A free program for Android, by Lutech Ltd.
Calculator Vault – Lock Photos is an easy-to-use app for locking your personal photos, videos, audio files, and more in a secure and easy-to-use way. You can use the app to protect the contents of your phone and keep them out of the reach of other people.
The app comes with a secure calculator that helps you perform mathematical calculations without having to worry about sharing your sensitive data with third parties. The app also includes a secure file vault that makes it easy to import and export your locked files from the app.
To create your own secure private photo vault, all you need to do is to enter a password and then create a PIN that will help you to access your photos, videos, and other locked files. The app also supports fingerprint lock and face recognition.
When you're finished with the setup, you can start protecting your photos, videos, and other sensitive files and data with the app. To do so, just enter the password you created and then enter the PIN that you created.