Enigma Machine
Forgive the bad pun in the title, I couldn’t resist myself! The following is a brief thought I had after reading a book on World War II code-breaking (the $20 word is cryptanalysis). Allow me to give you a brief history lesson.
In World War II, Nazi Germany used a machine called “Enigma” to encode secret messages from the German High Command to the various Wehrmacht, Luftwaffe, and Kriegsmarine divisions in the field. The Enigma was an ingenious device—it replaced a letter with another, different letter based on the path of an electrical current through rotating rotors. It was small and compact—slightly larger than a child’s lunchbox. Output from the Enigma machine would be blocks of five characters, complete and utter gibberish to anyone without another Enigma machine. The book Enigma, by Robert Harris, gives the most chilling description of the Enigma machine I have seen, so permit me to quote it for you here:
Electric current on a standard Enigma flowed from keyboard to lamps via a set of three wired rotors (at least one of which turned a notch every time a key was struck) and a plugboard with twenty-six jacks. The circuits changed constantly; their potential number was astronomical, but calculable. There were five different rotors to choose from (two were kept spare), which meant they could be arranged in any one of sixty possible orders. Each rotor was slotted onto a spindle and had twenty-six possible starting positions. Twenty-six to the power of three was 17,576. Multiply that by the 60 potential rotor-orders and you got 1,054,560. Multiply that by the possible number of plugboard connections—about 150 million million—and you were looking at a machine that had around 150 million million million different starting positions….And the Germans changed these daily, sometimes twice a day.
To give you a better idea of what that number means—it has eighteen zeros. If all six billion people on Earth had one starting position apiece, and took one day to test, it would take 25 billion days—over 68 thousand years, to try every possibility. Keep in mind, too, that the above figures only correspond to the Enigma machine used in Wehrmacht and Luftwaffe communications. The German navy, the Kriegsmarine, used Enigma with four rotors, instead of three. This increases the total number of possibilities to 8,773,939,200,000,000,000,000, or almost 9 sextillion. In the face of such staggering figures, it would have been all too easy for the Allied powers to simply give up and stop trying to crack the Enigma code. However, they had a secret weapon on their side—the Bombe. continue reading…
