US Patent 7145481 Method and apparatus for trusted keyboard scanning

A keyboard scan engine integrated on a chipset to initiate a keyscan process. The keyboard scan engine detects a key depression. When in a trusted mode, the keyboard scan engine transmits a key code, corresponding to the key depression, through a trusted internal bus interface. When in a non-trusted mode, the keyboard scan engine transmits the key code through an interface to be processed by an onboard keyboard controller.