The movie ‘The Imitation Game’, which is about Alan Turing and the breaking of the German WWII Enigma code, brought a few questions to mind.
Did the Allies have an equivalent ‘unbreakable’ code for their secret messages, and were the Germans or Japanese ever able to crack it (that we know of)?
If the Axis didn’t crack the Allie’s codes, what did we know about encryption that the Germans didn’t? I know about the Native American Code Talkers, but I don’t think they were used to relay every critical message throughout the entire war.
How did the Allies hide the fact that they had broken the Enigma code without tipping off the Germans?
Was their an equivalent, but different, Japanese ‘Enigma’ type code that also had to be broken, and was it broken?
Just thinking off the top of my head here, I’m sure others will correct/make me look stupid/corroborate with sources…
The Germans never considered Enigma truly ‘unbreakable’, simply so complex that cracking a message would take insane man-hours, so they never though it worthwhile that anyone would try.
Enigma was used for particular types of military messages, and as the German army was quite mobile, the Enigma machine was mobile, and therefore the encryption mechanisms could only be so complex before the machine got too heavy and bulky.
The British however used Typex, which was a souped up, considerably more complex, but also bulky and heavy, version of Enigma. Without getting as advanced into computers as the British did, the Germans had no hope, really, of cracking it.
The real impressive work, I consider to be the British cracking of the Lorenz cipher, which was a separate encryption used for high-level political and strategic command communications by the Germans. Without ever having seen one, the mathematicians at Bletchley reverse-engineered it and built Colossus, the first ever programmable computer, to crack it.
Astounding stuff!
Sometimes it was as simple as misunderstanding the signal (the German counterattack in late 1944 in France genuinely caught the Allies by surprise), or that the Germans did enhance their codes (the three Services has separate Enigma encryptions, routinely revised and updated, and notoriously partway through the war the Navy cypher was further complicated with an additional wheel on the machine!), each step of which put Bletchley back in the dark, for a bit.
And there was also the fact that sometimes they deliberately allowed soldiers and sailors to get into serious trouble despite having the intelligence to avoid it. Many convoys were deliberately sent into direct danger of U-boat attack, and many died, as it was important to have just enough defeats to stop the Germans getting suspicious that their codes had been cracked.
I remember vaguely that the Japanese diplomatic code, Magic, was cracked in 1941. Sorry, can’t say much more than that…
The allies would occasionally ignore intelligence learned from Enigma encoded messages just to protect the knowledge that they had cracked the Enigma. A lot of supply ships were probably sunk that could have been saved, but the military commanders felt that it was more important to keep the code break secret than to save these particular targets.
We broke several Japanese codes, one of which gave us a huge benefit at Midway.
The British had a machine called Typex which was similar in concept and design to Enigma.
The U.S. had a machine called the ECM Mark II.
There were others.
The U.S. also had Indian code talkers, the most famous of which are the Navajo which were featured in the movie Windtalkers (well, famous now, their existence was a well kept secret for long after WWII). Definitely not an Enigma style of message coding, but noteworthy for never being broken.
WWII Allied codes were not seriously compromised, if they were at all compromised
A big part of the story is that a German encoding machine was stolen from the factory by an employee of Polish descent, who gave it to the Poles, who gave it to the British.
In one case the Germans were allowed to bomb a British target unhindered (the city of Coventry).
I don’t think the Japanese had an enigma equivalent that was broken. It was the fabulously inspired US cryptology teams which deserve credit. BTW it was not necessary to read anywhere near 100% of the enemy traffic to obtain vital information:
The Japanese codes were thoroughly broken, and pretty early in the war, yes.
In fact, that is what led to Isoroku Yamamoto (the admiral and strategist behind Pearl Harbour) getting bushwhacked in '43.
Which itself should have been a glaring, neon, 10 feet tall sign for the Japanese because there simply was no way an American squadron could have “just happened” upon a small flight of Japanese planes island-hopping so deep within Japanese airspace, especially when no other such combat patrols were seen anywhere else. No way in hell. It was a gigantic intelligence fuckup on the US’ part.
But the Japanese never changed their codes, so they must have figured it was just bad luck
Imagine intentionally sending ships into harms way, knowing they will be attacked and likely sunk, and that men will die because you don’t want to reveal that you have broken the enemy’s code. That must have led to a lot of sleepless nights. I wonder if the families of those lost men ever knew they were sacrificed for the greater good.
Every time you use any fruits of spying you risk exposing your methods. Getting Yamamoto was judged to be worth that risk. The fact the Japanese did not connect the dots means the gamble paid off in spades.
What you and I don’t know now is how confident the US was then that the Japanese didn’t have an effective response even if they discovered the US had broken their code systems. Heck, for all we know now, the Japanese may have known or at least believed they were compromised, but had been unable to develop alternate systems, gain confidence in them, deploy them, and put them into use yet.
So, IMO, declaring the decision to assassinate Yamamoto as a “gigantic fuck-up” is, well, at least unsupported hyperbole.
However, there were certainly Allied codes that the Germans were (rather easily) reading. The bizarre aspect that this led to were instances during the Battle of the Atlantic where Bletchley was breaking Donitz’s instructions to his U-boats, then the Admiralty reacting to these by sending orders to convoys to adjust course in ciphers that the Germans could read. Whereupon Donitz would issue new orders and so on.
The German failure was not noticing this was happening. The British failure was allowing this in the first place - of all people, they should have realised the risk.
What the Poles (and, to a lesser extent, the French) had told us. Then the imagination to do everything on an industrial scale.
And the tensile strength of paper tape. This has seriously been suggested as one of the really great secrets of WWII. Breaking Lorenz depended on several devices (most notably Colossus) that crucially involved running ticker tapes past crude optical scanners at extremely high speed to effectively search through lots of possibilities. The Germans never twigged to any of that.
(That said, for all the sheer intellectual elegance of the Lorenz story and all that followed from it, I’ve never been convinced that it was either anywhere near as important or as complicated as breaking Enigma. At least in retrospect, I can fairly easily get my head round Lorenz. Enigma is just intrinsically harder.)
Purple is the most famous. Michael Smith’s already mentioned book The Emperor’s Codes is a very good history of the scale of the efforts involved. (Smith is British and so is really telling the story from a Bletchley point of view, but that has the advantage of emphasising just how much of the British codebreaking efforts were directed against Japan, an otherwise usually neglected topic.)
I’m no expert, but I’m not sure that the technical details of the Japanese side of things has been declassified to the extent that the breaking of Enigma and Lorenz has.
The naval and diplomatic codes, yes. Not the Japanese Army code. That wasn’t cracked until about midway through the war when codebooks were captured at the Battle of Sio around the beginning of 1944:
Note that the Army code required two parts to decrypt. One was the main codebook that didn’t change (or maybe changed only once a year) and the other changed monthly. If the US codebreakers didn’t somehow obtain the monthly update, then they couldn’t decrypt that month’s messages. However, they usually managed to do this because someone in the Japanese Army was sure to be lax in their security (it only takes one).
I couldn’t find a page describing this, but I’m sure there’s something out there.
It came very close though. David Hatch, the director of the National Cryptological Museum was interviewed on the “Secrets of War” documentary on Breaking the Japanese Code, Hatch remarked that indeed the Japanese did assume that the Americans had deciphered one of their codes after Yamamoto was killed, but the Americans were lucky when the Japanese guessed wrong on what specific code the Americans had broken. And so the Japanese continued to help the allied cause with great information.
IIRC, The Imperial Japanese Cipher…PURPLE…was broken when engineers from Western Electric realized the code had qualities consistent with telephone switching equipment.
They managed to create a decoding machine without even seeing the original.
The Polish Cipher Bureau broke the original enigma code in 1932 and turned over all their information to the British at the outbreak of WWII. Among the many things the British learned from the Poles was the value of mathematicians in cryptanalysis. It seems obvious now, but up to that point, the British favored linguists for code breaking.
SIGSALY is a good example of the robustness of the Allies encryption infrastructure. It involved digital computers, encryption key streams written on vinyl records sent by secured couriers etc.to provide real-time encrypted voice communication between continents.
The German equivalent to Bletchley Park was B-dienst, which did indeed break several Royal Navy ciphers.
The Germans did have successes against Allied codes, but unlike the Allies, they didbn’t centralize their cryptography efforts in one place; B-dienst was the Kriegsmarine’s facility, the Luftwaffe had its own, so on and so forth. As you can imagine this resulted in much duplication of effort and failure to share ideas, which was precisely as terrible an idea as it sounds. But that was the Nazi way of doing things.
See above. The Allies just did a better job organizing their efforts.
“The Imitation Game” was an awesome movie as movies go but it was in many ways extremely loose with the facts, so please don’t take it as a history lesson. It is simply not at all true that Alan Turing was a mad genius who was the only person who thought a machine could crack codes, nor was it a tiny little team that helped him. A number of geniuses were involved in that and by no stretch of the imagination was Turing’s work something he had to do in a back room. In fact, the machine you see them use in the movie is called a “bombe,” and is so named because it actually was developed as an improvement on a Polish invention, which was called a bomba kryptologiczna, “cryptologic bomb.” Turing also travelled to the USA to help their cryptanalysis efforts.
Turing, incidentally, was already working for Bletchley Park before the war started, on a part time basis; when war was declared he immediately began full time. His genius was well known to the British command, he didn’t have to convince mean old Edward Longshanks.
Nor, for that matter, was it the idea of Turing and his team to hold back intelligence to win the war, nor was it something MI6 did. Holding back on the actions you take on intelligence is an old concept long predating WWII and was something Allied command did, not Turing.
Incidentally, the character of Christopher, the boy Turing falls in love with, did exist and he did die of tuberculosis. Joan Clarke was also a real person, and Turing was briefly engaged to her.
It is also worth noting that the Ultra program wasn’t perfect at solving Enigma messages; if the machine was altered in design, as indeed it was several times, it became unbreakable until it was re-solved, and good signals discipline could prevent decipherment. The bit in the movie about using a German signaller’s girlfriend’s name as a key is actually true; much of the decoding was often accomplished by German signalmen doing stupid things, like using AAA or QWE or their sweetheart’s names over and over as the initial machine settings. Bletchely Park called such habits “sillies,” because they were just silly, but different parts of the German forces were varyingly prone to sillies; the Luftwaffe was infamously prone to giving away such things, while the SS managed to never have a code broken, according to some sources.
Depends, and there are ways to cover your tracks.
For example, if you pinpoint the position of a submarine through radio intercepts or Huff Duff triangulation or radar (all of which were hush hush), then immediately sending a couple destroyers/a flight of torpedo bombers straight at it could be somewhat suspicious. If it happens to every submarine in a particular sector, then it’s **very **suspicious.
But if you take care to only bump the rate of submarine killing, say, 30%, then it might just be a bad month. And if you take the precaution of sending a scout plane to “spot” the submarine first, so that it might in turn be reported by the submarine (or noted in the captain’s log, in case the destroyers/bombers fail at their job) then it’s just business as usual, no reason to suspect the Allies have anything special going on.
OTOH, when you send one flight of planes at precisely the place one VIP is doing a one-time trip, and there was no other reason for those planes to be there, there can’t be any luck involved, can there ? It’s very clumsy.
Evidently. But it probably wasn’t, at that.
He was just one guy. Not even a very important guy - from Midway onwards the Japanese didn’t let him do his job any more, and it’s not like he had very much to do his job with. The decision seems to have been driven more by “this is for Pearl Harbour you bastard !” and token morale boosting reasons than any real strategic advantage.
The irony of the code-talkers was that the Navajo language probably was genuinely uncrackable, with the resources any of the Axis had… but they didn’t actually use the Navajo language. To “increase” security, they instead used a code developed based on the Navajo language, but the code was such that, had the Axis realized just how simple it was, they could have solved it in an afternoon. All it was was a letter-substitution cipher, with English-language letters being represented by Navajo words. And you don’t need to know what those words mean to be able to figure out what letter each one represents.
Yeah, I did some research on Enigma a few years ago for a grad paper and I don’t remember the Allies purposefully ignoring major news from Ultra. Whenever possible they tried to provide a “cover story” for how the intelligence might have been gathered by other means but they would still take action even if they couldn’t.
(I thought I read about the Brits creating a fictitious spy ring in Switzerland that was the source of the Ultra intelligence. However, there’s nothing in the wiki article on Ultra so I might be mixing it up with something else.)
The Allies had no idea how long they could keep cracking Enigma. Changing the mechanics of the Enigma would break all attempts to crack it and make the cryptologists start over, but the Germans did that only once: the Kriegsmarine added a rotor (or two) at one point and Bletchley wasn’t able to crack it for another 6 months or so. The Allies decided to use the intelligence while they still had it.
