Enigma compromised

The Germans maintained a deep faith in Enigma throughout the Second World War--a faith that aided allied codebreakers. What would the effects on the Allied codebreaking if the Germans believed, rightly or not, that a fully intact Enigma machine with codebooks and wheels had been captured intact by the British.
 
The losses for the British will be tempered by their complete control of the German intelligence network, thus they'll know about it soon enough (probably before it happens), and try to develop a new way of cracking the German codes.
 
Would it be that much of a problem? Even if the Germans believe that the British have recovered an intact Enigma machine wouldn't they just be able to change the daily codes, ring orders and plug connections? The machine itself would be a help with attempting to attack the system but I was under the impression that it was those changes that made it impossible, or at least impossible in a short enough time as to be not measured in decades or centuries, to decrypt them without the use of automation.
 
The Germans maintained a deep faith in Enigma throughout the Second World War--a faith that aided allied codebreakers. What would the effects on the Allied codebreaking if the Germans believed, rightly or not, that a fully intact Enigma machine with codebooks and wheels had been captured intact by the British.

This was considered and dismissed. That is the German leaders thought it probable that Enigma machines and the key books had been captured. They considered this only a temporary problem as they key tables were good for a month at the maximum, the keys were for only a few users and useless for all the others who were issued different sets of keys for the month. They also understood the probabillity of finding the correct key by conventional methods to be many billions to one odds. Some of the services enhanced their Enigma security by adding additional scrambler wheels. By 1940 three rotor machines were common, and the navy changed to four rotor machines. So, even if several machines or key table were captured the enemy would only be able to decrypt a few obsolete messages.

What the German leaders did not grasp was:

The actual combination of settings was far less than thought.

The complete mathmatical basis for the operation of the machine had been worked out before 1939. This was the largest contribution of the Polish codebreakers and enabled the codebreakers to efficiently organize their search for the key used for a message.

That the machines had been reversed engineered & high speed machines for searching the message key had been built. The idea that the Poles of all people had done this as early as 1937 was not even considered, and the massive IBM machines of 1943-44 were even further from consideration.

The overconfidence of the German leaders in this is illustrated by poor enforcement of discipline on the comm. operators. Sloppy practice made it so much easier for the enemy to find the correct key for groups of messages. One common rookie mistake was to send the same message text repeatedly in different keys. When such errors were spotted it made things so much easier for the code breakers. Another error was to use repetitive text in each message. ie some radio operators included the letters "HH" at the end of each message.

Simply tightening discipline on the operators and comm officers would have helped the Germans much. Reducing the quantity of radio traffic would have helped. Better use of couriers and the European telephone system would ahve vastly lowered the exposure of German militiary messages. However many German leaders thought the greater danger was of 'spies' tapping into the telephone systems.

Would it be that much of a problem? Even if the Germans believe that the British have recovered an intact Enigma machine wouldn't they just be able to change the daily codes, ring orders and plug connections? The machine itself would be a help with attempting to attack the system but I was under the impression that it was those changes that made it impossible, or at least impossible in a short enough time as to be not measured in decades or centuries, to decrypt them without the use of automation.

Automation. Precisely. That was the purpose of the first "Bomby" built by the Poles, and their improved versions, all the way up to the monster machines built by NCR and IBM. The Germans captured several examples of the British TYPEX & US SIGABA machines, which were also rotor bases systems. They fussed around with them for some years but decided a systematic decryption of messages from those machines impractical.

Germany did have alternatives to the Enigma system. It would have been a demanding task building alternative machines & replacing the Enigma system with new and all the training along with it.
 

Deleted member 1487

The losses for the British will be tempered by their complete control of the German intelligence network, thus they'll know about it soon enough (probably before it happens), and try to develop a new way of cracking the German codes.

It didn't work like that; the Allies didn't control Germany's intelligence services, though they did have Canaris and some members of the German resistance feeding them info, but it was intermittent. It's unlikely that the British would know, because IOTL when the Germans suspected Enigma was compromised they added a fourth code wheel that totally caught the Allies by surprise; it would take until they captured a copy of the machine and code books that they were able to break back in.
Ultra though was overhyped in its effectiveness; most of the time the info was only sporadic and came in after its usefulness. There were periods the Allies were totally shut out of it too. In reality the success of the BoA can from Huff Duff, which just needed the Germans to broadcast a message and they could home in on them, which the Uboats stupidly did frequently. Other than that when it really became effective in 1944 the war was pretty much won anyway and still the Allies were surprised by the Germans like in the Ardennes.

So if the Germans figured things out after after adding the fourth rotor wheel in 1943 they would probably just abandon the machine, because attempts to use more rotors resulted in a lot of issues for them. The Allies aren't as effective in 1943-44, but the BoA is won around the same time and the Normandy landings work out about the same. During the ground fighting the Allies probably don't do so well in Italy or France, but they still win. There might be a German attempt to send false information for a one-off trick, but that would be about the extent of the changes from the German side. Overall not much different.
 
Mark Clark's landing in North Africa was an exellent chance to capture someone with ultra knowledge and torture the shit out of them
 
It didn't work like that; the Allies didn't control Germany's intelligence services, though they did have Canaris and some members of the German resistance feeding them info, but it was intermittent. It's unlikely that the British would know, because IOTL when the Germans suspected Enigma was compromised they added a fourth code wheel that totally caught the Allies by surprise; it would take until they captured a copy of the machine and code books that they were able to break back in.
Sorry, should have specified, the controlled the entire German intelligence network in Britain.
 
I was told (don't have a reference), during a visit to Bletchley, that the Germans captured an intact British cypher machine after Dunkirk.

They noticed that it worked on the same principles as Enigma. So they didn't waste effort trying to break British codes as it would obviously be impossible.

Has anyone else heard of this story?
 
I was told (don't have a reference), during a visit to Bletchley, that the Germans captured an intact British cypher machine after Dunkirk.
.....
Has anyone else heard of this story?
I cant remember the date or circumstances, but the Germans captured more than one of the British TYPEX machines.

TYPEX
http://www.cryptomuseum.com/crypto/uk/typex/

And yes the German analysts concluded it was impractical to 'break' into and decrypt messages.
 
Mark Clark's landing in North Africa was an exellent chance to capture someone with ultra knowledge and torture the shit out of them

USAAF brigadier general Varnum violated a direct order and went on a bomber mission over enemy territory in 1943. He was shot down and captured in Germany. Fortunatly the Germans never caught a clue that he was cognizant of ULTRA and understood the Enigma system penetration. I'm unsure if the British general O Conner had knowledge of the ULTRA system & Enigma when captured in 1941.
 

Deleted member 1487

I cant remember the date or circumstances, but the Germans captured more than one of the British TYPEX machines.

TYPEX
http://www.cryptomuseum.com/crypto/uk/typex/

And yes the German analysts concluded it was impractical to 'break' into and decrypt messages.
Not quite:
http://chris-intel-corner.blogspot.com/2012/09/german-army-codebreakers-vs-typex.html
http://chris-intel-corner.blogspot.com/2011/10/typex-investigation-wwii-mystery.html
http://chris-intel-corner.blogspot.com/2011/08/something-interesting-on-typex.html
Britain has kept info about its coding failures quite, so we don't know for sure what happened there; the Germans destroyed much of their records about the subject. Basically all sides postwar had their own reasons for keeping quiet about the code breaking successes and failures, so the story is pretty opaque yet about what was going on with Typex among other things. The Germans did apparently have far more success codebreaking them we thought, because the Allies were not keen on revealing their failures, while the Germans weren't exactly is a position to talk about their successes in this field.
 

Nick P

Donor
I read somewhere (a history of early computing published c1995) that postwar Britain supplied encoding machines similar to the Enigma devices to their colonies and allies in Africa. This enabled the British to read the messages with little hassle and take actions to preserve their interests.

Is there any truth in this factoid?
 
USAAF I'm unsure if the British general O Conner had knowledge of the ULTRA system & Enigma when captured in 1941.

No, I am pretty sure he didn't.He was just a corps commander at the time. Wavell was in the loop, (possibly Andrew Cunningham and Arthur Longmore as well), but not relatively junior commanders.
 
The Germans maintained a deep faith in Enigma throughout the Second World War--a faith that aided allied codebreakers. What would the effects on the Allied codebreaking if the Germans believed, rightly or not, that a fully intact Enigma machine with codebooks and wheels had been captured intact by the British.

Nothing.

The Germans were not so stupid as to believe that no Enigma machine would ever fall into enemy hands. They knew that it happened at various times.

They recognized that if that happened, the enemy would be able to read all Enigma traffic on the key used with that machine - until the captured keys ran out in a month or so.

The Germans believed, not without reason, that it was impossible to solve an Enigma key by mathematical induction, and that the number of possible settings for an Enigma (in particular the four trillion possible plugboard settings) made it impossible to solve a key by brute force trials of all large numbers of keys.

They overlooked the mathematical tools developed by Polish and British cryptanalysts, which enabled them to break Enigma. They also overlooked severe operational errors in their use of Enigma (Cillies, the Herivel Tip, Parkerismus, repetitive messages) which greatly assisted the Allies in breaking keys. And they did not imagine the electromechanical bombes which allowed the Allies to test far more possible keys than the Germans expected.

However, there are other ways the Germans could have learned that Enigma was compromised. In 1939-1940, the core of the Polish Cipher Bureau worked at Vignolles in France under the aegis of the Deuxième Bureau, in full collaboration with GC&CS at Bletchley Park. The break into Enigma in early 1940 was a joint achievement, and of the several thousand decrypts in the next three months, about half were produced at Vignolles.

Vignolles was occupied by the Germans in June 1940; the codebreakers had evacuated, leaving no clues for the Germans. But what if they had failed to clean up everything? What if the Germans discovered a file cabinet of ciphertexts and decryptions? Or worse yet, a a file of notes on the decryption methods?

The Deuxième Bureau staff who supervised the Vignolles center did not go off to join Free France; they remained in the service of the Vichy government. In fact they had the Poles resume work in southern France, from September 1940 until November 1941. Thus the Vichy government (or men nominally subordinate to it) held the Enigma secret. They kept it - but what if they hadn't? What if one of the French supervisors lost his only son to the British attack at Mers-el-Kebir?
 
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