Section 4.6 - 4.8

I still don't get why the meet in the middle attack works or what the properties of the double DES are that make it suck.
The use of a salt for password security seems very clever to me. Its a nice practical side to the crypto in the book. Sometimes little things added to the implementation of these systems can work out nicely and the salt is a novel example of making DES more secure without actually modifying the algorithm itself.