title: Is this byte array a password-protected PDF document?
body: <p>I have a C# byte array, and I need to know if it's a password-protected PDF document.  How can I make this determination?</p>
  
  <p>I'm inspecting the document for the PDF magic cookie to determine if it's a PDF document, but I don't know what's best when determining if it's password protected.</p>
  
  <p>I don't need to open the document (though, as long as there's no UI required -- this is a background process, I'm OK with doing that if it helps).</p>
  
  <p>I just need to know if there's a password on this PDF document.</p>
  
  <p><strong>EDIT:</strong> If you cite iTextSharp, I'd be very grateful if you'd cite a specific resource within that API that addresses this concern.</p>