German Cryptanalytic Attacks on the British World War II “TYPEX” Machine

https://www.cs.columbia.edu/~smb/blog//2018-08/2018-08-24.html

by sohkamyung • 8 years ago

73 19 8 years ago

cs.columbia.edu

Moodles2• 8 years ago

This is nice to see because I've always found it surprisingly difficult to get any information whatsoever on the German efforts in WWII.

Generally rotar machines were used a lot before WWII by banks and such. The Enigma and Typex were much more difficult to crack than commercial products because of the plugboard, while commercial machines only had spinning rotors. I think the Typex didn't have the weakness that letter x encrypts to x either. The Germans basically concluded that it was even tougher than the unbreakable Enigma so gave up.

Germany also had little success because, unlike in Bletchley Park, they didn't exactly tolerate eccentric academic types. The codebreaking efforts of the Germans were also so incredibly fragmented across different departments that once two different departments had a bust up on the street.

Wikipedia has some good references: https://en.wikipedia.org/wiki/German_code_breaking_in_World_...

wycs• 8 years ago

That and they brutality exterminated many of their most talented mathematicians.

raffael-vogler• 8 years ago

The codebreaking efforts of the Germans were also so incredibly fragmented across different departments that once two different departments had a bust up on the street.

Hitler also systematically embedded a divide and conquer principle in organizations. Basically all institutions were duplicated to have them compete against each other instead of potentially forming an opposition against Hitler.

imrelaxed• 8 years ago

USSR did the same thing. Pretty sure it was done to promote competition and not for divide and conquer. Secret police was more than enough to handle dissidents. Hitler and his party actually had a lot of support because most of the bad stuff they did was hidden from the people or justified super hard through propaganda. And as bad as the Nazis were overall they still managed to have major successes in economy and science.

jacquesm• 8 years ago

Germany also had little success because, unlike in Bletchley Park, they didn't exactly tolerate eccentric academic types.

Would Konrad Zuse qualify? If so the allies were pretty lucky he wasn't born a few years earlier.

stan_rogers• 8 years ago

It was the fact that a letter could never encrypt to itself that was, perhaps, the single biggest fault of the Enigma. In routine messages, the position of expected or candidate plaintext could be inferred from a lack of correlation of any characters, and any candidate plugboard configurations that forced auto-mapping could be immediately discarded. (Rotor choices, particularly the right-hand wheel, could be determined statistically, leaving the ring settings and plugboard configuration as the tedious, time-consuming bit.)

sgt1013• 8 years ago

Interesting conjecture at the end; GCHQ retained two Colossus machines until the 1970's. The Russians knew that Colossus existed and GCHQ knew that the Russians knew. Why retain Colossus - people tend to say that it was because there were networks of rotor machines in use in less sophisticated countries, but given the us or them nature of the cold war it seems unlikely that there was sufficient value in retaining them through the 50's. My guess is that there was some sort of elaborate counter bluff played out with the Soviets; that they believed that the Brits thought that they were unaware of Colossus and so would be duped by traffic sent over rotor networks... but what was in it for the Brits?

rleigh• 8 years ago

Maybe because the Russians didn't know that GCHQ knew that the Russians knew that GCHQ had Colossus!

sgt1013• 8 years ago

Could be...

qubex• 8 years ago

Colossus was used to break Tunny (encrypted teleprinter traffic) and, as far as I can deduce (despite that machine also using rotors of an entirely different kind) was useless in analysing Enigma-type traffic. The desire to hide the achievements of Colossus at Bletchley Park was an (apparently successful) attempt to goad the Soviet Union into adopting similar cipher systems after the war so that the same techniques could be applied by the Western powers to read Soviet signals. The ruse largely worked.

tialaramex• 8 years ago

Yes! This is so important and yet so often not understood even by people who've supposedly been to Bletchley where they spell it out pretty clearly in their museum.

Tunny (the German thought of this as "Lorenz" because that was the manufacturer name) is an actual stream cipher, more or less. It's making pseudo-random bits and XORing them with plaintext to produce a ciperhtext. The plaintext is Baudot code rather than, say, ASCII, but it's definitely bits. Lorenz is doing this in (by modern standards) a ludicrously mechanical steampunk-looking way, but that's what it's doing. Even though to our modern eyes it looks not so different from Enigma in terms of the principle of operation it's entirely different and radically more like how things would be done decades later.

Salsa20 and ChaCha are modern stream ciphers, they're designed for modern binary computers rather than a mechanical contraption, but the core underlying principles are the same as Lorenz. If you can make a lot of "random-looking" bits from a small key you can XOR them with your plain input to produce a ciphertext, nobody can decipher it without knowing the key in order to generate the same "random" bits.

Most cryptosystems you use today have block ciphers inside them, which work quite differently, but some will have a stream cipher, a descendent of Lorenz inside them - spiting out "random-looking" bits.

sgt1013• 8 years ago

But the Soviets knew that Tunny was broken, because Cairncross passed it to them, GCHQ knew this. The Russians weren't stupid - it was very clear that the Brits could read SS cipher traffic, the SS used Lorenz. I have read (but can't find it) that the Soviets used captured Lorenz.. but it is odd.

German Cryptanalytic Attacks on the British World War II “TYPEX” Machine

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