ViewSonic SC-T25, VS, handles certificates , cert, for different applications in Base64-encoded DER format . If You open the certificate file, with a simple text editor, it shall begin with "---- BEGIN CERTIFICATE ----" and end with "---- END CERTIFICATE ----" if it is the right format. The most simple way to load the cert, is to use "Method 1" . Please note that You log in with the CLIENT , PC/Mac, user/password. Another method is "Method 3" . In this example I will load Citrix Intermediate Certs to the SC-T25 from a USB stick.