After a reproduction program is installed on a PC, a key for CD ripping is furnished e.g., from an FD. With the key for CD ripping, the music contents in a CD can be copied to a PC, however, it is not possible to download music contents from an EMD server for copying on a PD. For storing the music contents distributed from the EMD server on the PD, the reproduction program first acquired a key for EMD different from the key for ripping over the network. By so doing, the contents data distributed over the network may be improved in safety.