Patent ID: 8713567

Claim:
In a system comprising an embedded system capable of operating as a virtualized system under supervision of a hypervisor or as a non-virtualized system under supervision of an operating system, a method comprising the steps of: executing the embedded system in a normal mode, if no execution of any security critical function is required by the embedded system, where the normal mode execution is performed under supervision of the operating system; switching, by the operating system, execution of the embedded system from normal mode to protected mode, by handing over the execution of the embedded system from the operating system to the hypervisor, in response to a determination that a security critical function execution is required by the embedded system, where protected mode execution is performed under supervision of the hypervisor; switching, under supervision of the hypervisor, the embedded system from protected mode to normal mode, when execution of the security critical function is no longer required by the embedded system; and decrypting and verifying, on the basis of at least one chip unique secret key accessible from a transition cryptographic module, the integrity of code associated with the hypervisor, the security critical function, and associated data, if the mode state of the mode state register is set to protected mode, or prohibiting access to any chip unique secret key if the mode state of the mode state register is set to normal mode.