If you're looking for an overview of cryptography in an easy-to-digest format, take a look at:<p><pre><code> The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography
</code></pre>
Amazon link: <a href="http://www.amazon.com/Code-Book-Science-Secrecy-Cryptography/dp/0385495323/ref=sr_1_3?ie=UTF8&qid=1326323359&sr=8-3" rel="nofollow">http://www.amazon.com/Code-Book-Science-Secrecy-Cryptography...</a><p>It is light on the math but Simon Singh does a great job reviewing cryptography over the last 4000 years. It was a fun summer read.