Virtual machine device having key driven obfuscation and method

A virtual machine device 100 comprising multiple operation routines 122,124, 126 each configured to perform a particular instruction, and a selector 110 configured to receive an encoded instruction, the encoded instruction being obtained by encoding a plain instruction with a code encoding, the selector is configured to select and activate a corresponding operation routine of the multiple operation routines, the corresponding operation routine is configured to perform the plain instruction corresponding to the encoded instruction, the selector 100 comprises a look-up means for looking-up an encoded instruction to select the corresponding operation routine.