PURPLE cipher machine
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The 1st Problem
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This problem is not difficult.... Except that it is necessary 
to create a simulator of the PURPLE machine (paper or computer). 
To achieve this goal, one must have read carefully the text 
accompanying the problem.

The 2nd problem
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The internal key is known. Just try all message keys.

The 3rd problem
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We know the external key: the start positions of the switches
and the value of the motion switch. The only unknown element 
is the plugboard setting.

The 4th problem
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We have the plaintext of one message and only the cryptogram
of a second messages. Both messages have been encrypted by the
same key. In addition we know the SIXES.

The 5th problem
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We know the beginning of the message. The SIXES and TWENTIES
are separated. We can say that the problem is realistic. 

The 6th problem
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We know noting. You must recover the whole key: Plugboard setting,
the start positions of the switches and the value of the motion
switch.