Germany realises Enigma has been cracked.

What if the Germans had realised that their security had been compromised, and that Enigma was not secure? If they had tightened up their security to the degree that Bletchley Park could no longer decrypt their transmissions, what would the effect have been on the war's outcome? Would the U-boat campaign would have been dramatically more successful for example?
 
Depends on the date of course:

IMO the most likely date was 9th February 1944 when the supply ship CHARLOTTE SCHLIEMANN was sunk in the Indian Ocean, this reaised some eyebrows on how possibly the British knew where she was and some Germans started questioning Enigma. Lets say the Germans take this seriously then and issue paper code books on top of enigma and it take the Allies 6 months to figure this out and break the paper/enigma combination.

Its late in the Uboats war then, this would reduce losses from this point on, but the Uboat war is already lost. It would certainly help the Germans in France on the ground because the Allies would be more blind about German movements.

--------------------------------------------------------------

If by some chance early in the war the German figure this out early, it would certainly help the uboat shipping war in 1943 when the allies used this knowledge to pick on tanker uboats, what would the effect of a smaller allied shipping pool be at this point????? (probably the Allies would delay Pacific offensives first, delays in the invasion of Silicy, Italy etc... second)

It would help Rommel out in late 42 getting more supplies to Africa (maybe he holds at El Ailiamen then).
 
Just found this document. In there it is claimed that the Germans produced a number of apparently secure cryptographic machines, but failed to implement them. It is very interesting reading.

A report on naval ciphers dated 10 July 1944, apparently written by the Signal Security Agency of the Navy High Command (OKM/4 SKL/II), stated that the solution of the naval Enigma was conceivable, based on "The assumption of extraordinary mechanical outlay on the part of the enemy for cryptographic activities though we (OKM/4 SKL/II) can conceive of a machine which would be suitable for this kind of work, we have none available or under consideration" since the whole question does not yet appear to justify undertaking such a difficult special constructional problem."

A quote from the text.
 
In OTL the Germans went through several variations on the Enigma machine (adding extra rotors etc.) resulting in several multiple month periods of blackout for ULTRA decrypts. In OTL these were far from fatal to the allied cause, therefore while a full shutdown of ULTRA will be a bloody nuisense I see no reason why it'd change the general course of the war.
 
The problem with the Navy is that it can't upgrade its machines all in one go, so there's a period where they have to use a 4-dial rotor like a 3-dial one, which gives the allies a foothold in working out the new technology.
 
The code can be 100% unbreakable and they will still have problems at sea.

The wolfpack tactic required a lot of radio traffic from base to boat and back again. It also required the shadowing boat to transmit a signal so its compatriots could form up on it for the attack.

They relied on High Frequency (HF) radio waves being difficult or impossible to direction find, which was reasonably true up until 1942 when all the inter-war work on HF detection bore fruit.

The Allies fixed the problem with Huff-Duff (HF/DF) so the "homing" U boat was now detectable by an escort at sea at beyond radar range (12-14 miles).

http://en.wikipedia.org/wiki/High-frequency_direction_finding
http://www.uboat.net/allies/technical/hfdf.htm
http://www.naval-history.net/xGM-Tech-HFDF.htm

HF/DF tends to be a rather unsung tool in the ASW toolkit but may well have been as important as centimetric radar itself.
 

BlondieBC

Banned
The problem with the Navy is that it can't upgrade its machines all in one go, so there's a period where they have to use a 4-dial rotor like a 3-dial one, which gives the allies a foothold in working out the new technology.

I never figured that one out. A cardinal rule is that you never send the same message with two different coding systems. Why can't say the Germans wait until they have enough machines for say all the U-boats, then go active on a certain day? What is the technical issue? You can fit two machines on the same U-boat, so having them flip systems on one day seems quite doable. We are talking about 10's of boats at sea at any given time, so it seems quite manageable. It seems like the Japanese switched code books without this issue coming up. Now there will be a window where you can't send out fleet wide weather reports and the like, but that is a small price to pay if you think your codes are broken.

And that does not even get into the issues of why you can't use good code books with the enigma machine. At one point the tried using separate code books for each submarine but the system had too many miscoded messages. Based on what I have seen with the system, it was more of training issue than anything else. IMO, the Germans could have had effectively unbreakable codes, at least for the U-boats and surface ships.
 

BlondieBC

Banned
Just found this document. In there it is claimed that the Germans produced a number of apparently secure cryptographic machines, but failed to implement them. It is very interesting reading.

Didn't the Italians have a one time pad system operation by then for their navy? It is more an issue of making it a priority.

What if the Germans had realised that their security had been compromised, and that Enigma was not secure? If they had tightened up their security to the degree that Bletchley Park could no longer decrypt their transmissions, what would the effect have been on the war's outcome? Would the U-boat campaign would have been dramatically more successful for example?


I guess it depends on what you believe by the word "dramatic". It will cause the UK to lose noticeably more ships and it will cause the TL to look different. I think the Nazi likely still lose. I don't have the tonnage lost per month, but you can likely get the effect range by assuming the numbers stay near the high end of the range. The UK was not about to starve to death IOTL. What you will see is lower production and less supplies making it to the battlefield, and this will cause the butterflies. The first time an operation is cancel or delayed a few weeks, it will start a chain reaction. So for example, if due to low supplies, the UK does not attack into Libya, then Rommel is greatly delayed to Africa or their may not be an Afrika Corp. Or Torch might be cancelled. And you will get odd production and supply shortages. For example in WW1, the Emden delay traffic out of India for 2 weeks, which resulted in an issue with the wool in Australia being harvested/shipped which resulted in uniform shortages.
 
Now there will be a window where you can't send out fleet wide weather reports and the like, but that is a small price to pay if you think your codes are broken.
And that's the point, at the time it really mattered (ie, when the Germans could have really hurt the British had they known), the British were playing very carefully, letting through a lot of minor German successes just to allay suspicion.

Also, as Andy42 has pointed out, there's a certain amount of radio traffic required to organise a wolf-pack, which will give the game away no matter how much effort the Germans put into making their codes unbreakable.

Didn't the Italians have a one time pad system operation by then for their navy? It is more an issue of making it a priority.
Ironically, yes they did, but dropped it after the Germans persuaded them that Enigma was better.
 
Last edited:

Cook

Banned
The wolfpack tactic required a lot of radio traffic from base to boat and back again. It also required the shadowing boat to transmit a signal so its compatriots could form up on it for the attack.
None of which actually requires a mechanical encryption device. Since the U-boat communication is direct to headquarters on shore and back, the best method is a One Time Letter Pad. The U-boat and shore have matching letter pads, these two pads are unique and contain random jumbled letters, the sequence of which never repeats. Without repeating sequences they cannot be broken, and because each set is unique, capturing a U-boat doesn’t gain you anything because the other boat’s letter pads are different. The short time period of a U-boat voyage means that the pad isn’t going to run out before the mission finishes.

For broadcast traffic a separate letter pad code book is required.

I’ve used this type of thing; it is very time consuming, but so was enigma.
 

BlondieBC

Banned
And that's the point, at the time it really mattered (ie, when the Germans could have really hurt the British had they known), the British were playing very carefully, letting through a lot of minor German successes just to allay suspicion.

Also, as Andy42 has pointed out, there's a certain amount of radio traffic required to organise a wolf-pack, which will give the game away no matter how much effort the Germans put into making their codes unbreakable.

Since I did so much WW1 work, I see things differently. Perspective matters. The German Navy had a tendency to be lax with codes. As good as the mid level officers of the German Army are in both wars, the Navy is bad. Almost a racial trait. Codes were broken right and left in WW1. Triangulation was huge as was other types of signal analysis. I have seen people claim it was know the UK broke the German naval codes interwar, but I have not personally verified this assertion. So it is shocking to me how bad the German navy codes were. Even if they never knew they were broken. Codes is an area you give max effort, not the sloppiness German navy.

There are many things the Germans can do in WW2 and WW1. The really did not learn from WW1, so they repeat the mistakes. They are too chatty. It gives away the location of the ships and makes codes easy to break. They don't use basic security. Lose one ship, you lose security to it all. In WW1, it was the same code books for all ships. In WW2, it was the same enigma. Why not do something basic like use a code book plus enigma? You can still send out weather reports and all point message just using enigma but send ships specific message also using a code book. Giving away your location is a very bad thing. And yes, the wolf packs are in just enigma, but every little bit helps. Or maybe just use code books that change weekly? or bi-weekly for all U-boats? Code books get lost. Coding machines are capture.

They tried to keep the locations secret for each U-boat by using different reference point for each U-boat, but the made too many mistakes. Simple concept. You setup each U-boat with 10-20 reference locations. Locations were given in reference to the point. So for example (10 miles east, 45 miles north of point D). This does not strike me as too hard to do, since we use things like phase lines in the army. And the army uses points for this all the time. "I see 4 tanks 1100 meters north and 200 meters north of point A", which would be say a bridge. We did this in a reserve unit with people with no more than a few days training on the radio. If we could do it, the German High U-boat command should be able to make it work. To me, this shows a lack of priority. So it is an easy problem to fix if there is either a desire to make your communication more secure or an idea it is insecure. The added a extra roater to the machine, so they had an idea they had an issue. Why they did not try to seriously fix the problem reflects poor leadership.
 
Since I did so much WW1 work, I see things differently. Perspective matters. The German Navy had a tendency to be lax with codes. As good as the mid level officers of the German Army are in both wars, the Navy is bad. Almost a racial trait. Codes were broken right and left in WW1. Triangulation was huge as was other types of signal analysis. I have seen people claim it was know the UK broke the German naval codes interwar, but I have not personally verified this assertion. So it is shocking to me how bad the German navy codes were. Even if they never knew they were broken. Codes is an area you give max effort, not the sloppiness German navy.
You've obviously never read up on the subject then, because in WW2 it was the Navy that was the most secure (discounting that Army mostly used telephone transmission rather than radio, and even then was cracked in early 1942), with a period between February and December 1942 where the 4 rotor enigma made messages entirely undecipherable, and indeed they were only ever able to decipher it at all due to capturing code-books.
 
Last edited:

BlondieBC

Banned
You've obviously never read up on the subject then, because in WW2 it was the Navy that was the most secure (discounting that Army mostly used telephone transmission rather than radio, and even then was cracked in early 1942), with a period between February and December 1942 where the 4 rotor enigma made messages entirely undecipherable.

It maybe secure compared to other German Services, but was it really secured compared to the USN or the RN? In war, you are measured against your competitors. And the use of landlines is a major security precaution, except the the German land forces did not even use them the entire time. The German Navy had indications its codes were broke on other occasions but only too the 4 rotor step. A lot more could have been reasonably expect to have been done.
 
What if the Germans had realised that their security had been compromised, and that Enigma was not secure? If they had tightened up their security to the degree that Bletchley Park could no longer decrypt their transmissions, what would the effect have been on the war's outcome? Would the U-boat campaign would have been dramatically more successful for example?

There were several possibilities for this.

It is not widely realized that French intelligence was a full partner with Britain in breaking Enigma in 1939-1940. In fact, the initial Polish break into Enigma was enabled when a French spy (Bertrand) obtained a complete set of Enigma documents (message formats, comm procedures, and some ciphertext/cleartext sets). His French colleagues weren't interested, so he passed them to the Poles. When Poland fell in 1939, the Polish codebreakers escaped to France, and went to work under Bertrand's command. At this time, German upgrades had secured Enigma, but the Franco-Poles and British were working on a new break, which came (as expected) in early 1940.

Then France fell. Fortunately, the codebreaking site was cleared of all papers before the Germans got there. The Poles escaped to Algeria.

Bertrand and his superiors in French intelligence stayed in France, remaining with the Vichy government. The Poles were brought back to southern France and resumed work - on the Vichy payroll! So for the next two years, the Vichy regime, which was regarded as a German satellite or puppet, and which was in combat with the Allies several times, had the Enigma secret but kept it from the Germans. (Though of course, I'm sure the spooks never told Petain or Laval about it.) Obviously, it could have been leaked at any time.

Then after TORCH, when Germany occupied southern France, the Poles again had to flee. No documents were left, but at least one of the Poles was picked up by the Germans. He passed himself off as an ordinary soldier, and was released. Another close call.

Finally, there was the possibility that the Germans would spot Enigma's vulnerabilties on their own. Gordon Welchman was one of the most important theorists at Bletchley Park. (He worked on techniques for code-breaking and traffic analysis, and helped design and build the famous bombes.) Welchman wrote later about these vulnerabilities, some of which were gross negligence by the Germans. He believed that a decent skeptical review of Enigma and German procedures (as specified and in practice) would have spotted most of them, and that without these German mistakes, Enigma would have been unbreakable. His conclusion was stark: "We were lucky."

Let's start with the worst-case possibility: a trove of documents is left behind in 1940 when the Poles evacuate the first time.

The effects start very soon. I have heard contradictory statements about Enigma in the Battle of Britain, but I find it hard to believe that it was not valuable to Fighter Command. In particular, Luftwaffe Enigma was broken early and thoroughly, and thus throughout the BoB, the British read the daily status reports from LW bases - numbers of planes and pilots in service, readiness and repair state. In reacting to German attacks and feints, it had to be valuable to know what strength the Germans actually had. (The extent of Luftwaffe decryption was immense. The British filed and cross filed everything they learned. It's been said that by 1944, the men who knew the most about the Luftwaffe were all in England.)

Perhaps more critical was the effect on the Battle of the Atlantic. Doenitz' wolfpack tactic depended on frequent communication between U-boats at sea and their HQ on shore. HQ would position U-boats in a picket line to detect a convoy. The spotter would report the convoy to HQ. HQ would then direct all the U-boats in the group to gather ahead of the convoy. Then the next night, the U-boats would attack the convoy en masse, overwhelming its escorts.

In late 1940 and early 1941, the U-boats sank a lot of British shipping. In mid-1941, the British captured much naval Enigma material, and broke the naval key. This allowed the Admiralty to move convoys around the U-boat picket lines. Losses dropped by 2/3. In February 1942, the U-boats switched to an enhanced Enigma for their use only. It was not broken for 10 months, and those were the worst of the war. A brief outage in early 1943 led to another spike in sinkings; and the U-boats were finally beaten in mid-1943 - by escort carriers, improved sonar, long-range aircraft, and more escorts.

If Enigma is secure, losses never drop in 1941. They are even worse in 1942 - U-boat operational Enigma was secure, but the British still read the traffic of the coastal forces, which escorted U-boats to and from bases. They continue bad through 1943. OTL the US shifted construction from landing craft to escort vessels late in the campaign, just before the battle was won, then had to shift back to get enough landing craft for D-Day.

If Enigma is secure, millions of tons of supplies don't even get to Europe, and the Allies have to build even more escorts. This could delay D-Day by several months.

Another area is the Mediterranean. Enigma decrypts allowed the scanty British forces at Malta to intercept a lot of Axis ships bringing supplies to North Africa. Without this advantage, the Panzer Armee Africa would be larger and better supplied. The North African campaign would be much longer and harder.

A final point: the British read the Enigma traffic from Abwehr outstations in France and Spain to Berlin. These outstations handled German spy operations in Britain. The success of the famous "Double-Cross" system was greatly assisted by the British reading the Germans' own reports, so they knew what the Germans actually believed or suspected about their agents.
 
...they were only ever able to decipher it at all due to capturing code-books.

Capturing codebooks was only part of the story. Captured keys allowed the reading of traffic on that key until the settings list ran out in 30 or 60 days.

What the Allies did in addition was break keys for which Enigma settings were completely unknown. This required four things.

1) The wiring of the Enigma rotors. This required capture of one Enigma machine.

2) The tables used for internal coding of the messages. For instance frequently used words and phrases were replaced by two-letter codes. This required capture of a set of signal books.

3) A crib; that is, a message whose text was known or guessed.

4) Several dozen "bombes" - the massive electromechanical devices which the Poles conceived, the British implemented, and the British and the U.S. built hundreds of. Each bombe could test tens of thousands of Enigma settings per day. With enough bombes, even a four-rotor TRITON message could be broken by brute force. And it was only necessary to break one message to get the day's settings and then read the entire day's traffic.
 

BlondieBC

Banned
A rule the Germans broke regularly. Gordon Welchman ranked it among their biggest cryptographic errors.

The amazing thing to me is they broke a lot of rules. There GHQ broke rules that a Battalion in the USA army would get in a lot of trouble for breaking.

1) Minimize radio traffic.
2) Send by land lines whenever possible. Still encrypt like going over open airwaves.
3) Don't send message in two different code forms. It is pretty easy to do. You don't send status reports up within a couple of hours of the time you switch code books.
4) Change code books daily at same time for all units.
5) There are a dozen of other little rules. Like the format of many messages sent from the platoon/company to battalion will have one format. They have a different format when I send to Brigade. It makes it harder to break the brigade codes if you don't have a 1 to 1 correlation between messages.

A couple years ago, I thought it was the modern US Army had just learned the lesson from WW2 and it was understandable that the Germans made these mistakes. When I looked at these issue for WW1 for my TL, i discovered that they were widely know in military circles early in WW1. Not only that, when I looked at books printed before 1928, it was widely know in the public arena. For example, the Germans broke Russian codes for the entire war. It is a lot of the reason the Germans were so much better than the Russians. France put huge effort into signal analysis. It is really criminal incompetence worthy of the torpedo fiasco that cause Germany issues. Lets just look at some easy things the Germans could have done with why they would have been done by a merely competent commander:

1) The LW bases daily status reports over the air. The French used signal analysis in WW1 to keep track of units. So cardinal rule is to broad cast as little as possible. After 24 hours stationary, my NG unit went to all land lines. It would have been trivially easy to use phone lines (public or dedicated) for these reports. If you happen to have your phone lines cut, you send a runner in a vehicle. Only units actually in the air use the radio or FLASH priority reports.

2) At one point, the Germans sent the attack plans for an Entire Army Group over the air. How about having the briefing officer carry the plans. Surely you use a lot of maps and tables in orders for 1 million men and these have to be hand delivered anyway. Now yes, the plane/train can crash, but at least then you know you have had a breech.

3) Just because you use an engima does not mean you can't code the message too with a code book/one time pad. I understand on time sensitive message or broadcast to all ships you may only use the engima, but a lot of message are ok to take an extra 10 minutes to decode. I have done codes, it is not fast, but most messages can be decoded pretty fast. Just a minute or two for a message since a lot of messages are pretty short. Something like "Arrived at station X at 14:00" is probably 3-10 letters depending on the coding system.

4) Don't micromanage so much. U-boats don't move that fast, so as long as you know its location within 100 miles, what is the big deal. You also should be able to estimate it fuel levels and supply levels pretty accurately at land based on standard tables.

5) They did not train the operators well. I have looked at some of the things too complicated to handle, and I can do them easily. I have less than 10 days total training on codes and procedures.


I guess it is my perspective, but I see a lot less "sheer allied brilliance" than the Germans made hugely dumb and obvious mistakes and the Allies took logical counter measures. It just happens that the Germans were so bad that what should have been a minor success and footnote to history is one of the great stories of WW1.
 
The amazing thing to me is they broke a lot of rules. There GHQ broke rules that a Battalion in the USA army would get in a lot of trouble for breaking.

2) Send by land lines whenever possible. Still encrypt like going over open airwaves.

Difficult in occupied countries... phone lines may be tapped and are frequently sabotaged. It is worth noting that one reason the 1944 Ardennes offensive was a surprise was that German forces operating in Germany didn't have this problem, and so produced much less radio traffic for the Allies to intercept and decrypt.
4) Change code books daily at same time for all units.
They did that, pretty much. Actually not "code books", but the current settings for each key.
A couple years ago, I thought it was the modern US Army had just learned the lesson from WW2 and it was understandable that the Germans made these mistakes. When I looked at these issue for WW1 for my TL, i discovered that they were widely know in military circles early in WW1.
I mentioned Gordon Welchman. After the war, he worked on signals intelligence and security in Britain and then in the U.S. (He was a RAND Corporation consultant to the Pentagon.) His Enigma book came out in the late 1970s, and included some discussion of the general subject and its lessons for future militaries.

The NSA and Britain's GCHQ tried to suppress the book. It was not that the stuff on Enigma was still hot. It was the emphasis that Welchman put on the mistakes the Germans made. NSA had (still has) a reputation of being able to crack any cipher by sheer power of mathematics and computing. They didn't like it Welchman revealing that codebreaking benefits a lot from errors by the code users - because then some of their current targets would tighten up procedures and eliminate errors they were making use of.

1) The LW bases daily status reports over the air.
Better than that. Every major army and navy unit had a Fliegerverbindungsoffizier (Air liason officer) from the Luftwaffe. The Flivo's job included a report to the Luftwaffe on the status of the unit - strength, readiness, expectations for the next few days.

3) Just because you use an engima does not mean you can't code the message too with a code book/one time pad.
That was done. The Germans had codebooks which translated common words and phrases into two-letter "bigrams". Weather reports were so coded. There were IIRC daily variations and changes in the bigram tables.

The cipher material captured in November 1942 which allowed Turing to break the TRITON code of the U-boats included the "Short Signal Book".

4) Don't micromanage so much. U-boats don't move that fast, so as long as you know its location within 100 miles, what is the big deal. You also should be able to estimate it fuel levels and supply levels pretty accurately at land based on standard tables.
"Wolfpack" operations do require that level of "micromanagement". And when deploying a scouting line of boats to detect passing convoys, it's important to have each boat in the right place - otherwise there would be huge gaps and the convoys could steam right through.

5) They did not train the operators well.
Among the greatest German errors was "Cillies". The three letter indicator and text settings for each message were to be picked at random by the encoding operator. Many operators used obvious or easily guessed settings. (One operator used his girlfriend's initials.)

I guess it is my perspective, but I see a lot less "sheer allied brilliance" than the Germans made hugely dumb and obvious mistakes....
That's what Welchman wrote. But it should also be noted that the Allies did apply a lot of intelligence. The German Enigma included a "plugboard" with trillions of possible settings. Welchman had a mathematical insight that allowed the entire plugboard to be solved in one go.

Other analysts spotted German weaknesses because they were looking very hard at all aspects of German traffic.
 
Last edited:
It maybe secure compared to other German Services, but was it really secured compared to the USN or the RN? In war, you are measured against your competitors. And the use of landlines is a major security precaution, except the the German land forces did not even use them the entire time. The German Navy had indications its codes were broke on other occasions but only too the 4 rotor step. A lot more could have been reasonably expect to have been done.

Both the USN and RN suffered from having their codes broken. The British BAMS merchant ship code used for convoys (a book code) was broken easily and early by the Germans.

Enigma was popular because it was "easy" compared to the alternatives. One time pads impose a large logistical problem on the users. Think how many units in the German armed forces there were with Enigma machines. Each of which is going to need a specialised one time pad - that their headquarters is going to need the counterpart to. And will need a seperate pad for their communications up the chain of command too. Who will also need seperate pads. And these all have to be delivered to front line units in a very carefully organised manner. And gods forbid that you lose your current pad to water/fire/enemy action.
 
Both the USN and RN suffered from having their codes broken. The British BAMS merchant ship code used for convoys (a book code) was broken easily and early by the Germans.

Enigma was popular because it was "easy" compared to the alternatives. One time pads impose a large logistical problem on the users. Think how many units in the German armed forces there were with Enigma machines. Each of which is going to need a specialised one time pad ...

Even as it was, Enigma imposed a burden which led to a grievous German error.

Each branch of the German armed forces had its own Enigma key - that is, its own daily settings for the machine. The key included the plugboard setting, the selection and order of the scrambler wheels, and the positions of the indicator rings on the scrambler wheels. Every month, all these settings had to be generated for 30 days for each of the keys in use.

At the start of the war there were only about six keys in use - Army, Navy, Luftwaffe, Wehrkreis, Abwehr, SS (IIRC). But very soon additional keys were created. The Navy soon had keys for general operations, U-boat operations, surface raiders, capital ships, U-boat training, and Mediterranean forces - and still others that I can't recall. The other services also added lots of keys.

Someone (Gordon Welchman called him Herr X) was responsible for generating all the keys and issuing them to the services. As the keys proliferated, Herr X's job got to be too much for him. He hit on a brilliant labor-saving idea: reuse components of old keys! He would take the plugboard setting from an old Luftwaffe key, the wheel order from an old Navy key, and the ring positions from an old Abwehr key, and issue the combination to the Army as a new key. Who'd ever know?

Well, at Bletchley Park, analyst Reg Parker was keeping logs of all broken Enigma key elements. He spotted Herr X's little trick almost immediately. This particular German error was dubbed Parkerismus, and it was an enormous gift. There were times in 1941 and 1942 when entire keys were known for almost a month in advance. The Germans eventually did recognize the weakness, or possibly Herr X got an assistant, so Parkerismus stopped, but it did immense damage to the Germans first.
 
Top