title: Can't find unmanaged DLL for adding digital signature to PDF
body: <p>I have trouble finding a library capable for digital signing PDF.</p>
  
  <p>I was able to create <a href="https://stackoverflow.com/questions/378247/digitally-sign-pdf-files">.Net app</a> for signing but now I need dll that will work without .Net framework.</p>
  
  <p>Does anyone knows good lightweight library for that? Commercial/NonCommercial</p>