A method creates and distributes cryptographic keys for securing communication at two terminals. Signals for creating correlated values in the two terminals are distributed via a first communication channel burdened with error, and the correlated values are present as keys. A checksum is formed on the basis of the first key present in the first terminal and the checksum is transferred to the second terminal via a second communication channel. A second checksum is formed on the basis of the second key present, and information derived from the two checksums is transferred via the second communication channel to a server. Based on the information derived from the checksums, the server determines a correction value, which, when applied to one or both keys, brings the keys into correspondence. The correction value is transferred to one or both terminals via the second communication channel and is applied to one or both keys.

A mobile secret communications method based on a quantum key distribution network, comprises the following steps: a mobile terminal registering to access the network and establishing a binding relationship with a certain centralized control station in the quantum key distribution network; after a communication service is initiated, the mobile terminals participating in the current communication applying for service keys from the quantum key distribution network; the quantum key distribution network obtaining addresses of the centralized control stations participating in service key distribution during the current communication, designating a service key generation centralized control station according to a current state indicator of each centralized control station; the service key generation centralized control station generating service keys required in the current communication and distributing the keys to the mobile terminals participating in the current communication.

The invention relates to a QKD System Active combiner (200) adapted to be installed in a QKD apparatus, said QKD apparatus comprising an emitter (100), a receiver (110) and QKD systems (102/112), wherein the emitter (100) is adapted to send communication signals to the receiver (110) through the QKD System Active combiner (200), characterized in that the QKD System Active combiner (200) comprises an active attenuation system comprising a processing unit (230) adapted to automatically control at least one variable optical attenuator (150) through a control channel (290) in order to control an attenuation of a signal to be sent to the receiver, and a detector/monitor (240) adapted to monitor the intensity of the signal downstream the attenuation, and wherein the processing unit is adapted to control the variable optical attenuator (150) based on a QBER information or an intensity of a signal received by the receiver, sent by the QKD systems (112) through a classical channel (250).

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.

There is provided an integrated-optic transmitter for transmitting light pulses to a further optical apparatus for generating a quantum cryptographic key according to at least one quantum cryptography technique. There is also provided an integrated-optic receiver for generating a quantum cryptographic key from light pulses received from a further optical apparatus. The transmitter apparatus splits incoming light into two paths to temporally separate the split light pulses and controls the output intensity of each split pulse as well as the phase of at least one of the split pulses. The receiver apparatus receives first and second light pulses and controls the output intensity of each said pulse between a first and a second optical detector. The light input into the second detector passes through an integrated element that controls the amount of light output into two paths that recombine before at least a portion is output to the second detector.

Bi-directional quantum interconnects are provided that include a first communication module and a second communication module. The first communication module includes a first quantum transmitter and a first quantum receiver, and the second communication module includes a second quantum transmitter and a second quantum receiver. The example interconnect further includes a first communication medium communicably coupling the first communication module and the second communication module such that communication is provided between the first quantum transmitter and the second quantum receiver and between the second quantum transmitter and the first quantum receiver via the first communication medium. The first quantum transmitter and the second quantum transmitter generate qubits having first and second quantum characteristics, respectively, to allow for bi-directional quantum communication over a common channel.

A quantum key distributed (QKD) apparatus for linking endpoint devices in a network, which includes: QKD links each including a quantum channel and a classical channel, wherein each endpoint has a QKD link; quantum transmitters to transmit quantum transmissions over a quantum channel of one of the QKD links; classical transceivers to transmit classical data over a classical channel of one of the QKD links and to receive classical data over the classical channel of said QKD link; and a controller connected to the quantum transmitters and the classical transceivers to route data generated for quantum transmission to an endpoint over a quantum channel of the QKD link of the endpoint; route classical data for classical transmission to an endpoint via a classical transceiver over a classical channel of the QKD link of the endpoint; and route classical data over the classical channel of the QKD link of an endpoint.

A system for performing a key exchange using a quantum key distribution protocol between first, second, and intermediary devices, wherein the intermediary device: receives first symbol set over a first quantum channel transmitted from first device and sends first receiving basis information to first device, receives second symbol set over a second quantum channel transmitted from second device and sends second receiving basis information to second device, generates first and second intermediate sets of symbols based on received first and second sets of symbols, generates third intermediate symbol set by combining first and second intermediate sets and sends third intermediate set to first and/or second device, whereby first and second devices perform the key exchange by exchanging with themselves first and second transmitting basis information and/or first and second receiving basis information to determine a final shared key based on first, second, and third intermediate symbol sets.

A repeater device that can achieve signal transferring and path switching in optical transmission lines susceptible to environmental changes is provided. The repeater device receives weak signal light and normal reference light and transmits them in a communication network. The repeater includes: an optical route selector that selects an input-side spatial link connected to an upstream adjacent node and an output-side spatial link connected to a downstream adjacent node; a link state detector that detects a link state of at least one of the input-side spatial link and the output-side spatial link, wherein the link state is an attenuation rate or a transmission rate; and a controller that controls the optical route selector to select an optimal pair of output-side spatial link and input-side spatial link according to the link state.

Key distribution comprises authenticating and registering locations of first and second terminals to a quantum identify provider (QIP) and a quantum location service provider (QLSP); determining security consensus between the first and second terminal and the QIP that identifies a first and second quantum key service provider (QKSP); executing a first key generation process for generating first and second system master keys that are determined based on first and second key parts from the first and second QKSP from first and second key generators that include one or more quantum generators; determining a shared security consensus between the first and second terminal that identifies a third and fourth QKSP; and, executing a second generation process for generating an end-user master for first and second terminal respectively based on third and fourth key parts from the third and fourth QKSP from third and fourth key generators that include one or more quantum key generators.