5.1-5.4 The Advanced Encryption Standard: Rijndael

• The hardest part to understand was how the inverse of the were found for decryption, especially how the ordering of ARK and MC changed places with the IMC and IARK.
• The interesting part of these sections was just better understanding how AES works and how the certain transformations change the text.

• Typically I have spent an hour and a half on the homework assignments. The last one I took about 3 hours to do. The lectures and the reading did prepare me for the homeworks.
• I really liked the guest speaker and seeing when codes where used in LDS history. I also like seeing examples. I think this helps me learn the best and understand each type of code best.
• I think just continuing giving examples makes the class the best.

3.11 Finite Fields

• The LFSR sequences was pretty hard to understand.
• It was pretty cool to see that you can get an inverse of a polynomial. I didn't think that was possible. It was a little confusing but interesting.

4.5-4.8

• The most interesting part of the reading was learning how Rocke Verser broke the DES encryption. It was interesting to find out that he used multiple people's computers to distribute the computer computations.
• The password security was also interesting to learn about. It seems very clever to use a one-way function.
• The hardest things to understand were the new modes of operation especially the cipher feedback. I understood the difference between the cipher feedback and the output feedback but they were both difficult to understand.

4.1,4.2,4.4

• The most interesting part of the reading was learning that DES is used in banking. That's pretty cool to see a very standard application of Cryptography.
• The whole concept of DES was hard to understand. It was tricky to understand how the ciphering works in DES and also the deciphering.

Sections 2.9-2.11 One-Time Pads, Pseudo-random Bit Generation, and Linear Feedback Shift Register Sequences

• The most interesting part was learning how we can use recursive relationships as keys in ciphering. From what I understood, you take a message, write it in binary code, then add the key, which happens to have a recursive relationship, then to decipher the message you re-add the key which yields the original code. It's cool that to decipher you just add the key again.
• It was hard to understand the One-Time Pads idea. I'm not sure how you'd get a random key in the way it described. I was a little confused on that, how do you know that the other party got the same key that you got?

Sections 3.8 & 2.5-2.8

• The most interesting part of this reading was story of Sherlock Holmes. It's cool to see how cryptography was used in stories. I also liked learning about block ciphers because I really like linear algebra, it's my favorite subject of mathematics.
• The hardest thing to understand was how to decipher the Playfair and ADFGX ciphers. I didn't really understand how it'd be easy to decipher these like the book said.

2.3 Vigenere Cipher

• Two parts of the reading that I thought were really interesting were that there are books without the letter e. That's pretty amazing. Another interesting part of the reading was how we can use the dot product of vectors in order to determine the length of the shift.
• The hardest part to understand was how we find the length of the key. Not necessarily, how we find the length of the key but rather how that method works. Although it makes sense, I didn't fully (theoretically) understand why there should be more coincidences when you displace the two strips the key length apart.

2.1-2.2 & 2.4

• I found that the digrams were the hardest to understand for me. It was hard to see how the book deciphered the code in section 2.4. I think the hardest part was figuring out what they were looking for (the frequencies of each letter in the document).
• I thought the affine ciphers were the most interesting. It was interesting to see how dividing by alpha when gcd(alpha,26) not equal to 1, messed up the cipher completely.

Codes and Ciphers in LDS History

• By far, the most interesting thing about the guest speaker was the fact that the Church used coded messages. I never knew this and thought it was amazingly cool. I also thought the Masonic code/pigpen code was pretty interesting and cool looking. I also thought the Larrabee's cipher was a pretty clever idea.
• The guest speaker said that the Church members used telegram codes to warn when there was a US marshal on board a train. I wasn't sure exactly how they used code in this instance. This was probably the hardest thing for me to understand. I think I missed something when she explained it.

3.2-3.3

• The most difficult material for me to understand was understanding fractions in modulos. This was very difficult and still a little fuzzy for me.
• The most interesting part was how you can divide both sides of a congruence by an integer p if gcd(p,n)=1 (where n is the mod of the congruence).

1.1-1.2 & 3.1

• The most difficult part of the reading was trying to understand how the Euclidean Algorithm works. The proof was pretty hard to understand.
• The most interesting part was learning how public keys work. From what I understood, Alice sends the information of encryption to everyone but she is the only one who knows how to decrypt it, then Bob encrypts a message and sends it back. The only part I don't understand is why Eve couldn't send a message to Alice masquerading as Bob.

• This is my 3rd year in school. I am a math major.
• I have taken Math 214 and 343 and 334 and 513 R. I am also taking 290 right now.
• I am taking 485, the cryptography class because it sounds very interesting to me to see math in such a specific application.
• I have experience with Matlab.
• I have used Matlab for two different classes and am semi comfortable using it on homework.
• My most influential math teacher was so successful because he had very hard problems but always helped us get through them and completely understand them. He also didn't have busy work. The assignments were short and hard.
• I can do a standing backflip.
• I am available during your office hours.