If you are looking to add an extra layer of security to Signal, you can lock your messages using your smartphone's lock screen security features. Here's how to add a screen lock to the Signal app.
By turning on the screen lock feature on your iPhone or iPad, your messages will be hidden until unlocked with Face ID, Touch ID, or the lock screen passcode. The same is true for Android. You will either need to authenticate yourself using a supported biometric security feature like your fingerprint, traditional password, or PIN.
How to lock messages in Signal application
Open the "Signal " application on your iPhone , iPad , or Android device .
After that, tap on your profile picture in the top-right corner.
If you haven't uploaded a custom photo, you'll find your username initials instead.
Select the "Privacy" option from the full list.
Finally, switch to the "Screen Lock" setting.
Once the feature is enabled, you can customize Screen Lock Timeout.
This setting allows you to set the time it takes for the Signal app to lock itself and to request the lock screen of your phone or tablet to unlock it.
From the window that pops up, select one of the options between 1 minute and 30 minutes and instantly.
You can now exit the app's settings menu, and from the app itself. The messaging app will close itself after the timeout period you chose in the previous instructions.
The next time you want to send a text message in Signal, you will need to unlock the app using your phone or tablet password, PIN, pattern, fingerprint sensor, Face ID, or any other biometric security feature.