You probably want to read my blog post about it: OpenSourc.ES Enigma and Bombe. Anyway this page gives you a brief overview:

  • The Enigma is a mechanical machine used in WW II by the Germans
  • It is a symmetric cipher
  • It uses rotors and a plugboard
    • the rotors change the "key" each time a letter is typed
    • the plugboard swaps two letters
  • There are an enormous number of possibilities but it can be cracked
  • The main flaw is that a letter can't be encoded by itself

This package allows you to encode/decode and crack messages.