Captcha-style system for files?

I couldn’t find a plugin to help me do this, but I am looking to integrate a captcha-style verification system to protect downloads of a file, instead of block spam comments or a contact form.

I made the mistake once of putting up an MSWord and PDF of my resume and it was still crawled by the spammers and they managed to get my email off the documents. Is there anyway to use a word or letter-verification system to make sure that only real people can download that file?