Here are some books I recommend:

"The Code Book" by Simon Singh is a well written history of classical and modern cryptography, and an easy read as well. "Violent Python: A Cookbook for Hackers, Forensic Analysts, Penetration Testers and Security Engineers" is devoted to using Python for modern computer security.

The Codebreakers: The Comprehensive History of Secret Communication from Ancient Times to the Internet is a more comprehensive history of code breakers by David Kahn.

Cryptography Engineering: Design Principles and Practical Applications goes into the implementation of many modern cryptography ciphers.

Learn Python the Hard Way is a free book that also teaches Python to complete beginners.