During World War II, the Enigma machine was used as a message encryption tool by the German military. While it was believed that the Enigma machine produced an unbreakable code, this turned out to not be the case. This thesis begins with a summary of six versions of the Enigma, five that were actually used in the field, and a theoretical version that would have maximized security. An analysis of security is done, in which combinatorics is used to count the number of possible unique settings for each version of the machine. Estimates are also provided for the time required to break each version of the machine using a brute-force attack with various processing speeds that were achievable at various times in history. Finally, descriptions are included of three Enigma simulators constructed for this thesis. These simulators include a three-dimensional paper simulator, a digital simulator written using the Python programming language, and an electromechanical simulator built to resemble an actual Enigma machine
