Question:  Calling CkXmlDSigGen.SetX509Cert causes Windows to show a dialog box requesting validation.  Is it possible to avoid the dialog box?

Answer: Yes.  The reason for displaying the dialog box  is because the cert + private key was imported with the option to enable strong private key protection.  Here’s a screenshot of the Window Certificate Import Wizard showing the two checkboxes:  One for strong private key protection (meaning show a dialog box), and the other for allowing the private key to be exported.   The solution is to remote the cert + private key from the system, and re-import with the enable strong private key protection checkbox unchecked.

windows cert import wizard