[GreenKeys] Enigma machines

[Brooke Clarke]

Hi Craig:

NCR in the U.S. built machines specifically to break the four rotor Enigma, 
see:  http://www.prc68.com/I/NCR.shtml

Have Fun,

Brooke Clarke
http://www.prc68.com

Craig Sawyers wrote:
>>     The reason it only has three rotors is that if they added
>> more, the
>> key forces required would be hopelessly high.  There was a 4-rotor
>> Enigma variant, but that never caught on.  Machines with more
>> rotors were built, but they were motor-driven, not manual, and
>> the WWII-vintage ones were bigger than a Teletype model 15.
> 
> No, not really.  Three rotors was felt to be secure enough for the first few
> years of the War, and required the combined ingenuity of the Polish and then
> the British at Bletchley Park to regularly break the codes.  The so-called
> Bombe was basically racks of motor driven three-wheel enigmas running in
> parallel. Patch wiring and initial setting was made according to a "crib"
> that was worked out by hand by cryptographers.
> 
> The four-wheel enigma was introduced by the Germans in early 1942 to
> increase coding security.  This gave Bletchley a major problem, giving a
> break black-out of several months.  The Bombe was hastily redesigned to add
> a fourth high-speed rotor (to give the same speed of break as the
> three-wheel, the fourth rotor had to go 26 times the speed of the third).
> The breakthrough came when U559 was forced to the surface after prolonged
> depth charging - four British seamen went aboard and managed to recover two
> crucial code books before the U-boat sunk and drowned two of the seamen.
> That gave much more information to Bletchey who, with the modified Bombe
> succeeded in regularly breaking the 4-wheel.
> 
> Whether or not it was hard to use is beside the point - it became a standard
> Enigma Machine variant in wide use in the later years of the war.
> 
> For a good grounding on all this stuff, have a look at Tony Sale's website
> http://www.codesandciphers.org.uk/ .  Tony was responsible for the rebuild
> of Colossus.  Post WW2 Tony was an MI5 operative, through the height of the
> cold war; he has some fascinating reminiscences!
> 
> Craig
> 
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