The section of the book that most caught my attention can be found at the beginning of Chapter 10. Marcus is in the early stages of setting up the Xnet and is beginning to realize that his heavily encrypted system is most likely already infiltrated by members of Homeland Security. He asks himself what the right course of action would be and makes clear his intentions of feeding the false information to both sides in what he calls a "man-in-the-middle attack". The process of steaming open letters is described and Marcus uses the metaphor of being a fat spider in the middle of communication to cause as much havoc as possible.
I find the idea of "man-in-the-middle attack" very interesting and it is something we have discussed a few times in our cryptography course. A prime example of this attack can be found in Singh chapter one when Mary Queen of Scots is imprisoned but still sends out instructions to attack Queen Elizabeth with weak encoding methods. Cryptanalysts were able to intercept Mary Queen of Scots's letters, thus allowing her to be incriminated and manipulated by Queen Elizabeth's men. Marcus's solution to the problem of a "man-in-the-middle attack" is crypto of course. He describes a confusing method of encryption involving a double key which creates a double enciphering. I, however, was more interested in Marcus's form of attack rather than his double key form of defense.