Most of the free Wordpress themes out there are having Creative Commons Attribute 2.0+ License. This means that you can modify the theme in anyway you want but you have to attribute the work in the manner specified by the author.

If you download the free WP themes from other sites using this type of license, you’ll notice that most of them have the footer section encrypted.

Many of you would like the freedom to change how the footer looks. With an encrypted footer, you can’t change things like adding a “Contact” link or an RSS button. You might also want to check whether there is no malicious code in the encryption.