Papercase

A private, offline locker for your important documents on Android.

Keep your passport, driver's licence, health card and other papers on your phone, encrypted and locked behind your fingerprint. Move them between your own devices over Wi-Fi without any cloud service, and back them up to a file you can open in KeePass.

No accounts. No servers. No tracking. Your documents never leave your devices unless you send them.

   

Status: early development. It works on the devices it's been tested on (a Samsung Galaxy Z Fold7 and a Samsung Galaxy tablet), but expect rough edges. Keep a backup.

What it does

Locker

• Store IDs, passports, licences, insurance cards and PDFs, with front/back photos, visas and extra pages.
• Everything is encrypted with a key held in your phone's secure hardware. The locker opens only after you unlock with your fingerprint or device PIN, and locks itself again when you leave.
• Give any document its own password for an extra layer.
• Crop photos to just the document: drag the corners and the page is straightened, even if it was photographed at an angle.
• Photos are cleaned of location, timestamps and camera details when you add them.
• Copy a document number with one tap; with auto-clear on, the clipboard is wiped after a few seconds.
• Get reminded before a document expires: choose how early on each one (a week to a year), and keep getting reminded every two weeks after it expires until you update it.

Move documents between your devices

• Show a QR code on one phone, scan it on the other, and the locker is sent directly over your local Wi-Fi.
• The sending phone shows which device is asking and must approve with fingerprint or PIN before anything is sent.
• Changes are merged: new documents are added, edits keep the newest version, and deletions carry over.

Back up to a file

• Export the locker as a standard KeePass (.kdbx) file, protected with a one-time token.
• The backup also opens in KeePassXC or KeePassDX, so your data is never locked into this app.
• Or turn on automatic backups: daily or weekly, to a folder you choose (including a synced folder), protected with a backup password you set. The 5 most recent are kept.

Passphrase

• A secondary feature for people who use a long master passphrase (for example for a KeePass database): store it under your fingerprint and copy it with one tap, from the app or a Quick Settings tile. The clipboard is wiped after a timeout you choose.

How your data is protected

At rest	AES-256-GCM, with the key in the Android Keystore (hardware-backed where available). The key can only be used within 10 minutes of a fingerprint or device-credential unlock.
Screen lock	Required to receive documents. If you remove your device's screen lock, Android destroys the key and the locker can't be opened, so keep a backup.
Per-document passwords	Attachments are encrypted with a key derived from that password. They stay encrypted in transfers and backups, and only open with the password.
Phone-to-phone transfer	Encrypted with a random 256-bit key that exists only in the QR code and is never sent over the network. The sender must approve the receiving device.
Backups	KeePass KDBX 4: AES-256 with Argon2id (64 MiB, 3 passes). The token is randomly generated.
Network	The app talks only to your other device on the local network, during a transfer you started. There are no analytics or crash reporting. (The Google Play version also asks the Play Store app whether an update is available.)

Known limitations:

• For password-protected documents, only the attachments are encrypted with the document password; the title, number and notes are protected by the locker key only (and are readable in a backup by anyone with its token).
• Samsung Keyboard keeps its own clipboard history, which other apps can't clear. The app explains how to turn it off.

Papercase collects no data at all. See the privacy policy.

Found a security issue? Please don't open a public issue. See Reporting security issues.

Install

The Google Play listing is on the way; the badge will work once it's live. Until then, download papercase-vX.Y.Z.apk from the latest release and open it on your phone to install. You may need to allow your browser or file manager to install apps.

To build it yourself:

git clone https://github.com/mattintech/papercase.git
cd papercase
./gradlew assembleFdroidDebug
adb install app/build/outputs/apk/fdroid/debug/app-fdroid-debug.apk

Requires Android 12 (API 31) or newer, and JDK 17+ to build.

Builds

There are two flavors with the same app ID:

• fdroid contains no Google libraries and works on any Android 12+ device. This is the build on the GitHub releases page.
• play is the Google Play build. It adds one thing: a prompt suggesting an update when Google Play has a newer version (never forced).

Debug builds install as a separate app, "Papercase Debug" (com.mattintech.papercase.debug), so they can sit next to the store version.

Moving from SecurePass

Papercase was previously called SecurePass. It's a new app ID, so data doesn't carry over automatically. In SecurePass, export a backup file, then use Import Backup File in Papercase with the same token. Older .spvault backups import too.

Support development

Papercase is free, with no ads and no tracking, and it always will be. If it's useful to you and you'd like to help cover the costs of development, you can buy me a coffee. Thank you.

Contributing

Contributions are welcome. Please open an issue first to talk about what you'd like to change, then fork the repo and send a pull request to the develop branch. See CONTRIBUTING.md.

License

Papercase is free software, licensed under the GNU General Public License v3.0.

KDBX support uses kotpass (Apache-2.0). Icons are from Google's Material Symbols (Apache-2.0).