So, I'm just a programmer -- I don't know much about cryptography so bare with me and my lack of knowledge in this realm. But essentially, I'm wanting to cache data that could be potentially volatile ( ie -- change or delete over time ). One solution I've thought of would be to encrypt the data ( server side ) and administer the key to the client -- here's the catch though: it expires within a given time frame ( ie, two or three days ). It can be refreshed or renewed, at every connection to the server but if the key is not refreshed, then ultimately I would like it to not be any good. That would mean the encryption method would need to use time as a factor ( so perhaps using a modulus / floor / round operator based on the current time to give you the actual encrypted data / things necessary to fully decrypt the data ). My only concern of course is that clients can modify the current time on their system. Perhaps I can find a trust-worthy source for the current time.
( Also, I understand that it is fundamentally silly to give data to a client when it's expected to be taken away, but I still am interested in finding a solution to this. ).
Does anybody know of something, or is there something that can steer me in the proper direction / achieve similar effects to what I'm after?