I’ve often wondered why other countries, especially Japan, could not have looked around and found some native population with a unique language they could use in the same way?
I guess the issue was finding some who would be trustworthy and accurate.
Bletchley Park were analysing about 150 different enemy ciphers by VE day, and for all the fuss about Enigma it was breaking Tunny and Sturgeon (variants of Lorenz) that was the truly amazing intellectual feat.
Towards the end of the war Lorenz was being used for high-level strategic and diplomatic communication between German High Command and various field armies. Lorenz was broken without ever laying eyes on an enciphering machine, after an operator sent the same message with minor differences twice, gifting the British a “depth” and allowing Tiltman and Tutte to work out the rotor layout and deduce that it was a Vernam cipher. Advanced techniques for guessing wheel settings were developed (Tutte’s statistical method and Turingismus, another statistical method that developed out of an early form of what we would now recognise as information theory, predating Shannon, that Turing developed to break Enigma, were the major ones) and a mocktup deciphering machine was made, modifying a British Typex, which allowed plaintext messages to be printed out after the wheel settings had been found. The methods for breaking Lorenz were so computationally intensive that it eventually led to the development of Colossus by Flowers, one of the world’s first computing machines.
In the space of six years, Bletchley Park more or less invented modern cryptanalysis, developed the precursors of information theory, and were building some of the first computing machines. Pretty amazing stuff. Further, all of this was hushed up until the 1970s, as the British government, perfidious as ever, were selling WW2 era cryptography machines to various other governments around the world, safe in the knowledge they could read all of the encrypted traffic. If you visit Bletchley Park today (well recommended), they have original working Bombes and a Colossus machine that you can see and walk around, as well as the original wooden huts that the likes of Turing, Flowers, Tiltman and Tutte were working in.
The bombe and Colossus at you can see are reproductions, all the originals were destroyed after the war. The Colossus is actually at the National Museum of Computing next to Bletchley. There was a spat between tnmoc and the Bletchley Park Trust a few years ago so they’re not directly connected any more. I’ve not been in several years, probably due another visit.
Curiously it may be that at least two Colossi were not destroyed immediately, but were trucked off to GCHQ. These may have seen out their days breaking codes in the cold war. Whether they survived beyond their useful lives is another matter. It would be a wonderful thing to find they are secreted away in a classified storeroom somewhere.
The other Colossi where broken up with sledge hammers, dumped into a pit, set on fire and then buried, somewhere in the grounds of Bletchly Park. Some time spent with a metal detector still might turn up something of interest.
Nitpicking but the Poles turned their code breaking information over to the French when Poland surrendered. It was the French who passed it on to the British when France was defeated.
I thought an American destroyer captured an Enigma; Wikipedia shows several instances of the Royal Navy capturingEnigma machines and settings.
Thank you for the correction.
There was many years ago what might be termed a mass of seemingly well-documented work which seemingly clinched the case in favor of a Coventry bombing deception. I caught that side of the story, but missed the follow-up by the other side.
The Brits had a working Enigma at the outset of the war and thus knew the rotor wiring which gave about 17000 permutations. Knowing the wiring, it would not have been hard to break enigma if that was all the machine did to encrypt messages. It was however, the plug panel (Stecker) which introduced more complexity into the Enigma. The Stecker allowed the operator to swap up to 10 pairs of letters (out of 13 pairs - 26 letters). A became D and D became A for example, plus nine other swaps. This made the Engima incredibly hard to crack.
These pairs changed daily and the daily combinations were listed along with rotor selection and settings in code books which every Enigma operator carried. On ships and subs, the ink was water soluble so that if captured, the operator could get it wet and render it useless.
This, and the move by the German Navy from three to four rotors, was why the allies went after the machines - hoping that the code books would be rescued also.
Anyone interested in this aspect should read Neal Stephenson’s Cryptonomicon. It’s partly fictional, and some bits that look like though they’re historical aren’t (e.g. Unit 2702 and its role in obfuscating Allied intelligence gains), but it’s thoroughly well researched and Stephenson’s prose is a joy to read.
It also includes a mathematical analysis on the impact of masturbation on the performance of cryptanalysts and a thesis on how to eat Cap’n Crunch. Which I’m pretty sure you won’t find anywhere else :).
The goal isn’t just to capture sensitive materials (like code books)-- It’s to capture sensitive materials without the enemy knowing that you’ve done it. If they know, then they can stop using those codes. Worse, if they know you’ve got the codebook, but you don’t know they know, then they can continue using it, to feed you deliberate misinformation.
The Germans probably knew that the Allies had gotten their hands on a few Enigma machines, but they wouldn’t have been worried about that: Just having the machines doesn’t give you the codes. At least, not without a lot of work. In fact, one of the core assumptions of modern cryptography is that the enemy should always be assumed to have your algorithms and machinery.
How did the bombe machine know when it had cracked a message? The movie showed it trying many different possibilities, but I wasn’t clear on how the machine knew when to stop.
The Enigma had one major problem which aided in decrypting messages. No letter could ever be substituted by itself. So a G could never code to a G, H to an H etc.
The Germans were creatures of habit and the code breakers at Bletchley Park would expect weather forecasts and other mundane transmissions to come early in the AM. Knowing that the message was a weather forecast, they were able to ‘guess’ what a short section of the message would be and then match that up against the actual transmitted code. They would match it up so that no letter was coded to itself and then use that - it was called a crib.
The crib would then be used to construct a Bombe Menu which you should probably read about here: Bombe - Wikipedia
They would then enter that menu into the Bombe and the Bombe would figure out every combination that it couldn’t be - called contradictions. If no contradictions were found, the machine would stop. A cryptologist would then take that particular rotor/stecker setting and see if the rest of the message could be decrypted with it. If not, they would try another bunch of wheel settings - each Bombe could emulate 36 Enigmas at a time, until the correct settings were found.
Just to add, once the daily rotor/stecker settings was broken, every message from that branch of the German military was immediately decipherable (the three branches all used slightly different Enigmas), until the settings changed for the next day.
The biggest push was to decode as quickly as possible, the Naval Enigma since the German Wolf Packs were decimating allied shipping. Prior to the Navy switching to the 4 rotor machine, Bletchley was figuring out the daily settings sometimes by 9 in the morning - they were that good at it.
The 4th rotor slowed them down for about a year. The allies grabbed a codebook from a captured UBoat but the unknown 4th wheel/reflector wiring was figured out when a German operator sent a 4 rotor message to a 3 rotor recipient who didn’t understand the message and asked for it to be sent again with the 4 rotor machine set up as a 3 rotor machine. The sending operator sent exactly the same message with the same wheel settings which gave away the wiring of the 4th rotor/reflector…
It’s brilliant stuff. Haven’t seen the movie yet. I hear it is good.
I think it is from a conversation with a friend of mine at the Library many years ago over an American capture of a U boat. An Ensign with a .45 frantically searching for the sea cocks or explosives on them. 
Or he may have been thinking about the capture of the U-505 which was done by American destroyers.
ninja’d!
Perhaps so.
Enigma machine videos for those who are interested.
How enigma worked
How the flaw that enabled determining the plug board settings quickly
IIRC, the codebreakers could take some shrewd guesses at the words to be deciphered:
H,I,T, most likely ends with L,E,R.
B,E,R, and L,I,N.
and so forth.