Section 6.1, October 9

To be honest I don't think that there is much hard in RSA. I actually love that about it. It is pretty darn straight forward. The hard part was finding the algorithm and not really doing it. If anything it takes a little to find out why the two expenotiations work, but other than that it is good.

The most interesting fact to me is that it just works. I love the idea of public key encryption. Finding ways where we can each know part of the answer, but it isn't enough to let us solve the problem. The very fact that this is possible truly amazes me. I wonder what lies further in this field that would allow us to find other public key algorithms that are faster and thus even more usable than RSA.

Section 3.6 - 3.7, October 7

The hardest part for me was to figure out all the different ways we were using Euler's function. It took me quite a while to understand while 0(p) = p - 1. Once I was able to understand that it started to come together why the other ones started to work out in my head.

The most interesting item was how we could find numbers that are essentially generators of all the other numbers. This is so important to me because I have studied the Duffie-Hillman algorithm where this decomes essential.

Section 3.4-3.5, October 5

The hardest part for me was following what exactly was happening in the Chinese remainder theorem. Following why I need the inverse and what to do with it, was really hard for me to follow. For some reason when I tried to follow the various symbols I lost track, it was only when I was able to think of it more as picture that I was able to get it.

The most interesting part was the modular exponentiation. It is funny how easy such an efficient way of doing the exponentiation is.

Test Improvment, October 2

I think the most important thing that we have studied to this point was how to critically think about codes. By learning the different ways of description algorithms we have seen better ways to think through problems. Most of the math is done by computers, but computers will never think up the methodologies, and that is what I feel that we are learning the most of it.

I would expect to see questions that deal with breaking algorithms, and showing how algorithms are built. This could happen as explanation questions or by doing small examples. I think it should mimic in-class stuff as much as possible.

I need to understand better the proofs of the math behind the cryptography. That has been the thing that I have had the hardest time following.

Section 5.1 - 5.4, September 30

To be completly honest this section was rather easy. This is because I have already implemented AES once this semester. Most likely the hardest part is the construction of the S-box. It is definately more involved and takes a little thought to get.

The most interesting part is the polynomial multiplication in the field of G(2^8). I love how everything can be worked out as simple machine instructions. It makes it really easy to implement in hardware and software.

Review, September 28

On average I have spent around two hours on each of the assignments. I felt that the lectures and the reading did help. I think the lectures were the most useful followed by the book when I forgot things.

I enjoy the class a lot. I really enjoy the lectures. You have a really good way of making things clear, and showing us why they work that way. I get most of what I read in the book, but anything I don't is quickly addressed in class. I also like the way that you show us examples of using computers and other methods to break codes. This makes everything snap in place in my mind.

Just keep up the examples. They really are what solidifies everything for me.

3.11, September 25

Initially the hardest thing to understand was how polynomial math was done mod a polynomial. I had forgeton how to do polynomial division and such it confused me until I saw it in the book. Also the ideas of finite fields were a little confusing, as it is an area of math that I have not studied until now.

The very idea of finite fields was the subject I found the most interesting. I would love to learn more about them and how they are used in other branches of math. Since I have already coded AES for another class, I know how the finite field F(2^8) works in AES, and as such I also think that is really cool.

4.5 - 4.8, September 23

The hardest thing to follow was all the little nuances that exhibited themselves in the different modes. The error correctly especially took me a little to understand since I have never dealt with it before. The way the key was having an eighth of it shifted off was what confused me at first.

The most interesting thing in the book was actually reading how DES was broken. That is actually my favorite part of this entire class, learning how various algorithms are attacked. It is interesting to me that we still choose brute forcing, as there really aren't many weaknesses that are usefull enough. I find it really interesting that till this day DES's greatest weakness is the length of the key. It is too bad that unlike AES it didn't allow multiples of keys. Though maybe AES should be changed to allow more than just the three that it does.

4.1, 4.2, 4.4; September 21

The most interesting deatil in this section would be about groups in encryption. I admit that I have never though of it possible that using two levels of encryption was the same as using on level with only one key. It was interesting to look at crypto-analysis from another angle.

The hardest part of the chapter to understand was the groups. Like other sections of the chapter it wasn't very hard (especially since I have already studied this algorithm in my Computer Security class.) Following the proof was the strangest part. The whole thing with the remainder and dividing mq still doesn't make sense to me.

Section 2.9-2.11, September 18

1. The was the first time I felt that there was anything truly hard to follow. The proof provided for breaking LSFRs was hard for me to follow. I get lost after we have proved that det (Mn) = 0 (mod 2). I guess I will have to wait to we discuss it in class to really understand it.

2. The most interesting part is what the begining of the section 2.11 talks about. The fact that their is often a trade off between security and usability/speed. I think this is a subject that might be very important for the future of cryptographic methods. We need to focus on secure algorithms that are both fast and accessable.

Section 2.5 - 2.8, September 16

1. The hardest part of this reading was in understanding how to break the Hill algorithm. Once again like the rest of the chapter it was hard, it was just the hardest of what their was. I was interesting to see how easy it was to find a working key matrix. I didn't notice that we need to first check the determinate, but it was easy after that.

2. The most interesting part was the Sherlock homes section. It was interesting because it is basically a subsitution cipher that goes to a different alphabet. It was also the most interesting because the story that accompinied it. So it was the most mathametically interesting, but certainly the most exciting part in the chapter.

Section 2.3, September 14

1. The hardest part to understand in this article was deciphering the key length used in the cipher. It is actually a really interesting analysis of the language, in the way that their is a higher chance of letters occurring the same with the shiften cipher. It does show me that to come up with breaks for older ciphers a solid knowledge of the language was needed.

2. The most interesting part for me was the cipher its self. I think it is really interesting how traditionally people took known ciphers and modified them so they make it harder to break. It is interesting how much harder it is to break these slightly shifted codes. It is also interesting because it represents a key being added to a known cipher who key before was just a pairing of letters to other letters.

2.1-2.2, 2.4, September 11

The most interesting part for me was the affine filter. It was interesting to see how such an easy modification could be used to increase the security of the message. I also enjoyed seeing a formal description of how to solve substitution ciphers. Often as students we just intuit the way things should be without knowing why they are that way.

Once again we haven't reached any really hard concepts so the hardest of what I did read was the formal description of how to break a cryptography cipher. This was because it made me pay attention to not only frequencies of letters, but also the frequencies at which letters occur together.

Guest Presentation, September 11

The presentation today was very interesting. I really loved to hear the different ways that things had been coded in the past. The most interesting one for me was the final cipher she showed us. It was interesting because it reminds me quite a bit of the way that modern symetric encryption works. You could even do a one-time pad with it if you had a long enough key.

It was also really interesting to see the other way they hid messages besides codes. It was a good stody of the history of codes, back when the key was not knowing the algorithm rather than not knowing the key.

Nothing really stood out as hard to understand, but that was just because the presenter did a great job.

Section 3.2-3.3, September 4

1) For me the most difficult part was doing modulus division. I am used to calculating the modulus of a number, but I have not had to do much arithmetic on it. I have never done division so it was really weird, and weird to have to think to check for relative primeness.

2) The most interesting part was also the modulus math. Like I said I have not done much math when dealing with congruency. Solving for x was new and cool.