sections 9.1-9.4

Difficult: Are we going to have to break any of these? Because I'm not sure I'd be able to until possible after reading later sections that probably go into methods to break them. Though I'm sure they are similar to how we break RSA and ElGamal. I also thought the ElGamal Signature Scheme was kind of complicated, but still kind of like the normal ElGamal encryption method, so maybe it's not as bad as it looks? Could you do examples of these methods in class?

Interesting: I thought it was interesting how the different encryption methods could be modified to create personalized signatures and also that this idea hasn't (explicitly) come up before these sections really. I also thought the difference between the signature with appendix and message recover scheme was interesting.

sections 8.4-8.5 and 8.7

Difficult: I'm kind of confused about how to use the birthday idea to attack different ciphers

Interesting: I found it interesting that they spent so much time talking about the probability of repeating birthdays when almost everyone already knows about the birthday paradox.

sections 8.1-8.2

Difficult: I thought the second hash method would be difficult to do--for long messages, especially.

Interesting: I thought the hash function in 8.2 was interesting because it was more effective than the first one described, I wonder what other hash methods there are that would be more effective.

sections 7.3-7.5

Difficult: I think the Diffie Hellman Key Exchange would to interesting and difficult to encrypt/decrypt by hand for sure, but I also think the Computational Diffie-Hellman Problem would be difficult to compute period. Could you show an example in class?

Interesting: The bit commitment section was really interesting. I had never really thought of it before, but it makes since in some situations that someone would make a bet/prediction or something like that and would not want the other person to know what they sent until a certain day/time. It's kind of like sending a gift before someone's birthday and not wanting them to open it until their birthday, even though it was sent early. I think it's a really cool way to accomplish this, because before, you just had an honor system so to speak, but this way, you can't change the bet/whatever, and Bob can't open it until you give him the 'key' so to speak.

section 7.2

Difficult: I still don't think I understand their notation very well, the whole x = L sub alpha (beta) thing is hard for me to keep track of which part means what,but I'm sure time/hw problems will help with that so I can keep them all straight. Are we going to be expected to factor all these bigger numbers and mod them in our heads/using only a basic calculator on the next exam? Because I'm pretty sure that would extend the amount I need to set aside for the test substantially.

Interesting: The Baby Step, Giant Step Attack was pretty interesting. I also thought the fact that they named the attack that was pretty funny. But it is cool that/interesting to think about since the two lists are interconnected and there's a match, but since it only works well for primes up to 10^20, it makes me wonder what a better method would be.

Sections 6.4.1 & 6.4.2

Difficult: I didn't understand the part about linear dependencies very well in 6.4.1. I'm also not sure I understood the matrix connection very clearly.

Interesting: it is really interesting how far we've come with factoring algorithms in the last 30 or so years and how big of an impact computers have had on our mathematical and other advances. Who knew such a relatively small thing would have such far reaching impacts?! It's pretty cool, not going to lie.

PS, as you can see below, I accidentally posted the entry on my personal blog instead of my Cryptography blog--sorry!!

sections 6.5-6.7 and section 7.1

Difficult: The discrete logarithm problem looked difficult, I didn't understand very well why n had to be the smallest positive integer such that alpha^n is congruent to 1 mod p for us to get that x=(L_alpha)(beta) though. Could you explain why in class?

Interesting: It's crazy how many people and computers it took to find the congruence relations of the desired type for this problem! and then how relatively they were able to reduce the matrix and determine the dependencies. I also thought the message was pretty interesting... mostly weird, but I guess it makes sense since they didn't want anyone to just arbitrarily guess what it was and get the moneys without doing the work.