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Mark Baldwin demonstrates the Enigma cipher machine, which he says "just changes one letter into another." The way it does that is much more complicated than you might imagine.
James Martin/CNETA black metal mechanical device resembling a typewriter sits in a wooden box. It could be just an oddity in an antique store, if it weren't for the black elliptical logo engraved in the wood. "Enigma," it reads.
That marks it as a Nazi cipher machine, used in World War II to encrypt messages sent over wireless radio by the German military. This funny device was then cutting edge, creating one of the world's strongest encryption keys. That gave Germany's lethal U-boats the power to communicate with each other about attacks on merchant ships, which devastated the UK throughout the war, taking thousands of lives and cutting off vital supplies and troops en route from North America.
The power of this machine prompted the Allied forces to launch an effort that used machines, mathematicians sworn to secrecy and some Naval derring-do to crack the code and read Germany's messages.
And it's not even a computer. As Enigma expert Mark Baldwin demonstrated on Wednesday to a crowd of employees at CBS Interactive, CNET's parent company, "it just changes one letter into another."
If you press one key on the stripped-down keyboard, a different letter lights up in the lampboard, an array of light-up letters arranged just above the keyboard. Users would type their messages into the machine and write down each replacement letter as it lit up. Then they would tap out the encrypted message in Morse code over the wireless radio, feeling sure that only someone with their own Enigma machine with the same exact settings could decipher it.
Looking at the machine, it's hard to believe it confounded some of the world's best technical experts, who spent years at places like the UK's secret codebreaking compound at Bletchley Park coming up with ways to crack it.
"It does look rather old fashioned, does it not, enclosed as it is in an oak case?" Baldwin said.
In fact, the Enigma is even older than World War II. One hundred years ago this week, Baldwin told us, German inventor Arthur Scherbius took out a patent for the Enigma machine. Designed to obscure messages sent over wireless radio, Scherbius tried, more or less unsuccessfully, to sell the machines to businesses and anyone else who might have a need for it until he died in an accident in 1929.
At that point, the company "is just swallowed up by the German government," Baldwin said, because it needed the technology to help hide its efforts to re-arm its military in potential violation of the Treaty of Versailles.
Mechanical complexity
But don't be fooled by Baldwin's understated description of the Enigma's function. Take a hint from his orange tie, which is decorated with schematics from an Enigma patent application filed in the UK before the war. The machine's innards created an exponentially eye-popping number of possible solutions to a given cipher. The number of possible solutions would take a whole paragraph to write out fully but can be expressed as about 3.3 x 10^114.
Here is the full number of possible solutions to a 3-rotor Enigma cipher. The short version is 3.3 x 10^114.
Laura Hautala / CNETEnigma enthusiast Ralph Simpson told CNET that if you gave 100,000 operators each their own Enigma machine, and they spent 24 hours a day, seven days a week testing a new setting every second, "it would take twice the age of the universe to break the code" by hand. And oh yeah, Baldwin reminded us, the Nazis changed the settings on the Enigma every night. Also, different divisions of the German military each used their own settings, creating around 30 different Enigma ciphers every day.
For potential codebreakers, "It's not 'Break Enigma once at Bletchley and read everything," Baldwin said. "It's a battle which you have to enter every night of the war."
The Enigma accomplishes its complexity with three rotors and a plugboard. When you press the letter "P" on the keyboard for example, an electrical current passes through the three rotors, each containing a jumble of 26 wires, and then back again to the lampboard, where the letter "J" might light up. If you press "P" again, the first rotor will turn, rearranging the wires so that the electrical path from the letter "P" on the keyboard now causes a new letter, such as "F," to light up.
Having three rotors, all of which can rotate, means that if the user pressed "P" over and over again, the machine would put out a random string of letters that wouldn't repeat itself for more than 19,500 keystrokes. When the German Navy added a fourth rotor to its U-boat Enigma machines in 1941, that increased to nearly 457,000 keystrokes.
Then there's the plugboard, located on the front of the Enigma as the operator looked at it. This introduced even more randomness to the machine and took care of a logistical problem for the Germans. A given Enigma rotor was wired in one of only eight configurations, even though 403 septillion (or million billion billion) configurations were possible. Rewiring the rotors in the field was more than the German military could ask of its rank and file, Baldwin said. So the plugboard let them change the output of the rotor for specific letters, essentially rewiring the rotors from the outside.
Hacking the cipher
To crack a cipher machine that complex without computers, Polish, British and American mathematicians came up with their own machines to simulate the Enigma and run through possible solutions much faster than a human could. These were the Bombes, developed first in the UK's Bletchley Park based off the Polish "Bomba," an early effort to crack the Enigma. They were then made faster and more powerful at a facility in Dayton, Ohio.
This is a U.S. Navy cryptanalytic bombe. The machines worked primarily against the German Navy's four-rotor Enigmas.
Daniel Terdiman/CNETAnd repeatedly, with some interruptions and false starts, the Allied forces did break Enigma codes. Germans didn't expect this to be possible, perhaps because they had too much faith in the number of possible solutions to a given Enigma cipher. "They were blinded by this large number," Baldwin said.
News that the UK and US could reliably break Enigma codes didn't become widely known until the 1970s. The first book that revealed the Bombe in English was published by F. W. Winterbotham in 1974, and the following year the British government began declassifying information about the project, Baldwin said.
Still not a computer
After his presentation, I pressed Baldwin on his insistence that the Enigma and the Bombe weren't computers, or even proto-computers. Despite his obvious appreciation for the machines, he repeated that they were single-purpose, electromechanical devices. And even though it was an innovative solution to cracking ciphers, the Bombe was simply several Enigmas running at once.
"It can't even add two to two," he said.
Well, then, what's even the point?