A processor system includes a processor and a first memory area storing a boot program code. The boot program code starts execution of an operating system when executed by the processor, and performs a cryptographic operation when the processor executes the boot program code. A second memory area stores one or more cryptographic keys and is only accessible to the boot program code. A third memory area stores the operating system. The processor retrieves the boot program code from the first memory area and executes the boot program code to start the execution of the operating system. The processor re-executes the boot program code to cryptographically encrypt data upon the basis of the cryptographic keys stored in the second memory area.