MA 479 / CSSE 490: Cryptography
Homework 3 problems inspired by Computer Science

Rose-Hulman Institute of Technology
A joint effort of the
Department of Mathematics
and the Department of Computer Science & Software Engineering
Spring term, 2002-2003

1. [4 points.]
   Implement S-DES. Ideally, allow it to be generalized easily to more than 2 rounds.

2. [4 points.]
   Implement a differential cryptanalysis attack on 3-round S-DES.

3. [12 points.]
   Implement a differential cryptanalysis attack on 6-round S-DES. (If you try this problem, stop by my office for a handout to get you going.)

4. [2 points? 4 points? More if you get carried away on this problem...]
   Design your own S-boxes for DES (not S-DES). Try to choose a design that makes it harder to break than regular DES. Explain (implement?) why your design makes it so.

5. [Various points.]
   You may do any problem from Homework 1 problems inspired by Computer Science or Homework 2 problems inspired by Computer Science (except any that you did for Homeworks 1 or 2, of course). The number of points for each is as listed in Homework 1 or 2.

6. [Variable points.]
   Email me a short description of a problem that you would like to solve, that is related to material that we have discussed in class (or might discuss, or ...). Include your best-guess for how many points that problem should be worth. IF I respond that it is an OK problem, you may then do the problem for credit. (You can do the problem even before I respond, of course, but then you are taking your chances on whether or not I give the OK on the problem.)