title: Prevent file from being edited
body: <p>What's the smartest way to prevent a textfile (e.g. xml) from being edited by a user?<br>
  I need to make sure that the file in which I store the usernames and there privileges for the desktop application can't be simply edited. </p>
  
  <p>Maybe I can generate a certificate of the file and the desktop applications checks this?</p>
  
  <p>I'm using C# in a WinForms app.</p>