165734 search keyword SID tracking

I am buying pay per click traffic from google adwords, yahoo publisher network, and MSN adcenter. I am sending this to landing pages for affiliate offers. I use sub ID tracking for the affiliate link so I can group keyword together for return on investment readouts. I would like to change this so that I can track this at the keyword level. The keyword the user searched for is put into the URL as a parameter that I also put into the pages dynamically so the phrase the user searched for appears on the page. I would like to use this keyword as the sub ID that I send to the merchant. I need to encrypt this so that the merchant doesn't know what keywords I am bidding on. These links also need to be "cloaked" using PHP code similar to what is described in the URL provided below. This is just how I do it now, it can be different as long as it works. We need this project completed as soon as possible. Please email me any questions. [login to view URL]