Nippon Telegraph and Telephone Corporation

Ntt Corporation

Sakae Chikara

Tetsutaro Kobayashi

Kaku Takeuchi

Tsunekazu Saito

A communication system according to one embodiment is a communication system including a plurality of communication apparatuses, in which each communication apparatus includes: an application program configured to perform encrypted communication with another communication apparatus; a protocol conversion unit configured to transmit a message representing a predetermined procedure when a key request for a shared key to be used in the encrypted communication is received from the application program; a state management unit configured to receive a message from the protocol conversion unit to manage an execution state of the procedure, and to transmit the message to a protocol driver supporting a predetermined key sharing protocol; and a protocol driver configured to request a key sharing system that executes the key sharing protocol, to generate the shared key, when the message is received from the state management unit.

Communication system, communication apparatus, method, and program

A cryptographic communication technology that is based on functional encryption and that can operate flexibly is provided. A conversion rule information pair is determined in advance, which has attribute conversion rule information prescribing a conversion rule for converting attribute designation information to attribute information used in a functional encryption algorithm and logical expression conversion rule information prescribing a conversion rule for converting logical expression designation information to logic information used in the functional encryption algorithm. One kind of conversion rule information included in the conversion rule information pair is used to obtain first attribute information or first logic information from input information. The first attribute information or the first logic information is used for encryption. Encryption information is decrypted with a decryption key generated by using second attribute information or second logic information obtained from user information by using the other kind of conversion rule information.

Cryptographic system, cryptographic communication method, encryption apparatus, key generation apparatus, decryption apparatus, content server, program, and storage medium

A cryptographic communication technology that is based on predicate encryption and that can operate flexibly is provided. A conversion rule information pair is determined in advance, which has attribute conversion rule information prescribing a conversion rule for converting attribute designation information to attribute information used in a predicate encryption algorithm and predicate conversion rule information prescribing a conversion rule for converting predicate designation information to predicate information used in the predicate encryption algorithm. One kind of conversion rule information included in the conversion rule information pair is used to obtain first attribute information or first predicate information from input information. The first attribute information or the first predicate information is used for encryption. Encryption information is decrypted with a decryption key generated by using second attribute information or second predicate information obtained from user information by using the other kind of conversion rule information.

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Tokyo, Japan

Sakae Chikara