Exam 2 Review Questions; Due November 12

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

I think that the most important ideas for these sections are the myriad methods we have studied to factor into primes. While I do not think that we can be asked to use the methods in a serious manner on the test, the ability to factor into primes was needed for breaking all of the new crypto systems we learned in these sections, so we will have to at least be able to explain the theory behind each method. Besides that, we have two new encryption methods (three if you count the Diffie Hellman key exchange), many electronic signature methods, and Hash functions. Oh my gosh, the hash functions!

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

I think that we will see many theoretical questions. I expect to be asked how to factor into primes by multiple methods, how to find the square root of numbers in modular arithmatic, and how to use these methods to break RSA and other systems. I expect something on the quadratic sieve, probably just having to explain how it works. I expect to have to be able to find simple discrete logarithms (probably ones small enough to list out the powers for) and explain more sophisticated methods to find discrete logs like the Phlig-Hellman algorithm and birthday attacks. I expect questions on probability of the birthday attack succeeding in various (possibly non-cryptographic) situations. Finally, I expect some questions on hash functions and using them for digital signatures. Mainly I expect things like the definition of a hash function and about strongly collision-free and preimage resistance.

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

I need to work on hash functions some more. I have trouble following the diagrams for the one true hash function we have discussed. Also, with so many factoring and discrete logarithm methods, I get mixed up as to what I should be doing where. Oh, and the prime tests. I almost forgot about them, so I need to look over them for sure.

Are there topics you are especially interested in studying during the rest of the semester? What are they?

I was hoping that we could look at some of the applications of these systems we have been studying. We have discussed how DES is used in television transmission and some uses of systems like one-time pads. But how do digital signatures work in the real world? What happens when I buy something online to keep my data safe? Other than that, I don't mind just learning new cryptosystems and how to break them.