Xamarin.Forms - Solitaire Encryption (Xamarin.Forms)
A C# port of the Solitaire encryption algorithm featured in Neal Stephenson's novel Cryptonomicon. The algorithm has been implemented in a Xamarin.Forms mobile app for iOS, Android, and the Universal Windows Platform (along with an NUnit test project containing the tests from the author's website). The algorithm itself is based on a deck of cards, however you don't see this when using the app; for more info check the source code^ or the details of how it works.
This sample illustrates the inclusion of a Unit Test project in a Xamarin.Forms solution and also a custom Button renderer.
^ The original port of this algorithm was done (by me) in 2002, and I've used that 2002-era code unchanged in this mobile app. It's kinda cool that 12-year-old C# code can just be dropped into an app that runs on iOS, Android, and the Universal Windows Platform.