The Spanish Link In Cracking the Enigma Code

peetm sends this quote from the BBC: "When the Spanish Civil War began in 1936, both Hitler's Germany and Mussolini's Italy sent troops to help the nationalists under Franco. But with the conflict dispersed across the country, some means of secure communication was needed for the German Condor Legion, the Italians and the Spanish forces under Franco. As a result, a set of modified commercial Enigma machines were delivered by Germany. ... A key figure in trying to understand it was Dilly Knox, a classicist who had been working on breaking ciphers since World War I. He was fascinated by the machine and began studying ways in which an intercepted message might in theory be broken, even writing his own messages, encrypting them and then trying to break them himself. But there was no opportunity to actually intercept a real message since German military signals were inaudible in Britain. However, the signals produced by the machines sent to Spain in 1936 were audible enough to be intercepted and Knox began work. ... Within six or seven months of having his first real code to crack, Knox had succeeded, producing the first decryption of an Enigma message in April 1937."

False claim?

[dbthelinguaphile]

Maybe the first Brit to read the code, but not the first person. The Poles began to read Enigma messages back in 1932-33 according to the excellently-researched "Enigma: Battle For the Code" by Hugh Sebag-Montefiore. The article is a little clearer, but still can lead one to assume that Dilly Knox was the first to break Enigma messages. He was not. Not to diminish his part in the Enigma saga, but the Poles were reading it long before any other nation.

The link that is referred is Poland

[UnknowingFool]

What the summary doesn't detail is that link is Poland. Germany gave Spain modified Enigma machines that did not have plugboards. Also non-military versions lacked the plugboard. Plugboards increased the complexity of the encryption. Poland working with Knox and the British was able to reverse engineer the workings of these early machines as the Poles could intercept the early signals but Britain could not. This early work led to the decoding of the German military versions later

Glitch in the story

[Anonymous Coward]

>... since German military signals were inaudible in Britain.

What? This is ridiculous, the ionosphere might not be cooperative some of the time, but most of the time if a signal could bounce from Germany to its destinations, it could also go a similar distance to the UK, or Gibraltar, or the many other places the Brits had listening posts.

Enigma Machine is Fascinating

[Webcommando]

The story behind the Enigma and how the codes were cracked are fascinating. I fell in love with the machine and the concept of rotors, symmetric encode/decode, and how the circuit and mechanical systems worked.

I was so into it that I wrote a simple free simulator for the iPhone [webcommando.com] that faithfully simulated a set of rotors and include quirks in behavior. It is old and not full featured (one set of rotors, no plug board, etc) but was a labor of love! Someone also has a full featured one for sale in the store now and there are numerous simulators on the net.

There is a paper based Enigma [mckoss.com] that is an excellent tool for teaching students about this historical device. If you are a WW2 buff, the Enigma is a must on your research list.

It's curious...

[fuzzyfuzzyfungus]

How little attention the Spanish civil war(and Franco) get. Once the foreign involvement kicked up, the place was practically a beta test for WWII, and Franco was far longer-lasting than some of his more dramatic colleagues in fascism. And yet, crickets...

Re:False claim?

[AvitarX]

The Poles were the first, and did so when other nations thought it impossible. The trick the Poles used relied on the fact that the message cipher was duplicated at the start of each message. Once the Germans stopped doing that, the British took over further advancing the decoding.

Definitely the Polish did it first though, using a machine assembled with plans acquired from the French.

Re:One Fatal Enigma Flaw

[UnknowingFool]

The other flaws that allowed the British to crack it were operational. The rotors used by the Germans were alphabetically arranged. Randomizing the order would have made reverse engineering harder.

There were settings that the operator selected that were supposed to be random but some Luftwaffe operators used the same settings over and over again. The German navy had a code book which dictated these settings were to which made them more secure unless the Allies obtained such a code book.

To prevent a capture, the book was printed on special paper that would disintegrate in contact with water. Captains were instructed to destroy the code books by throwing them overboard. The Allies captured a German vessel that had such a book. The vessel captain abandoned the vessel and then returned to collect his personal belongings rather than destroy the code books.

Towards the end of the war, U-boat captains correctly guessed that the Allies were deciphering the messages. So the Germans created more rotors and added a 4th slot to the Enigma. This 4 rotor version was only deployed on U-boats;however , to communicate with land based 3 rotor versions a switch could be made to freeze the 4th rotor. Allies listening to U-boat messages to land were able to reverse engineer the additional rotors as the first 3 rotors could be determined.

Re:False claim?

[dbthelinguaphile]

You're right. The Poles had the method. They had bombes, which were kind of primitive mechanical computers to crunch the numbers. They also had perforated sheets to keep track of what letters were being used. Their problem was the fact that they just couldn't produce enough of either to keep up. The Navy codes only needed capture of codebooks and machine settings until the Americans got involved and began to crank out bombes in large numbers.

Not the only Spaniard who helped

[K8Fan]

Actually, a different Spaniard may have had more to do with breaking the German codes.

Joan Pujol Garcia [wikipedia.org] was a Catalan double agent known to the Germans as Arabel and to the British as Garbo. He became so trusted by the Germans that they gave him their current codes (though not an Enigma machine). He would encrypt his reports, transmit them by radio to Madrid, where they would be re-encrypted and sent on to Berlin. Thus he was able to supply Bletchley with both a current code and the plaintext.

For his services to the Allies, he was awarded an MBE by King George VI.

For his services to the Third Reich, he was awarded the Iron Cross by Hitler.

He was a vital part of Operation Fortitude and convinced the Nazis that the Normandy invasion was a dirversion. He may well have been the greatest bullshit artist who ever lived.