http://www.rsa.com/rsalabs/faq/3-6-4.html

Some of the links in the link above might help. A search for the inventor "Rivest" on google might turn up some good links. Rivest also has a book "Algorithms" that might discuss RC5. I have a copy and will look when I get home and post agin if it has a good discription. And there is a patent that has a full discription.

Bobby