How It Works

Recording a pain level

When you tap a pain level, the application sends a simple number (0 to 4) to the server along with the current time. That's it — just a number and a timestamp. No personal details, no device information, no location data.

If you add an optional note, it is encrypted on your device before it leaves. The server receives and stores a scrambled version that it cannot read. Only your device can unscramble it later.

Logging in with your fingerprint

Pain Recorder uses your device's built-in biometric hardware (fingerprint reader or face recognition) instead of passwords. There is nothing to remember, nothing to type, and nothing that can be stolen in a data breach.

Your biometric data (fingerprint image, face scan) never leaves your device. The device simply confirms "yes, this is the owner" to the application. The server never sees or stores any biometric information.

How your notes are protected

Think of it like a lockbox that only your device has the key to:

1. When you first use the app, your device creates a unique pair of keys — one to lock (encrypt) and one to unlock (decrypt).
2. Before your note leaves your device, it is locked with the encryption key.
3. The locked note is sent to the server, which stores it as-is. The server does not have the unlock key.
4. When you view your notes later, your device uses the unlock key (which never left) to read them.

Nobody else — not the server operator, not another user, not even someone with direct access to the database — can read your notes.

How your identity is protected

The server does not store your name, email, or any personal information. Instead, it knows you by a random code that was generated when you registered.

Even this random code is scrambled (hashed) before being stored with your pain records. This means that even if someone accessed the database directly, they would see pain levels attached to meaningless codes — with no way to trace them back to you.

Viewing your notes in the Day timeline

When you open the Day view, your pain events are listed with the time and severity level. If an event has a note attached, a small + button appears next to it.

1. Your device automatically retrieves the encrypted notes from the server.
2. Each note is decrypted on your device using the private key that never left it.
3. The decrypted text stays hidden until you tap the + button to reveal it.
4. Tap − to hide it again. Each note toggles independently.

Notes are kept collapsed by default so you can scan your day at a glance and only expand the entries you want to read. If you are on a different device that does not have your decryption key, the note will show as [encrypted] — confirming it is safely protected.

Learn about the Day, Week and Month views →

Data flow overview

Here is what happens when you record a pain level with a note:

The server stores only the number, the encrypted note (which it cannot read), and a scrambled user code.