Kabushiki Kaisha Toshiba

Akira Murakami

Yoshimichi Tanizawa

Hideaki Sato

Ririka Takahashi

Kazuaki Doi

Mamiko Kujiraoka

Alex Dixon

According to an embodiment, a quantum cryptographic device includes a memory and one or more processors coupled to the memory. The one or more processors are configured to: tabulate information on an application key transmitted and received by using a quantum cryptographic key and output an application-key information tabulation result; calculate a unit price of the application key based on the application-key information tabulation result; and display information that is display information including the unit price of the application key.

Quantum cryptographic device, quantum cryptographic communication fee calculation system, and quantum cryptographic communication fee calculation method

According to an embodiment, an application-key management system includes a plurality of application-key management devices and a comprehensive management device. The application-key management devices each include: a first memory configured to store an application key in one or more separated logical drives for each sharing destination of the application key shared by quantum cryptographic communication; and a first processor coupled to the first memory. The first processor is configured to: receive, from the comprehensive management device, a deletion request of specifying a logical drive storing the application key to be deleted among the logical drives; and delete the application key stored in the logical drive specified by the deletion request.

Application-key management system, application-key management device, application-key management method, and computer program product

According to one embodiment, an information processing method includes a monitoring step and a key provision step. The monitoring step includes monitoring an operation state of an information processing device including a key generating unit that generates key information shared among a plurality of devices using a quantum key distribution technique. The key provision step includes providing the generated key information when the operation state satisfies a predetermined condition and stopping the provision of the generated key information when the operation state does not satisfy the condition.

Information processing method, and computer program product

According to an embodiment, an information processor includes a memory and one or more hardware processors coupled to the memory. The one or more hardware processors are configured to function as a calculating unit, a determining unit, and a generating unit. The calculating unit is configured to calculate a key length. The determining unit is configured to determine a block size corresponding to a unit of processing in key generation and an outputtable size indicating the size of a key outputtable by the key generation. The generating unit is configured to generate a key having the key length by a hash operation using a matrix having a size determined by the block size and the outputtable size.

Key generation device, key generation method, and computer program product

According to an embodiment, a transmission device is for a second quantum communication system sharing a quantum communication channel with a first quantum communication system, and includes a generator, a modulator, a controller, and a changer. The generator is configured to generate a photon. The modulator is configured to transmit a quantum signal generated by modulating the photon to a reception device. The controller is configured to control the generator and the modulator. The changer is configured to input, to the controller, control signals for changing an operation timing of the generator and an operation timing of the modulator when an error rate of the quantum signal of the first quantum communication system and an error rate of the quantum signal of the second quantum communication system are equal to or higher than a predetermined threshold.

Transmission device, multi-quantum communication system, and multi-quantum communication method

According to an embodiment, a quantum key distribution device includes first and second operation units. The first operation unit is configured to perform a first operation as a key distillation operation. The first operation unit includes a hardware circuit for performing a part of the first operation. The key distillation operation includes a sifting operation for a photon bit string generated through quantum key distribution with another quantum key distribution device via a quantum communication channel. The second operation unit is configured to perform a second operation as a key distillation operation other than the first operation. The second operation unit includes a circuit for a part of the second operation. The first operation unit stores intermediate data generated by the first operation. The second operation unit generates, by the second operation, a cryptographic key being the same as for the another quantum key distribution device from the intermediate data.

Quantum key distribution device, quantum key distribution system, and quantum key distribution method

A transmitting device according to an embodiment include a transmission unit, a storage unit, a cache unit, a reception unit, and a sifting processing unit. The transmission unit transmits a transmission photon to a receiving device. The storage unit stores transmission photon information including transmission timing at which the transmission photon is transmitted, a transmission bit indicated by the transmission photon, and a transmission base of the transmission photon. The cache unit stores, one or more pieces of transmission information including the transmission timing after an elapse of a no-use period of the transmission photon. The reception unit receives, from the receiving device, the reception timing and a reception base of the reception photon. The sifting processing unit performs sifting processing on the transmission bit by making a correlation between the transmission base and the reception base on the basis of the reception timing and the transmission timing.

Transmitting device, quantum communication system, and quantum communication method

According to an embodiment, a quantum-key distribution apparatus includes a quantum-key sharer, a shifter, a corrector, a privacy amplifier, and an estimator. The quantum-key sharer performs photon sharing processing and acquires a photon bit string. The shifter generates a shared bit string by performing shifting processing. The corrector generates a corrected bit string by correcting errors in the shared bit string by performing error correction processing. The privacy amplifier generates an encryption key by performing privacy amplification processing that compresses the corrected bit string. The estimator estimates an encryption-key generation rate based on an output value and a given value at execution phases of respective pieces of processing of the photon sharing processing, the shifting processing, the error correction processing, and the privacy amplification processing.

Quantum-key distribution apparatus, quantum-key distribution method, and computer program product

According to an embodiment, a communication device is connected to another communication device through a quantum communication channel and a classical communication channel to share an encryption key. The device includes a photon detector, a measurer, a difference generator, and a transmitter. The photon detector is configured to detect photons transmitted from the other communication device through the quantum communication channel. The measurer is configured to measure time when each photon is detected by the photon detector as time stamp information. The difference generator is configured to generate difference time stamp information as a difference between time obtained by adding particular information to the time indicated by the time stamp information previously measured by the measurer and time indicated by the time stamp information subsequently measured by the measurer. The transmitter is configured to transmit the difference time stamp information to the other communication device through the classical communication channel.

Communication device, quantum key distribution system, quantum key distribution method, and computer program product

According to an embodiment, a receiver is connected to transmitters through photon communication channels and data communication channels to generate identical cryptographic keys to be shared with each transmitter. The receiver includes a sharing unit, a key distilling unit, a data communication controller, and a calculator. The key sharing unit is configured to generate a shared bit string through quantum key distribution with each transmitter via a corresponding photon communication channel. The key distilling unit is configured to generate the cryptographic keys from the respective shared bit strings. The data communication controller is configured to receive from each transmitter first information about a corresponding cryptographic key via a corresponding data communication channel. The calculator is configured to calculate the photon timeslots based on at least the first information. The data communication controller is configured to transmit the photon timeslots to the transmitters.

Growing community of inventors

Kawasaki, Japan

Akira Murakami