How can I encrypt a file (video/audio/image), save to SDCard, then decrypt that same file and play it via VideoView?

Question

I am trying to create an app that would download a file from a remote server and save it to the SD card. The file is quite confidential so I need an encryption for this. I would like it to be saved as encrypted. When I want to play the file, it should only be played on my media player which has the decrypt code. No other player can play that file. How is this possible? Thanks for any suggestions you may have.

Answer 1

If you don't want to be bothered with a delay by decrypting the entire file before to be able to start the playing, you should consider a streaming architecture. A typical design involves the javax.crypto.CipherInputStream class and a local http instance. For an example of that kind of design, look at something like LocalSingleHttpServer.