Those interested in cryptology and coding theory should definitely consider "The Code Book" by Simon Singh. It's a great account of how cryptology was used throughout history.
Simon Singh is a fantastic pop-sci writer. His Big Bang was an incredibly accessible accounting of the history of astronomy, and how the slow, messy, incremental accumulation of knowledge about space eventually led to the Big Bang theory and beyond.
I agree, just finished reading it. Does a good job explaining cryptography and its evolution through time. As well as having interesting examples and being well written.
