Comment 10 for bug 1574300

I am struggling with the same issue. This page gives some information on what I have been trying. http://gorka.eguileor.com/vbox-vmware-in-secureboot-linux/. I have successfully done mokutils --import but that key does not appear in the keyctl system_keyring list. In my case modinfo does not show the signature information as shown in that page . In order to verify the driver was even touched, you can grep for "~Module signature appended~" after signing.