HP077: Enigma

HP077: Enigma

First Code Broken on 2/20/2006. Here is what it said.

Second Code Broken on 3/7/2006. Here is what it said.


Welcome to History Podcast. I’m Jason Watts your host and you are listening to episode 77. Before we start here is a audio file I received from Bob of Baseball History Podcast.

Thanks Bob! That was awesome!

On August 30 Juan from LA called in this request to the history hotline:

Thank you very much for calling into the history hotline Juan!

First lets do a little background on the Engima device. Once called “the greatest secret of World War II after the atom bomb”. The device was invented during the second world war which ran between 1939 and 1945. The principal players where the Axis Powers which included Germany, Italy, and Japan and the Allies which included France, Great Britain, the United States, the Soviet Union and to a less extent China. The Enigma was most famously used by Germany during the war to keep its information secret when transmitting.

The Enigma was a class of cipher machine generally known as rotor systems. Pneumatic and optical systems have been built, but we will only be discussing the electrical variety. Typically, these electrical cipher machines employ wired rotors as a means of generating a multiplicity of substitutions. Such a rotor generally consists of a small disk. On each of the two sides of the rotor are 26 electrical contacts arranged in a circle near the edge. (The normal A-Z alphabet sequence is often engraved on the periphery of the rotor, providing a convenient means of aligning it at specific positions against a benchmark.) The contacts on one side of the rotor are connected by wires in mixed order to the contacts on the opposite side. In this way an arbitrary set of one-to-one connections (i.e. Simple monoalphabetic substitutions) is realized between the two opposite sides of the rotor. A set of these rotors is usually arranged in a stack called a basket; the rotation of each of the rotors in the stack causes the next one to rotate. In some systems, each rotor advances one step in a regular sequence much as the wheels in an odometer advance 1/10 of a revolution for every full revolution of its driving wheel. In operations, the rotors in the stack provide an electrical path from contact to contact through all of the rotors. In a straight through rotor system, closing the key contact on a typewriter-like keyboard sends a current to one of the contacts on the end rotor. The current then passes through the maze of interconnections defined by the remaining rotors in the stack and their relative rotational positions to a point on the output plate, where it is connected to either a printer or an indicator, thereby producing the cipher equivalent of a plain text letter.

During World War II and important variation was introduced: the output end plate was a reflector to which 13 pairs of electrical contacts on the end rotor were connected. In this type of arrangement, an electrical current flows through the rotor stack and is then turned back to pass through a second time. The output is taken from a contact in the same set to which the input was made. Accordingly, if A encrypted to W, then conversely W encrypted to A, for a particular set of rotors and positions. The advantage of this scheme is that when a pair of rotor machines is set to the same starting configuration, plain text input to one machine generates cipher text, which when input to the other reproduces the plaint text. The reflector also ensures that the cipher text symbol is different from the plain text symbol. The German enigma cipher machine of WW II made use of this innovation. Although the Germans are famous for using the rotor cypher machines the credit for their invention goes to an American, Edward H. Herbern, for first recognizing that by hardwiring a mono-alphabetic substitution in the connections from the contacts on one side of a collection of such rotors, poly-alphabetic substitution of almost arbitrary complexity could be realized. Herbern also realized that a permutation in which several letters were shifted by the same amount in the rotor connections , say A to D and B to E, was cryptographically weaker that one in which this partial periodicity was minimized and designed his rotors accordingly. Starting in 1921 and continuing through the next decade, Herbern a series of steadily evolving that were evaluated by the U.S. Navy and undoubtedly lead to the united states superior position in cryptology as compared to the Axis Powers during world war II.

At almost the same time that Herbern was inventing the rotor cipher machine in the United States, European engineers, notobaly Hugo A. Koch of the Netherlands and Arthur Scherbius of Germany, independently discovered the rotor concept and designed machines that became precures to the best known cipher machine in history, the German Enigma.

Breaking the code:

Bletchley Park

In the summer of 1939, a small team of codebreakers arrived at the Government Code and Cipher School’s (GC&CS) new home at Bletchley Park, Buckinghamshire. Their mission was to crack the backbone of German military and intelligence communications, the Enigma cipher.

The Germans thought Enigma was unbreakable. The combination of rotating wheels, electrical contacts and wires meant that the odds against anyone who did not know the machine’s settings being able to break Enigma were 150 million to one!

But Bletchley Park achieved a breakthrough when the Poles passed on their knowledge of how the machine worked. This helped the codebreakers exploit a design weakness in Enigma – that no letter could ever be encrypted as itself.

At the same time, Bletchley Park mathematician Alan Turing realized that ‘cribs’ offered a way of cracking Enigma. A ‘crib’ is a piece of encrypted text whose true meaning is known or can be guessed. German messages were formulaic in places and the first line often contained standard information, for example weather conditions. Once a crib was known, it was still necessary to check thousands of potential Enigma settings to read a message, and to do this quickly Turing designed a electro-mechanical codebreaking machine called a Bombe. Each Bombe simulated the actions of 10 Enigma machines and was able to check all potential settings at high speed.

Cracking the ‘impenetrable’ Enigma code enabled Britain to foil Luftwaffe bombing raids, minimize U-Boat attacks and secure sea-based supply routes

Further codebreaking success enabled Bletchley Park to exploit Lorenz, a highly sophisticated cipher used personally by Hitler and his High Command. But many of the messages still took several weeks to decipher – a computing machine was needed. The result was Colossus, the world’s first programmable electronic computer, designed by Max Newman.

Colossus was the size of a living room and weighed about one ton. Its 2,400 valves replicated the pattern of an encrypted Lorenz message as electrical signals. This breakthrough in computing remained a secret for many years, to the extent that two Americans took the credit for inventing the computer in 1945. But the creation of Colossus proved to be a key contributor to the success on D-Day.

It is estimated that over 10,000 people worked at Bletchley Park at the height of its wartime activity. Their work affected the fate of nations and helped shorten the war by at least two years. But by March 1946, the people were gone and every scrap of evidence of their codebreaking exploits had been removed from Bletchley Park.

Here is the article that Juan was probably talking about…

from Discover magazine, August 2006, p.20

The losing side in World War II just can’t seem to catch a break. More than 60 years since the end of hostilities, a team of amateur cryptologist’s have set to work trying to crack three previously undecoded messages that were encrypted by the Nazis’ famous Enigma machine – and they are making speedy progress.

The original cracking of the Enigma code was an early and crucial Allied triumph in WW II. The Germans’ encryption machine used a system of mechanical rotors (build your own enigma or cipher device, like the one form da vinci code movie) to garble messages in such a way they code be decoded only by someone with the preset key and the knowledge of how to arrange the rotors. However, sleuths including Alan Turing (who) and Donald Michie (who) at the Bletchley Park (where) facility in Britain eventually broke the code by isolating certain repeated phrases and guessing what they might be – the once fashionable “Heil, Hitler,” for instance. The Nazis eventually realized the game was up and changed their keys. They also added an extra rotor, thus increasing the level of encryption by an order of magnitude.

Now even these later messages are yielding their secrets. The M4 project, led by German violinist Stefan Krah, uses the spare computing power of enthusiast connected online to solve the encryptions. So far more than 2,100 computer terminals have signed up since January, and by March two of the secret Kriegsmarine messages had been decoded.

Not that the text is really interesting. “They’re just routine messages about attacks on a convoy and so on,” says Ralph Erskine, an amateur historian who published the undecoded intercepts in Cyptologia back in 1995. “It’s more that modern technology had succeeded where Bletchley Park couldn’t.”

by Anne Casselman

There are a ton of links to very cool sites about the Engima machine at historyonair.com. There are also links to books about Enigma on the site. Remember, if you are going to by from Amazon please click on our links to get to their site and the podcast will get a small percentage from Amazon. Thank you!

This episodes frapper mappers are:

  1. Nick Cohen-Meyer in Tottori, Japan
  2. Kelly Harris in St. Louis, Missouri, she says, “Great show. Keep up the good work.” Thank you Kelly!
  3. Mik Parkin in Sheffield, England
  4. Emil in Edmonton, Alberta, Emil says, “Love the show!!!” Thank for the explanation marks Emil and How do you think the oilers are going to do this season?
  5. Bobby from Kingsport, Tennessee

Thank you all for taking the time to posting your encouraging words. If you would like I could use some more positive feedback on itunes. If you would like to have your name read on this podcast please add yourself to the frapper map by clicking on the frapper link at historyonair.com.

As some of you have already noticed the feed for the podcast in itunes has been updated to display all the episodes. If you are not seeing all the episodes chances are you are on an old feed. Add the number one to the end and you should see all the changes.

I will be attending the podcast and portable media expo this September 29-30. I hope to see you there. I will be at the OC Podcasters booth number 619. Please stop by if you can.

Since I will be away at the conference this weekend it may delay the podcast next week. Also, I’m extending the contest for this months book. Call the history hotline and give me a intro. Leave your email address also so I can let you know you have won. All entries must be received by October 15! The prize will be a copy of The Assassins’ Gate: America in Iraq by George Packer. 

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