Mitsubishi Electric Corporation

Sachihiro Ichikawa

Takashi Ito

Katsuyuki Takashima

Takato Hirano

Nori Matsuda

Mitsuhiro Hattori

Takumi Mori

Tsunato Nakai

Tadakazu Yamanaka

A data storage system () uses an encryption scheme in which an encrypted file can be decrypted using a decryption key when a decryption condition set in the encrypted file is satisfied by a user attribute set in the decryption key. The data storage system () stores encrypted files encrypted by the encryption scheme in a file storage apparatus (). When user attribute is specified from a user terminal (), the data storage system () extracts the encrypted file of which the decryption condition is satisfied by the specified user attribute from among the encrypted files stored in the file storage apparatus (), and displays the extracted encrypted files classified by decryption condition.

File storage system and user terminal

An input unit inputs a predicate which describes a plurality of selected elements being elements selected by a user. A predicate generation unit extracts two or more than two selected elements that are dependent on the same element in a higher layer, from the plurality of selected elements described in the predicate. Furthermore, the predicate generation unit reduces the number of elements described in the predicate by replacing a description of the two or more than two selected elements extracted with a description of the element in the higher layer.

Information processing apparatus, information processing method, and program

An invalidation scheme of a secret key is implemented, which is usable for a functional encryption scheme. In a cryptographic processing systememploying 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 deviceis provided, which carries out a relay between a user terminalcarrying out encryption and decryption of data and an encrypted data storage devicestoring encrypted data. The encrypted data management devicedetermines 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, and sets a different value as key information in the encrypted data based on the determination result. Then, the encrypted data management devicesends the encrypted data in which the key information is set to the user terminal

Encrypted data management device, encrypted data management method, and encrypted data management program

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Tokyo, Japan

Sachihiro Ichikawa