4.3-4.4

In this section I really didn't understand differntial cryptanalysis at all. It looks like it could be really cool if someone explained it to me, but all the figures and numbers made it confusing. A sentence or paragraph explaining what was going on might have worked a bit better. On the other hand I thought that the thing about how if a crypto system is in a group then double encryption becomes equivelant to single encryption, but if it isn't then the double encryption effectively doubles the key length.