Support loading der files

Author: timlegge

lib/XML/Enc.pm

@@ -969,6 +969,10 @@ sub _load_key {
         local $/ = undef;
         $text = <$KEY>;
         close $KEY;
+        if ($file =~ m/der$/ ) {
+            my $priv = Crypt::PK::RSA->new($file);
+            $text = $priv->export_key_pem('private');
+        }
         if ( $text =~ m/BEGIN ([DR]SA) PRIVATE KEY/ ) {
             my $key_used = $1;