"The Code Book", by Simon Singh, would be a good companion read. It covers much of the above, and is both compelling and well-written. Edit: Fixed from "Code"

"The Code Book", by Simon Singh, would be a good companion read. It covers much of the above, and is both compelling and well-written. Edit: Fixed from "Code" to "The Code Book". Although "Code" (Charles Petzold), on a different subject, is also excellent.