<div dir="ltr"><div>Alan Turing is one of my personal heroes. What the English did to him after the war was shameful. An excellent biography of him ( David Leavitt's _The_Man_Who_Knew_Too_Much_ ( <a href="http://www.barnesandnoble.com/w/man-who-knew-too-much-david-leavitt/1102002740?ean=9780393329094">http://www.barnesandnoble.com/w/man-who-knew-too-much-david-leavitt/1102002740?ean=9780393329094</a> ) is still available I believe. He was one of the greatest mathematicians of the 20th century, and all of us use his ideas every day.<br>
<br></div>-- CHS<br><br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sat, Aug 10, 2013 at 5:35 PM, Jay Lozier <span dir="ltr"><<a href="mailto:jslozier@gmail.com" target="_blank">jslozier@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><u></u>
<div><div>It did help that the Allies also occasionally captured the current code books for the U-boots. One the U-boots was actually captured (U505) and is now in Chicago.</div><div><br></div><div>From what I read the German Navy and Army had very good code discipline and rarely provided any cribs to the Allies. The Luftwaffe was apparently fairly sloppy and tended to provide cribs to the Allies. </div>
<div><br></div><div>One of the more important tactics was direction finding and then home in on the signal</div><div><div class="h5"><div><br></div><div>On Sat, 10 Aug 2013 17:05:27 -0400, Boris Borisov <<a href="mailto:bugyatl@gmail.com" target="_blank">bugyatl@gmail.com</a>> wrote:<br>
</div><br><blockquote style="margin:0 0 0.80ex;border-left:#0000ff 2px solid;padding-left:1ex"><div dir="ltr">In my high school ages I had a book ( probably still have it ) about Enigma and how it works. My mind got wrecked by the complexity of mathematics involved!<br>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">
On Sat, Aug 10, 2013 at 4:54 PM, Ron Frazier (ALE) <span dir="ltr"><<a href="mailto:atllinuxenthinfo@techstarship.com" target="_blank">atllinuxenthinfo@techstarship.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi all,<br>
<br>
I may have mentioned this here before, years ago, but considering the nsa stuff, I thought it would be interesting to share.<br>
<br>
Last night I dug up a movie from a rarely used box I have and watched it. It's called Enigma.<br>
<br>
<a href="http://www.amazon.com/Enigma-Dougray-Scott/dp/B00006FD9P" target="_blank">http://www.amazon.com/Enigma-Dougray-Scott/dp/B00006FD9P</a><br>
<br>
It's about the British and American cryptanalysis and code breaking project during WWII circa 1940 - 1945. The movie is R rated, and I could do without the parts that make it so. However, the other core content of the movie is fascinating, and is based on truth. I am not a history buff, but I do like this movie.<br>
<br>
After watching the movie, I read about 29 pages from the following wikipedia articles about Bletchly Park and Bombes. Yes that last thing is spelled correctly, as I will explain.<br>
<br>
<a href="http://en.wikipedia.org/wiki/Bletchly_Park" target="_blank">http://en.wikipedia.org/wiki/Bletchly_Park</a><br>
<a href="http://en.wikipedia.org/wiki/Bombe" target="_blank">http://en.wikipedia.org/wiki/Bombe</a><br>
<br>
The articles state that the efforts of the code breakers in Britain and the US reduced the length of the war by 2 - 4 years and that the outcome of the war without their efforts would have been in question. A caption in the movie says these endeavors saved millions of lives. None of this was disclosed to the public until the 1970's.<br>
<br>
The main concern (relevant to this topic) of the British and later the US was the German Enigma machine. This is a brilliant little piece of engineering. It had an alphanumeric keyboard, a series of movable and rotatable rotors, and a plug board where wires could be attached in various combinations. The operator would type a plaintext letter on the keyboard, and a corresponding ciphertext letter would light up on a lamp board. That ciphertext would be transmitted by U-Boats, etc. by radiotelegraph. Gears inside would rotate the rotors, so, the next time you pressed the same plaintext letter, you would get a different ciphertext letter.<br>
<br>
Even though the allies had some captured enigma machines or clones of them, unless the rotor sequence, rotor position, and plug board wires were set up properly, they would not be able to decrypt the enemy's messages. The 4 rotor Enigma machine had 18x10^19 different ways of being set up. If my math is right, that's more than the permutations of a 66 bit binary key. Decrypting the German U-Boat signals was critical to protect convoys of allied ships from being sunk by the U-Boats. This was a VERY sophisticated cipher scheme for it's time. There are comments in the articles to the effect that, if the system had been properly used, it would have probably been unbreakable.<br>
<br>
Alan Turing, sometimes known as the father of computer science, helped the British develop the bombe machines, which were 1 - 2 TON electromechanical monsters which replicated the function of 2 or more enigma machines, with large numbers of rotating drums (or later relays), but which could be driven at high speed by motors. If the British or American cryptanalysts could get a crib, a piece of known plaintext with a matching piece of known ciphertext, like a weather report where the format and data was known, they could use that as a baseline to set up the bombe. Using the known data, the bombe machines would try various possible combinations of enigma setup sequences at high speed until a possible option was found that could possibly decipher the other ciphertext messages for which there was no crib. The cryptanalysts would further analyze this data, and eventually select a few possible setup sequences. Those would be tested by trying to decrypt the German communications. If the result came out German, then the allies could read the German comm traffic FOR A DAY OR TWO. The next day, they had to figure out the code again. This went on for years, and the allies eventually decrypted thousands of German messages. At one point in time, there were 12,000 employees at Bletchly Park.<br>
<br>
So, you might say the Bitish and American code breakers saved our collective butts.<br>
<br>
There is a simplified description of of how all this works, with examples, in the articles. Now, I've never claimed to be a math wizard. But, this stuff, even from 1940, makes my eyes cross. I'm glad someone understands it, and I'm sure modern crypto systems are much more complex.<br>
<br>
Anyway, hats off to the cryptographers for what they do, WHEN it's in the best interest of society.<br>
<br>
I just thought you all would find this interesting, as I did, even though history is not usually my thing.<br>
<br>
Sincerely,<br>
<br>
Ron<br>
<br>
<br>
-- <br>
<br>
(PS - If you email me and don't get a quick response, you might want to<br>
call on the phone. I get about 300 emails per day from alternate energy<br>
mailing lists and such. I don't always see new email messages very quickly.)<br>
<br>
Ron Frazier<br>
<a href="tel:770-205-9422" value="+17702059422" target="_blank">770-205-9422</a> (O) Leave a message.<br>
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</blockquote></div><br></div>
</blockquote><br><br><br></div></div><div><div>-- </div><div><div>Jay Lozier<br><a href="mailto:jslozier@gmail.com" target="_blank">jslozier@gmail.com</a></div><div><br></div></div></div></div><br>_______________________________________________<br>
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<br></blockquote></div><br></div>