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The students were reminded about the final exam and the DES papers were collected. Again Mr. Radomirovic presided and wrote:
Enigma: I answered some questions about how the device worked roughly, and other minor things. I pointed out the things you suggested, since I found them worth mentioning again. I explained in brief again, what enabled the winners of WW2 to break Enigma ($$$, Flaws in Design of the System, Human Factors). I couldn't answer the question what happened after the Germans started using the converted teletype system, since I haven't seen the end of the tape either. 
I had earlier sent a message to Mr. Radomirovic which included what follows:
Some comments you may care to make could include the following: 
1. SOURCE: Enigma was an "electromechanical system" and was bought from its commercial manufacturer and changed a bit. 
2. Once "deployed" (actually distributed and put into use by the Germans) the investment in material, time, money, training, etc. was VERY SUBSTANTIAL. There were many locations, some remote, and many people involved. So changes in either the physical setup or the operating procedure could not be made casually or frequently. This is reality. 
3. The initial "breaks" into the Enigma cryptosystem were done with the aid of corruption ($$$): certain designs, pictures, and key schedules plans were sold to the Polish Secret Service. This helped quite a bit. 
4. Breaking Enigma "wholesale" (that is, on a large scale, using the
information repeatedly) was done some years later in England. You may want
to mention some of the following, as seems useful to you.

Then we started with the review. I passed out the Math sheet and
asked them to have a quick look at it, and to notice that everything
on that paper has been done in class before. Then I asked them to
solve problems 14 (then 58, etc.), to ask me if they get stuck. They
were allowed to work in groups if they preferred to. They would ask
me to show this or that problem and I would do it. Some of them were
faster, others were slower. The faster ones finished or almost
finished the Math paper. Everybody should have solved, or at least
pretended to know how to solve the first 14 problems by the end of the
class. Problems 5,6,7 seemed hard to them. I had to explain all three
of them. (To some of them I even had to explain problem 4).
They wanted to see Problem 8 as well. Only the Math (or similar) majors (I suppose) seemed to be able to figure out 9 by themselves. So I did that, too. I talked to them about problems 12 to 14 without writing anything down on the blackboard. Then the class was over. 15 minutes before that I passed out the crypto review sheet, since some of them were almost done with the Math stuff. I should've had a watch. I didn't think time would pass by so fast. Most of them picked up a policy review sheet, some of them probably forgot (since there are more policy papers left than math & crypto). Of course I was asked how the Final Exam will be like. I told them "pretty much the same". So then they started interpreting "pretty much the same". Could it be exactly the same? I answered I don't know, I haven't seen the final exam, I guess the numbers will be different. I wasn't prepared for that kind of question, although I should have known that they will ask. 
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