Highly Encrypted

My cryptography professor is an intelligent, kindly, and well-spoken man; perhaps his only failing as a professor of mathematics is that he is too easily convinced by confused students that he has made a mistake. The prime example came today during an example of the Cipher Feedback Mode (CFB) of the Block Cipher. This isn't really a great cipher (it's no longer considered secure), but it's good for the math class. We're doing fine until Prof. Brualdi tried to give us an example. He didn't have one in his notes, so he was working it out as he went. We didn't go more than two steps before a very vocal and moderately ignorate segment of the class had casued him to beleive he had made a mistake when he had not,and the confusiion compounded as we continued. (It didn't help that we were using only 1s and 0s, which become quite confusing because of the inherrent repetion.) After about 10 minutes of struggling with the numbers, Prof. Brualid figured out where the class lead him astray, and righted things. Finally he asked, "does this look right?" One guy in the back row replied, "I don't care anymore."