3.5,3.6 due on October 1

What was the most difficult part of the material for you?

Keeping track of exactly what is going on in the Chinese remainder theorem is a little interesting. Lots of mods!

What was the most interesting part?

I really like the idea of modular exponentiation. I think it is cool that we can talk about what would be huge numbers, but which are manageable mod n.

Questions, due on September 28

Which topics and ideas do you think are the most important out of those we have studied?

I think that the knowledge of the purpose and uses of a cryptosystem, and the most common methods of attach, are the most important topics we have covered.

What kinds of questions do you expect to see on the exam?

I expect to see some of the basic results we have learned from number theory; definitions of certain ciphers; decrypting basic examples of ciphers; conceptual questions about various aspects of cryptography (methods of attack, etc.)

What do you need to work on understanding better before the exam?

I need to better memorize the specifics about the different ways to encrypt using a block cipher. I do not know how much of the DES/AES algorithms you want us to memorize, but if that is going to be tested extensively I would need to memorize those specifics as well.

5.1-5.4, due on September 26

What was the most difficult part of the material for you? 

Keeping everything straight, especially in the encryption, was tiresome. There are no hard individual concepts, but keeping a bunch of little ideas strung together in the right way can be tricky.

What was the most interesting part of the material?

Learning how to pronounce "Rijndael"! Seriously, every time I would read it I would have a new crazy pronunciation attempt in my mind. I am glad to finally be enlightened.

Questions, due on September 24

How long have you spent on the homework assignments? Did lecture and the reading prepare you for them?

I have spent typically 2 - 3 hours on homework assignments. The readings and lectures are very helpful in preparing for them.

What has contributed most to your learning in this class thus far?

No on element has been dominant in learning. An environment of reading, lecture, guided assignments, and self exploration have led to my learning thus far.

What do you think would help you learn more effectively or make the class better for you? (This can be feedback for me, or goals for yourself.)

I am not sure how much programming you want to be part of the class. I personally have usually built my own code to crack ciphers, rather than use the provided applets. I feel that this has been beneficial to me, and had I just used the applets I may not have understood the ciphers as well. However, this is not always feasible (ie the one time pad). And again, I am not sure how much programming you want to be required for the course.

3.11, due on September 21

What was the most difficult part of the material for you?

This was a good review of 372 for me. It was a more in depth chapter than the previous. Some of the results were not immediately understandable.

What was the most interesting part?

I am excited to learn how AES used GF(2^8). I think it is going to be interesting to see.

4.5-4.8, due on September 18

What was the most difficult part of the material for you?

The notation for all the different bit shifts is new to me.

What was the most interesting part?

I liked learning about the history of DES.

2.9-2.11, due on September 14

What was the most difficult part of the material for you? 

The proofs regarding linear feedback shift registers were more intensive than we have previously seen. Remembering all the details might be a challenge.

What was the most interesting part? 

I like how the one-time pad paradigm changes the question from generating a secure system to generating reproducible but high entropy sequences of random bits.

3.8 and 2.5-2.8, due on September 12

What was the most difficult part of the material for you?

The German World War I cipher had some interesting steps. It took me a little while to understand why decryption works.

What was the most interesting part of the material?

I really like the concepts behind Hill's cipher. I enjoyed learning about the concepts of diffusion and confusion.

2.3, due on September 10

What was the most difficult part of the material for you?

Understanding why the displacement revealed the key length.

What was the most interesting part of the material?

I loved the formulation of the code breaking as a linear algebra problem. I think it is a cool and elegant way to think about it. Plus, linear algebra operations have been optimized to death so the computation would be readily available.

2.1-2.2 and 2.4, due on September 7

What was the most difficult part of the material for you?

Decrypting the affine cipher is interesting. I would need to remember the formulas in order to do so.

What was the most interesting part of the material?

I liked how the book outlined each of the four problems associated with breaking ciphers. It showed the various dangers of using different ciphers.

Guest lecturer, due on September 7

What was the most difficult part of the material for you?

There was nothing terribly mathematical about the presentation. Reading the Deseret alphabet was difficult (impossible) for me.

What was the most interesting part of the material?

I find it very interesting how many different schemes were used. There were a lot of different things the early saints tried.