This page explains how, in enough detail to be checked.
## What is protected
Encrypted on your device before upload: the content of every item (note text, photos, videos, audio, documents, scans, places, links), its **title** and **description**, the optional secure fields of a note (such as passwords and card numbers), a note's attachments, and the small preview pictures. The search index kept on your phone is encrypted too.
## What we can still see
Encryption does not hide everything, and we tell you what remains: your account details (email and name), the **type** of each item (note, photo, ...), its **size** and dates, your **tag names**, how many items you have, and the technical data any online service sees (such as your IP address when you connect). We never see the words in your notes, the pictures in your photos, or the names of your items.
## How the keys work
- Each account has one **master key**, made on your phone from the device's secure random number generator. It is stored only in your phone's secure storage (iOS Keychain, Android Keystore). **It is never sent to us.**
- Each item gets its **own random key**, which is wrapped (encrypted) by your master key. Because items do not share a key, one exposed key exposes one item.
- Items are encrypted with **AES-256-GCM**, which also detects tampering. Each encrypted piece is bound to the item it belongs to, so the server cannot swap one item's data for another's.
## Adding another device
You sign in on the new device, which shows a QR code. On a device you already trust, you scan it and confirm. The two devices agree a one-time secret directly (**X25519** key agreement, **HKDF-SHA256**), and your master key travels encrypted under it. Our server only relays the encrypted package; it cannot open it. The code must be scanned in person, and the trusted device checks it belongs to your account.
## Recovery
When you set up your account you can create a **12-word recovery phrase**. It is generated on your phone and shown once. We never see it and keep no copy. The phrase is stretched with **Argon2id**, (a memory-hard function designed to slow password guessing: 64 MiB, 3 passes) and the result encrypts a copy of your master key, so you can restore your data on a new phone with the phrase.
**If you lose every device and the phrase, nobody, including us, can recover your data.** That is the price of not holding your keys.
## On your phone
Search works offline from a small database on your phone. It is encrypted with **SQLCipher** (AES-256) under a random key stored only in secure storage, kept out of backups, and deleted when you sign out.
Temporary files made when you view or share an item are cleaned up automatically (and again at launch and sign-out). Your connection to our services uses **TLS**. We never put an access credential for our file storage in the app.
## The standards we use
| Purpose | Standard |
|---|---|
| Encrypting items, keys and records | AES-256-GCM (NIST SP 800-38D) |
| Agreeing a key between devices | X25519 (RFC 7748) |
| Deriving keys | HKDF with SHA-256 (RFC 5869) |
| Protecting the recovery key | Argon2id (RFC 9106), 12 words from the BIP-39 list |
| Local search database | SQLCipher (AES-256) |
| Network | TLS |
We use published, widely reviewed algorithms and well-known open-source implementations. We did not invent any cryptography; what is ours is how the pieces are combined, which is why we publish it.
## What encryption cannot do
- It cannot protect a phone that is unlocked in someone else's hands, or malware on your phone.
- Anything you **copy, export or share** from Unifile (a copied password, a shared photo) leaves protection and is yours to handle.
- Someone who has **both** your account password and your recovery phrase can read your data. Keep the phrase offline and private.
- Metadata listed above stays visible to us.
*Last updated: October 12, 2026. Unifile is a product of COMMbits Inc.*