Kabushiki Kaisha Toshiba

Kazuaki Doi

Yoshimichi Tanizawa

Akihito Ogawa

Kazuo Watabe

Takashi Usui

Hideaki Okano

Ririka Takahashi

Chikara Tanioka

Mamiko Kujiraoka

Hideaki Sato

Masahiro Saito

Hironori Uchikawa

Akira Murakami

Mari Matsumoto

Hidefumi Takamine

Toshiki Nakashima

Yutaro Ishigaki

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

A quantum-cryptographic-communication system according to an embodiment includes a key-integrated-management device, quantum-cryptography devices, and key-management-inspection devices. An inspection-target-value-calculating unit calculates an inspection-target value based on quantum-cryptography-device information related to a quantum-cryptography device. An expected-value-calculating unit calculates an expected value based on at least one of wiring information of a QKD link connected to the inspection-target-quantum-cryptography device; weather information of the site installed with the inspection-target-quantum-cryptography device; and the quantum-cryptography-device information. A permissible-value-calculating unit calculates a permissible value based on at least one of the wiring information, the weather information, and the quantum-cryptography-device information. A determining unit determines whether the inspection-target value is within the range of (expected value)−(permissible value) and within the range of (expected value)+(permissible value); and, when the inspection-target value is outside the range of (expected value)−(permissible value) and outside the range of (expected value)+(permissible value), transmits anomaly detection to a key integrated management device.

Quantum cryptographic communication system, key management inspection device, key management inspection method, and computer program product

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 an embodiment, a quantum communication device is adapted to correct first sift key data acquired by performing sift processing with respect to a quantum bit string received from a transmission device via a quantum communication path. The quantum communication device includes a determination unit and a correction unit. The determination unit determines setting information of error correction on the first sift key data from an estimated error rate of the first sift key data and a margin of the estimated error rate. The correction unit generates corrected key data by performing the error correction with the setting information.

Quantum communication device, quantum communication system, and quantum communication method

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 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

According to an embodiment, a decoding apparatus for a low-density parity-check (LDPC) code includes a first calculator, a second calculator, and a selector. The first calculator is configured to perform row processing based on a first decoding algorithm. The second calculator is configured to perform row processing based on a second decoding algorithm having a lower error correction capacity than that of the first decoding algorithm. The selector is configured to select an output value from the row processing performed by the second calculator when an error in an output value from the row processing performed by the first calculator is greater than an error in the output value from the row processing performed by the second calculator.

Decoding apparatus, decoding method, and computer program product

According to an embodiment, a quantum communication device includes a sift processor, an estimator, a determination unit, and a corrector. The sift processor is configured to acquire sift processing data by referring to a cryptographic key bit string in a predetermined bit string with a reference basis randomly selected from a plurality of bases via a quantum communication channel. The estimator is configured to acquire an estimated error rate of the sift processing data. The determination unit is configured to determine order of the sift processing data in which an error is to be corrected based on the estimated error rate and difference data between a processing speed of error correcting processing and a processing speed of privacy amplification processing. The corrector is configured to acquire one piece of the sift processing data in the order determined by the determination unit, and generate error correcting processing data.

Quantum communication device, quantum communication method, and computer program product

According to an embodiment, a quantum communication device includes a receiver, a sift processor, an estimator, first and second storages, a determination unit, an error corrector, a measurement unit, and a privacy amplifier. The sift processor acquires sift processing data by referring to a cryptographic key bit string in a predetermined bit string with a reference basis randomly selected from a plurality of bases. The estimator acquires an estimated error rate by estimating an error rate of the sift processing data from an error rate of part of the sift processing data. When a sift processing data volume stored in the first storage is not smaller than a first threshold, the determination unit determines order of the sift processing data to be corrected based on an estimated error rate, an error rate range that a check matrix can correct, and estimated correction time, and the check matrix used for correction.

According to an embodiment, in a parity check matrix creation method, all N column vectors in the mask matrix are different. A submatrix having M rows&#xd7;L columns obtained by arbitrarily extracting L continuous columns from the mask matrix includes Bfirst correction rows and Bith correction rows. The Bfirst correction rows have at least one '1' in total in each of Afirst correction columns. Each of the Bith correction rows has at least one '1' in total in A(i&#x2212;1)th correction columns and has &#x201c;1&#x201d; in one of Aith correction columns included in a column set excluding the first correction columns to (i&#x2212;1)th correction columns. The Bith correction rows include at least one &#x201c;1&#x201d; in total in each of the Aith correction columns. A sum from Ato Aequals L.

Parity check matrix creation method, encoding apparatus, and recording/reproduction apparatus

According to an embodiment, a signal processing apparatus includes a first signal processor, a second signal processor and a third signal processor. The first signal processor suppresses an offset component remaining in a reproduction signal read from an optical recording medium to obtain a first signal. The second signal processor suppresses a nonlinear distortion component remaining in the first signal to obtain a second signal. The third signal processor suppresses a correlation noise component remaining in the second signal to obtain a third signal.

Signal processing apparatus capable of suppressing non-linear noise component during reading optical recording medium

According to one embodiment, in an information recording medium including a plurality of data layers, at least one pre-format area is provided on each of the data layers and is circumferentially divided into a plurality of segments. Management information including data layer identification information for identifying the data layers is recorded in at least one of the segments in each of the data layers, using the marks include BCA marks extending radially uniformly. On adjacent ones of the data layers, the BCA marks associated with the management information are recorded in differently positioned segments which are not opposed to each other.

Information recording medium, information reproducing apparatus, management information reproducing method, information recording/reproducing apparatus and identification information reproducing/recording method

According to one embodiment, an information recording and reproducing apparatus including, a focus control module, an objective lens control module, a calculation module, and a tracking control module. If, detection the recording marks line, to focus a laser light of a second wavelength to the recording layer through an objective lens and to operation a recording layer tracking control using a tracking error signal taken out from a second reflected light and a laser light of a first wavelength to a track groove through the objective lens and to operation a guide layer tracking control to control the objective lens using a tracking error signal taken out from a first reflected light.

Writable information recording and reproducing apparatus

According to one embodiment, a pickup head includes a plurality of light sources, a first objective lens, second objective lens, a driving unit, a first control unit, a second control unit, light receiving units. The first objective lens focuses a first light beam at a first recording layer. The second objective lens focuses a second light beam at a second recording layer. The driving unit moves the first objective lens and the second objective lens in a first direction and a second direction. The first control unit corrects displacement from target track along the first direction. The second control unit controls a moving direction of a position of the second light spot in the second direction.

Pickup head, information recording method and reproducing method

According to one embodiment, an optical pickup configured to record and to reproduce on a layer of a disk, including, a light source configured to emit a laser beam, an objective lens including a variable use magnification and configured to focus the laser beam on the layer, a collimator lens configured to change the magnification of the objective lens by moving along an optical axis direction, and a liquid crystal module configured to generate spherical aberration to cancel a coma aberration which may occur because an object point and an image point of the objective lens at the use magnification do not exist on an optical axis of the objective lens.

Growing community of inventors

Kawasaki, Japan

Kazuaki Doi