A free program for Android, by Droid Keypad.

Calculator Lock – Gallery Vault & Video Hider is a free, secure, and easy-to-use app. It helps you to hide photos, videos, and other files from unauthorized access. You can also import your private images, videos, audio, and files into the secure repository and no one knows its existence except you.

Calculator Lock – Gallery Vault & Video Hider can be used on any device that runs on Android 5.0 or higher.

To hide photos, videos, and other files, you need to install the Calculator Lock app on your device. You will be guided through the installation process. After the installation is complete, you need to open the Calculator Lock app. You will be guided through the first step of the setup process. You need to enter the password and the secret phrase.

The next step is the security code. You need to enter the code and confirm the security. After that, you can start hiding your photos, videos, and other files.