How Poles cracked Nazi Enigma secret

[v2]

A silk scarf bearing the image of a horse race was a suitably cryptic gift for a Polish mathematician to receive from a British code-breaker.



The Poles had got there first - that seemed to be the message.

Dillwyn "Dilly" Knox was delighted with the Polish copy of an Enigma - a top secret German military cipher machine.

But his meeting with code breakers in Poland in July 1939 - just weeks before Hitler invaded their country - had initially put him in a sour mood. He had been struggling to figure out the machine's wiring - a key part of the complex jigsaw puzzle called Enigma.

more: BBC NEWS | Europe | How Poles cracked Nazi Enigma secret

[timshatz]

That is one of the great untold stories in history. Guy who figured it out had never even seen Enigma. Figured it out from the undecrypted output.

Talk about brilliant.

[parsifal]

The German Naval codes were broken in late May 1941, resulting in a number of successes, perhaps the most significant being the ability to route convoys around the U-Boat packs, and thereby reduce the shipping losses considerably. Ten in early 1942 the Germans added a seventh rotor to the U-Boat cyphers, and this blinded both the US and the British ASW forces once again. This contributed to the massacre of shipping off the US coast in 1942. Finally, in late '42, the U-Boat cyphers were again broken, and the rest, as they say, is history

[wheelsup_cavu]

Thanks V2.
I had read some about this but I only had a vague understanding of what happened.


Wheels

[v2]

here the breakers:
Marian Rejewski - Wikipedia, the free encyclopedia
Henryk Zygalski - Wikipedia, the free encyclopedia
Jerzy Ró?ycki - Wikipedia, the free encyclopedia

[timshatz]

I've been reading about it for a decade or two. Think I have a pretty decent understanding of it and every time I think about what those guys did, especially Rejewski, I am really amazed. The leaps he made in intuition that brought him to the solution are way beyond my capabilities and almost beyond my understanding of the leap. Einstien, I get. This guy's stuff makes you work to keep up with it. Even when you know how it's going to turn out!

Alan Touring was probably in the same league but not as comprehensive as a person. Touring was something of a mess socially, but intellectually peerless. Rejewski was brilliant and a real person.

[fibus]

True.
Turing.
The Post Office of GB did a great job creating the 'bombes".
It was brilliant all around.
The Enigma machine was designed for commercial use before ww2. A quick trip to the patent office would have revealed everything one needed to know.
In the classified world of secrecy no one would tell us if they did.

[timshatz]

True.
Turing.
The Post Office of GB did a great job creating the 'bombes".
It was brilliant all around.
The Enigma machine was designed for commercial use before ww2. A quick trip to the patent office would have revealed everything one needed to know.
In the classified world of secrecy no one would tell us if they did.

Yeah, a guy in Germany designed it right after the end of WW1. Thought of the commercial applications.

Guess nobody thought to look at the patent office. Not a bad idea, when you get right down to it.

[Guns'n'Props]

Re-"A quick trip to the patent office would have revealed everything one needed to know." - it really depends on the info used to draw the patent. If this were detailed enough a mathematician could probably find some "weakness" eg something that could cause a repeating pattern or cycle, but ultimately the strength of this machine was that such repetitions would take very long to re-occur probably after thousands of messages using the same wheels and stecker board settings.

Apart from the outstanding work done by the Poles and Bletchley Park geniuses it was the enigma operators who gave the game away by repeatedly using standard terms and phrases which could be used as cribs by the codebreakers (at Bletchley). Since they would know the origin of the message they would have a good idea of the words or phrases to trawl for. This weakness was known to the Germans but like any office worker sending lots of emails everyday they would resort to the same message construction to make life easier especially if there were many to send and with similar content.

[RabidAlien]

They were also over-confident in their "unbreakable" machines, and while they knew the dangers involved with regular codes, I don't think they were too worried with regards to the Enigma machine. Leo Marks, in his book "Between Silk and Cyanide" (excellent read, BTW), mentions how the Germans always signed off their encoded messages with "HH" (heil Hitler). SOE on occasion used this against them, signing off their messages with "HH" to see if the operator on the other end did the same....which would let them know if they were talking to the actual secret agent or to a Nazi, and that the agent was blown.

Very interesting stuff!

[Guns'n'Props]

Actually Admiral Doenitz did suspect from time to time especially when the English tried to ambush some UBoats in places very much off the beaten track - and didn't pull it off ! I can get get you the story if you like, it's somewhere in some RN history I've got. Every time he went back to the mathematicians they told him it was humanly impossible owing to the astronomical possibilities of breaking the code MANUALLY. They did not consider the Brits could be using machines to reduce the odds.

Then again as mentioned earlier in this thread the Germans did progressively increase security by introducing new wheels, introducing a short message code book to reduce the risk of cribbing (knowing what words the message is likely to contain) I mentioned earlier etc. Notwithstanding some periods of decoding blackout Bletchley got back into the game by sheer genius, lucky breaks, info from other sources and the usual operators bad practices.

[RabidAlien]

One thing I found out recently was that a lot of the Nazi operators would sign off with "HH" (heil Hitler). Makes for one very easy phrase to locate and extrapolate the rest of the key-code from.