Hello,
I am interested in finding out ways of protecting download links for digital content aside the use of adding a Nonce (http://en.wikipedia.org/wiki/Cryptographic_nonce) and a unique URL which expires after first use.<p>I would like to end up with links that when used once, becomes invalid for next use. This is to prevent users from sharing the links with their friends.<p>Links and pointers to resources are appreciated.