A method of data transmission, and more particularly a secure method of data transmission. The method comprises generating and sending a classical data stream and quantum data stream from a source to a destination. The step of generating and sending a classical data stream from the source to the destination comprises encrypting the data stream with the repeated use of a once-seen pad. Observing the quantum data stream received at the destination, may indicate eavesdropping and if so, the classical data stream is modified and sent from the source to the destination, including stopping the repeated use of the once-seen pad. The same once-seen pad may be used a number of times provided no third party has seen data encrypted by the once-seen pad.

A method of exchanging a combined cryptographic key between a first node and a second node, the first node and the second node being connected through a first communication and a second communication network, wherein the first communication network is a quantum communication network wherein information is encoded on weak light pulses; and the first node and the second node being configured to: exchange one or more first cryptographic keys on the first communication network; exchange one or more second cryptographic keys using the second communication network; and form the combined cryptographic key by combining the one or more first cryptographic keys and the one or more second cryptographic keys, such that the first node and the second node share knowledge of the combined cryptographic key.

An imaging and quantum cryptography apparatus comprising alight-refracting optical setup (101), a light-directing optical setup (102), an imaging sensor (103) capturing light refracted from the light-refracting optical setup and directed to the imaging sensor by the light-directing optical setup and at least one of a quantum key distribution (QKD) transmitter (104) generating a QKD light signal and transmitting the QKD light signal via the light-directing optical setup and through the light-refracting optical setup and a QKD receiver (105) acquiring and decoding light signals refracted from the light-refracting optical setup and directed to the QKD receiver by the light-directing optical setup. The imaging sensor, the at least one of QKD transmitter and QKD receiver, and the alignment unit, all use the same light-directing optical setup and the same light-refracting optical setup.

A system and method for securing communications between a plurality of users communicating over an optical network. The system utilizes a fixed or tunable source optical generator to generate entangled photon pairs, distribute the photons and establish a key exchange between users. The distribution of entangled photon pairs is implemented via at least one wavelength selective switch.

A quantum key distribution system includes a quantum security key management (QSKM) device, a plurality of quantum security key distribution (QSKD) devices, and a quantum security key service (QSKS) device. The QSKD device splits an identity-based system private key into a plurality of system sub-private keys, and distributes the plurality of system sub-private keys to a corresponding number of the QSKD devices. The QSKS device forwards a request for acquiring an authorized private key from a first QSKD device to a predetermined number of second QSKD devices. The predetermined number of second QSKD devices each generate an identity-based authorized sub-private key from the system sub-private key. The first QSKD device acquires, from the predetermined number of second QSKD devices, the identity-based authorized sub-private keys, and reconstructs an identity-based authorized private key based on the identity-based authorized sub-private keys.

Systems, apparatuses, methods, and computer program products are disclosed for session authentication using quantum line switching. An example system includes encoding circuitry configured to generate, based on a first set of quantum bases, a set of qbits, and transmit the first subset of qbits over a first quantum line. The encoding circuitry is configured not to transmit the first set of quantum bases. The system further includes switching circuitry configured to receive the first subset of qbits over the first quantum line, and transmit it over a second quantum line. The system further includes first decoding circuitry configured to receive the first subset of qbits, and decode, based on a second set of quantum bases, the first subset of qbits to generate a first decoded set of bits. The system further includes first session authentication circuitry configured to generate a session key based on the first decoded set of bits.

In some example embodiments, there is provided an apparatus. The apparatus may include a frequency shifter configured to shift a reference signal to a portion of an optical spectrum separate from another portion of the optical spectrum being used by a signal of interest; and a polarization rotator configured to provide the reference signal shifted and rotated by the polarization rotator. The apparatus may also include a modulator configured to modulate the signal of interest with coherent state information from which quantum key information is derivable. Related systems, methods, and articles of manufacture are also disclosed.

Disclosed herein are technologies regarding a communication device and server which are capable of cryptographic communication based on quantum cryptography. A communication device for quantum cryptography authentication includes: an optical communication unit configured to receive a series of first quantum signals generated by passing through a first quantum filter of the communication device; a quantum signal generation unit configured to generate the first quantum signals by setting up the first quantum filter in a reception path for a series of second quantum signals generated and sent by a server; and a processor configured to select the setup of the first quantum filter based on a series of randomly generated first quantum states, and to control the quantum signal generation unit to generate the first quantum signals by using the first quantum filter.

Disclosed herein are technologies regarding a communication device and server which are capable of cryptographic communication based on quantum cryptography. The communication device includes: a quantum signal generation unit configured to generate a series of first quantum signals by using a first quantum filter; an optical transmission unit configured to send the series of first quantum signals to a server; and a processor configured to select the first quantum filter based on a series of randomly generated first quantum states, and to control the quantum signal generation unit to generate the series of first quantum signals by using the first quantum filter.

An apparatus for enhancing secret key rate exchange over quantum channel in QKD systems includes an emitter system with a quantum emitter and a receiver system with a quantum receiver, wherein both systems are connected by a quantum channel and a service communication channel. User interfaces within the systems allow to define a first quantum channel loss budget based on the distance to be covered between the quantum emitter and the quantum receiver and the infrastructure properties of the quantum channel as well as a second quantum channel loss budget associated to the loss within the realm of the emitter system. The emitter system is adapted to define the optimal mean number of photons of coherent states to be emitted based on the first and the second quantum channel loss budgets.