SYSTEMD-BOOT-SYSTEM-TOKEN.SERVICE(8)



SYSTEMD-BOOT-SYSTEM-TOKsystemd-boot-systemSYSTEMD-BOOT-SYSTEM-TOKEN.SERVICE(8)

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:

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

       o   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).

       o   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

systemd 245                               SYSTEMD-BOOT-SYSTEM-TOKEN.SERVICE(8)

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