This simulator is fully compatible with the real Enigma machine, so if you manage to get the machine settings for them, you can even read real messages that were sent on the Enigma (but remember, they were written in German).
To send a message, you need to pick out some settings (instructions for the specific settings are in the app) and make sure that whoever you are sending the message to has these same settings. Once you have all the settings entered, type your message in the box, press Run, and send the enciphered text to somebody! You should probably agree on the settings beforehand, because sending the settings along with the message defeats the purpose of encrypting the message before sending it.
If you receive a message, first set your simulator to the settings you agreed on, then type or paste the encrypted message into the box, press Run, and the decrypted message will come out!
Disclaimer: The Enigma cipher was broken by mathematicians back when “computers” were mechanical devices, not electronic. Each computer back then was built for a specific purpose and while faster than a human, was still incredibly slow by today’s standards. Smartphones are better and faster than even the computers in NASA’s Space Shuttle (and Enigma was around 50 years old when the shuttle was built). Just because the average person can’t figure out the settings doesn’t mean that government agencies, corporations, the Illuminati, or someone looking over your shoulder won’t be able to figure out the settings used and read your message. The Enigma cipher should NOT be considered secure! Use at your own risk.
Rotor wirings taken from Tony Sale’s website http://www.codesandciphers.co.uk/enigma
This app uses the WheelView widget, created by Yuri Kanivets https://code.google.com/p/android-wheel/