Abstract: According to an embodiment, a communication device is connected to a plurality of external devices which share key information with each other. The communication device includes a detector and an instructing unit. The detector is configured to, from among the external devices, detect an external device that has been subject to attack. The instructing unit is configured to issue an instruction to stop using key information which is shared with the detected external device.

Abstract: According to an embodiment, a quantum key distribution device includes a quantum key distributor, a sifter, a corrector, an identifier, a classifier, a calculator, and a privacy amplifier. The quantum key distributor obtains a photon string from a photon string of two or more intensities of light pulses. The sifter obtains pulse information indicating the light pulse to which each bit of a shared bit string corresponds. The corrector corrects an error included in the shared bit string and generates a post-correction bit string. The identifier generates error position information. The classifier classifies each bit of the post-correction bit string. The calculator calculates the error rate for each light pulse and each base using the error position information. The privacy amplifier generates a cryptographic key from the post-correction bit string on the basis of the error rate.

Abstract: According to an embodiment, a communication device is connected with external devices by quantum communication channels and a classical communication channel, and generates an encryption key with photons exchanged over the quantum communication channel. The communication device includes an acquirer, a calculator, a selector, and a communicating unit. The acquirer is configured to acquire a quantum error rate for each quantum communication channel. The calculator is configured to calculate a metric of a first path to each external device based on the quantum error rate. The selector is configured to select a second path in the classical communication channel to a specific one of the external devices based on the metric. The communicating unit is configured to transmit an application key to the specific one of the external devices over the second path.

Abstract: A communication device assigns a key taking the degree of priority of applications into account in a case where a key generation/sharing system in which a plurality of applications are connected to a node is not able to realize key assignment that satisfies the key rates requested by the plurality of applications. For example, the device realizes a method of assigning an application key that takes the degree of priority into account according to which control is performed in such a way that the key rate requested by an important application is preferentially satisfied.

Abstract: According to an embodiment, a quantum key distribution (QKD) device includes a sharing unit, a correcting unit, a deciding unit, a calculator, and a privacy amplifier. The sharing unit is configured to generate a shared bit string through quantum key distribution with each other QKD device connected via quantum communication channels. The correcting unit is configured to generate a corrected bit string through an error correction process on the shared bit string. The deciding unit is configured to calculate an error rate in the corresponding quantum communication channel with respect to each other QKD device, and decide on a combined error rate from error rates calculated. The calculator is configured to calculate, based on the combined error rate, a length of an encryption key to be shared. The privacy amplifier is configured to generate the encryption key having the calculated length of the encryption key from the corrected bit string.

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 quantum key distribution (QKD) device includes a sharing unit, a correcting unit, a deciding unit, a calculator, and a privacy amplifier. The sharing unit is configured to generate a shared bit string through quantum key distribution with each other QKD device connected via quantum communication channels. The correcting unit is configured to generate a corrected bit string through an error correction process on the shared bit string. The deciding unit is configured to calculate an error rate in the corresponding quantum communication channel with respect to each other QKD device, and decide on a combined error rate from error rates calculated. The calculator is configured to calculate, based on the combined error rate, a length of an encryption key to be shared. The privacy amplifier is configured to generate the encryption key having the calculated length of the encryption key from the corrected bit string.

Abstract: According to an embodiment, a communication apparatus includes a cryptographic key storage, a transmitter, a receiver, and a sharing controller. The cryptographic key storage stores therein one or more cryptographic keys shared with an external device. The transmitter transmits specifying information that specifies at least one of the cryptographic keys to the external device. The receiver receives determination information that indicates a result of determination, which is made by the external device based on the specifying information, on whether the shared cryptographic key is consistent between the apparatus and the external device. When receiving the determination information indicating that the shared cryptographic key is inconsistent between the apparatus and the external device, the sharing controller deletes the cryptographic key specified by the specifying information from the cryptographic key storage.

Abstract: According to an embodiment, a communication device includes a storage unit and a determiner. The storage unit is configured to store therein a degree of priority and a first requested volume for each of one or more applications that use an encryption key. The first requested volume indicates a volume of the encryption key requested by the each of applications. The determiner is configured to determine a volume of the encryption key to be assigned to each application in such a way that a first total value that is a total of the volume of the encryption key to be assigned to the application is equal to or smaller than a second total value that is a total value of a volume of the encryption key assignable and that the encryption key of the first requested volume is preferentially assigned to the application whose degree of priority is higher.

Abstract: According to an embodiment, a communication device includes an acquirer and a determiner. The acquirer is configured to acquire a first history value for each of one or more applications that use an encryption key. The first history value indicates a history value of a volume of the encryption key used by the each of one or more applications. The determiner is configured to determine a volume of the encryption key to be assigned to the corresponding application, according to the first history value.

Abstract: According to an embodiment, a communication device is connected to a first network and a second network. The communication device includes a generating unit and a converting unit. The generating unit is configured to generate a first set of route information that is route information of the first network. The converting unit is configured to convert the first set of route information, and generate a second set of route information that is route information of the second network.

Abstract: According to an embodiment, a communication device is connected to a plurality of external devices which share key information with each other. The communication device includes a detector and an instructing unit. The detector is configured to, from among the external devices, detect an external device that has been subject to attack. The instructing unit is configured to issue an instruction to stop using key information which is shared with the detected external device.

Abstract: According to an embodiment, a communication device is structured to be connected to a plurality of external devices. The communication device includes an acquisition unit and a selector. The acquisition unit is configured to acquire resource information that represents a resource of cryptographic keys available from each external device. The selector is configured to select a path from among a plurality of paths for one of the external devices, based on a bottleneck and a hop count of the resource on the path.