title: Encrypt and Decrypt video file after downloading
body: <p>I have a table view that contain video files, I want to download this video file from url and show download progress for every cell , and after finishing downloading, I want to encrypt downloaded video file and when user want to open video I have to decrypt this and show to user. but I did not find a solution for encrypt and decrypt  the video file.
  someone have any solution for encrypt and decryption for video file.</p>