In OpenShift doc page: https://docs.openshift.com/container-platform/4.12/hardware_enablement/kmm-kernel-module-management.html

Section: Adding the keys for secureboot

There's a typo in the procedure, step 2:

oc create secret generic my-signing-key-pub --from-file=key=<my_signing_key_pub.der>

This is not correct.  It should be:

oc create secret generic my-signing-key-pub --from-file=cert=<my_signing_key_pub.der>

for All OCP releases 4.12 thorough 4.14.

4.12, 4.13, 4.14, 4.15