In the present invention, a program is provided with a dummy module into which a watermark can be inserted without any effect on the operation of the program, and an digital signature. It is thereby possible for a distributor to insert a watermark for specifying a user to the dummy module, and to prevent unauthorized leakage of the program by the distributor. Further, by providing the program body with an digital signature, it is possible to prevent tampering of the program by the distributor.