Section 3.8 and 2.5-2.8, Due on September 15

Difficult: I didn't understand the point of the short section on ASCII. It seems like whether we use the "A=0, B=1, C=2...Z=25" method or ASCII to turn our letters into numbers, it is hardly different. The first method can be easily modified to include numbers 0-9, and so build any number we want, and also has been modified for various punctuation, according to the alphabet conversion applet. Maybe ASCII is useful just because not as many people are familiar with it? I also had some trouble with the decryption method for the ADFGX cypher. I would like to see that in action with an example.

Reflective: I've really enjoyed the substitution cyphers we have studied up to section 2.7, but it seems that the block cypher is indeed a better idea. The good thing about most substitutions, I think, is that they are very easy to understand. But block cyphers were not difficult to understand (with a little knowledge of linear algebra and modular arithmetic), and they are more difficult to break. It seems like a know plaintext or known cyphertext attack would be easier to prevent than a direct unknown cyphertext attack.