Make updater check interity & authenticity of server-returned XML (XMLDsig)

This security enhancement depends on notepad-plus-plus/wingup#102.

Author: donho

PowerEditor/src/Parameters.cpp

@@ -9972,6 +9972,15 @@ void  NppParameters::buildGupParams(std::wstring& params) const
 
 	SecurityGuard sgd;
 
+	//
+	// Verify integrity & authenticiy of server-returned XML (XMLDsig) 
+	//
+
+	params += L" -chkCert4InfoXML";
+
+	params += L" -chkCertKeyId4XML=";
+	params += sgd.signer_key_id();
+
 	//
 	// Verify integrity & authenticiy of the downloaded installer
 	//