From: "Ara.T.Howard" <ahoward@...>
Date: 2004-08-18T02:40:59+09:00
Subject: Re: POT (partly offtopic) Re: Q: Shifting a hash anf and array

On Wed, 18 Aug 2004, Meino Christian Cramer wrote:

> Three days ago I saw a british film on TV about the decyphering of the
> Enigma machine in Blechtley Park...FASZINATING! Very good film!
>
> What follows was a googling party "in search of the Enigma".... ;)
>
> I found a bash script, which implements a lot of different Enigmas
> and I thought it would be a good opportunity to learn more Ruby to
> implement the Enigma in Ruby.
>
> One of the basic concepts of the Enigma machine are the wheels. Those
> wheels had 26 input terminals on the one side and 26 output terminals
> on the other side. Each terminal was representing one letter. The
> connnection between the front and back terminals were "crossed wired"
> -- or irregular (right word?). What was put as an "A" on the front
> came out as (fro example) "Q" on the back.
>
> Three or four wheels were packed on one axis. Which each letter input
> the wheels were rotated one position (I haven't figured out, how
> exactly this works until now...). That means: "AAA" came out as (for
> example) "QZF" and not as "QQQ".
>
> I thought of implementing the wheels as such
> not-integer-but-ordered-indexed "arrays". And my question about all
> this rotating and shiofting stuff was to figure out how to "rotate"
> my wheel-arrays.
>
> There much other stuff to figure out...there was also a "Reflector"
> (whatever it was used for) and a so called "Steckerboard" ("Stecker"
> is german for "plug", but every site about the Enigma calls this a
> "Steckerboard" and "...the code was steckered..." ("connected" or
> "plugged in" or so in English)
>
> OT: If anyone knows a good site with detailed description of the
> mechanical "inside" and the meachnisms of the different Enigma
> machines...hu,hu...me! Here, please! :)))
>
> Sorry for this longish "book about the Enigma" :))).
>
> But I thought it could be interesting.

very.  something like this perhaps?

   jib:~ > cat b.rb
   require 'arrayfields'
   module Enigma
     class Wheel < Array
       FORWARD = 0
       BACKWARD = 1
       attr :terminals
       def initialize terminals
         self.fields = *terminals
         self.replace terminals
       end
       def rotate! direction = FORWARD
         if direction == FORWARD
           push shift
         else
           unshift pop
         end
       end
       def inspect
         fields.inject(''){|s,f| s << "#{ f } - #{ self[f] }\n"}
       end
     end
   end

   w = Enigma::Wheel.new %w(A B C D E F)
   p w
   w.rotate!
   p w


   jib:~ > ruby b.rb
   A - A
   B - B
   C - C
   D - D
   E - E
   F - F

   A - B
   B - C
   C - D
   D - E
   E - F
   F - A


keep us tuned!

-a
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