ENCRYPTED DATA ADMINISTRATION DEVICE, ENCRYPTED DATA ADMINISTRATION METHOD, AND ENCRYPTED DATA ADMINISTRATION PROGRAM

摘要

An invalidation scheme of a secret key is implemented, which is usable for a functional encryption scheme. In a cryptographic processing system 10 employing an encryption scheme with which if attribute information and key information set in encrypted data do not correspond to attribute information and key information set in a secret key, the encrypted data cannot be decrypted using the secret key, an encrypted data management device 200 is provided, which carries out a relay between a user terminal 100 carrying out encryption and decryption of data and an encrypted data storage device 300 storing encrypted data. The encrypted data management device 200 determines whether or not a user whose secret key is invalid is included in users having attribute information set in the encrypted data acquired from the encrypted data storage device 300, and sets a different value as key information in the encrypted data based on the determination result. Then, the encrypted data management device 200 sends the encrypted data in which the key information is set to the user terminal 100.