Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A communication device includes a plurality of key distributing units, a plurality of communicating units, a monitoring unit, and a switching unit. The plurality of key distributing units have a quantum key distribution function for sharing a quantum key with an external distribution device. The plurality of communicating units communicate with an external communication device using the quantum key. The monitoring unit monitors operational status indicating at least one of transmission-reception status of photons in the quantum key distribution function, generation status of generating the quantum key, and obtaining status of obtaining the quantum key. The switching unit switches a control target, which either represents one of the key distributing units or represents one of the communicating units, from a first control target to a second control target other than the first control target according to the operational status.

Abstract: A communication device includes a plurality of key distributing units, a plurality of communicating units, a monitoring unit, and a switching unit. The plurality of key distributing units have a quantum key distribution function for sharing a quantum key with an external distribution device. The plurality of communicating units communicate with an external communication device using the quantum key. The monitoring unit monitors operational status indicating at least one of transmission-reception status of photons in the quantum key distribution function, generation status of generating the quantum key, and obtaining status of obtaining the quantum key. The switching unit switches a control target, which either represents one of the key distributing units or represents one of the communicating units, from a first control target to a second control target other than the first control target according to the operational status.

Abstract: A communication device to allocate shared keys to plural channels includes a storage, a receiver, a storage controller, an allocator, and an encryption processor. The storage includes a predetermined number of storage areas to store one or more shared keys shared with a destination device. The receiver is configured to receive a shared key. The storage controller controls storing the received shared key in any of the storage areas every time the shared key is received. The allocator can allocate the storage areas to communication channels used for communicating encrypted data between the communication device and the communication destination device, based on a ratio predetermined for each communication channel. The encryption processor can, according to a cryptosystem determined for the each communication channel, encrypt data and decrypt the encrypted data by using the shared key acquired from the storage area allocated to each communication channel.

Abstract: A communication device includes a providing unit, a flow control unit, and a cryptography processing unit. The providing unit provides a cryptographic key generated using quantum key distribution technology. The flow control unit, if the cryptographic key has not been provided at time of reception of target data for cryptography processing, performs, with respect to the received data, an operation selected from among a first operation of destroying the data, a second operation of holding the data, and a third operation of attaching, to the data, information indicating that the cryptographic key has not been provided, and then outputting the data. The cryptography processing unit, with respect to data output from the flow control unit, performs the cryptography processing using the cryptographic key.

Abstract: 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.

Abstract: 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.

Abstract: According to an embodiment, a communication device includes a receiver, an allocator, a first communication unit, an encryption processor, a second communication unit, and a controller. The receiver is configured to receive a shared key shared with another device. The allocator is configured to allocate the shared key to a transmission key or a reception key. The first communication unit is configured to receive data from an application. The encryption processor is configured to encrypt the data with the transmission key and decrypt the data encrypted by the other device with the reception key. The second communication unit is configured to communicate with the other device by using the encrypted data. The controller is configured to control at least one of allocation of the shared key, traffic of the first communication unit, and traffic of the second communication unit, by using state information of the device.

Abstract: 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.

Abstract: According to an embodiment, a communication device is connected with another communication device through a quantum communication channel with a shared encryption key. The device includes a communication unit, a sifter, a corrector, a calculator, and an extractor. The communication unit is configured to acquire a sequence of photons through the quantum communication channel and acquire a photon bit string corresponding to the sequence of photons. The sifter is configured to generate a shared bit string from the photon bit string by sifting processing using basis information. The corrector is configured to generate a corrected bit string by correcting an error included in the shared bit string. The calculator is configured to generate a hash-calculated bit string by performing hash calculation on the corrected bit string. The extractor is configured to extract, as the key, from the hash-calculated bit string, a bit string having the length of the key.

Abstract: According to an embodiment, a communication system includes a plurality of communication apparatuses. Each of the communication apparatuses includes a key generator and a synchronization processor. The key generator generates shared keys shared with another communication apparatus. The synchronization processor synchronizes at least one of order of using the generated shared keys and roles played when the generated shared keys are used, with another communication apparatus based on a rule determined in advance.

Abstract: A communication device in embodiments is a quantum key distribution device connectable to another quantum key distribution device through a quantum communication channel to share an encryption key therebetween, and includes a common processing unit, one or more individual processing units, and a distribution unit. The common processing unit outputs intermediate data based on bit information obtained by transmitting or receiving sequence of photons with the another quantum key distribution device through the quantum communication channel. Each individual processing unit generates or provides the encryption key in accordance with the intermediate data. The distribution unit distributes the intermediate data that is output from the common processing unit to two or more distribution destination that include the individual processing units.

Abstract: According to an embodiment, a communication apparatus that offers an encryption key shared with another communication apparatus to an application, and includes a calculator and a communication controller. The calculator is configured to calculate limit information for limiting a call for a request message in which the application requests the encryption key, based on at least one of a sharing rate of the encryption key and an accumulated volume of the encryption key. The communication controller is configured to transmit a response message with the limit information to the application, the response message returning the encryption key as a response to the request message.

Abstract: According to an embodiment, a communication apparatus includes a memory and one or more hardware processors configured to function as a reception unit, a sharing control unit, and a transmission unit. The reception unit is configured to receive, from an application, an acquisition request for an encryption key to be used for encrypted data communication between the application and a communication counterpart thereof. The sharing control unit is configured to, with another communication apparatus connected to the communication counterpart, share the encryption key using quantum key distribution when being able to share the encryption key using quantum key distribution, and share the encryption key using a key sharing scheme other than quantum key distribution when being unable to share the encryption key using quantum key distribution. The transmission unit is configured to transmit, to the application, the encryption key and information indicating a scheme used for sharing the encryption key.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: According to one embodiment, a key sharing device includes one or more processors function as a plurality of individual processing units. Each of the individual processing units performs any one of a plurality of individual processing operations included in processing that generates a cryptographic key by quantum key distribution. The cryptographic key is shared between the key sharing device and another key sharing device. The individual processing unit includes a control unit that controls execution of the corresponding individual processing operation according to a usage state of a storage that stores result information at least one of a result of an individual processing operation and identification information for identifying the result.