The intention is to encrypt the data (AES 256) at the server level with a "master" key/passphrase, but then send a 'time-bombed' generated key that would enable decrypting the data... but only for a certain amount of time - e.g. 2-4 hours.
I've been led to believe that this is possible - however I haven't found any documentation indicating how to generate temporary keys.
If this concept is possible a link to, or indication of what the API/method call would be named would be helpful. If this is possible, but only in other encryption schemes (e.g. SHA-512?) I'd be grateful for a nudge in the right direction.