A free app for Android, by HT Digital Solutions.
What is Calculator Lock: Gallery Vault, and how do you use it?
Calculator Lock is an amazing way to protect your privacy and security on your Android phone. The app can hide and lock your private photos, videos, and other files so that nobody can access them without a correct password.
To use Calculator Lock, you will first set the security of your phone, and then you will set the security for each application. Once you have set the security for each application, you will be able to select the files you want to hide.