title: C# CF: file encryption/decryption on the fly
body: <p>i've seen many article on encrypt/decrypt of file and typically a button is used to choose the file for encrypt and another button to decrypt the file.</p>
  
  <p>i've seen some application like truecrypt and probably others which does file encryption on-the-fly with transparent. this means that when a encrypted file is clicked to access, it will automatically decrypt and play/open the file. then when the file is closed, it will automatically encrypt again.</p>
  
  <p>some have said that the only way to detect file open is through file system filter.</p>
  
  <p>but is there other ways to do this in c# compact framework?</p>