To enroll secure boot custom keys enter the BIOS/UEFI, go to Security > Secure Boot and disable it.

You should aim for something like this, UEFI should be in setup mode with SB disabled.

Go to Key Management and delete all Vendor variables and enroll your own. You can do it from the mounted ISO file where you have them stored. Press enter on each of the “Platform Key”, “Key Exchange Keys” and “Authorized Signature” and select the corresponding file from your ISO.

After the custom keys have been enrolled.

System should now be in User, Not active mode

You can now enable SB again, F4 to save and exit and try booting from you custom ISO which is signed by the above enrolled keys.

• Supermicro X11SSL-nF

• https://www.supermicro.com/manuals/motherboard/C232/MNL-1782.pdf