The brutal treatment of the protagonist, Marcus Yarrow, in Chapters 3 and 4, following the Bay Bridge bombing was something that suck out to me as I tried to put myself in the situation and how I would have reacted. One less obvious theme related to cryptography which I noticed was the appearance of guilt that results from Marcus’ heavy defense of his privacy. It is human nature to feel that someone who does not want to tell you everything would be hiding something bad from you. Marcus’ actions in his first encounter with the Department of Homeland Security’s interrogation seemed to point to him trying to hide something. Although Marcus only tried to resist for a short amount of time, and the treatment by the Department of Homeland Security was less than proper, he did show resistance which could have prompted some reaction by the DHS.
The concept of no cipher being better than a bad cipher was also present in this scene. The idea of this is that a ciphered message which is broken could do more harm to the party enciphering than if the same message was discovered not enciphered. Although there were no ciphers, the passwords and security precautions made by Marcus made him look guiltier just as an enciphered message could have done. In this scene the passwords were not "broken" but instead were taken by force, which in the long run, has the same overall effect. Regardless of the means of discovering a secret, the fact that it was a secret makes it seem worse to the party discovering it.
Image: This is Secret by Trey Ratcliff