[ale] [OT] speaking of british (motorcycle thread) - interesting crypto info circa 1940

[Boris Borisov]

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!


On Sat, Aug 10, 2013 at 4:54 PM, Ron Frazier (ALE) <
atllinuxenthinfo at techstarship.com> wrote:

> Hi all,
>
> I may have mentioned this here before, years ago, but considering the nsa
> stuff, I thought it would be interesting to share.
>
> Last night I dug up a movie from a rarely used box I have and watched it.
>  It's called Enigma.
>
> http://www.amazon.com/Enigma-**Dougray-Scott/dp/B00006FD9P<http://www.amazon.com/Enigma-Dougray-Scott/dp/B00006FD9P>
>
> 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.
>
> 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.
>
> http://en.wikipedia.org/wiki/**Bletchly_Park<http://en.wikipedia.org/wiki/Bletchly_Park>
> http://en.wikipedia.org/wiki/**Bombe <http://en.wikipedia.org/wiki/Bombe>
>
> 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.
>
> 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.
>
> 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.
>
> 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.
>
> So, you might say the Bitish and American code breakers saved our
> collective butts.
>
> 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.
>
> Anyway, hats off to the cryptographers for what they do, WHEN it's in the
> best interest of society.
>
> I just thought you all would find this interesting, as I did, even though
> history is not usually my thing.
>
> Sincerely,
>
> Ron
>
>
> --
>
> (PS - If you email me and don't get a quick response, you might want to
> call on the phone.  I get about 300 emails per day from alternate energy
> mailing lists and such.  I don't always see new email messages very
> quickly.)
>
> Ron Frazier
> 770-205-9422 (O)   Leave a message.
> linuxdude AT techstarship.com
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