Section 4.5-4.8, Due September 22

Difficult: I found the Cipher Feedback mode a bit difficult to understand, and along with that the Output Feedback mode, so apparently my struggle has to do with the part that is similar between the two. I think I do not fully understand how to get X_2 from X_1. It seems like we concatenate the ciphertext from encoding the first 8 bits onto the end of X_1, and then drop the first 8 bits from X_1 to obtain X_2. Am I understanding this right? If I am, then it seems that what we are doing with OFB is concatenation of the first 8 bits of X_1 to the last 8 bits of X_1, and then dropping the first 8 bits, to get X_2. That should be a cyclic process though, so it would seem undesirable.

Interesting: Section 4.6, about breaking DES was quite interesting. I think that now that a method has been found, then it will be a better idea for there to be a new standard rather than the triple DES that seems to be what the book favors. The book says there are just many more possible keys for a triple DES, but fails to take into account that technology is still advancing rapidly. What took many computers to do in the 90's can already be done with just one now, and processing speed and memory storage is still being increased.