Section 2.4.3, due on September 10

I had a very difficult time understand the the phi function. I am not quite sure what it is intended to do. In other words, I cannot really see where we are going by learning this particular piece.

However, I think I have heard of something like this function in the past that allows one to encrypt. I think it went something like raising to a power, and then raising that integer to another power mod something to get it back to the original. I guess I will find out in a bit.