If you are concerned about security within your apps, you will want to disable the ability to taker screenshots of your app. This was a feature introduced in Windows Phone 8 as well as Windows Store 8.1 apps. With universal apps, you can now disable screenshots with the same one line of code
Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().IsScreenCaptureEnabled = false;
This allows the application itself to not allow screenshots. So if you are running on desktop and you take a screen shot, the application will show black.
Here is what it looks like on desktop with screen capture enabled
Here is what it looks like on desktop with screen capture disabled
I’m not able to get the phone emulator to take a physical screenshot (just the emulator screenshot) so I cannot show this. And until a new phone build comes out I cannot show it.