SZ40 cipher machine
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1st problem
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We know everything (the internal key and the message key).
If, moreover, the working of the machine SZ40 is known, the 
message can easily be decrypted, even with manual means.

2nd problem
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We have plenty of messages in depth (4) and we have plenty of cribs.
That should be enough to find the internal key. 
After you have found the key, you can use the turing's method.

3rd problem
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The internal key is known. You must find the external key. 

4th problem
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You have only two messages in depth to find the key. Happily, there
are related.

5th problem
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We have a very long crib. After you have found the key, 
you can use the turing's method.

6th problem
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The problem is very hard, indeed we know nothing (just the Language).
But the message is long (about 4000 character). You can use statistical methods. There were used on Colossus.

7th problem
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The problem is very hard, indeed we know nothing (just the Language).
But the message is very long (about 11000 character). You can use statistical methods. There were used on Colossus.

8th problem
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The problem is hard. We know only the CHI wheels and their setting.
You can use a Colossus simulator.