Enigma M3 is a free iPhone app I released back in 2009. At the time, I was developing a course for middle schoolers on cryptography. One of the topics covered is the Enigma machine, an electromagnetic device used by the Germans to encrypt messages during World War II. Learning about this ingenious device inspired me to write this app.
The rotor and reflector wheels are configurable, but alas, the plugboard is not.
Download it from the App Store.