Encrypted URL download link
Hello. I've been asked to design and develop a website which will have downloadable files (pdf, wav and mp3).
The URL (links) for these files need to be "hidden" so that only authorised people can download them.
Is there any way of supplying users of the site with a "once-only" encrypted URL link to the file that they want to download?
This could either be:
1. a password that ONLY works for their email address,
2. a URL that expires after a short time,
3. a script that moves the selected files into a temp directory with a random name, and deletes them after a short time.
4. an exe that downloads them without showing the user the links.
I'm stumped. Does anyone know how to do any of the above?
Are there any scripts (any language) out there already written that do something similar?
Can anyone think of a better solution?