Enigma-Cracking Bombe Recreated

toxcspdrmn writes "Volunteers at Bletchley Park have recreated a working replica of the electromechanical bombe used to crack the Germans' Enigma encryption. The bombe was designed by Polish cryptologists and refined by Alan Turing and colleagues at Bletchley Park. The replica joins a recreated electronic Colossus — generally considered the first electronic computer. Impressive work when you consider that Winston Churchill ordered the originals to be completely destroyed at the end of WWII."

Comments

Marian Rejewski

[Ignignot]

How on earth can you mention this device without saying Rejewski's name? He is the one that originally cracked the enigma code, and did all of the hard cryptanalysis long before those guys in the UK got anywhere. He barely gets a footnote in history, while the machines that were built get all of the credit. Ultimately they were just collections of vaccuum tubes - it was Rejewski that gave them a purpose. Turing was brilliant of course and should be revered, but not alone.

Re:Marian Rejewski

[Mahy]

Turing didn't just wire the thing up: He came up with the approach that allowed them to deal with the plug board.

It is even less well known that Turing's Bombes were unable to solve the 4-wheel Naval Enigma. The 4-wheel Naval Enigma was actually solved by engineers working for NCR in Dayton Ohio, led by Joe Desch. Their contributions were classified until the mid-90s, and so were not well known. See:

1) http://www.daytoncodebreakers.com/
2) http://en.wikipedia.org/wiki/Joseph_Desch

Re:Marian Rejewski

[igb]

No one with half an understanding underestimates Rejewski's contributions, but your article is somewhat wide of the mark. Firstly, Rejewski's work focussed on the attacks on the double-encipherment of the message setting in the indicators prior to about 1940. By use of the bomba he was able to produce tables of `males' and `females' which indicated the circumstances under which the double-encipherment of the indicator offered a route into the message settings. Rejewski's method didn't require any knowledge of the plain text, but did crucially depend on the structure of the indicators. His work was replicated in the UK in the construction of Jeffries Sheets.

However, although Turing/Welchman's bombe paid explicit homage to the Polish work in the choice of name, its task was fundamentally different. The bombe provided a means to look for message settings based on the cipher text and conjectured plain text. Its weakness was the requirement for plain text, which was a massive task to obtain through traffic analysis of sterotyped messages, `kisses' with broken systems such as the Dockyard Key, weather reports transmitted in other cipher systems and so on. Its strength was that it was independent of the indicator system, which was one of the easier things to change in the Enigma system.

The Polish contribution lay in the machines themselves, the analysis of the indicator systems and the bomba (bomby? spelling may be wrong): together they showed other people that Enigma could be attacked, and provided a plentiful supply of cribs. Had the Poles not succeeded, it's unlikely that the British could have got the resources for their work. But to claim that the Polish work was the basis for the Bletchley work subsequent to the changes in the indicator system is not right.

And, if we're being picky, there might have been the odd vacumn tube in the implementation of the diagonal board's ``all on or none on'' algorithm. But bombes were essentially mechanical devices. The four-rotor ones must have been amazing to be near...

ian

Re:Deserved honour, indeed.

[joe 155]

I too share your admiration of the fantastic work which was done there.

One of the worst things Churchil did was not allowing the continuation of this project and continual research in the field. As an English man and a Conservative I feel thats been one of our worst own goals... Silicon Vally could have been in Kent (or, even better, Grimsby!). But then again we did something similar to Babage and his difference engine.

Still, it's nice to see what some of the greatest people in the world at the time did in their field, even if it does bring up old regrets...

Pictures hard to come by

[OakDragon]

Still, I found some more.

Re:Deserved honour, indeed.

[2sheds]

> One of the worst things Churchil did was not allowing the continuation of this project

Well, he did allow continuation, it's just that it was under ultratight security in a department that would become today's GCHQ (Government Communications HQ - our equivalent of the NSA). The reason for that security is obvious; he wanted Britain to keep the competitive advantage of being able to spy on friends and allies without anyone being aware of that ability. Go and read up on the history of British SIGINT during the post war years if you're interested. There's a fair bit on Wikipedia about GCHQ and it's precedessor, the Government Code and Cipher School (Bletchley Park to you and me).