The present invention provides an improved technology of preventing illegal use and execution of a
software program provided to a computer
system. More particularly, the present invention is directed to a Processor of a type in which a memory managing unit is installed therein to manage storing operation of code / data in main memory and includes, as one of
instruction set, an execution permitting instruction to permit execution of a
program code (application) in the main memory. The procedure of execution permitting instruction is defined by a microprogram and includes an
authentication procedure for authenticating the right to use the program beside a procedure for setting predetermined data in the memory managing unit in this invention. Execution of the
software program is permitted only when the
authentication processing is completed successfully. Because the
authentication operation is performed within the processor, it is almost impossible to monitor or detect it from the exterior. Also, by using a processor ID unique to the processor
chip as identification information for use in the authentication
processing, the right to use a specific
software program can be limited to a single processor.