Validate Referrer Script

I'm attempting to use a 'site seal' for one of my products. This is much like an ssl site seal. What I would like is a script that allows seal to be clicked, then popup window opens.... The referrer url should be checked against a database entry or textfile. If referrer url is listed in db or textfile, the output shows url information. If referrer url is not listed, output would reflect this and show generic 'not authorized' page. I'm a very honest and fair buyer. Please don't ask me for payment upfront and ridiculous bids will simply be ignored :) Thanks