Random Download Key Generator

I just put up a site for my new music label, Amazing Wow (amazingwow.org)

We’re an online music label that gives all our music away for free download online, and make money off ads. Everything has worked fine so far, but as of right now, all our albums are accessible via a one click zip link on the download pages.

What I want to do is figure out someway to make it only possible to get the albums from being on our page (and hence seeing the ads), so that people can’t just link to the album’s download site directly.

I’m thinking a random key generator, like what MegaUpload et. al. use would be the best way, but was wondering if anyone had heard of a plugin that could do as such on WP. Or if anyone has any other ideas for making the page necessary to visit for downloading the link, that’d be great.

Thanks!

Ben