If anybody wants to read a nicely written book (for beginners) Simon Singh wrote a very good book on cryptography called The Code Book. It starts out with very simple cyphers and shows how they progressed to the amazing stuff we have today. Dude has a website but he pushes his books to much.
His Links are really good tho...
www.simonsingh.com
The only other book by him that I read was Fermat's Last Theorem. It was better than I thought a book about a math problem could ever be... but it was still a book about a math problem.
