sbctl (Secure Boot Manager) is a user-friendly secure boot key manager capable of setting up secure boot, offer key management capabilities, and keep track of files that needs to be signed in the boot chain.
It is possible to change USE flags for the sbctl package:
USE flags for app-crypt/sbctl Secure Boot key manager
|Verify upstream signatures on distfiles
After making USE modifications, ask Portage to update the system so the changes take effect:
emerge --ask --changed-use --deep @world
emerge --ask app-crypt/sbctl