title: How to check if an ePub file is DRM-protected?
body: <p>Is there any programmatic way to safely check whether if an epub file is DRM-protected (encrypted)?</p>
  
  <p>I have found that there might be a rights.xml and an encryption.xml in the META-INF directory.
  Does the existance of any or both of these files mean that the content is encrypted and if not, is there any other way to check?<br>
  (To be clear, I do not want to read ePubs with DRM at all, I just want to check whether they are encrypted or not.)</p>