Enigma

The enigma machine was a rotor-based cypher machine used throughout the second world war by the various branches of the German military in order to send encrypted messages. It had a huge array of possible settings, making it incredibly difficult to crack. This was however eventually managed by a group of British scientists, and the information acquired because of this was hugely important in bringing the war to an end.
This android app emulates this magnificent piece of engineering. Users can use this to encrypt messages to send to one another, hide spoilers on public forums by encrypting them, or simply as a tool to use for learning about how these machines worked. The app includes all features of the original machine, allowing the user to customise their own start set up and use a keyboard and lampboard to output each encoded letter as the original machine did.