Hey, that's a lot like what I built--and from the comments so far, the gripes about having to trust that the files are not modified would also apply to Cryptasia (http://www.cryptasia.com).

Having to trust that the site won't be hacked is an interesting problem--I suppose both our projects could be made more Trustworthy if users had a separate service that ensures that files served by the website don't change... a Chrome extension might be an interesting way to do this validation. Sounds like another weekend task :)

Anyway, cool project!