After a user terminal executes a data usage accounting procedure for a contents
provider, enciphered copyrighted digital data generated by enciphering chargeable
copyrighted digital data using encryption key data, digital sample preview data
generated from an outline of the copyrighted digital data at a non-chargeable level
without enciphering, decryption key data for deciphering the enciphered copyrighted
digital data, and additional data required for accounting are transmitted from
the contents provider to the user terminal over a network.
