fixes related to MSP digital signature

Change-Id: I06bcf0d2cc8c4915eff3658905087be6a2eadca6
(cherry picked from commit 557cfd3bb1e9eb2792b0aa3831ad107d52ed9909)
Reviewed-on: https://gerrit.libreoffice.org/11093
Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>