CSE21 TAKE-HOME PROBLEM WINTER QUARTER 1997
This problem is a take home problem for the final exam. It is due at or before the end of the scheduled final exam. The purpose is to give you experience in carefully writing up an explanation to an application of the material in CSE21.
The following ANSI C code is an encryption program to encrypt text files. The corresoponding decryption program is also attached. This is not a standard encryption scheme of any sort, but was made up just for CSE21 to illustrate the combinatorial material.
You are asked to do the following:
(1) Give a careful written explanation of how the encryption works.
(2) Give a careful written explanaton of how the decryption works.
(3) Give an estimation of the size of the set of all keys. Give meaning to this estimate by describing how long it would take to break this system by trying all keys and by trying to put this number in perspective for the nonmathematical person.
The rules are that you can help each other and get help from anyone else who is willing to discuss this with you (including, of course, the TAs, readers, and instructor). The only condition is that the final write up be your own. In other words, once you understand this, sit down and write up your report by yourself. I would expect it to be about four or five pages total if you give some examples and try to explain clearly what is going on.