http://www.abhishektripathi.com/encrypting-footer-links-free-theme-developers-take-notice/ The site is currently down, but he will hopefully bring up the site. I think he is also a member here Ohh FOrget it,,, Looks like the guy ios absconding after scamming membere here in DP..
There some program for you: zend encode, ioncube, scopbin... For example you can use eval(base64('Base64_encode_string')