Real time US debt clock

Create a javascript that displays the US national debt in real time, with numbers changing live on the page (just like [this one (1)][1] ) The algorithm will be based on a fixed formula, but it will have to check periodically (perhaps a few times every day) with the official count that is displayed and updated for every business day on the [US Treasury website (2)][2] and correct itself. The script used on the site linked above (1) claims to do something similar to what I am looking for. It also seems to have a way so that the script is protected from people who want to copy it. Protection is a requirement for this project as well, and the script should work only when the url from which it is called is authorized by me (I will have a list of authorized urls)