[FDE] USB device that can send keystrokes?

[Ali, Saqib]

>  So you need a device that registers as a HID (keyboard) and
>  automatically starts sending keystrokes (any key or special key
>  sequences?) without running any app on the "guest" system?!

yup exactly.

i wonder why no one has created such a device. it should be fairly
easy to create something like this. The keyboard is recognized at the
boot time (BIOS and boot-loader level), so no additional keyboard
drivers are required to be loaded.