I've released my third book, "Hacking Secret Ciphers with Python" for free under a Creative Commons license. This book is aimed at people who have no experience programming or with cryptography. The book goes through writing Python programs that not only implement several ciphers but also can hack these ciphers. Each chapter presents a new program and explains how the source code works.
You can download the book from http://inventwithpython.com/hacking 100% of the proceeds from the book sales will be donated to the Electronic Frontier Foundation, Creative Commons, and The Tor Project. -- http://mail.python.org/mailman/listinfo/python-list
