Patent ID: 6839837

Claim:
A cryptosystem key updating system for preventing illegal use of software, comprising encryption encryption means for encrypting secret information; secret information storage means for storing the secret information; cryptosystem key storage means for storing a cryptosystem key used for decrypting the secret information stored in the secret information storage means; illegal access determining means for determining whether an illegal access to the system is performed; and cryptosystem key updating means for: providing the updated same key for a first cryptosystem key used for reencrypting the secret information stored in the secret information storage means and a second cryptosystem key which is stored as an updated cryptosystem key in the cryptosystem key storage means if the illegal access determining means detects no illegal access; providing different keys for the first and second cryptosystem keys if the illegal access determining means detects an illegal access; and wherein the cryptosystem key updating means updates the first and second cryptosystem keys for each access to the system, and subsequently reencrypts the secret information stored in the secret information storage means using the updated first cryptosystem key.