Install vboot-kernel-utils by entering the following commands in the terminal:
sudo apt update sudo apt install vboot-kernel-utils
Description:
Chrome OS verified boot utils required to sign kernels
This package provides the futility program (including the vbutil_kernel program required to sign custom kernels in order to get them booted by Chrome OS devices (i.e. Chromebooks)).
Homepage: https://chromium.googlesource.com/chromiumos/platform/vboot_reference
Version: 0~R63-10032.B-3
Section: universe/admin