DIGITAL INFORMATION PROTECTION SYSTEM AND ITS METHOD

摘要

PURPOSE: To provide a digital information protection system and its method without information leaked to a third person and with the difficulty of illegal copying performed by a correct user. CONSTITUTION: The information identifier of information to be utilized selected from an information terminal device 2 by a user is sent to a calculator card 3 and given a sign, this is transmitted to an information center 1, in the information center 1 a key WK is produced for ciphering the information to be utilized, this is stored in the calculator card 3 via the information terminal device 2, a WK request message including a random number (r) is sent from the information terminal device 2 to the calculator card 3, the stored key WK is set to the information terminal device 2 and the information to be utilized ciphered with the key WK and distributed from the information center 1 is decoded with the set key WK.