NAME

       systemd-boot-system-token.service - Generate an initial boot loader system token and
       random seed

SYNOPSIS

       systemd-boot-system-token.service

DESCRIPTION

       systemd-boot-system-token.service is a system service that automatically generates a
       'system token' to store in an EFI variable in the system's NVRAM and a random seed to
       store on the EFI System Partition ESP on disk. The boot loader may then combine these two
       randomized data fields by cryptographic hashing, and pass it to the OS it boots as
       initialization seed for its entropy pool. The random seed stored in the ESP is refreshed
       on each reboot ensuring that multiple subsequent boots will boot with different seeds. The
       'system token' is generated randomly once, and then persistently stored in the system's
       EFI variable storage.

       The systemd-boot-system-token.service unit invokes the bootctl random-seed command, which
       updates the random seed in the ESP, and initializes the 'system token' if it's not
       initialized yet. The service is conditionalized so that it is run only when all of the
       below apply:

       •   A boot loader is used that implements the Boot Loader Interface[1] (which defines the
           'system token' concept).

       •   Either a 'system token' was not set yet, or the boot loader has not passed the OS a
           random seed yet (and thus most likely has been missing the random seed file in the
           ESP).

       •   The system is not running in a VM environment. This case is explicitly excluded since
           on VM environments the ESP backing storage and EFI variable storage is typically not
           physically separated and hence booting the same OS image in multiple instances would
           replicate both, thus reusing the same random seed and 'system token' among all
           instances, which defeats its purpose. Note that it's still possible to use boot loader
           random seed provisioning in this mode, but the automatic logic implemented by this
           service has no effect then, and the user instead has to manually invoke the bootctl
           random-seed acknowledging these restrictions.

       For further details see bootctl(1), regarding the command this service invokes.

SEE ALSO

       systemd(1), bootctl(1), systemd-boot(7)

NOTES

        1. Boot Loader Interface
           https://systemd.io/BOOT_LOADER_INTERFACE