WO2019100694A1 - 生成密钥的设备和方法 - Google Patents

生成密钥的设备和方法 Download PDF

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Publication number
WO2019100694A1
WO2019100694A1 PCT/CN2018/090471 CN2018090471W WO2019100694A1 WO 2019100694 A1 WO2019100694 A1 WO 2019100694A1 CN 2018090471 W CN2018090471 W CN 2018090471W WO 2019100694 A1 WO2019100694 A1 WO 2019100694A1
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WIPO (PCT)
Prior art keywords
key
sub
optical signal
modulated optical
signal
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PCT/CN2018/090471
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English (en)
French (fr)
Inventor
李政宇
苏长征
邹扬
蔡永旌
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Priority to EP18880754.9A priority Critical patent/EP3678306B1/en
Publication of WO2019100694A1 publication Critical patent/WO2019100694A1/zh
Priority to US16/868,789 priority patent/US11444758B2/en
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/70—Photonic quantum communication
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
    • H03M1/12—Analogue/digital converters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/548—Phase or frequency modulation
    • H04B10/556—Digital modulation, e.g. differential phase shift keying [DPSK] or frequency shift keying [FSK]
    • H04B10/5561—Digital phase modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/61—Coherent receivers
    • H04B10/64—Heterodyne, i.e. coherent receivers where, after the opto-electronic conversion, an electrical signal at an intermediate frequency [IF] is obtained
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/001—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols using chaotic signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/06—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols the encryption apparatus using shift registers or memories for block-wise or stream coding, e.g. DES systems or RC4; Hash functions; Pseudorandom sequence generators
    • H04L9/065—Encryption by serially and continuously modifying data stream elements, e.g. stream cipher systems, RC4, SEAL or A5/3
    • H04L9/0656—Pseudorandom key sequence combined element-for-element with data sequence, e.g. one-time-pad [OTP] or Vernam's cipher
    • H04L9/0662—Pseudorandom key sequence combined element-for-element with data sequence, e.g. one-time-pad [OTP] or Vernam's cipher with particular pseudorandom sequence generator
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)
    • H04L9/0822—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) using key encryption key
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0852—Quantum cryptography
    • H04L9/0858—Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding

Definitions

  • This application relates to the field of quantum communication technologies, and more particularly to an apparatus and method for generating a key.
  • the quantum secure communication system based on the principle of quantum mechanics can guarantee the security of the key in the transmission process.
  • the key is no longer transmitted in the form of an electrical signal, but in the form of a quantum signal.
  • quantum mechanics there is a classic theory "the Heisenberg uncertainty principle", according to which it can be inferred that if an eavesdropper eavesdrops during key transmission, the key is measured. The measurement operation must interfere with the coherent state of the key, so that if the key carried by the original quantum signal is A, the key carried by the quantum signal is B after being eavesdropped. If the sender and receiver devices find that the decrypted bit error rate exceeds the preset threshold during the decryption process, the key B obtained by the receiving device is considered to be incorrect, and thus the key A is leaked. .
  • the light source is modulated by a random key generated by a random source to generate a modulated optical signal carrying a random key, and the transmitting device directly stores the random key as the initial key A locally.
  • the random key may be, for example, a random number between -1 and +1, or a random number between -10 and +10. Due to the defects inherent in the modulation device that modulates the light source in the preparation module, the modulated modulated light carrying the random key does not all correspond to the random key. Therefore, the modulated light carrying the random key transmitted through the channel may not correspond to the initial key A stored locally by the transmitting device.
  • the receiving device receives the modulated light carrying the random key
  • the initial key B obtained by detecting the modulated light carrying the random key does not correspond to the initial key A stored locally by the transmitting device.
  • the sender device will advertise a small amount of information of the initial key A to the receiving device, and the receiving device may determine that the detected initial key B does not correspond to the initial key A saved by the transmitting device. In this way, the sender device and the sink device discard the initial keys A and B, and re-prepare and transmit the new initial key. Repeated cycles will greatly reduce the success rate of initial key preparation and transmission, resulting in wasted system resources.
  • an apparatus for generating a key comprising a key generator, a modulator, a light source generator, a first beam splitter, a data acquirer, an attenuator, and a memory, among them:
  • the key generator is configured to generate a first key
  • the modulator is configured to modulate the first key onto a first source signal to obtain a modulated optical signal
  • the first beam splitter is configured to split the modulated optical signal to obtain a first sub-modulated optical signal and a second sub-modulated optical signal;
  • the attenuator is configured to attenuate the first sub-modulated optical signal, so that the number of photons included in the first sub-modulated optical signal is lower than a preset value, and after transmitting the attenuation to the receiving end device First sub-modulated optical signal;
  • the data acquirer is configured to acquire a second key carried by the second sub-modulated optical signal, and store the second key in the memory, where the second key is The errored key occurs when the first key is modulated to the first light source signal, and the second key is a key to be used when communicating with the receiving end device.
  • the device for generating a key avoids directly using the first key as a key for communicating with the receiving device, but acquires a key carried by the modulated modulated optical signal, and receives and receives the key.
  • the key carried by the end device is highly correlated with the key carried by the modulated optical signal and the key carried by the modulated optical signal actually sent by the transmitting device. In this way, the occurrence of a weak correlation between the second key saved by the transmitting device and the key communicated with the receiving device is avoided. Further, the success rate of key preparation and transmission can be improved, thereby avoiding waste of system resources.
  • the first sub-modulated optical signal can be attenuated by the attenuator to attenuate the power of the light source generator, such as the laser output, to a very weak coherent state required by the CV-QKD protocol, that is, the number of photons included in each cycle is lower than hundred.
  • the CV-QKD system it is possible to modulate the source signal and then attenuate it, or first attenuate the source signal and then modulate it.
  • the device further includes a second beam splitter
  • the data acquirer includes a heterodyne detector, a first analog to digital converter, and a processor, where:
  • the second beam splitter is configured to split the original light source signal generated by the light source generator to obtain the first light source signal and the second light source signal;
  • the heterodyne detector is configured to detect the second sub-modulated optical signal and the second source signal to obtain a first analog electrical signal carrying regular component information of the second sub-modulated optical signal;
  • the first analog-to-digital converter is configured to perform analog-to-digital conversion on the first analog electrical signal to obtain a first digital electrical signal carrying regular component information of the second sub-modulated optical signal, and send the processing to the processing Device
  • the processor is configured to acquire the second key based on regular component information of the second sub-modulated optical signal and a preset first data acquisition algorithm.
  • the processor is configured to:
  • the detection efficiency of the heterodyne detector Based on the regular component information of the second sub-modulated optical signal, the detection efficiency of the heterodyne detector, the intensity information of the second source signal, the splitting ratio of the first beam splitter, the attenuator
  • the transmission rate and the preset first data acquisition algorithm acquire the second key.
  • the preset first data acquisition algorithm is:
  • ⁇ D is the detection efficiency of the heterodyne detector
  • I LO is the intensity information of the second source signal
  • k 240 is the splitting ratio of the first beam splitter
  • ⁇ 310 is the attenuator
  • the transmittance, V A is the equivalent entanglement state variance
  • X and P are the regular component information of the second sub-modulated optical signal
  • x A and p A constitute the second key.
  • the modulated optical signal before the modulated optical signal is attenuated into a quantum signal, it is first split, and the split second sub-modulated optical signal is detected by a heterodyne detector. Since the second sub-modulated optical signal entering the heterodyne detector and the quantum signal entering the channel have the same modulation characteristics, only the magnitude of the linear attenuation is different in intensity, so the detection result of the heterodyne detector and the actually transmitted quantum signal There is a good correlation between them.
  • the key carried by the second sub-modulated light can be obtained by adopting a preset first data acquisition algorithm, taking into account the photoelectric conversion coefficient during the detection process and the transmittance at the time of attenuation in consideration of the influence factor on the key. At this time, the correlation between the key carried by the second sub-modulated light and the key carried by the actually transmitted quantum signal is very good.
  • the device further includes a third beam splitter, a fourth beam splitter and a fifth beam splitter, the data acquirer comprising a first photodetector, a second photodetector, A homodyne detector, a second analog to digital converter, and a processor, wherein:
  • the third beam splitter is configured to split the original light source signal generated by the light source generator to obtain the first light source signal and the second light source signal;
  • the fifth beam splitter is configured to split the second sub-modulated optical signal to obtain a third sub-modulated optical signal and a fourth sub-modulated optical signal;
  • the first photodetector is configured to detect the third sub-modulated optical signal to obtain a second analog electrical signal that carries the intensity information of the third sub-modulated optical signal;
  • the fourth beam splitter is configured to split the second source signal to obtain a first sub-source signal and a second sub-source signal;
  • the homodyne detector is configured to detect the first sub-light source signal and the fourth sub-modulation optical signal to obtain a signal that carries the first sub-light source signal and the fourth sub-modulated optical signal coherent a third analog electrical signal of intensity information;
  • the second photodetector is configured to detect the second sub-light source signal to obtain a fourth analog electrical signal carrying the intensity information of the second sub-light source signal;
  • the second analog-to-digital converter is configured to perform analog-to-digital conversion on the second analog electrical signal to obtain a second digital electrical signal carrying intensity information of the third sub-modulated optical signal; Performing analog-to-digital conversion on the electrical signal to obtain a third digital electrical signal carrying the intensity information of the signal after the first sub-light source signal and the fourth sub-modulated optical signal are coherent; performing analog-to-digital conversion on the fourth analog electrical signal, Obtaining a fourth digital electrical signal carrying the intensity information of the second sub-light source signal, and transmitting the signal to the processor;
  • the processor is configured to calculate, according to the intensity information of the third sub-modulated optical signal, the strength information of the signal after the first sub-light source signal and the fourth sub-modulated optical signal are coherent, and the second sub-light source signal
  • the strength information and the preset second data acquisition algorithm acquire the second key.
  • the processor is configured to:
  • the intensity information of the third sub-modulated optical signal, the intensity information of the signal after the first sub-light source signal and the fourth sub-modulated optical signal are coherent, the intensity information of the second sub-light source signal, the first The second key is obtained by a splitting ratio of the beam splitter, a transmittance of the attenuator, and a preset second data acquisition algorithm.
  • the preset second data acquisition algorithm is:
  • I S is the intensity information of the third sub-modulated optical signal
  • I LR is the intensity information of the second sub-light source signal
  • I BHD is the coherence of the first sub-light source signal and the fourth sub-modulated optical signal.
  • the intensity information of the signal, k 240 is the splitting ratio of the first beam splitter, ⁇ 310 is the transmittance of the attenuator, V A is the equivalent entangled state variance, and x A and p A constitute the The second key.
  • the first photodetector, the second photodetector, and the homodyne detector are used to replace the heterodyne detector to detect the optical signal.
  • the heterodyne detector can detect the two regular components of the second sub-modulated optical signal, namely the X component and the Y component.
  • the first photodetector, the second photodetector, and the homodyne detector are used to replace the heterodyne detector for detection, and no light is needed inside the first photodetector, the second photodetector, and the homodyne detector.
  • the signal is split, so that the requirements of the device itself are low and easy to implement.
  • the processor is further configured to determine the first key and the first key and the second key determined according to a preset number of times of determining the second key And a first key generated by the key generator, and determining, according to the inverse conversion relationship corresponding to the conversion relationship and the first key, the adjusted first key;
  • the modulator is configured to modulate the adjusted first key onto the first source signal to obtain a modulated optical signal.
  • the key determined by the algorithm to communicate with the receiving device is too different from the first key, which may result in a key determined by the algorithm to communicate with the receiving device, although it has a good relationship with the actually transmitted quantum signal. Correlation, but the probability distribution of the two regular components of the actually transmitted quantum signal does not meet the requirements of the modulation system. For Gaussian modulation, for example, we hope that the probability distributions of the two regular components of the actually transmitted quantum signal satisfy two independent Gaussian distributions.
  • a method of generating a key the method being implemented by the apparatus provided by the first aspect.
  • the device for generating a key avoids directly using the first key as a key for communicating with the receiving device, but acquires a key carried by the modulated modulated optical signal, and receives and receives the key.
  • the key carried by the end device is highly correlated with the key carried by the modulated optical signal and the key carried by the modulated optical signal actually sent by the transmitting device. In this way, the occurrence of a weak correlation between the second key saved by the transmitting device and the key communicated with the receiving device is avoided. Further, the success rate of key preparation and transmission can be improved, thereby avoiding waste of system resources.
  • FIG. 1 is a schematic structural diagram of a CV-QKD system according to an exemplary embodiment
  • FIG. 2 is a schematic structural diagram of an apparatus for generating a key according to an exemplary embodiment
  • FIG. 3 is a schematic structural diagram of an apparatus for generating a key according to an exemplary embodiment
  • FIG. 4 is a schematic structural diagram of an apparatus for generating a key according to an exemplary embodiment
  • FIG. 5 is a schematic structural diagram of an apparatus for generating a key according to an exemplary embodiment
  • FIG. 6 is a schematic structural diagram of an apparatus for generating a key according to an exemplary embodiment
  • FIG. 7 is a schematic structural diagram of an apparatus for generating a key according to an exemplary embodiment
  • FIG. 8 is a schematic structural diagram of an apparatus for generating a key according to an exemplary embodiment
  • FIG. 9 is a schematic structural diagram of an apparatus for generating a key according to an exemplary embodiment.
  • FIG. 10 is a schematic flowchart diagram of a method for generating a key according to an exemplary embodiment
  • FIG. 11 is a schematic flowchart diagram of a method for generating a key according to an exemplary embodiment
  • FIG. 12 is a schematic flowchart diagram of a method for generating a key according to an exemplary embodiment
  • FIG. 13 is a schematic flowchart diagram of a method for generating a key according to an exemplary embodiment.
  • the closest practical quantum security communication technology is QKD (Quantum Key Distribution) technology, which functions to realize unconditional secure distribution of symmetric keys under the premise of sharing part of the security key.
  • QKD Quantum Key Distribution
  • the implementation is that the transmitting device encodes the coherent state of the quantum signal (the quantum signal is a signal that is attenuated by the modulated optical signal) according to the random key, and is transmitted by the receiving device after being transmitted through the channel. Detection, and then the transmitting device and the receiving device perform post processing through the classical channel, for example, measuring base alignment and data sifting, parameter estimation (PE), data error correction (EC), and privacy enhancement. (privacy amplification, PA), which ultimately causes the communicating parties to share the same set of security keys.
  • PE parameter estimation
  • EC data error correction
  • PA privacy enhancement
  • the QKD technology can be divided into DV-QKD (Discrete-Variable Quantum Key Distribution) technology and CV-QKD (Continuous-Variable Quantum Key Distribution). Distribute) technology.
  • the DV-QKD technology encodes a single photon signal to achieve quantum key distribution.
  • the CV-QKD technique encodes very weak coherent states to achieve quantum key distribution.
  • the method and device for generating a key provided by the embodiments of the present application are mainly proposed for the CV-QKD system.
  • the main instrument for implementing the encoding process of the coherent state is the modulator.
  • different modulation methods such as Gaussian modulation, QPSK (Quadrature Phase Shift Keyin) modulation, etc.
  • IM Intensity Modulator
  • PM Phase Modulator
  • cascading modulation devices which can phase modulate the source signal.
  • intensity modulation to achieve the preparation of any coherent state in the phase space.
  • an IQ (In-phase Quadrature) modulator or a DPQPSK (Dual Polarization Quadrature) modulator can be used to perform one or two polarization directions on the source signal. Preparation of any coherent state on.
  • the device may include a key generator 210, a modulator 220, a light source generator 230, a first beam splitter 240, and data.
  • the device can be a sender device in a quantum key distribution system.
  • the key generator 210 is connected to the electrical input end of the modulator 220, and optionally, can be electrically connected; the light source generator 230 is connected to the optical input end of the modulator 220, optionally, The optical path is connected; the output of the modulator 220 is coupled to the input of the first beam splitter 240, and optionally, may be connected by an optical path.
  • the first beam splitter 240 includes a first output end and a second output end, and the second output end of the first beam splitter 240 is coupled to the input end of the data acquirer 250, optionally, can be connected by an optical path; data acquisition The output of the device 250 is coupled to the memory 260 and, optionally, can be electrically connected.
  • the key generator 210 is configured to generate a first key.
  • the modulator 220 is configured to modulate the first key onto the first source signal to obtain a modulated optical signal.
  • the first beam splitter 240 is configured to split the modulated optical signal to obtain a first sub-modulated optical signal and a second sub-modulated optical signal.
  • the attenuator 310 is configured to attenuate the first sub-modulated optical signal such that the number of photons included in the first sub-modulated optical signal is lower than a preset value, and send the attenuated first sub-modulated optical signal to the receiving end device.
  • the data acquirer 250 is configured to acquire a second key carried by the second sub-modulated optical signal, and store the second key in the memory 260.
  • the second key is a key after the error is generated when the first key is modulated to the first light source signal, and the second key is a key to be used when communicating with the receiving end device.
  • the light source generator 230 can generate a light source signal. After the light source signal enters the modulator 220, it can be modulated by the first key generated by the key generator 210 to generate a modulated light signal, and the modulated light signal carries the first Key information.
  • the first key may be a random key.
  • a random key can be generated by the quantum random number generator, and the probability distribution of the generated random key can be made to satisfy the Gaussian distribution or other distribution required by the CV-QKD protocol.
  • the quantum signal finally transmitted from the transmitting device carries the first key.
  • the device in the modulator 220 is, for example, an AWG (Arbitrary Wave Generator) / ADC (Analog-to-digital converter), a driver, an IM (Intensity Modulator) / PM
  • the inherent defect of the (Phase Modulator) causes the modulation to be inaccurate.
  • the quantum signal finally transmitted from the transmitting device does not carry the first key.
  • the waveform of the electrical signal has problems such as overshoot, oscillation, noise, etc., and there is also a nonlinearity between the first key and the first key.
  • the problem, as well as the pre-first key, will have a certain impact on the subsequent modulation results, and the output electrical signal has problems such as poor time domain jitter.
  • the impedance between the optical modulation device and the driver output cannot be completely matched, resulting in inconsistent frequency response, large influence of AC, and ultimately unsatisfactory parameters, extinction ratio, and unstable operating point. .
  • the modulated optical signal may be split by the first beam splitter 240 to obtain a first sub-modulated optical signal and a second sub-modulated optical signal.
  • the first sub-modulated optical signal may be used as a signal transmitted to the receiving end device to transmit the prepared key to the receiving end device.
  • the second sub-modulated optical signal can then be used as a signal to detect the result of the modulation.
  • the second sub-modulated optical signal is input to the data acquirer 250, and the key carried by the second sub-modulated optical signal is acquired by the data acquirer 250. Since the splitting ratio of the first beam splitter 240 can be known, the correspondence relationship between the light field states of the first sub-modulated optical signal and the second sub-modulated optical signal can be determined.
  • the splitting ratio of the first beam splitter 240 may be set to 50:50, and if the splitting ratio is 50:50, the first sub-modulated optical signal and the second sub-modulated optical signal have the same intensity information and the same phase information. .
  • the association between the key carried by the second sub-modulated optical signal acquired by the data acquirer 250 and the key carried by the first sub-modulated optical signal is related to the key carried by the first sub-modulated optical signal. Sexually large.
  • the association refers to that the key carried by the first sub-modulated optical signal has a one-to-one correspondence with the key carried by the second sub-modulated optical signal, or even has a linear relationship.
  • the key is stored locally on the transmitting end device for subsequent post-processing operations to finally share a set of secure secrets with the receiving end device. key.
  • the optical path for transmitting the optical signal may be a medium capable of transmitting light, such as an optical fiber, and preferably a polarization maintaining fiber may be selected. If a polarization-maintaining fiber is used, it can ensure that the optical signal does not change its polarization state during transmission. If the polarization state of the optical signal is changed, it will affect its coherent state, and the data carried by the final optical signal will also change.
  • the first sub-modulated optical signal may be attenuated by the attenuator 310 to attenuate the power of the light source generator 230, such as a laser, to a very weak coherent state required by the CV-QKD protocol, ie, per cycle.
  • the number of photons contained is less than one hundred. It should be noted that, for the CV-QKD system, it is possible to modulate the source signal and then attenuate it, or first attenuate the source signal and then modulate it. However, in the embodiment of the present application, it is preferable to modulate the light source signal and then attenuate it.
  • beam splitter and attenuator 310 are common energy attenuating devices that do not have an unpredictable effect on the data carried by the optical signal.
  • the second key obtained by the data acquirer 250 is converted into a security key by post-processing (data filtering, parameter estimation, data error correction, security enhancement), and the security key can be applied in the secure communication: in the encryption phase,
  • the receiving end device receives the first sub-modulated optical signal in the embodiment, and detects the first sub-modulated optical signal to obtain an electrical signal corresponding to the first sub-modulated optical signal, which is determined by a preset algorithm.
  • the key carried by the electrical signal, and the key is also post-processed to obtain the security key a.
  • security keys for encryption there are other ways to apply security keys for encryption, and examples are not given here.
  • the device for generating a key provided by the embodiment of the present application may be used in a local oscillator system or a local local oscillator system.
  • the CV-QKD system can be divided into two categories: the LO is generated at the transmitting end device, which is called the associated local oscillator system; The local end system is generated by the receiving device.
  • the LO may be a light source signal described in the embodiment of the present application for performing key detection together with the quantum signal.
  • the device for generating a key avoids directly using the first key as a key for communicating with the receiving device, but acquires a key carried by the modulated modulated optical signal, and receives and receives the key.
  • the key that the end device communicates with, the key carried by the acquired modulated optical signal is highly correlated with the key carried by the modulated optical signal actually sent by the sending end device. In this way, the occurrence of a situation in which the key stored by the source device and the key communicated with the source device are weak is avoided. Further, the success rate of key preparation and transmission can be improved, thereby avoiding waste of system resources.
  • the device may include a key generator 210, a modulator 220, a light source generator 230, a first beam splitter 240, and an attenuation.
  • the device for generating a key may further include a second beam splitter 410, which includes a heterodyne detector 451, a first analog to digital converter 452, and a processor 453.
  • the key generator 210 is connected to the electrical input of the modulator 220, and optionally, can be electrically connected; the output of the modulator 220 is connected to the input of the first beam splitter 240, optionally Ground can be connected by an optical path.
  • the first beam splitter 240 includes a first output and a second output.
  • the input end of the second beam splitter 410 is connected to the light source generator 230, and optionally, can be connected by an optical path; the second output end of the first beam splitter 240 is connected to the first input end of the heterodyne detector 451 Optionally, it may be connected by an optical path; the first output end of the second beam splitter 410 is connected to the optical input end of the modulator 220, optionally, may be connected by an optical path; the second of the second beam splitter 410 The output is connected to the second input of the heterodyne detector 451, optionally connected by an optical path; the output of the heterodyne detector 451 is connected to the input of the first analog to digital converter 452, optionally Can be electrically connected.
  • the output of the first analog-to-digital converter 452 is connected to the first input end of the processor 453, and optionally, can be electrically connected; the first output end of the processor 453 is connected to the memory 260, optionally, Electrical connection.
  • the second beam splitter 410 is configured to split the original light source signal generated by the light source generator to obtain a first light source signal and a second light source signal.
  • the modulator 220 is configured to modulate the first key onto the first source signal to obtain a modulated optical signal.
  • the first beam splitter 240 is configured to split the modulated optical signal to obtain a first sub-modulated optical signal and a second sub-modulated optical signal.
  • the attenuator 310 is configured to attenuate the first sub-modulated optical signal such that the number of photons included in the first sub-modulated optical signal is lower than a preset value, and send the attenuated first sub-modulated optical signal to the receiving end device.
  • the heterodyne detector 451 is configured to detect the second sub-modulated optical signal and the second light source signal to obtain a first analog electrical signal carrying the regular component information of the second sub-modulated optical signal.
  • the first analog-to-digital converter 452 is configured to perform analog-to-digital conversion on the first analog electrical signal to obtain a first digital electrical signal carrying the regular component information of the second sub-modulated optical signal, and send the signal to the processor 453.
  • the processor 453 is configured to acquire a key carried by the second sub-modulated optical signal based on the regular component information of the second sub-modulated optical signal and the preset first data acquiring algorithm.
  • the memory 260 is used to store the second key.
  • the second key is a key after the error is generated when the first key is modulated to the first light source signal, and the second key is a key to be used when communicating with the receiving end device.
  • the device to which the device for generating a key provided by this embodiment can be applied and its functions are introduced as follows:
  • Laser A narrow linewidth laser that produces continuous or pulsed linear polarization.
  • Beam splitter divides the input optical signal into two outputs.
  • a polarization maintaining beam splitter can be selected.
  • Modulator Modulates the optical signal.
  • the modulator may include a modulator in which IM and PM are cascaded, a QPSK modulator, and the like.
  • Quantum random number generator Generates a random key according to the required modulation pattern. Specifically, a random number is obtained from a quantum random number generator, and then a random key is generated according to the required modulation pattern.
  • the input optical signal can be delayed to match the time difference of the signals on other optical paths to the same device.
  • HD Heterodyne Detector
  • ADC Analog-to-digital converter
  • Attenuator The intensity of the optical signal input thereto can be attenuated.
  • FIG. 4 The structure diagram of the device for generating a key constructed by the above device is shown in FIG. 4, and the working process of the device internal device for generating a key is as follows:
  • the duty cycle of the pulse can be controlled between 1% and 99%.
  • the envelope of the optical pulse formed by chopping the laser light by the pulse generator is a 5 ns wide square wave waveform.
  • the laser is not input to the pulse generator to generate a light pulse, and when the laser is input to the modulator, the laser is naturally modulated to cause different periods of the laser.
  • the disadvantage of this is that the obtained signal is not a perfect square wave.
  • the modulation device cannot perform instantaneous conversion, but there is a conversion time, modulation in the conversion time.
  • the signal is not accurate. Therefore, in the present embodiment, it is preferable to chop the laser light to generate a light pulse, and the light pulse can be used as the original light source signal described in this embodiment.
  • the light pulse is divided into two by the polarization maintaining beam splitter 1, one of which can be used as the first light source signal, and the other of which can be used as the second light source signal.
  • the polarization maintaining beam splitter 2 splits the modulated optical signal to obtain the first sub-modulated optical signal and the second sub-modulated optical signal, and transmits the attenuation through the first output terminal to the receiving end device through the attenuator and conforms to the CV.
  • the polarization maintaining beam splitter 1 splits the original light source signal to obtain a first light source signal and a second light source signal.
  • the HD detects the second sub-modulated optical signal and the second light source signal, and the second sub-modulated optical signal and the second source signal simultaneously reach the HD.
  • the second source signal may be delayed by the delay device. It should be noted that if the laser generated by the laser is continuous, narrow linewidth, and the coherence time is long, the delay measurement can be performed without setting the delay device to obtain more accurate measurement results in the HD.
  • the HD detects the second sub-modulated optical signal and the second light source signal to obtain a first analog electrical signal carrying the regular component information of the second sub-modulated optical signal, and is sampled by the ADC to obtain the second sub-modulated optical signal.
  • the second key may be acquired in the processor based on the regular component information carried in the first digital electrical signal and the preset first data acquisition algorithm. This data can be used as the sender device data for subsequent post processing required in the CV-QKD protocol. It should be noted that after the structure of the device for generating a key provided in this embodiment is introduced, the preset first data acquisition algorithm is described in detail.
  • the device for generating a key provided in FIG. 3 may be applied to a local local oscillator system, and the local local oscillator system does not require the transmitting device to provide an LO (light source signal) to the receiving device.
  • the device for generating a key provided in this embodiment is to be applied in the associated local oscillator system, it is necessary to add the sixth beam splitter 420 and the combiner 430 based on the device provided in FIG.
  • the structure of the device that generates the key is shown in Figure 5.
  • the combiner can be a polarization combiner.
  • the input end of the sixth beam splitter 420 is connected to the light source generator 230 through an optical path, and the first output end of the sixth beam splitter 420 is connected to the first input end of the combiner through an optical path, and the sixth beam splitter 420 is The two output ends are connected to the input end of the second beam splitter 410 through an optical path, and the output end of the attenuator 310 is connected to the second input end of the combiner through an optical path.
  • the sixth beam splitter 420 is configured to split the light source signal to obtain two signals, one is input as an LO input to the combiner and the quantum signal is combined, and the other is used as a light source signal for preparing a quantum signal carrying the key.
  • a combiner is used to combine the LO with the quantum signal carrying the key.
  • the transmitting device adopts a dual polarization modulation scheme, since the source signal needs to be independently modulated in both polarization directions, the instruments for generating keys in both polarization directions can be applied in the embodiment. Structure.
  • the key used for modulation in the first polarization direction is A 1 and the key used for modulation in the second polarization direction is A 2 .
  • the modulated optical signal in the first polarization direction is obtained by the data acquirer, and the key is obtained as B 1 .
  • the modulated optical signal in the second polarization direction is obtained by the data acquirer, and the key is obtained as B 2 .
  • the key B 1 and the key B 2 are respectively stored for use in a key for communicating with the receiving device.
  • the processor is configured to use the regular component information of the second sub-modulated optical signal, the detection efficiency of the heterodyne detector, the intensity information of the second light source signal, the splitting ratio of the first beam splitter, and the transmission of the attenuator Rate, and a preset first data acquisition algorithm, to acquire a second key.
  • the preset first data acquisition algorithm may be:
  • ⁇ D is the detection efficiency of the heterodyne detector
  • I LO is the intensity information of the second source signal
  • k 240 is the splitting ratio of the first beam splitter 240
  • ⁇ 310 is the transmittance of the attenuator 310
  • V A is the equivalent entangled state variance
  • X and P are the regular component information of the second sub-modulated optical signal
  • x A and p A constitute the second key.
  • the quantum signal carrying the key information is sent from the transmitting end, and the analog-to-digital converter collects the information that the regular component of the modulated optical signal is converted into the analog electrical signal, so it is assumed that the preset first data acquisition algorithm is mainly It consists of two steps:
  • the first algorithm assumes that the following parameters are known: the detection efficiency ⁇ D of the heterodyne detector 451, the intensity information I LO of the second source signal, the intensity information of the first sub-modulated optical signal and the intensity of the second sub-modulated optical signal.
  • x A and p A form a second key
  • the data acquired by the first analog-to-digital converter 452 is an x ADC and a p ADC
  • the second sub-modulated optical signal outputted by the heterodyne detector 451 can be deduced according to the sampling rule thereof.
  • the regular component information is X and P
  • the quantum signal sent from the attenuator 310 to the channel can be inferred to have the average of the two regular components as shown in Equation 2:
  • Equation 3 The key for communicating with the receiving device is shown in Equation 3:
  • Equation 4 For Gaussian modulation, the function in the above equation is specifically shown in Equation 4:
  • x A and p A may both be positive in the actual system, may be negative, or may be positive and negative, there are four representations, depending on the additional phase difference definition of different beam splitters.
  • the idea of the first algorithm described above is that the transmittance of a passive device such as a beam splitter is substantially constant, which can be determined in advance.
  • the laser's energy relationship through these passive devices is simple.
  • the second algorithm is derived from the first algorithm.
  • the first algorithm it is necessary to know the scale factor of many passive devices and to measure the intensity information of the optical signal. These parameters are essentially all to determine the ratio between the intensity information of the optical signal entering the heterodyne detector 451 and the intensity information of the quantum signal fed into the channel from the attenuator 310, and in the first algorithm we assume them Is a linear relationship. Therefore, a quantum HD with an integrated detection efficiency of ⁇ QD can be directly connected to the channel and a calibration process can be performed.
  • the output of the quantum HD is set to x het and p het , which can be assumed to have the following relationship with X and P detected by the heterodyne detector 451:
  • k x , k p can be derived in the following two ways:
  • ⁇ > represents averaging a piece of data.
  • the variance of the vacuum noise can be defined as 1.
  • ⁇ X 2 , ⁇ P 2 is the statistical variance of X and P, The statistical variance of x het , p het .
  • the key for communicating with the receiving device is:
  • x A and p A may both be positive in the actual system, may be negative, or may be positive and negative, and there are four representations.
  • the preset first data acquisition algorithm provided above converts the detection result of the second sub-modulation signal into a key for communicating with the receiving device. If possible, the detection result of the first key and the second sub-modulation signal may be matched based on the first key, the detection result of the second sub-modulation signal, and other algorithms, and obtained by the receiving end device. The key to communication.
  • the system needs to be recalibrated, even the key generated by this round is discarded.
  • the modulated optical signal before the modulated optical signal is attenuated into a quantum signal, it is first split, and the split second sub-modulated optical signal is detected by HD. Since the second sub-modulated optical signal entering the HD and the quantum signal entering the channel have the same modulation characteristics, only linearly attenuating in intensity, so there is a good correlation between the detection result of the HD and the actually transmitted quantum signal. Sex. After the photoelectric conversion coefficient and the attenuation coefficient in the detection process are taken into consideration by the preset first data acquisition algorithm, the key carried by the second sub-modulated light can be obtained. At this time, the correlation between the key carried by the second sub-modulated light and the key carried by the actually transmitted quantum signal is very good.
  • the device for generating a key avoids directly using the first key as a key for communicating with the receiving device, but acquires a key carried by the modulated modulated optical signal, and receives and receives the key.
  • the key carried by the end device is highly correlated with the key carried by the modulated optical signal and the key carried by the modulated optical signal actually sent by the transmitting device. In this way, the occurrence of a weak correlation between the second key saved by the transmitting device and the key communicated with the receiving device is avoided. Further, the success rate of key preparation and transmission can be improved, thereby avoiding waste of system resources.
  • the device may include a key generator 210, a modulator 220, a light source generator 230, a first beam splitter 240, and an attenuation.
  • the device may further include a third beam splitter 510, a fourth beam splitter 520, and a fifth beam splitter 530.
  • the data acquirer 250 may specifically include a first photodetector 551, a second photodetector 552, and a homodyne detection.
  • the key generator 210 is connected to the electrical input of the modulator 220, and optionally, can be electrically connected; the output of the modulator 220 is connected to the input of the first beam splitter 240, optionally Ground can be connected by an optical path.
  • the first beam splitter 240 includes a first output and a second output.
  • the input end of the third beam splitter 510 is connected to the light source generator 230, and optionally, can be connected by an optical path; the first output end of the third beam splitter 510 is connected to the light input end of the modulator 220, optionally The ground may be connected by an optical path; the second output of the first beam splitter 240 is coupled to the input of the fifth beam splitter 530, and optionally may be connected by an optical path; the first output of the fifth beam splitter 530 The end is connected to the input end of the first photodetector 551, and optionally, can be connected by an optical path; the output end of the first photodetector 551 is connected to the first input end of the second analog to digital converter 554, optionally Ground, can be electrically connected.
  • the second output end of the fifth beam splitter 530 is connected to the first input end of the homodyne detector 553, optionally, can be connected by an optical path; the output of the homodyne detector 553 and the second analog to digital converter 554
  • the second input terminals are connected, and optionally, can be electrically connected.
  • the second output end of the third beam splitter 510 is coupled to the input end of the fourth beam splitter 520, and optionally, may be connected by an optical path; the first output end of the fourth beam splitter 520 and the homodyne detector 553
  • the second input ends are connected, optionally connected by an optical path; the second output end of the fourth beam splitter 520 is connected to the input end of the second photodetector 552, and optionally, can be connected by an optical path;
  • the output of the second photodetector 552 is coupled to the third input of the second analog to digital converter 554, and may alternatively be electrically connected.
  • the output of the second analog-to-digital converter 554 is connected to the first input end of the processor 453, and optionally, can be electrically connected; the first output end of the processor 453 is connected to the memory 260, optionally, Electrical connection.
  • the modulator 220 is configured to modulate the first key onto the first source signal to obtain a modulated optical signal.
  • the first beam splitter 240 is configured to split the modulated optical signal to obtain a first sub-modulated optical signal and a second sub-modulated optical signal.
  • the third beam splitter 510 is configured to split the original light source signal generated by the light source generator to obtain a first light source signal and a second light source signal.
  • the fifth beam splitter 530 is configured to split the second sub-modulated optical signal to obtain a third sub-modulated optical signal and a fourth sub-modulated optical signal.
  • the first photodetector 551 is configured to detect the third sub-modulated optical signal to obtain a second analog electrical signal carrying the intensity information of the third sub-modulated optical signal.
  • the fourth beam splitter 520 is configured to split the second source signal to obtain a first sub-source signal and a second sub-source signal.
  • the attenuator 310 is configured to attenuate the first sub-modulated optical signal such that the number of photons included in the first sub-modulated optical signal is lower than a preset value, and send the attenuated first sub-modulated optical signal to the receiving end device.
  • the homodyne detector 553 is configured to detect the first sub-light source signal and the fourth sub-modulation optical signal to obtain a third analog electrical signal carrying the intensity information of the first sub-light source signal and the fourth sub-modulated optical signal coherent signal .
  • the second photodetector 552 is configured to detect the second sub-light source signal to obtain a fourth analog electrical signal carrying the intensity information of the second sub-light source signal.
  • the second analog-to-digital converter 554 is configured to perform analog-to-digital conversion on the second analog electrical signal to obtain a second digital electrical signal carrying the intensity information of the third sub-modulated optical signal, and perform analog-to-digital conversion on the third analog electrical signal to obtain a third digital electrical signal carrying the first sub-light source signal and the intensity information of the signal after the fourth sub-modulated optical signal is coherent; performing analog-to-digital conversion on the fourth analog electrical signal to obtain an intensity information carrying the second sub-light source signal Four digital electrical signals.
  • the processor 453 is configured to use intensity information of the third sub-modulated optical signal, intensity information of the signal after the first sub-light source signal and the fourth sub-modulated optical signal are coherent, intensity information of the second sub-light source signal, and preset
  • the second data acquisition algorithm acquires the second key.
  • the most important difference between the device for generating a key and the device for generating a key provided by the previous embodiment is that the first photodetector 551 and the second photodetector in this embodiment are used. 552.
  • the homodyne detector 553 replaces the heterodyne detector 451 of the previous embodiment.
  • the heterodyne detector 451 detects the regular component of the second sub-modulated optical signal
  • the present embodiment detects the intensity information of the second sub-modulated optical signal through the first photodetector 551, and passes through the second photodetector.
  • the 552 detects the intensity information of the first light source signal, and detects the intensity information of the signal after the second sub-modulated light signal is coherent with the first light source signal by the homodyne detector 553. After determining the three intensity information, the phase difference between the second sub-modulated optical signal and the first source signal can be derived. Finally, the intensity information of the second sub-modulated optical signal, the phase difference between the second sub-modulated optical signal and the first source signal, and the regular component of the second sub-modulated light have a conversion relationship, so that only the conversion between them is known.
  • the relationship after determining the intensity information of the second sub-modulated optical signal, the phase difference between the second sub-modulated optical signal and the first light source signal, determining the regular component of the second sub-modulated light. Then, in the embodiment, the problem of acquiring the second key by using the preset second data acquisition algorithm is converted to determining the intensity information of the second sub-modulated optical signal, the phase of the second sub-modulated optical signal, and the first light source signal. Poor question.
  • the method of how to obtain the second key by the regular component of the second sub-modulated light can still adopt the method provided in the previous embodiment.
  • the heterodyne detector 451 can detect the second The sub-modulation two regular components of the optical signal, namely the X component and the Y component.
  • the heterodyne detector 451 In order to detect the two regular components of the second sub-modulated optical signal, it is necessary to perform a splitting operation on the second sub-modulated optical signal again inside the heterodyne detector 451.
  • the consistency of the splitting ratio inside the heterodyne detector 451 and the consistency of the delay are required to be high. When the deviation occurs, the detection result may be biased.
  • the first photodetector 551, the second photodetector 552, and the homodyne detector 553 are used to replace the heterodyne detector 451 in the previous embodiment, in the first photodetector 551, the second optoelectronic device.
  • the detector 552 and the homodyne detector 553 do not need to perform the splitting operation on the optical signal, so that the requirements of the device itself are low and easy to implement.
  • the processor is configured to use, according to the intensity information of the third sub-modulated optical signal, the strength information of the signal after the first sub-light source signal and the fourth sub-modulated optical signal are coherent, the intensity information of the second sub-light source signal, and the first sub-point
  • the splitter ratio of the beam splitter, the transmittance of the attenuator, and a preset second data acquisition algorithm acquire the second key.
  • the preset second data acquisition algorithm may be:
  • I S is the intensity information of the third sub-modulated optical signal
  • I LR is the intensity information of the second sub-light source signal
  • I BHD is the intensity information of the signal after the first sub-light source signal and the fourth sub-modulated optical signal are coherent
  • k 240 is the splitting ratio of the first beam splitter
  • ⁇ 310 is the transmittance of the attenuator
  • V A is the equivalent entangled state variance
  • x A and p A constitute the second key.
  • the intensity information of the third sub-modulated optical signal is I S
  • the intensity information of the second sub-light source signal is I LR
  • the first sub-light source signal
  • the fourth sub- The intensity information of the signal after the modulated optical signal is coherent is I BHD .
  • the splitting ratio of the fourth beam splitter 520 and the fifth beam splitter 530 are both 50:50.
  • the processor 453 is based on the intensity information I S of the third sub-modulated optical signal, the intensity information I BHD of the signal after the first sub-light source signal and the fourth sub-modulated optical signal, and the second sub-light source signal carried by the fourth digital electrical signal.
  • the intensity information I LR determines the regular components X and P of the second sub-modulated optical signal. These conversion relationships can be determined in the case where the splitting ratio of the fourth beam splitter 520 and the fifth beam splitter 530 and the conversion efficiency of the detector are determined.
  • Equation 13 the relationship shown in Equation 13 is as follows:
  • phase difference information of the second sub-modulated optical signal from the first source signal based on I S , I LR , I BHD , and Equation 14
  • the homodyne detector 553 can be replaced with a third photodetector, and the signal of the second sub-modulated optical signal detected by the third photodetector is coherent with the first source signal.
  • the intensity information is I PD . Determining phase difference information of the second sub-modulated optical signal from the first source signal based on I S , I LR , I PD , and Equation 15
  • the key to communicate with the receiving device is:
  • f x and f p are two functions, which are different according to different modulation systems.
  • the above function relationship is very simple. Take the variance of the equivalent entangled state (dual-mode squeezed state) of the sender as V A. The above relationship is:
  • x A and p A may both be positive in the actual system, may be negative, or may be positive and negative, there are four representations.
  • the fourth beam splitter 520 and the fifth beam splitter 530 are not ideal beam splitters, the two calibrations of the fourth beam splitter 520 and the fifth beam splitter 530 may also be determined.
  • the second parameter is the transmittance from the input of the fourth beam splitter 520 to the second output of the beam splitter, denoted as ⁇ 42 .
  • the fifth beam splitter 530 also has two parameters, namely ⁇ 51 and ⁇ 52 . Then there is the correction relationship shown by Equation 20 and Equation 21:
  • FIG. 7 The structure diagram of the device for generating a key constructed by the above device is shown in FIG. 7, and the working process of the device internal device for generating a key is as follows:
  • the duty cycle of the pulse can be controlled between 1% and 99%.
  • the light pulse is divided into two by the polarization maintaining beam splitter 1, one of which can be used as the first light source signal, and the other of which can be used as the second light source signal.
  • the polarization maintaining beam splitter 2 splits the modulated optical signal to obtain the first sub-modulated optical signal and the second sub-modulated optical signal, and transmits the attenuation through the first output terminal to the receiving end device through the attenuator and conforms to the CV.
  • the polarization maintaining beam splitter 3 splits the second sub-modulated optical signal to obtain a third sub-modulated optical signal and a fourth sub-modulated optical signal.
  • the polarization maintaining beam splitter 4 splits the second light source signal to obtain a first sub-light source signal and a second sub-light source signal.
  • the third sub-modulated optical signal is input to the PD 1 for detection.
  • the second sub-light source signal is input to the PD 2 for detection.
  • the fourth sub-modulated optical signal and the first sub-light source signal are input to the BHD for detection.
  • the first sub-light source signal may be delayed by the delay device. It should be noted that if the laser generated by the laser is continuous, narrow line width, and the coherence time is long, the delay measurement operation can be performed without setting the delay device to obtain more accurate measurement results in the BHD.
  • the PD1 detects the third sub-modulated optical signal to obtain a second analog electrical signal carrying the intensity information of the third sub-modulated optical signal.
  • the BHD detects the first sub-light source signal and the fourth sub-modulation optical signal to obtain a third analog electrical signal carrying the intensity information of the first sub-light source signal and the fourth sub-modulated optical signal coherent signal.
  • the PD2 detects the second sub-light source signal to obtain a fourth analog electrical signal carrying the intensity information of the second sub-light source signal.
  • the above analog electrical signals can be converted into digital electrical signals, so that the processor can operate or process the information carried by the digital electrical signals.
  • the second key may be acquired in the processor based on the information carried by the digital electrical signals and the preset second data acquisition algorithm. This data can be used as the sender device data for subsequent post processing required in the CV-QKD protocol.
  • the device for generating a key provided in this embodiment may be applied to a local local oscillator system, and the local local oscillator system does not need the sending end device to provide an LO (light source signal) to the receiving end device.
  • the device for generating a key provided by this embodiment is to be applied in the associated local oscillator system, it is necessary to add a beam splitter and a combiner on the basis of the provided device.
  • the combiner can be a polarization combiner.
  • the transmitting device adopts a dual polarization modulation scheme, since the source signal needs to be independently modulated in both polarization directions, the instruments for generating keys in both polarization directions can be applied in the embodiment. Structure.
  • the heterodyne detector 451 in the previous embodiment is replaced by the first photodetector 551, the second photodetector 552, and the homodyne detector 553, so that the heterodyne detector 451 is avoided.
  • Obtaining the two regular components of the second sub-modulated optical signal requires the operation of splitting the second sub-modulated optical signal again within the heterodyne detector 451.
  • the step of offset compensation If the homodyne detector 553 is replaced with a third photodetector, the device that generates the key contains a simpler device.
  • the device for generating a key avoids directly using the first key as a key for communicating with the receiving device, but acquires a key carried by the modulated modulated optical signal, and receives and receives the key.
  • the key carried by the end device is highly correlated with the key carried by the modulated optical signal and the key carried by the modulated optical signal actually sent by the transmitting device. In this way, the occurrence of a weak correlation between the second key saved by the transmitting device and the key communicated with the receiving device is avoided. Further, the success rate of key preparation and transmission can be improved, thereby avoiding waste of system resources.
  • the device may include a key generator 210, a modulator 220, a light source generator 230, a first beam splitter 240, and a first The second beam splitter 410, the heterodyne detector 451, the first analog to digital converter 452, the processor 453, the attenuator 310, and the memory 260.
  • the output of modulator 220 is coupled to the input of first beam splitter 240, optionally via an optical path.
  • the first beam splitter 240 includes a first output and a second output.
  • the input end of the second beam splitter 410 is connected to the light source generator 230, optionally through an optical path, and the second output end of the first beam splitter 240 is connected to the first input end of the heterodyne detector 451.
  • the first output of the second beam splitter 410 is coupled to the optical input of the modulator 220, optionally through an optical path, and the second output of the second beam splitter 410 is coupled to the optical input.
  • the second input end of the heterodyne detector 451 is connected, optionally connected by an optical path, and the output end of the heterodyne detector 451 is connected to the input end of the first analog to digital converter 452, optionally electrically connected .
  • the output of the first analog-to-digital converter 452 is coupled to the first input of the processor 453, optionally electrically, and the first output of the processor 453 is coupled to the memory 260, optionally electrically connection.
  • the second input of the processor 453 is connected to the output of the key generator 210, optionally electrically connected, and the second output of the processor 453 is connected to the electrical input of the modulator 220, optionally Can be electrically connected.
  • the modulator 220 is configured to modulate the first key onto the first source signal to obtain a modulated optical signal.
  • the first beam splitter 240 is configured to split the modulated optical signal to obtain a first sub-modulated optical signal and a second sub-modulated optical signal.
  • the second beam splitter 410 is configured to split the original light source signal to obtain a first light source signal and a second light source signal.
  • the attenuator 310 is configured to attenuate the first sub-modulated optical signal such that the number of photons included in the first sub-modulated optical signal is lower than a preset value, and send the attenuated first sub-modulated optical signal to the receiving end device.
  • the heterodyne detector 451 is configured to detect the second sub-modulated optical signal and the second light source signal to obtain a first analog electrical signal carrying the regular component information of the second sub-modulated optical signal.
  • the first analog to digital converter 452 is configured to perform analog to digital conversion on the first analog electrical signal to obtain a first digital electrical signal carrying the regular component information of the second sub-modulated optical signal.
  • the processor 453 is configured to acquire the second key based on the regular component information carried in the first digital electrical signal and the preset first data acquisition algorithm.
  • the memory 260 is used to store the second key.
  • the second key is a key after the error is generated when the first key is modulated to the first light source signal, and the second key is a key to be used when communicating with the receiving end device.
  • the processor 453 is further configured to determine a conversion relationship between the first key and the second key based on the first key and the second key determined in a process of determining the second key by a preset number of times; acquiring the key
  • the first key generated by the generator 210 determines the adjusted first key based on the inverse conversion relationship corresponding to the conversion relationship and the first key.
  • the modulator 220 is configured to modulate the adjusted first key onto the first source signal to obtain a modulated optical signal.
  • the reason that the key that is determined by the algorithm to communicate with the receiving device is too different from the first key may be different, for example, the offset of the IM has a significant drift.
  • the key determined by the algorithm to communicate with the receiving device is too different from the first key, which may result in a key determined by the algorithm to communicate with the receiving device, although it has a good relationship with the actually transmitted quantum signal.
  • Correlation but the probability distribution of the two regular components of the actually transmitted quantum signal does not meet the requirements of the modulation system. For Gaussian modulation, for example, we hope that the probability distributions of the two regular components of the actually transmitted quantum signal satisfy two independent Gaussian distributions.
  • the device for generating a key may provide that the key determined by the algorithm to communicate with the receiving device is not much different from the first key, so that the key generated by the current round does not need to be discarded.
  • This embodiment provides a way to calibrate the system from the data layer, that is, to calibrate the system by a data pre-compensation operation.
  • the system is calibrated from the data layer, the physical characteristics of the device included in the modulator 220 cannot be actually improved. Therefore, the noise modulation error of the system still exists, so the calculation result is performed by the receiving end device. The key to communication is still necessary.
  • the duty cycle of the pulse can be controlled between 1% and 99%.
  • the light pulse is divided into two by the polarization maintaining beam splitter 1, one of which can be used as the first light source signal, and the other of which can be used as the second light source signal.
  • the compensated data is obtained by performing a pre-compensation operation according to the data pre-compensation relationship table. It should be noted that, during system initialization, the data pre-compensation relationship table is the original mapping, that is, there is no compensation operation.
  • the polarization maintaining beam splitter 2 splits the modulated optical signal to obtain the first sub-modulated optical signal and the second sub-modulated optical signal, and transmits the attenuation through the first output terminal to the receiving end device through the attenuator and conforms to the CV.
  • the polarization maintaining beam splitter 1 splits the original light source signal to obtain a first light source signal and a second light source signal.
  • the HD detects the second sub-modulated optical signal and the second light source signal, and the second sub-modulated optical signal and the second source signal simultaneously reach the HD.
  • the second source signal may be delayed by the delay device.
  • the HD detects the second sub-modulated optical signal and the second light source signal to obtain a first analog electrical signal carrying the regular component information of the second sub-modulated optical signal, and is sampled by the ADC to obtain the second sub-modulated optical signal.
  • the second key may be acquired in the processor based on the regular component information carried in the first digital electrical signal and the preset first data acquisition algorithm.
  • the processor further, in the processor, comparing the first key generated by the quantum random number generator with the compensated key data for modulating the second sub-modulated optical signal, to perform the comparison result according to the comparison result Update the data precompensation relationship table described earlier. It can be seen that the data pre-compensation relationship table is dynamically changed according to the modulation characteristics of the system. If the system modulation characteristics change slowly, the updated data pre-compensation relationship table may be consistent with the pre-update data pre-compensation relationship table.
  • the purpose of calibrating the system by the data pre-compensation operation proposed in this embodiment is to minimize the orientation deviation generated in the modulator 220. Therefore, the relationship recorded by the data pre-compensation relationship table is actually modulation data (x mod , p mod ). And the average of the results of the output after modulation The relationship between the modulation data and the average of the results of the output after modulation can be seen in Equation 22:
  • the average value of the acquired second keys may be counted according to each set of regular components of the acquired second key. If the amount of data that can be used for statistics after the system is initialized is not large enough, in order to improve the accuracy, the regular component of the generated key may be accumulated multiple times and then counted.
  • the data may be estimated based on the results of the previous statistics and the results of the current statistics, and the predicted data pre-compensation relationship table for the next generated key is obtained.
  • the data is statistically calculated for the ith time, and the obtained function is f xi , f pi .
  • the average value of the acquired second key obtained by the previous i statistics is a sequence
  • It can be used as a prediction of the data pre-compensation relationship table when the key is generated next time. In this case, prediction errors will inevitably occur.
  • a suitable prediction method is a digital PID control algorithm.
  • the random key is generated according to the probability distribution required by the modulation system, and is denoted as x ori , p ori .
  • the compensated data is recorded as x mod , p mod .
  • the data pre-compensation operation described in this embodiment is based on x ori , p ori to obtain the operation of x mod , p mod .
  • x ori , p ori can be used as the original key
  • x mod p mod can be used as the second key.
  • any of these inverse functions can be selected.
  • an original image closest to the distance (x ori , p ori ), that is, the inverse function corresponding to the minimum value of (x mod -x ori ) 2 +(p mod -p ori ) 2 can be selected.
  • the data pre-compensation operation provided by this embodiment is also applicable to a device for generating a key of the heterodyne detector 451 replaced by the first photodetector 551, the second photodetector 552, and the homodyne detector 553. in.
  • This embodiment proposes to add a data pre-compensation operation to the device for generating a key, which can solve the problem that the actual modulation result due to the orientation deviation of the modulator 220 does not conform to the probability distribution required by the modulation system.
  • the noise deviation of the modulator 220 is compensated for when the key used for modulation is generated to finally reach the key carried by the actually transmitted quantum signal and the key communicated with the receiving device. They have a high degree of correlation between them, and they all conform to the effect of the probability distribution required by the modulation system.
  • the device for generating a key avoids directly using the first key as a key for communicating with the receiving device, but acquires a key carried by the modulated modulated optical signal, and receives and receives the key.
  • the key carried by the end device is highly correlated with the key carried by the modulated optical signal and the key carried by the modulated optical signal actually sent by the transmitting device. In this way, the occurrence of a situation in which the association between the second key held by the source device and the key communicated with the source device is weak is avoided. Further, the success rate of key preparation and transmission can be improved, thereby avoiding waste of system resources.
  • An exemplary embodiment of the present application provides a method for generating a key. As shown in FIG. 10, the processing flow of the method may include the following steps:
  • Step S710 generating a first key.
  • Step S720 modulating the first key onto the first light source signal to obtain a modulated light signal.
  • the first source signal may be generated by a light source generator such as a laser
  • the first key may be generated by a key generator such as a quantum random number generator.
  • Step S730 splitting the modulated optical signal to obtain a first sub-modulated optical signal and a second sub-modulated optical signal.
  • the modulated optical signal can be split by a beam splitter.
  • Step S740 the first sub-modulated optical signal is attenuated such that the number of photons included in the first sub-modulated optical signal is lower than a preset value, and the attenuated first sub-modulated optical signal is sent to the receiving end device.
  • the first sub-modulated optical signal attenuated by the attenuator can be automatically propagated to the receiving device through an optical path such as an optical fiber.
  • Step S750 Acquire a second key carried by the second submodulation optical signal, and store the second key in the memory, where the second key is an error when the first key is modulated to the first source signal. Key, and the second key is the key to be used when communicating with the receiving device.
  • the key carried by the second sub-modulated optical signal may be acquired by the data acquirer, and the key carried by the second sub-modulated optical signal is stored in a memory, such as a memory, for subsequent communication with the receiving device.
  • the first light source signal may be generated by the light source generator. After the first light source signal enters the modulator, it may be modulated by the first key generated by the key generator to generate a modulated light signal, and the modulated light signal carries The first key.
  • the first key may be a random key.
  • a random key can be generated by the quantum random number generator, and the probability distribution of the generated random key can be made to satisfy the Gaussian distribution required by the CV-QKD protocol.
  • the modulated optical signal that is finally transmitted from the transmitting device that is, the quantum signal carries the first key.
  • the modulation is inaccurate, and in fact, the quantum signal finally transmitted from the transmitting device does not carry the first key.
  • the inherent defects of the devices involved in the modulator (1) from the electrical signal outputted by the driver: the waveform of the electrical signal has overshoot, oscillation, noise, etc., and there is also a nonlinear relationship with the first key.
  • the problem, as well as the front first key will have a certain impact on the subsequent modulation results, and the output electrical signal has problems such as poor time domain jitter.
  • the impedance between the optical modulation device and the driver output cannot be completely matched, resulting in inconsistent frequency response, large influence of AC, and ultimately unsatisfactory parameters, extinction ratio, and unstable operating point. .
  • the modulated optical signal may be split by the first beam splitter to obtain a first sub-modulated optical signal and a second sub-modulated optical signal.
  • the first sub-modulated optical signal may be used as a signal transmitted to the receiving end device to transmit the prepared key to the receiving end device.
  • the second sub-modulated optical signal can then be used as a signal to detect the result of the modulation.
  • the second sub-modulated optical signal is input to the data acquirer, and the key carried by the second sub-modulated optical signal is acquired by the data acquirer.
  • the splitting ratio of the first beam splitter can be known, it can be set to 50:50. If the splitting ratio is 50:50, the first sub-modulated optical signal and the second sub-modulated optical signal have the same optical field state.
  • the association between the key carried by the second sub-modulated optical signal acquired by the data acquirer and the key carried by the first sub-modulated optical signal in the actual sub-modulated optical signal is related to the optical field state. Sexually large.
  • the association refers to that the key carried by the first sub-modulated optical signal has a one-to-one correspondence with the key carried by the second sub-modulated optical signal, or even has a linear relationship.
  • the key is stored locally on the transmitting end device for subsequent post-processing operations to finally share a set of secure keys with the receiving end device. .
  • the first sub-modulated optical signal can be attenuated by the attenuator to attenuate the power of the light source generator, such as a laser, to a very weak coherent state required by the CV-QKD protocol.
  • the attenuator it is possible to modulate the source signal and then attenuate it, or first attenuate the source signal and then modulate it.
  • beam splitters and attenuators are common energy attenuating devices that do not have an unpredictable effect on the data carried by the optical signal.
  • the method for generating a key provided by the embodiment of the present application may be used for a local oscillator system or a local local oscillator system.
  • the method for generating a key avoids directly using the first key as a key for communicating with the receiving device, but acquiring a key carried by the modulated modulated optical signal, and using the key as a key.
  • the key that is communicated with the receiving device and the key carried by the modulated optical signal is highly correlated with the key carried by the modulated optical signal actually sent by the transmitting device. In this way, the occurrence of a weak correlation between the second key saved by the transmitting device and the key communicated with the receiving device is avoided. Further, the success rate of key preparation and transmission can be improved, thereby avoiding waste of system resources.
  • An exemplary embodiment of the present application provides a method for generating a key. As shown in FIG. 11, the processing flow of the method may include the following steps:
  • Step S810 generating a first key.
  • Step S820 modulating the first key onto the first light source signal to obtain a modulated light signal.
  • the first source signal may be generated by a light source generator such as a laser
  • the first key may be generated by a key generator such as a quantum random number generator.
  • Step S830 splitting the modulated optical signal to obtain a first sub-modulated optical signal and a second sub-modulated optical signal.
  • the modulated optical signal can be split by a beam splitter.
  • Step S840 the first sub-modulated optical signal is attenuated such that the number of photons included in the first sub-modulated optical signal is lower than a preset value, and the attenuated first sub-modulated optical signal is sent to the receiving end device.
  • the first sub-modulated optical signal obtained by splitting the beam splitter can be automatically propagated to the receiving end device through an optical path such as an optical fiber.
  • Step S850 detecting regular component information of the second sub-modulated optical signal.
  • the second sub-modulated optical signal may be detected by a heterodyne detector, and the regular component information carried by the same may be obtained.
  • Step S860 acquiring a second key based on the regular component information of the second sub-modulated optical signal and the preset first data acquisition algorithm.
  • the key carried by the second sub-modulated optical signal may be determined in the processor based on the regular component information of the second sub-modulated optical signal and the preset first data acquisition algorithm.
  • Step S870 storing the second key, wherein the second key is a key after the error is generated when the first key is modulated to the first light source signal, and the second key is to communicate with the receiving device.
  • the key to be used.
  • the key carried by the second sub-modulated optical signal may be acquired by the data acquirer, and the data is stored through a memory such as a memory.
  • step S860 may include: detecting efficiency of the heterodyne detector based on the regular component information of the second sub-modulated optical signal, and detecting the regular component information of the second sub-modulated optical signal, when detecting the regular component information
  • the second source signal has the same phase as the first source signal.
  • the preset first data acquisition algorithm may be:
  • ⁇ D is the detection efficiency of the heterodyne detector
  • I LO is the intensity information of the second source signal
  • k 240 is the splitting ratio of the modulated optical signal
  • ⁇ 310 is the attenuation of the first sub-modulated light
  • the transmittance, V A is the equivalent entangled state variance
  • X and P are the regular component information of the second sub-modulated optical signal
  • x A and p A constitute the second key.
  • the method for generating a key avoids directly using the first key as a key for communicating with the receiving device, but acquiring a key carried by the modulated modulated optical signal, and using the key as a key.
  • the key carried by the receiving device and the key carried by the modulated optical signal are highly correlated with the key carried by the modulated optical signal actually sent by the transmitting device. In this way, the occurrence of a weak correlation between the second key saved by the transmitting device and the key communicated with the receiving device is avoided. Further, the success rate of key preparation and transmission can be improved, thereby avoiding waste of system resources.
  • An exemplary embodiment of the present application provides a method for generating a key. As shown in FIG. 12, the processing procedure of the method may include the following steps:
  • Step S910 generating a first key.
  • Step S920 modulating the first key onto the first light source signal to obtain a modulated light signal.
  • the first source signal may be generated by a light source generator such as a laser
  • the first key may be generated by a key generator such as a quantum random number generator.
  • Step S930 splitting the modulated optical signal to obtain a first sub-modulated optical signal and a second sub-modulated optical signal.
  • the modulated optical signal can be split by a beam splitter.
  • Step S940 the first sub-modulated optical signal is attenuated such that the number of photons included in the first sub-modulated optical signal is lower than a preset value, and the attenuated first sub-modulated optical signal is sent to the receiving end device.
  • the first sub-modulated optical signal obtained by splitting the beam splitter can be automatically propagated to the receiving end device through an optical path such as an optical fiber.
  • Step S950 detecting intensity information of the third sub-modulated optical signal, intensity information of the third light source signal, and intensity information after the fourth sub-modulated optical signal is coherent with the fourth light source signal, wherein the third sub-modulated optical signal and the fourth The sub-modulated optical signal is an optical signal obtained by splitting the second sub-modulated optical signal, and the third light source signal and the fourth light source signal have the same phase as the first light source signal.
  • the third sub-modulated optical signal may be detected by the first photodetector, and the intensity information of the third sub-modulated optical signal is obtained.
  • the third light source signal can be detected by the second photodetector, and the intensity information of the third light source signal can be obtained.
  • the signal after the fourth sub-modulated optical signal and the fourth source signal are coherent can be detected by the homodyne detector, and the intensity information after the fourth sub-modulated optical signal and the fourth source signal are coherent is obtained.
  • the homodyne detector can also be replaced with a third photodetector.
  • Step S960 acquiring, according to the intensity information of the third sub-modulated optical signal, the intensity information of the third light source signal, the intensity information after the fourth sub-modulated optical signal is coherent with the fourth light source signal, and the preset second data acquisition algorithm.
  • the second key is a code that specifies the intensity of the third sub-modulated optical signal.
  • Step S970 storing the second key, wherein the second key is a key after the error is generated when the first key is modulated to the first light source signal, and the second key is to communicate with the receiving device.
  • the key to be used.
  • the step S960 may include: performing intensity information based on the third sub-modulated optical signal, intensity information of the third light source signal, intensity information after the fourth sub-modulated optical signal and the fourth source signal are coherent, and performing the modulated optical signal.
  • the splitting ratio of the split, the transmittance for attenuating the first submodulated light, and a preset second data acquisition algorithm acquire the second key.
  • the preset second data acquisition algorithm may be:
  • I S is the intensity information of the third sub-modulated optical signal
  • I LR is the intensity information of the third source signal
  • I BHD is the intensity information after the fourth sub-modulated optical signal is coherent with the fourth source signal
  • k 240 is the pair
  • ⁇ 310 is the transmittance for attenuating the first sub-modulated light
  • V A is the equivalent entangled state variance
  • x A and p A constitute the second key.
  • the key carried by the second sub-modulated optical signal may be acquired by the data acquirer, and the data is stored through a memory such as a memory.
  • the method for generating a key avoids directly using the first key as a key for communicating with the receiving device, but acquiring a key carried by the modulated modulated optical signal, and using the key as a key.
  • the key carried by the receiving device and the key carried by the modulated optical signal are highly correlated with the key carried by the modulated optical signal actually sent by the transmitting device. In this way, the occurrence of a weak correlation between the second key saved by the transmitting device and the key communicated with the receiving device is avoided. Further, the success rate of key preparation and transmission can be improved, thereby avoiding waste of system resources.
  • An exemplary embodiment of the present application provides a method for generating a key. As shown in FIG. 13, the processing flow of the method may include the following steps:
  • Step S1010 Determine a conversion relationship between the first key and the second key based on the first key and the second key determined in a process of determining the second key by a preset number of times.
  • Step S1020 Acquire a generated first key, and determine an adjusted first key based on an inverse conversion relationship corresponding to the conversion relationship and the generated first key.
  • Step S1030 modulating the adjusted first key onto the first light source signal to obtain a modulated light signal.
  • the first source signal may be generated by a light source generator such as a laser
  • the first key may be generated by a key generator such as a quantum random number generator.
  • Step S1040 splitting the modulated optical signal to obtain a first sub-modulated optical signal and a second sub-modulated optical signal.
  • the modulated optical signal can be split by a beam splitter.
  • Step S1050 Attenuating the first sub-modulated optical signal, so that the number of photons included in the first sub-modulated optical signal is lower than a preset value, and transmitting the attenuated first sub-modulated optical signal to the receiving end device.
  • the first sub-modulated optical signal attenuated by the attenuator can be automatically propagated to the receiving device through an optical path such as an optical fiber.
  • Step S1060 detecting regular component information of the second sub-modulated optical signal.
  • the second sub-modulated optical signal may be detected by a heterodyne detector, and the regular component information carried by the same may be obtained.
  • Step S1070 Acquire a second key based on the regular component information of the second submodulation optical signal and the preset first data acquisition algorithm.
  • the second key may be acquired in the processor based on the regular component information of the second sub-modulated optical signal and the preset first data acquisition algorithm.
  • step S1080 the second key is stored.
  • the second key is a key after the error is generated when the first key is modulated to the first light source signal, and the second key is a key to be used when communicating with the receiving end device.
  • the method for generating a key avoids directly using the first key as a key for communicating with the receiving device, but acquiring a key carried by the modulated modulated optical signal, and using the key as a key.
  • the key carried by the receiving device and the key carried by the modulated optical signal are highly correlated with the key carried by the modulated optical signal actually sent by the transmitting device. In this way, the occurrence of a weak correlation between the second key saved by the transmitting device and the key communicated with the receiving device is avoided. Further, the success rate of key preparation and transmission can be improved, thereby avoiding waste of system resources.

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Abstract

本申请是关于一种生成密钥的设备和方法，属于量子通信技术领域。该方法包括：将第一密钥调制到第一光源信号上，得到调制光信号；对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号；对第一子调制光信号进行衰减，以使得第一子调制光信号每周期包含的光子数量低于预设值，向接收端设备发送衰减后的第一子调制光信号；获取第二子调制光信号携带的第二密钥，将第二密钥存储在存储器中，其中，第二密钥是将第一密钥调制到第一光源信号时出现误码后的密钥，且第二密钥是与接收端设备进行通信时待使用的密钥。通过本申请实施例提供的生成密钥的方法，可以提高密钥制备和传输的成功率，从而避免了对系统资源造成浪费。

Description

生成密钥的设备和方法
本申请要求于2017年11月24日提交中国国家知识产权局、申请号为201711194180.1、发明名称为“生成密钥的设备和方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请是关于量子通信技术领域，尤其是关于一种生成密钥的设备和方法。
背景技术
随着科学技术的进步，全球信息化程度的逐步加深，人们对通信安全的要求越来越高。如何保证通信安全就成了人们研究的课题。
在不断地探索的过程中，人们发现可以通过基于量子力学原理的量子保密通信体制来保证密钥在传输过程中的安全。在量子保密通信体制中，密钥不再以电信号的形式进行传输，而是以量子信号的形式进行传输。在量子力学中，存在一经典理论“海森堡测不准原理”，根据该理论可以推断，如果窃听者在密钥传输的过程中进行窃听，就要对密钥进行测量。而测量操作必定会对密钥的相干态产生干扰，这样假如原本量子信号携带的密钥为A，在被窃听之后，量子信号携带的密钥为B。发送端设备和接收端设备如果在解密的过程中通过通信发现解密的误码率超过预设阈值，则认为接收端设备拿到的密钥B为错误的，因此也就知道密钥A已泄露。
上述密钥的具体制备过程可以见图1。在制备模块中，通过随机源产生的随机密钥对光源进行调制，以生成携带随机密钥的调制光信号，发送端设备直接将随机密钥作为初始密钥A在本地保存。其中，随机密钥可以是例如-1到+1之间的随机数，或者-10到+10之间的随机数。由于制备模块中对光源进行调制的调制器件本身存在的缺陷，调制出的携带随机密钥的调制光并不都能与随机密钥相对应。因此，通过信道发送出去的携带随机密钥的调制光，和发送端设备在本地保存的初始密钥A可能并不对应。进而，接收端设备接收到携带随机密钥的调制光时，对携带随机密钥的调制光进行探测得到的初始密钥B与发送端设备在本地保存的初始密钥A不对应。最终，在后处理阶段，发送端设备会公布少量的初始密钥A的信息给接收端设备，接收端设备可以确定探测得到的初始密钥B与发送端设备保存的初始密钥A不对应。这样发送端设备和接收端设备会丢弃初始密钥A和B，重新制备并传输新的初始密钥。周而复始会大大降低初始密钥制备和传输的成功率，造成系统资源的浪费。
发明内容
本申请提供了以下技术方案：
根据本申请实施例的第一方面，提供一种生成密钥的设备，所述设备包括密钥生成器、调制器、光源发生器、第一分束器、数据获取器、衰减器以及存储器，其中：
所述密钥生成器，用于生成第一密钥；
所述调制器，用于将所述第一密钥调制到第一光源信号上，得到调制光信号；
所述第一分束器，用于对所述调制光信号进行分束，得到第一子调制光信号和第二子调制光信号；
所述衰减器，用于对所述第一子调制光信号进行衰减，以使得所述第一子调制光信号每周期包含的光子数量低于预设值，向所述接收端设备发送衰减后的第一子调制光信号；
所述数据获取器，用于获取所述第二子调制光信号携带的第二密钥，将所述第二密钥存储在所述存储器中，其中，所述第二密钥是将所述第一密钥调制到所述第一光源信号时出现误码后的密钥，且所述第二密钥是与所述接收端设备进行通信时待使用的密钥。
本申请实施例提供的生成密钥的设备，避免直接将第一密钥作为与接收端设备进行通信的密钥，而是获取调制后的调制光信号携带的密钥，并将其作为与接收端设备进行通信的密钥，获取出的调制光信号携带的密钥与发送端设备实际发送出的调制光信号携带的密钥关联性较高。这样，避免了发送端设备保存的第二密钥和与接收端设备进行通信的密钥的关联性较弱的情况的发生。进一步地，可以提高密钥制备和传输的成功率，从而避免了对系统资源造成浪费。
通过衰减器可以对第一子调制光信号进行衰减，以将光源发生器如激光器输出的功率较强的激光衰减至CV-QKD协议要求的极微弱相干态，即每周期包含的光子数量低于一百。需要说明的是，对于CV-QKD系统来说，先对光源信号进行调制再进行衰减，或先将光源信号进行衰减再进行调制，都是可以的。但是，在本申请实施例中，优选地先对光源信号进行调制再进行衰减。因为，在光源信号进行衰减之前，光源信号的功率还是较强的，其不易受量子噪声影响，因此在数据获取器中对其进行测量的精度较高。
在一种可能的实现方式中，所述设备还包括第二分束器，所述数据获取器包括外差探测器、第一模数转换器以及处理器，其中：
所述第二分束器，用于对所述光源发生器生成的原始光源信号进行分束，得到所述第一光源信号和第二光源信号；
所述外差探测器，用于对所述第二子调制光信号和所述第二光源信号进行探测，得到携带所述第二子调制光信号的正则分量信息的第一模拟电信号；
所述第一模数转换器，用于对所述第一模拟电信号进行模数转换，得到携带所述第二子调制光信号的正则分量信息的第一数字电信号，发送给所述处理器；
所述处理器，用于基于所述第二子调制光信号的正则分量信息以及预设的第一数据获取算法，获取所述第二密钥。
在一种可能的实现方式中，所述处理器，用于：
基于所述第二子调制光信号的正则分量信息、所述外差探测器的探测效率、所述第二光源信号的强度信息、所述第一分束器的分束比、所述衰减器的透过率、以及预设的第一数据获取算法，获取所述第二密钥。
在一种可能的实现方式中，所述预设的第一数据获取算法为：
Figure PCTCN2018090471-appb-000001
其中，η D为所述外差探测器的探测效率，I LO为所述第二光源信号的强度信息，k 240为 所述第一分束器的分束比，η 310为所述衰减器的透过率，V A为等效纠缠态方差，X和P为所述第二子调制光信号的正则分量信息，x A和p A构成所述第二密钥。
在实施中，在将调制光信号衰减为量子信号之前，首先对其进行分束，并对分束后的第二子调制光信号通过外差探测器进行探测。由于进入外差探测器的第二子调制光信号和进入信道的量子信号具有的调制特性相同，仅在强度上相差线性衰减的大小，因此外差探测器的探测结果和实际发送出去的量子信号之间具有良好的关联性。通过预设的第一数据获取算法，把探测过程中的光电转换系数和衰减时的透过率考虑到对密钥的影响因素中之后，即可得到第二子调制光携带的密钥。此时，第二子调制光携带的密钥和实际发送出去的量子信号携带的密钥之间的关联性就非常好。
在一种可能的实现方式中，所述设备还包括第三分束器、第四分束器和第五分束器，所述数据获取器包括第一光电探测器、第二光电探测器、零差探测器、第二模数转换器以及处理器，其中：
所述第三分束器，用于对所述光源发生器生成的原始光源信号进行分束，得到所述第一光源信号和第二光源信号；
所述第五分束器，用于对所述第二子调制光信号进行分束，得到第三子调制光信号以及第四子调制光信号；
所述第一光电探测器，用于对所述第三子调制光信号进行探测，得到携带所述第三子调制光信号的强度信息的第二模拟电信号；
所述第四分束器，用于对第二光源信号进行分束，得到第一子光源信号以及第二子光源信号；
所述零差探测器，用于对所述第一子光源信号和所述第四子调制光信号进行探测，得到携带所述第一子光源信号以及第四子调制光信号相干后的信号的强度信息的第三模拟电信号；
所述第二光电探测器，用于对所述第二子光源信号进行探测，得到携带所述第二子光源信号的强度信息的第四模拟电信号；
所述第二模数转换器，用于对所述第二模拟电信号进行模数转换，得到携带所述第三子调制光信号的强度信息的第二数字电信号；对所述第三模拟电信号进行模数转换，得到携带所述第一子光源信号以及第四子调制光信号相干后的信号的强度信息的第三数字电信号；对所述第四模拟电信号进行模数转换，得到携带所述第二子光源信号的强度信息的第四数字电信号，发送给所述处理器；
所述处理器，用于基于所述第三子调制光信号的强度信息、所述第一子光源信号与第四子调制光信号相干后的信号的强度信息、所述第二子光源信号的强度信息、以及预设的第二数据获取算法，获取所述第二密钥。
在一种可能的实现方式中，所述处理器，用于：
基于所述第三子调制光信号的强度信息、所述第一子光源信号与第四子调制光信号相干后的信号的强度信息、所述第二子光源信号的强度信息、所述第一分束器的分束比、所述衰减器的透过率、以及预设的第二数据获取算法，获取所述第二密钥。
在一种可能的实现方式中，所述预设的第二数据获取算法为：
Figure PCTCN2018090471-appb-000002
Figure PCTCN2018090471-appb-000003
其中，I S为所述第三子调制光信号的强度信息，I LR为所述第二子光源信号的强度信息，I BHD为所述第一子光源信号与第四子调制光信号相干后的信号的强度信息，k 240为所述第一分束器的分束比，η 310为所述衰减器的透过率，V A为等效纠缠态方差，x A和p A构成所述第二密钥。
用第一光电探测器、第二光电探测器、零差探测器去替换掉外差探测器对光信号进行探测。外差探测器可以探测得到第二子调制光信号的两个正则分量，即X分量与Y分量。为了探测得到第二子调制光信号的两个正则分量，需要在外差探测器的内部对第二子调制光信号再次进行分束操作。为了得到精准的探测结果，就要对外差探测器内部的分束比例的一致性和延时的一致性作较高的要求，当出现偏差时，探测结果就会存在偏差。进一步地，还可能需要对数据获取算法进行改进，以对偏差进行补偿。而采用第一光电探测器、第二光电探测器、零差探测器去替换掉外差探测器进行探测，在第一光电探测器、第二光电探测器、零差探测器内部无需再对光信号进行分束操作，这样对器件本身的要求低，容易实现。
在一种可能的实现方式中，所述处理器，还用于基于在预设次数的确定第二密钥的处理过程中确定的第一密钥和第二密钥，确定第一密钥和第二密钥的转换关系；获取所述密钥生成器生成的第一密钥，基于所述转换关系对应的逆转换关系和所述第一密钥，确定调整后的第一密钥；
所述调制器，用于将调整后的第一密钥调制到第一光源信号上，得到调制光信号。
通过算法确定的与接收端设备进行通信的密钥与第一密钥相差太大，会导致通过算法确定的与接收端设备进行通信的密钥，虽然它和实际发送出去的量子信号具有良好的关联性，但实际发送出去的量子信号的两个正则分量的概率分布并不能满足调制制式的要求。比如对于高斯调制，我们希望实际发送出去的量子信号的两个正则分量的概率分布分别满足两个独立的高斯分布。
根据本申请实施例的第二方面，提供一种生成密钥的方法，该方法通过第一方面所提供的设备实现。
本申请的实施例提供的技术方案可以包括以下有益效果：
本申请实施例提供的生成密钥的设备，避免直接将第一密钥作为与接收端设备进行通信的密钥，而是获取调制后的调制光信号携带的密钥，并将其作为与接收端设备进行通信的密钥，获取出的调制光信号携带的密钥与发送端设备实际发送出的调制光信号携带的密钥关联性较高。这样，避免了发送端设备保存的第二密钥和与接收端设备进行通信的密钥的关联性较弱的情况的发生。进一步地，可以提高密钥制备和传输的成功率，从而避免了对系统资源造成浪费。
应当理解的是，以上的一般描述和后文的细节描述仅是示例性和解释性的，并不能限 制本申请。
附图说明
此处的附图被并入说明书中并构成本说明书的一部分，示出了符合本申请的实施例，并与说明书一起用于解释本申请的原理。在附图中：
图1是根据一示例性实施例示出的一种CV-QKD系统的结构示意图；
图2是根据一示例性实施例示出的一种生成密钥的设备的结构示意图；
图3是根据一示例性实施例示出的一种生成密钥的设备的结构示意图；
图4是根据一示例性实施例示出的一种生成密钥的设备的结构示意图；
图5是根据一示例性实施例示出的一种生成密钥的设备的结构示意图；
图6是根据一示例性实施例示出的一种生成密钥的设备的结构示意图；
图7是根据一示例性实施例示出的一种生成密钥的设备的结构示意图；
图8是根据一示例性实施例示出的一种生成密钥的设备的结构示意图；
图9是根据一示例性实施例示出的一种生成密钥的设备的结构示意图；
图10是根据一示例性实施例示出的一种生成密钥的方法的流程示意图；
图11是根据一示例性实施例示出的一种生成密钥的方法的流程示意图；
图12是根据一示例性实施例示出的一种生成密钥的方法的流程示意图；
图13是根据一示例性实施例示出的一种生成密钥的方法的流程示意图。
通过上述附图，已示出本申请明确的实施例，后文中将有更详细的描述。这些附图和文字描述并不是为了通过任何方式限制本申请构思的范围，而是通过参考特定实施例为本领域技术人员说明本申请的概念。
具体实施方式
这里将详细地对示例性实施例进行说明，其示例表示在附图中。下面的描述涉及附图时，除非另有表示，不同附图中的相同数字表示相同或相似的要素。以下示例性实施例中所描述的实施方式并不代表与本申请相一致的所有实施方式。相反，它们仅是与如所附权利要求书中所详述的、本申请的一些方面相一致的装置和方法的例子。
最接近实用的量子保密通信技术是QKD(Quantum key distribution，量子密钥分发)技术，其功能是在已共享部分安全密钥的前提下，实现对称密钥的无条件安全分发。对于一个单向QKD系统，其实现方式是，发送端设备根据随机密钥对量子信号(量子信号是调制光信号经过衰减的信号)的相干态进行编码，在通过信道传输后被接收端设备进行检测，然后发送端设备和接收端设备通过经典信道进行后处理，例如测量基比对与数据筛选(sifting)、参数估计(parameter estimation，PE)、数据纠错(error correction，EC)、保密增强(privacy amplification，PA)，最终使得通信双方共享同一组安全密钥。
QKD技术从对信息在空间维度上的编码可以分为DV-QKD(Discrete-Variable Quantum Key Distribution，离散变量量子密钥分发)技术和CV-QKD(Continuous-Variable Quantum Key Distribution，连续变量量子密钥分发)技术。
DV-QKD技术是对单光子信号进行编码来实现量子密钥分发。CV-QKD技术是对极微 弱相干态进行编码来实现量子密钥分发。本申请实施例提供的生成密钥的方法和设备，主要是针对CV-QKD系统提出的。
在CV-QKD系统中，实现相干态的编码过程的主要仪器是调制器。在调制器中，根据具体采用的协议，可以采用不同的调制方式，例如高斯调制、QPSK(Quadrature Phase Shift Keyin，四相移相键控)调制等。用于实现不同的调制方式的调制器件也有多种，比如IM(Intensity Modulator，强度调制器)和PM(Phase Modulator，相位调制器)级联而成的调制器件，它们可以对光源信号进行相位调制和强度调制来实现相空间上的任意相干态的制备。此外，还可以使用IQ(In-phase Quadrature，同相正交)调制器或者DPQPSK(Dual Polarization Quadrature，双极化四相移相键控)调制器等来实现对光源信号进行一个或者两个偏振方向上的任意相干态的制备。
本申请一示例性实施例提供了一种生成密钥的设备，如图2所示，该设备可以包括密钥生成器210、调制器220、光源发生器230、第一分束器240、数据获取器250、衰减器310以及存储器260。该设备可以是量子密钥分发系统中的发送端设备。
在结构方面，密钥生成器210与调制器220的电输入端相连接，可选地，可以电性连接；光源发生器230与调制器220的光输入端相连接，可选地，可以通过光路连接；调制器220的输出端与第一分束器240的输入端相连接，可选地，可以通过光路连接。第一分束器240包括第一输出端和第二输出端，第一分束器240的第二输出端与数据获取器250的输入端相连接，可选地，可以通过光路连接；数据获取器250的输出端与存储器260相连接，可选地，可以电性连接。
在功能方面，密钥生成器210用于生成第一密钥。调制器220用于将第一密钥调制到第一光源信号上，得到调制光信号。第一分束器240用于对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号。衰减器310用于对第一子调制光信号进行衰减，以使得第一子调制光信号每周期包含的光子数量低于预设值，向接收端设备发送衰减后的第一子调制光信号。数据获取器250用于获取第二子调制光信号携带的第二密钥，将第二密钥存储在存储器260中。
其中，第二密钥是将第一密钥调制到第一光源信号时出现误码后的密钥，且第二密钥是与接收端设备进行通信时待使用的密钥。
在实施中，光源发生器230可以产生光源信号，光源信号进入到调制器220之后，可以被密钥生成器210所生成的第一密钥调制，生成调制光信号，调制光信号携带了第一密钥的信息。其中，第一密钥可以是随机密钥。可以通过量子随机数发生器生成一个随机密钥，并可以让生成的随机密钥的概率分布满足CV-QKD协议要求的高斯分布或者其他分布。
在理想状态下，最终从发送端设备发送出的量子信号会携带第一密钥。然而，由于调制器220中的器件如AWG(Arbitrary wave generator，任意波形发生器)/ADC(Analog-to-digital converter，数模转换器)、驱动器、IM(Intensity Modulator，强度调制器)/PM(Phase Modulator，相位调制器)的固有缺陷导致调制不准确，实际上最终从发送端设备发送出去的量子信号携带的并非是第一密钥。其中对于调制器220中涉及的器件的固有缺陷，(1)从驱动器输出的电信号来看：电信号的波形存在过冲、震荡、噪声等问题，与第一密钥间也会存在非线性的问题，以及前置第一密钥会对后续调制出的结果产生一定影 响，输出的电信号存在时域抖动差等问题。(2)从光学调制器件来看：光学调制器件与驱动器输出之间的阻抗无法完全匹配，导致频率响应不一致，交流的影响较大，最终啁啾参数、消光比不理想，以及工作点不稳定。
由于调制器220中涉及的器件导致调制不准确，第一密钥会产生一定的变化，因此，调制后的调制光信号实际携带了什么样的数据我们是不确定的。故而，需要获取调制光信号中携带的密钥，即第二密钥。具体做法是，可以通过第一分束器240将调制光信号进行分束，得到第一子调制光信号和第二子调制光信号。第一子调制光信号可以作为向接收端设备发送的信号，以将制备的密钥发送到接收端设备。第二子调制光信号则可以作为检测调制结果的信号。将第二子调制光信号输入到数据获取器250中，通过数据获取器250获取第二子调制光信号携带的密钥。由于可以获知第一分束器240的分束比，因此就可以确定第一子调制光信号和第二子调制光信号的光场态的对应关系。可以设置第一分束器240的分束比为50∶50，如果分束比为50∶50，则第一子调制光信号和第二子调制光信号具有相同的强度信息以及相同的相位信息。由于第一子调制光信号携带的密钥与光场态相关，因此，通过数据获取器250获取到的第二子调制光信号携带的密钥与第一子调制光信号携带的密钥的关联性较大。其中，关联性指的是第一子调制光信号携带的密钥与第二子调制光信号携带的密钥是一一对应的，甚至是具有线性关系的。最后，当数据获取器250获取出第二子调制光信号携带的密钥之后，将密钥存在发送端设备本地，用于后续执行后处理操作，以和接收端设备最终共享一组安全的密钥。
另外，需要说明的是，在生成密钥的设备中，用于传输光信号的光路可以是能够透光的介质，如光纤，优选地可以选择保偏光纤。如果使用保偏光纤，可以保证光信号在传输的过程中，不会改变它的偏振状态。如果改变了光信号的偏振状态，则会影响它的相干态，最终光信号携带的数据也会发生改变。
在实施中，通过衰减器310可以对第一子调制光信号进行衰减，以将光源发生器230如激光器输出的功率较强的激光衰减至CV-QKD协议要求的极微弱相干态，即每周期包含的光子数量低于一百。需要说明的是，对于CV-QKD系统来说，先对光源信号进行调制再进行衰减，或先将光源信号进行衰减再进行调制，都是可以的。但是，在本申请实施例中，优选地先对光源信号进行调制再进行衰减。因为，在光源信号进行衰减之前，光源信号的功率还是较强的，其不易受量子噪声影响，因此在数据获取器250中对其进行测量的精度较高。此外，不同于调制器220，分束器和衰减器310都是普通的能量衰减器件，不会对光信号携带的数据产生不可测的影响。
通过数据获取器250获取的第二密钥，经过后处理(数据筛选、参数估计、数据纠错、保密增强)转换为安全密钥，安全密钥可以应用在保密通信中：在加密阶段，可以用安全密钥对一段待加密信息进行加密，例如用安全密钥a与待加密信息b通过函数y＝f(a，b)进行加密得到密文y。在解密阶段，接收端设备预先接收到本实施例中的第一子调制光信号，对第一子调制光信号进行探测得到与第一子调制光信号对应的电信号，通过预设的算法确定电信号携带的密钥，将密钥同样经过后处理得到安全密钥a。接收端设备可以通过安全密钥a和函数y＝f(a，b)的逆函数，将密文y恢复成未加密的形式，得到信息b。当然，还有其他应用安全密钥进行加密的方式，在此不一一进行举例。
可选地，本申请实施例提供的生成密钥的设备可以用于随路本振系统，也可以用于本 地本振系统。
其中，在CV-QKD系统中，根据LO(Local Oscillator，本振光)产生位置可以将CV-QKD系统分为两类：LO在发送端设备产生的，称为随路本振系统；LO在接收端设备产生的，称为本地本振系统。其中，LO可以是本申请实施例中所述的光源信号，用于与量子信号一起进行密钥检测。
本申请实施例提供的生成密钥的设备，避免直接将第一密钥作为与接收端设备进行通信的密钥，而是获取调制后的调制光信号携带的密钥，并将其作为与接收端设备进行通信的密钥，获取的调制光信号携带的密钥与发送端设备实际发送出的调制光信号携带的密钥关联性较高。这样，避免了发送端设备保存的密钥和与接收端设备进行通信的密钥的关联性较弱的情况的发生。进一步地，可以提高密钥制备和传输的成功率，从而避免了对系统资源造成浪费。
本申请一示例性实施例提供了一种生成密钥的设备，如图3所示，该设备可以包括密钥生成器210、调制器220、光源发生器230、第一分束器240、衰减器310、数据获取器250以及存储器260。生成密钥的设备还可以包括第二分束器410，数据获取器250包括外差探测器451、第一模数转换器452以及处理器453。
在结构方面，密钥生成器210与调制器220的电输入端相连接，可选地，可以电性连接；调制器220的输出端与第一分束器240的输入端相连接，可选地，可以通过光路连接。第一分束器240包括第一输出端和第二输出端。第二分束器410的输入端与光源发生器230相连接，可选地，可以通过光路连接；第一分束器240的第二输出端与外差探测器451的第一输入端相连接，可选地，可以通过光路连接；第二分束器410的第一输出端与调制器220的光输入端相连接，可选地，可以通过光路连接；第二分束器410的第二输出端与外差探测器451的第二输入端相连接，可选地，可以通过光路连接；外差探测器451的输出端与第一模数转换器452的输入端相连接，可选地，可以电性连接。第一模数转换器452的输出端与处理器453的第一输入端相连接，可选地，可以电性连接；处理器453的第一输出端与存储器260相连接，可选地，可以电性连接。
在功能方面，第二分束器410用于对光源发生器生成的原始光源信号进行分束，得到第一光源信号和第二光源信号。调制器220用于将第一密钥调制到第一光源信号上，得到调制光信号。第一分束器240用于对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号。衰减器310用于对第一子调制光信号进行衰减，以使得第一子调制光信号每周期包含的光子数量低于预设值，向接收端设备发送衰减后的第一子调制光信号。外差探测器451用于对第二子调制光信号和第二光源信号进行探测，得到携带第二子调制光信号的正则分量信息的第一模拟电信号。第一模数转换器452用于对第一模拟电信号进行模数转换，得到携带第二子调制光信号的正则分量信息的第一数字电信号，发送给处理器453。处理器453用于基于第二子调制光信号的正则分量信息以及预设的第一数据获取算法，获取第二子调制光信号携带的密钥。存储器260用于存储第二密钥。
其中，第二密钥是将第一密钥调制到第一光源信号时出现误码后的密钥，且第二密钥是与接收端设备进行通信时待使用的密钥。
在具体应用场景中，首先本实施例提供的生成密钥的设备可以应用到的器件及其功能 介绍如下：
(1)激光器：产生连续的或脉冲式的线偏振的窄线宽激光。
(2)分束器：将输入的光信号分为两路输出。可选地，可以选择保偏的分束器。
(3)调制器：对光信号进行调制。调制器可以包括IM与PM级联而成的调制器、QPSK调制器等。
(4)量子随机数发生器：根据要求的调制码型生成随机密钥。具体地，从量子随机数发生器中获取随机数，而后根据要求的调制码型生成随机密钥。
(5)延时器：可以对输入的光信号进行延时操作，以匹配其他光路上的信号到达同一个器件的时差。
(6)HD(Heterodyne Detector，外差探测器)：可以对输入的光信号进行探测，输出携带光信号的两个正则分量信息的模拟电信号。
(7)ADC(Analog-to-digital converter，模数转换器)：将模拟电信号转换成数字电信号。
(8)衰减器：可以将输入其的光信号的强度进行衰减。
上述器件搭建的生成密钥的设备的结构示意图如图4所示，生成密钥的设备内部器件的工作流程如下：
(1)由激光器产生线偏振、窄线宽、连续的激光输入到脉冲生成器生成高消光比的光脉冲。其中，脉冲的占空比可以控制在1％～99％之间。例如，系统重复频率为100MHz，设置生成的脉冲的占空比为50％，则通过脉冲生成器对激光进行斩波后所形成的光脉冲的包络为5ns宽方波的波形。然而，不将激光输入到脉冲生成器生成光脉冲，在将激光输入到调制器时，通过对激光的调制操作自然会使激光产生不同的周期。但这样做的缺点是得到的信号并不是完美的方波，因此当前一周期和现周期的调制数据不相同时，调制器件无法做到瞬时转换，而是存在一个转换时间，转换时间内的调制信号是不准确的。因此，在本实施例中优选对激光进行斩波以生成光脉冲，光脉冲即可作为本实施例所述的原始光源信号。
(2)光脉冲经过保偏分束器1被一分为二，一路可以作为第一光源信号，另一路可以作为第二光源信号。
(3)通过调制器将随机密钥调制到第一光源信号上。
(4)保偏分束器2对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号，通过第一输出端向接收端设备发送经过衰减器进行衰减且符合CV-QKD协议要求的极微弱相干态的第一子调制光信号。保偏分束器1对原始光源信号进行分束，得到第一光源信号和第二光源信号。HD对第二子调制光信号和第二光源信号进行探测，第二子调制光信号和第二光源信号同时到达HD。为了让第二子调制光信号和第二光源信号可以同时到达HD，可以对第二光源信号通过延时器进行延时操作。需要说明的是，如果激光器产生的激光是连续的、窄线宽的，且相干时间较长，则可以不设置延时器进行延时操作就可以在HD中得到较为精准的测量结果。
(5)HD对第二子调制光信号和第二光源信号进行探测，得到携带第二子调制光信号的正则分量信息的第一模拟电信号，经过ADC采样，得到携带第二子调制光信号的正则分量信息的第一数字电信号。在处理器中可以基于第一数字电信号中携带的正则分量信息以及预设的第一数据获取算法，获取第二密钥。该数据可以作为后续用于进行CV-QKD协议中要求的后处理所使用的发送端设备数据。需要说明的是，在介绍完本实施例提供的生成密钥 的设备的结构之后，会对预设的第一数据获取算法进行详细介绍。
可选地，图3中提供的生成密钥的设备可以应用于本地本振系统中，本地本振系统不需要发送端设备提供LO(光源信号)给接收端设备。而如果本实施例提供的生成密钥的设备如果要应用在随路本振系统中，就需要在图3中提供的器件的基础上，再添加第六分束器420和合束器430，添加后的生成密钥的设备的结构见图5。可选地，合束器可以为偏振合束器。第六分束器420的输入端与光源发生器230通过光路连接，第六分束器420的第一输出端与合束器的第一输入端通过光路连接，第六分束器420的第二输出端与第二分束器410的输入端通过光路连接，衰减器310的输出端与合束器的第二输入端通过光路连接。
第六分束器420用于对光源信号进行分束，得到两路信号，一路作为LO输入到合束器与量子信号进行合束，另一路作为制备携带密钥的量子信号的光源信号。合束器用于将LO与携带密钥的量子信号进行合束。
可选地，如果发送端设备采用的是双偏振调制方案，由于对光源信号在两个偏振方向都需要独立调制，因此两个偏振方向上的生成密钥的仪器都可以应用本实施例中提供的结构。
在实施中，例如，第一偏振方向上用于调制的密钥为A 1，第二偏振方向上用于调制的密钥为A 2。通过数据获取器获取第一偏振方向上的调制光信号，得到密钥为B 1。通过数据获取器获取第二偏振方向上的调制光信号，得到密钥为B 2。分别将密钥B 1和密钥B 2进行存储，用于与接收端设备进行通信的密钥。
下面将对预设的第一数据获取算法进行详细介绍：
可选地，处理器用于基于第二子调制光信号的正则分量信息、外差探测器的探测效率、第二光源信号的强度信息、第一分束器的分束比、衰减器的透过率、以及预设的第一数据获取算法，获取第二密钥。
可选地，预设的第一数据获取算法可以为：
Figure PCTCN2018090471-appb-000004
其中，η D为外差探测器的探测效率，I LO为第二光源信号的强度信息，k 240为第一分束器240的分束比，η 310为衰减器310的透过率，V A为等效纠缠态方差，X和P为第二子调制光信号的正则分量信息，x A和p A构成第二密钥。其具体推导过程可以见下面所述：
最终从发送端发送出去的是携带密钥信息的量子信号，而模数转换器采集到的是调制光信号的正则分量转换为模拟电信号的信息，因此假设预设的第一数据获取算法主要包括两个步骤：
一、确定模数转换器采集到的模拟电信号与正则分量之间的转换关系。
二、将外差探测器451的第一输入端输入的光信号的正则分量转换为从发送端设备发送出去的量子信号所携带的密钥。
根据上述思路此处介绍两种算法思想。以图3-1A为例。第一种算法，假设已知下列参数：外差探测器451的探测效率η D，第二光源信号的强度信息I LO，第一子调制光信号的强度信息与第二子调制光信号的强度信息的比值k 240，发送第一子调制光信号时对第一子调制光进行衰减的透过率η 310，发送端设备等效纠缠态(双模压缩态)的方差(其值是协议规定 的)V A。设x A和p A构成第二密钥，第一模数转换器452采集得到的数据为x ADC和p ADC，根据其采样规则可以反推出外差探测器451输出的第二子调制光信号的正则分量信息为X和P，则可以推知从衰减器310送入信道的量子信号其两个正则分量均值为公式2所示：
Figure PCTCN2018090471-appb-000005
与接收端设备进行通信的密钥为公式3所示：
x A＝f x(x 310，p 310)，p A＝f p(x 310，p 310)    (公式3)
对于高斯调制，上式中的函数具体为公式4所示：
Figure PCTCN2018090471-appb-000006
Figure PCTCN2018090471-appb-000007
需要说明的是，x A和p A在实际系统中可能都取正，可能都取负，也可能是一正一负，共有四种表示方式，这取决于不同分束器的额外相差定义。
上述第一种算法的思路在于分束器等被动器件的透过率是基本恒定的，其可以事先测定。而激光经过这些被动器件其能量变化关系简单。
第二种算法源自第一种算法。在第一种算法中需要知道许多被动器件的比例系数，并需要测定光信号的强度信息。这些参数实质上都是为了确定进入外差探测器451的光信号的强度信息和从衰减器310送入信道的量子信号的强度信息之间的比值，且在第一种算法中我们假设了它们是一种线性关系。因此，可以在信道中直接接入一个综合探测效率为η QD的量子HD，并进行一个校准过程。量子HD的输出结果设为x het和p het，它和外差探测器451的探测得到的X和P之间可以假设有如下关系：
Figure PCTCN2018090471-appb-000008
Figure PCTCN2018090471-appb-000009
其中，
Figure PCTCN2018090471-appb-000010
代表真空噪声，是一个随机变量。具体地，在第二种算法中，k x，k p可以通过下述两种方式进行推导：
1)平均值方法
假设在校准过程中，所发送的数据均值不为零，则考虑到真空噪声的均值为零，则有：
Figure PCTCN2018090471-appb-000011
其中，<>代表对一段数据求平均。
2)方差方法
假设在校准过程中，所发送的数据均值为零(或很接近零)，则可以考虑使用统计方差的方式来计算：
Figure PCTCN2018090471-appb-000012
Figure PCTCN2018090471-appb-000013
其中，真空噪声的方差可以定义为1。ΔX 2，ΔP 2为X和P的统计方差，
Figure PCTCN2018090471-appb-000014
为x het，p het的统计方差。
在确定出比例系数k x，k p后，通过外差探测器451的探测结果可以推知：x 310＝k xX，p 310＝k pP。进而得出与接收端设备进行通信的密钥为：
x A＝f x(x 310，p 310)，p A＝f p(x 310，p 310)    (公式9)
对于高斯调制，上式中的函数具体为：
Figure PCTCN2018090471-appb-000015
Figure PCTCN2018090471-appb-000016
或
Figure PCTCN2018090471-appb-000017
Figure PCTCN2018090471-appb-000018
需要说明的是，x A和p A在实际系统中可能都取正，可能都取负，也可能是一正一负，共有四种表示方式。上述提供的预设的第一数据获取算法是将第二子调制信号的探测结果转换为与接收端设备进行通信的密钥。在可能的情况下，还可以基于第一密钥、第二子调制信号的探测结果以及其他算法，将第一密钥、第二子调制信号的探测结果进行拟合，得到与接收端设备进行通信的密钥。
如果通过算法确定的与接收端设备进行通信的密钥与第一密钥相差太大，则需要重新校准系统，甚至放弃本轮生成的密钥。
在本实施例中，在将调制光信号衰减为量子信号之前，首先对其进行分束，并对分束后的第二子调制光信号通过HD进行探测。由于进入HD的第二子调制光信号和进入信道的量子信号具有的调制特性相同，仅在强度上相差线性衰减的大小，因此HD的探测结果和实 际发送出去的量子信号之间具有良好的关联性。通过预设的第一数据获取算法，把探测过程中的光电转换系数和衰减系数考虑到对密钥的影响因素中之后，即可得到第二子调制光携带的密钥。此时，第二子调制光携带的密钥和实际发送出去的量子信号携带的密钥之间的关联性就非常好。
本申请实施例提供的生成密钥的设备，避免直接将第一密钥作为与接收端设备进行通信的密钥，而是获取调制后的调制光信号携带的密钥，并将其作为与接收端设备进行通信的密钥，获取出的调制光信号携带的密钥与发送端设备实际发送出的调制光信号携带的密钥关联性较高。这样，避免了发送端设备保存的第二密钥和与接收端设备进行通信的密钥的关联性较弱的情况的发生。进一步地，可以提高密钥制备和传输的成功率，从而避免了对系统资源造成浪费。
本申请一示例性实施例提供了一种生成密钥的设备，如图6所示，该设备可以包括密钥生成器210、调制器220、光源发生器230、第一分束器240、衰减器310、数据获取器250以及存储器260。该设备还可以包括第三分束器510、第四分束器520和第五分束器530，数据获取器250具体可以包括第一光电探测器551、第二光电探测器552、零差探测器553、第二模数转换器554以及处理器453。
在结构方面，密钥生成器210与调制器220的电输入端相连接，可选地，可以电性连接；调制器220的输出端与第一分束器240的输入端相连接，可选地，可以通过光路连接。第一分束器240包括第一输出端和第二输出端。第三分束器510的输入端与光源发生器230相连接，可选地，可以通过光路连接；第三分束器510的第一输出端和调制器220的光输入端相连接，可选地，可以通过光路连接；第一分束器240的第二输出端与第五分束器530的输入端相连接，可选地，可以通过光路连接；第五分束器530的第一输出端与第一光电探测器551的输入端相连接，可选地，可以通过光路连接；第一光电探测器551的输出端与第二模数转换器554的第一输入端相连接，可选地，可以电性连接。第五分束器530的第二输出端与零差探测器553的第一输入端相连接，可选地，可以通过光路连接；零差探测器553的输出端与第二模数转换器554的第二输入端相连接，可选地，可以电性连接。第三分束器510的第二输出端与第四分束器520的输入端相连接，可选地，可以通过光路连接；第四分束器520的第一输出端与零差探测器553的第二输入端相连接，可选地，可以通过光路连接；第四分束器520的第二输出端与第二光电探测器552的输入端相连接，可选地，可以通过光路连接；第二光电探测器552的输出端与第二模数转换器554的第三输入端相连接，可选地，可以电性连接。第二模数转换器554的输出端与处理器453的第一输入端相连接，可选地，可以电性连接；处理器453的第一输出端与存储器260相连接，可选地，可以电性连接。
在功能方面，调制器220用于将第一密钥调制到第一光源信号上，得到调制光信号。第一分束器240用于对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号。第三分束器510用于对光源发生器生成的原始光源信号进行分束，得到第一光源信号和第二光源信号。第五分束器530用于对第二子调制光信号进行分束，得到第三子调制光信号以及第四子调制光信号。第一光电探测器551用于对第三子调制光信号进行探测，得到携带第三子调制光信号的强度信息的第二模拟电信号。第四分束器520用于对第二光源信号 进行分束，得到第一子光源信号以及第二子光源信号。衰减器310用于对第一子调制光信号进行衰减，以使得第一子调制光信号每周期包含的光子数量低于预设值，向接收端设备发送衰减后的第一子调制光信号。零差探测器553用于对第一子光源信号和第四子调制光信号进行探测，得到携带第一子光源信号以及第四子调制光信号相干后的信号的强度信息的第三模拟电信号。第二光电探测器552用于对第二子光源信号进行探测，得到携带第二子光源信号的强度信息的第四模拟电信号。第二模数转换器554用于对第二模拟电信号进行模数转换，得到携带第三子调制光信号的强度信息的第二数字电信号；对第三模拟电信号进行模数转换，得到携带第一子光源信号以及第四子调制光信号相干后的信号的强度信息的第三数字电信号；对第四模拟电信号进行模数转换，得到携带第二子光源信号的强度信息的第四数字电信号。处理器453用于基于第三子调制光信号的强度信息、第一子光源信号与第四子调制光信号相干后的信号的强度信息、第二子光源信号的强度信息、以及预设的第二数据获取算法，获取第二密钥。
其中，本实施例中提供的生成密钥的设备与上一实施例提供的生成密钥的设备的最主要的区别就是，用本实施例中的第一光电探测器551、第二光电探测器552、零差探测器553替换掉上一实施例中的外差探测器451。上一实施例中外差探测器451探测的是第二子调制光信号的正则分量，而本实施例通过第一光电探测器551探测第二子调制光信号的强度信息，通过第二光电探测器552探测第一光源信号的强度信息，通过零差探测器553探测第二子调制光信号与第一光源信号相干后的信号的强度信息。在确定这三个强度信息之后，可以推算出第二子调制光信号与第一光源信号的相位差。最后，第二子调制光信号的强度信息、第二子调制光信号与第一光源信号的相位差与第二子调制光的正则分量之间有一转换关系，因此，只要知道它们之间的转换关系，当确定了第二子调制光信号的强度信息、第二子调制光信号与第一光源信号的相位差之后，就可以确定第二子调制光的正则分量。那么，本实施例中通过预设的第二数据获取算法获取第二密钥的问题，就转换为确定第二子调制光信号的强度信息、第二子调制光信号与第一光源信号的相位差的问题。之后如何通过第二子调制光的正则分量获取第二密钥的方法依然可以采用上一实施例提供的方法。
至于为什么要用第一光电探测器551、第二光电探测器552、零差探测器553去替换掉上一实施例中的外差探测器451，是因为外差探测器451可以探测得到第二子调制光信号的两个正则分量，即X分量与Y分量。为了探测得到第二子调制光信号的两个正则分量，需要在外差探测器451的内部对第二子调制光信号再次进行分束操作。为了得到精准的探测结果，就要对外差探测器451内部的分束比例的一致性和延时的一致性作较高的要求，当出现偏差时，探测结果就会存在偏差。进一步地，还可能需要对数据获取算法进行改进，以对偏差进行补偿。本实施例中采用第一光电探测器551、第二光电探测器552、零差探测器553去替换掉上一实施例中的外差探测器451，在第一光电探测器551、第二光电探测器552、零差探测器553内部无需再对光信号进行分束操作，这样对器件本身的要求低，容易实现。
可选地，处理器用于基于第三子调制光信号的强度信息、第一子光源信号与第四子调制光信号相干后的信号的强度信息、第二子光源信号的强度信息、第一分束器的分束比、衰减器的透过率、以及预设的第二数据获取算法，获取第二密钥。
可选地，预设的第二数据获取算法可以为：
Figure PCTCN2018090471-appb-000019
Figure PCTCN2018090471-appb-000020
其中，I S为第三子调制光信号的强度信息，I LR为第二子光源信号的强度信息，I BHD为第一子光源信号与第四子调制光信号相干后的信号的强度信息，k 240为第一分束器的分束比，η 310为衰减器的透过率，V A为等效纠缠态方差，x A和p A构成第二密钥。
在实施中，对于预设的第二数据获取算法，假设：第三子调制光信号的强度信息为I S，第二子光源信号的强度信息为I LR，第一子光源信号以及第四子调制光信号相干后的信号的强度信息为I BHD。第四分束器520以及第五分束器530的分束比都是50∶50。处理器453基于第三子调制光信号的强度信息I S、第一子光源信号以及第四子调制光信号相干后的信号的强度信息I BHD、第四数字电信号携带的第二子光源信号的强度信息I LR，确定第二子调制光信号的正则分量X和P。这些转换关系在确定第四分束器520以及第五分束器530的分束比、探测器的转换效率的情况下，就可以确定。
其中，假设第一光电探测器探测到的数据为
Figure PCTCN2018090471-appb-000021
其光电转换效率为η E1；第二光电探测器探测到的数据为
Figure PCTCN2018090471-appb-000022
其光电转换效率为η E2；零差探测器探测到的数据为V BHD，其综合光电转换效率为η BHD，则有公式13所示的关系：
Figure PCTCN2018090471-appb-000023
基于I S、I LR、I BHD以及公式14，确定第二子调制光信号的与第一光源信号的相位差信息
Figure PCTCN2018090471-appb-000024
Figure PCTCN2018090471-appb-000025
可选地，在本实施例中，可以将零差探测器553换成第三光电探测器，假设第三光电探测器探测到的第二子调制光信号的与第一光源信号相干后的信号的强度信息为I PD。基于I S、I LR、I PD以及公式15，确定第二子调制光信号的与第一光源信号的相位差信息
Figure PCTCN2018090471-appb-000026
Figure PCTCN2018090471-appb-000027
在确定I S和
Figure PCTCN2018090471-appb-000028
后，以第一光源信号为参考点，第二子调制光信号的正则分量X和P可以表示为公式16的形式：
Figure PCTCN2018090471-appb-000029
第二子调制光信号的正则分量X和P与从衰减器310送入信道的量子信号其两个正则分量的关系为：
Figure PCTCN2018090471-appb-000030
Figure PCTCN2018090471-appb-000031
在得到x 310和p 310后，与接收端设备进行通信的密钥为：
x A＝f x(x 310，p 310)，p A＝f p(x 310，p 310)    (公式18)
其中，f x，f p是两个函数，根据不同的调制制式有所区别。对于高斯调制而言，上述函数关系十分简单，以发送方等效纠缠态(双模压缩态)的方差为V A为例，上述关系即为：
Figure PCTCN2018090471-appb-000032
Figure PCTCN2018090471-appb-000033
在实施中，x A和p A在实际系统中可能都取正，可能都取负，也可能是一正一负，共有四种表示方式。此外，还需要说明的是，如果第四分束器520以及第五分束器530不是理想的分束器，还可以确定第四分束器520以及第五分束器530的标定的两个参数。以第四分束器520为例，第一个参数是，从第四分束器520的输入端到分束器的第一输出端的透过率，记为η 41。第二个参数是，从第四分束器520的输入端到分束器的第二输出端的透过率，记为η 42。相同地，第五分束器530也存在两个参数，即η 51和η 52。则有公式20和公式21所示的修正关系：
Figure PCTCN2018090471-appb-000034
或
Figure PCTCN2018090471-appb-000035
以及：
Figure PCTCN2018090471-appb-000036
上述器件搭建的生成密钥的设备的结构示意图如图7所示，生成密钥的设备内部器件的工作流程如下：
(1)由激光器产生线偏振、窄线宽、连续的激光输入到脉冲生成器生成高消光比的光脉冲。其中，脉冲的占空比可在控制在1％～99％之间。
(2)光脉冲经过保偏分束器1被一分为二，一路可以作为第一光源信号，另一路可以作为第二光源信号。
(3)通过调制器将随机密钥调制到第一光源信号上。
(4)保偏分束器2对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号，通过第一输出端向接收端设备发送经过衰减器进行衰减且符合CV-QKD协议要求的极微弱相干态的第一子调制光信号。保偏分束器3对第二子调制光信号进行分束，得到第三子调制光信号以及第四子调制光信号。保偏分束器4对第二光源信号进行分束，得到第一子光源信号以及第二子光源信号。将第三子调制光信号输入到PD1中进行探测。将第二子光源信号输入到PD2中进行探测。将第四子调制光信号和第一子光源信号输入到BHD中进行探测。
如果要求第四子调制光信号和第一子光源信号同时到达BHD，可以对第一子光源信号通过延时器进行延时操作。需要说明的是，如果激光器产生的激光是连续的、窄线宽的，且相干时间较长，则可以不设置延时器进行延时操作就可以在BHD中得到较为精准的测量结果。
(5)PD1对第三子调制光信号进行探测，得到携带第三子调制光信号的强度信息的第二模拟电信号。BHD对第一子光源信号和第四子调制光信号进行探测，得到携带第一子光源信号以及第四子调制光信号相干后的信号的强度信息的第三模拟电信号。PD2对第二子光源信号进行探测，得到携带第二子光源信号的强度信息的第四模拟电信号。经过ADC采样，可以将上述模拟电信号转换成数字电信号的形式，这样便于处理器对这些数字电信号携带的信息进行运算或者处理。在处理器中可以基于这些数字电信号携带的信息以及预设的第二数据获取算法，获取第二密钥。该数据可以作为后续用于进行CV-QKD协议中要求的后处理所使用的发送端设备数据。
可选地，本实施例中提供的生成密钥的设备可以应用于本地本振系统中，本地本振系统不需要发送端设备提供LO(光源信号)给接收端设备。而如果本实施例提供的生成密钥的设备如果要应用在随路本振系统中，就需要在已提供的器件的基础上，再添加一个分束器和一个合束器。可选地，合束器可以为偏振合束器。
可选地，如果发送端设备采用的是双偏振调制方案，由于对光源信号在两个偏振方向都需要独立调制，因此两个偏振方向上的生成密钥的仪器都可以应用本实施例中提供的结构。
在本实施例中，用第一光电探测器551、第二光电探测器552、零差探测器553去替换掉上一实施例中的外差探测器451，避免了外差探测器451为了探测得到第二子调制光信号的两个正则分量而需要在外差探测器451的内部对第二子调制光信号再次进行分束的操作弊端。在本实施例中，无需对进入零差探测器553的信号再次分束，从而省去了需要对数据获取算法进行改进，以对外差探测器451才会带来的分束和延时造成的偏差进行补偿的步骤。如果将零差探测器553换成第三光电探测器，则生成密钥的设备包含的器件更加简单。
本申请实施例提供的生成密钥的设备，避免直接将第一密钥作为与接收端设备进行通信的密钥，而是获取调制后的调制光信号携带的密钥，并将其作为与接收端设备进行通信的密钥，获取出的调制光信号携带的密钥与发送端设备实际发送出的调制光信号携带的密钥关联性较高。这样，避免了发送端设备保存的第二密钥和与接收端设备进行通信的密钥的关联性较弱的情况的发生。进一步地，可以提高密钥制备和传输的成功率，从而避免了对系统资源造成浪费。
本申请一示例性实施例提供了一种生成密钥的设备，如图8所示，该设备可以包括密钥生成器210、调制器220、光源发生器230、第一分束器240、第二分束器410、外差探测器451、第一模数转换器452、处理器453、衰减器310以及存储器260。
在结构方面，调制器220的输出端与第一分束器240的输入端相连接，可选地可以通过光路连接。第一分束器240包括第一输出端和第二输出端。第二分束器410的输入端与光源发生器230相连接，可选地可以通过光路连接，第一分束器240的第二输出端与外差 探测器451的第一输入端相连接，可选地可以通过光路连接，第二分束器410的第一输出端与调制器220的光输入端相连接，可选地可以通过光路连接，第二分束器410的第二输出端与外差探测器451的第二输入端相连接，可选地可以通过光路连接，外差探测器451的输出端与第一模数转换器452的输入端相连接，可选地可以电性连接。第一模数转换器452的输出端与处理器453的第一输入端相连接，可选地可以电性连接，处理器453的第一输出端与存储器260相连接，可选地可以电性连接。处理器453的第二输入端与密钥生成器210的输出端相连接，可选地可以电性连接，处理器453的第二输出端与调制器220的电输入端相连接，可选地可以电性连接。
在功能方面，调制器220用于将第一密钥调制到第一光源信号上，得到调制光信号。第一分束器240用于对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号。第二分束器410用于对原始光源信号进行分束，得到第一光源信号和第二光源信号。衰减器310用于对第一子调制光信号进行衰减，以使得第一子调制光信号每周期包含的光子数量低于预设值，向接收端设备发送衰减后的第一子调制光信号。外差探测器451用于对第二子调制光信号和第二光源信号进行探测，得到携带第二子调制光信号的正则分量信息的第一模拟电信号。第一模数转换器452用于对第一模拟电信号进行模数转换，得到携带第二子调制光信号的正则分量信息的第一数字电信号。处理器453用于基于第一数字电信号中携带的正则分量信息以及预设的第一数据获取算法，获取第二密钥。存储器260用于存储第二密钥。其中，第二密钥是将第一密钥调制到第一光源信号时出现误码后的密钥，且第二密钥是与接收端设备进行通信时待使用的密钥。处理器453还用于基于在预设次数的确定第二密钥的处理过程中确定的第一密钥和第二密钥，确定第一密钥和第二密钥的转换关系；获取密钥生成器210生成的第一密钥，基于转换关系对应的逆转换关系和第一密钥，确定调整后的第一密钥。调制器220用于将调整后的第一密钥调制到第一光源信号上，得到调制光信号。
具体地，处理器453还用于基于在预设次数的确定第二密钥的处理过程中确定的第一密钥和第二密钥，确定第一密钥和第二密钥的转换函数y＝f(x)，其中，y为第二密钥，x为第一密钥；获取密钥生成器210生成的第一密钥x 1，将y＝x 1，代入y＝f(x)的逆函数，得到x 2，作为调整后的第一密钥。
在实施中，导致通过算法确定的与接收端设备进行通信的密钥与第一密钥相差太大的原因可能有多样，比如IM的偏置点出现了明显的漂移等。通过算法确定的与接收端设备进行通信的密钥与第一密钥相差太大，会导致通过算法确定的与接收端设备进行通信的密钥，虽然它和实际发送出去的量子信号具有良好的关联性，但实际发送出去的量子信号的两个正则分量的概率分布并不能满足调制制式的要求。比如对于高斯调制，我们希望实际发送出去的量子信号的两个正则分量的概率分布分别满足两个独立的高斯分布。
在实施中，如果第二密钥与第一密钥相差太大，则需要重新校准系统，甚至放弃本轮生成的密钥。在本实施例中，提供的生成密钥的设备可以使得通过算法确定的与接收端设备进行通信的密钥与第一密钥相差不大，从而无需放弃本轮生成的密钥。本实施例提供一种从数据层面对系统进行校准的方式，即通过数据预补偿操作对系统进行校准。
出现上述种情况时，一一对所有器件进行问题排查是必要的，但这种操作方式也存在一定的困难性。因此，在本实施例中，提出通过数据预补偿操作来修正调制结果出现的明 显的定向偏差的情况。举个例子对定向偏差进行说明，如果大量重复地将数据X1和P1调制到量子信号上，调制后量子信号的检测结果是X2和P2，则定向偏差描述的是X2、P2的均值偏离X1、P1的情况。其中，<X2>-X1≠0，<P2>-P1≠0。与此相对的情况可以称之为噪声性偏差，即当X2≠X1，P2≠P1时，<X2>-X1＝0，<P2>-P1＝0。
由于在本实施例中，是从数据层面对系统进行校准的，无法实际改善调制器220包含的器件的物理特性，因此系统的噪声性调制误差依然存在，所以通过探测结果计算与接收端设备进行通信的密钥仍然是必要的。
在具体应用场景中，生成密钥的设备的结构示意图如图9所示，生成密钥的设备内部的工作流程如下：
(1)由激光器产生线偏振、窄线宽、连续的激光输入到脉冲生成器生成高消光比的光脉冲。其中，脉冲的占空比可在控制在1％～99％之间。
(2)光脉冲经过保偏分束器1被一分为二，一路可以作为第一光源信号，另一路可以作为第二光源信号。
(3)通过调制器对第一光源信号进行调制。但是这里调制所用的数据不再是从量子随机数发生器直接获取过来的，而实际采用的是补偿后的数据。具体地，补偿后的数据是随机密钥根据数据预补偿关系表，进行预补偿操作而得到的。需要说明的是，在系统初始化时，数据预补偿关系表是原始映射，即没有任何补偿操作。
(4)保偏分束器2对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号，通过第一输出端向接收端设备发送经过衰减器进行衰减且符合CV-QKD协议要求的极微弱相干态的第一子调制光信号。保偏分束器1对原始光源信号进行分束，得到第一光源信号和第二光源信号。HD对第二子调制光信号和第二光源信号进行探测，第二子调制光信号和第二光源信号同时到达HD。为了让第二子调制光信号和第二光源信号可以同时到达HD，可以对第二光源信号通过延时器进行延时操作。
(5)HD对第二子调制光信号和第二光源信号进行探测，得到携带第二子调制光信号的正则分量信息的第一模拟电信号，经过ADC采样，得到携带第二子调制光信号的正则分量信息的第一数字电信号。在处理器中可以基于第一数字电信号中携带的正则分量信息以及预设的第一数据获取算法，获取第二密钥。
(6)还需要在处理器中，将量子随机数发生器生成的第一密钥与用于调制该第二子调制光信号的补偿后的密钥数据进行比对，以根据比对结果去更新前面所述的数据预补偿关系表。可以见得，该数据预补偿关系表是根据系统调制特性动态变化的。如果系统调制特性变化较为缓慢，则更新后的数据预补偿关系表可能与更新前的数据预补偿关系表一致。
本实施例中提出的通过数据预补偿操作对系统进行校准的目的是尽量减小调制器220中产生的定向偏差，因此数据预补偿关系表记录的关系其实是调制数据(x mod，p mod)和调制后输出的结果的平均值
Figure PCTCN2018090471-appb-000037
之间的关系，调制数据与调制后输出的结果的平均值的关系式可以见公式22：
Figure PCTCN2018090471-appb-000038
为了确定上述公式22中的函数f x，f p，可以根据获取的第二密钥的每一组正则分量，统计获取的第二密钥的平均值。如果在系统初始化过后的可以用于进行统计的数据量不够 大，为了提高准确性，可以累积多次生成密钥的正则分量时再进行统计。
但如果系统调制特性变化较快，则可以根据上次统计的结果，和本次统计的结果进行推算，得到预测出的下一次生成密钥时的数据预补偿关系表。比如，假设第i次进行数据统计，得到的函数为f xi，f pi，则对于同一组调制数据(x modi，p modi)，前i次统计得到的获取的第二密钥的平均值是一个序列
Figure PCTCN2018090471-appb-000039
根据此序列有多种方式可以外推出第i+1个数值
Figure PCTCN2018090471-appb-000040
Figure PCTCN2018090471-appb-000041
可以作为下一次生成密钥时对数据预补偿关系表的一种预测。在这种情况中，不可避免的会出现预测误差。但由于，第一，实际中系统调制特一般不可能变化十分迅速的变化，第二，当实际中系统调制特确实变化十分迅速时，通过合适的预测方式预测出下一次生成密钥时的数据预补偿关系表是具备一定效果的。其中，合适的预测方式如数字PID控制算法。
假设随机密钥是按照调制制式所要求的概率分布生成的，记为x ori，p ori。经过补偿后的数据记为x mod，p mod。本实施例中所述的数据预补偿操作就是基于x ori，p ori求得x mod，p mod的操作。其中，x ori，p ori可以作为原始密钥，x mod，p mod可以作为第二密钥。
存在多种方法能够使得实际发送出去的量子信号的两个正则分量的概率分布满足调制制式所要求的概率分布。在本实施例中选取一种简单的方式进行介绍：令
Figure PCTCN2018090471-appb-000042
则有如下关系：
x ori＝f x(x mod，p mod)，p ori＝f p(x mod，p mod)    (公式23)
基于x ori，p ori，求得满足函数f x，f p关系的x mod，p mod，可以表述为f x，f p的逆函数，即：
Figure PCTCN2018090471-appb-000043
当存在多个逆函数时，可以选择这些逆函数中的任意一个。优选地可以选择距离(x ori，p ori)最近的一个原象，即(x mod-x ori) 2+(p mod-p ori) 2的最小值对应的那个逆函数。
可选地，本实施例提供的数据预补偿操作同样可以应用于采用第一光电探测器551、第二光电探测器552、零差探测器553替换的外差探测器451的生成密钥的设备中。
本实施例提出了在生成密钥的设备中增加了数据预补偿操作，它可以解决由于调制器220的定向偏差而导致的实际调制结果不符合调制制式所要求的概率分布的问题。此外，将调制器220的噪声性偏差，在生成用于进行调制的密钥时对密钥进行补偿，以最终达到实际发送出的量子信号携带的密钥和与接收端设备进行通信的密钥，它们之间既具有较高的关联性，它们又都符合调制制式所要求的概率分布的效果。
本申请实施例提供的生成密钥的设备，避免直接将第一密钥作为与接收端设备进行通信的密钥，而是获取调制后的调制光信号携带的密钥，并将其作为与接收端设备进行通信的密钥，获取出的调制光信号携带的密钥与发送端设备实际发送出的调制光信号携带的密钥关联性较高。这样，避免了发送端设备保存的第二密钥和与接收端设备进行通信的密钥 的关联性较弱的情况的发生。进一步地，可以提高密钥制备和传输的成功率，从而避免了对系统资源造成浪费。
本申请一示例性实施例提供了一种生成密钥的方法，如图10所示，该方法的处理流程可以包括如下的步骤：
步骤S710，生成第一密钥。
步骤S720，将第一密钥调制到第一光源信号上，得到调制光信号。
在实施中，可以通过光源发生器如激光器生成第一光源信号，通过密钥生成器如量子随机数发生器生成第一密钥。
步骤S730，对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号。
在实施中，可以通过分束器对调制光信号进行分束。
步骤S740，对第一子调制光信号进行衰减，以使得第一子调制光信号每周期包含的光子数量低于预设值，向接收端设备发送衰减后的第一子调制光信号。
在实施中，通过衰减器进行衰减的第一子调制光信号可以通过光路如光纤自动传播到接收端设备。
步骤S750，获取第二子调制光信号携带的第二密钥，将第二密钥存储在存储器中，其中，第二密钥是将第一密钥调制到第一光源信号时出现误码后的密钥，且第二密钥是与接收端设备进行通信时待使用的密钥。
在实施中，可以通过数据获取器获取第二子调制光信号携带的密钥，通过存储器如存储器将第二子调制光信号携带的密钥存储，后续用于与接收端设备进行通信。
在实施中，可以通过光源发生器产生第一光源信号，第一光源信号进入到调制器之后，可以被密钥生成器所生成的第一密钥调制，生成调制光信号，调制光信号携带了第一密钥。其中，第一密钥可以是随机密钥。可以通过量子随机数发生器生成一个随机密钥，并可以让生成的随机密钥的概率分布满足CV-QKD协议要求的高斯分布。
在理想状态下，最终从发送端设备发送出的调制光信号即量子信号携带第一密钥。然而，由于调制器中涉及的器件如AWG/ADC、驱动器、IM/PM的固有缺陷导致调制不准确，实际上最终从发送端设备发送出去的量子信号携带的并非是第一密钥。其中对于调制器中涉及的器件的固有缺陷，(1)从驱动器输出的电信号来看：电信号的波形存在过冲、震荡、噪声等问题，与第一密钥间也会存在非线性的问题，以及前置第一密钥会对后续调制出的结果产生一定影响，输出的电信号存在时域抖动差等问题。(2)从光学调制器件来看：光学调制器件与驱动器输出之间的阻抗无法完全匹配，导致频率响应不一致，交流的影响较大，最终啁啾参数、消光比不理想，以及工作点不稳定。
由于调制器中涉及的器件导致调制不准确，因此，调制后的调制光信号实际携带了什么样的数据我们是不确定的。故而，需要获取调制光信号携带的密钥。具体做法是，可以通过第一分束器将调制光信号进行分束，得到第一子调制光信号和第二子调制光信号。第一子调制光信号可以作为向接收端设备发送的信号，以将制备的密钥发送到接收端设备。第二子调制光信号则可以作为检测调制结果的信号。将第二子调制光信号输入到数据获取器中，通过数据获取器获取第二子调制光信号携带的密钥。由于可以获知第一分束器的分束比，可以设置为50∶50。如果分束比为50∶50，则第一子调制光信号和第二子调制光信号 具有相同的光场态。由于第一子调制光信号携带的密钥与光场态相关，因此，通过数据获取器获取的第二子调制光信号携带的密钥与实际中第一子调制光信号携带的密钥的关联性较大。其中，关联性指的是第一子调制光信号携带的密钥与第二子调制光信号携带的密钥是一一对应的，甚至是具有线性关系的。最后，当数据获取器获取出第二子调制光信号携带的密钥之后，将密钥存在发送端设备本地，用于后续执行后处理操作，以和接收端设备最终共享一组安全的密钥。
在实施中，可以通过衰减器可以对第一子调制光信号进行衰减，以将光源发生器如激光器输出的功率较强的激光衰减至CV-QKD协议要求的极微弱相干态。需要说明的是，对于CV-QKD系统来说，先对光源信号进行调制再进行衰减，或先将光源信号进行衰减再进行调制，都是可以的。但是，在本申请实施例中，优选地先对光源信号进行调制再进行衰减。因为，在光源信号进行衰减之前，光源信号的功率还是较强的，其不易受量子噪声影响，因此在数据获取器中对其进行测量的精度较高。此外，不同于调制器，分束器和衰减器都是普通的能量衰减器件，不会对光信号携带的数据产生不可测的影响。
可选地，本申请实施例提供的生成密钥的方法可以用于随路本振系统，也可以用于本地本振系统。
通过本申请实施例提供的生成密钥的方法，，避免直接将第一密钥作为与接收端设备进行通信的密钥，而是获取调制后的调制光信号携带的密钥，并将其作为与接收端设备进行通信的密钥，获取出的调制光信号携带的密钥与发送端设备实际发送出的调制光信号携带的密钥关联性较高。这样，避免了发送端设备保存的第二密钥和与接收端设备进行通信的密钥的关联性较弱的情况的发生。进一步地，可以提高密钥制备和传输的成功率，从而避免了对系统资源造成浪费。
本申请一示例性实施例提供了一种生成密钥的方法，如图11所示，该方法的处理流程可以包括如下的步骤：
步骤S810，生成第一密钥。
步骤S820，将第一密钥调制到第一光源信号上，得到调制光信号。
在实施中，可以通过光源发生器如激光器生成第一光源信号，通过密钥生成器如量子随机数发生器生成第一密钥。
步骤S830，对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号。
在实施中，可以通过分束器对调制光信号进行分束。
步骤S840，对第一子调制光信号进行衰减，以使得第一子调制光信号每周期包含的光子数量低于预设值，向接收端设备发送衰减后的第一子调制光信号。
在实施中，通过分束器分束得到的第一子调制光信号可以通过光路如光纤自动传播到接收端设备。
步骤S850，检测第二子调制光信号的正则分量信息。
在实施中，可以通过外差探测器对第二子调制光信号进行检测，并得到其携带的正则分量信息。
步骤S860，基于第二子调制光信号的正则分量信息以及预设的第一数据获取算法，获取第二密钥。
在实施中，可以在处理器中，基于第二子调制光信号的正则分量信息以及预设的第一数据获取算法，确定第二子调制光信号携带的密钥。
步骤S870，将第二密钥进行存储，其中，第二密钥是将第一密钥调制到第一光源信号时出现误码后的密钥，且第二密钥是与接收端设备进行通信时待使用的密钥。
在实施中，可以通过数据获取器获取第二子调制光信号携带的密钥，通过存储器如存储器将数据存储。
可选地，步骤S860可以包括：基于第二子调制光信号的正则分量信息、对第二子调制光信号的正则分量信息进行检测的外差探测器的探测效率、在检测正则分量信息时所使用的第二光源信号的强度信息、对调制光信号进行分束的分束比、对第一子调制光进行衰减的透过率、以及预设的第一数据获取算法，获取第二密钥，其中，第二光源信号与第一光源信号具有相同相位。
可选地，预设的第一数据获取算法可以为：
Figure PCTCN2018090471-appb-000044
其中，η D为外差探测器的探测效率，I LO为第二光源信号的强度信息，k 240为对调制光信号进行分束的分束比，η 310为对第一子调制光进行衰减的透过率，V A为等效纠缠态方差，X和P为第二子调制光信号的正则分量信息，x A和p A构成第二密钥。
关于本实施例中的方法，其中具体的操作方式已经在有关该设备的实施例中进行了详细描述，此处将不做详细阐述说明。
通过本申请实施例提供的生成密钥的方法，避免直接将第一密钥作为与接收端设备进行通信的密钥，而是获取调制后的调制光信号携带的密钥，并将其作为与接收端设备进行通信的密钥，获取出的调制光信号携带的密钥与发送端设备实际发送出的调制光信号携带的密钥关联性较高。这样，避免了发送端设备保存的第二密钥和与接收端设备进行通信的密钥的关联性较弱的情况的发生。进一步地，可以提高密钥制备和传输的成功率，从而避免了对系统资源造成浪费。
本申请一示例性实施例提供了一种生成密钥的方法，如图12所示，该方法的处理流程可以包括如下的步骤：
步骤S910，生成第一密钥。
步骤S920，将第一密钥调制到第一光源信号上，得到调制光信号。
在实施中，可以通过光源发生器如激光器生成第一光源信号，通过密钥生成器如量子随机数发生器生成第一密钥。
步骤S930，对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号。
在实施中，可以通过分束器对调制光信号进行分束。
步骤S940，对第一子调制光信号进行衰减，以使得第一子调制光信号每周期包含的光子数量低于预设值，向接收端设备发送衰减后的第一子调制光信号。
在实施中，通过分束器分束得到的第一子调制光信号可以通过光路如光纤自动传播到接收端设备。
步骤S950，检测第三子调制光信号的强度信息、第三光源信号的强度信息和第四子调制光信号与第四光源信号相干后的强度信息，其中，第三子调制光信号和第四子调制光信号是对第二子调制光信号进行分束得到的光信号，第三光源信号和第四光源信号与第一光源信号具有相同相位。
在实施中，可以通过第一光电探测器对第三子调制光信号进行探测，并得到第三子调制光信号的强度信息。可以通过第二光电探测器对第三光源信号进行探测，并得到第三光源信号的强度信息。可以通过零差探测器对第四子调制光信号与第四光源信号相干后的信号进行探测，得到第四子调制光信号与第四光源信号相干后的强度信息。可选地，零差探测器也可以换成第三光电探测器。
步骤S960，基于第三子调制光信号的强度信息、第三光源信号的强度信息、第四子调制光信号与第四光源信号相干后的强度信息、以及预设的第二数据获取算法，获取第二密钥。
步骤S970，将第二密钥进行存储，其中，第二密钥是将第一密钥调制到第一光源信号时出现误码后的密钥，且第二密钥是与接收端设备进行通信时待使用的密钥。
可选地，步骤S960可以包括：基于第三子调制光信号的强度信息、第三光源信号的强度信息、第四子调制光信号与第四光源信号相干后的强度信息、对调制光信号进行分束的分束比、对第一子调制光进行衰减的透过率、以及预设的第二数据获取算法，获取第二密钥。
可选地，预设的第二数据获取算法可以为：
Figure PCTCN2018090471-appb-000045
Figure PCTCN2018090471-appb-000046
其中，I S为第三子调制光信号的强度信息，I LR为第三光源信号的强度信息，I BHD为第四子调制光信号与第四光源信号相干后的强度信息，k 240为对调制光信号进行分束的分束比，η 310为对第一子调制光进行衰减的透过率，V A为等效纠缠态方差，x A和p A构成第二密钥。
在实施中，可以通过数据获取器获取第二子调制光信号携带的密钥，通过存储器如存储器将数据存储。
关于本实施例中的方法，其中具体的操作方式已经在有关该设备的实施例中进行了详细描述，此处将不做详细阐述说明。
通过本申请实施例提供的生成密钥的方法，避免直接将第一密钥作为与接收端设备进行通信的密钥，而是获取调制后的调制光信号携带的密钥，并将其作为与接收端设备进行通信的密钥，获取出的调制光信号携带的密钥与发送端设备实际发送出的调制光信号携带的密钥关联性较高。这样，避免了发送端设备保存的第二密钥和与接收端设备进行通信的密钥的关联性较弱的情况的发生。进一步地，可以提高密钥制备和传输的成功率，从而避免了对系统资源造成浪费。
本申请一示例性实施例提供了一种生成密钥的方法，如图13所示，该方法的处理流程可以包括如下的步骤：
步骤S1010，基于在预设次数的确定第二密钥的处理过程中确定的第一密钥和第二密钥，确定第一密钥和第二密钥的转换关系。
步骤S1020，获取生成的第一密钥，基于转换关系对应的逆转换关系和生成的第一密钥，确定调整后的第一密钥。
步骤S1030，将调整后的第一密钥调制到第一光源信号上，得到调制光信号。
在实施中，可以通过光源发生器如激光器生成第一光源信号，通过密钥生成器如量子随机数发生器生成第一密钥。
步骤S1040，对调制光信号进行分束，得到第一子调制光信号和第二子调制光信号。
在实施中，可以通过分束器对调制光信号进行分束。
步骤S1050，对第一子调制光信号进行衰减，以使得第一子调制光信号每周期包含的光子数量低于预设值，向接收端设备发送衰减后的第一子调制光信号。
在实施中，通过衰减器进行衰减的第一子调制光信号可以通过光路如光纤自动传播到接收端设备。
步骤S1060，检测第二子调制光信号的正则分量信息。
在实施中，可以通过外差探测器对第二子调制光信号进行检测，并得到其携带的正则分量信息。
步骤S1070，基于第二子调制光信号的正则分量信息以及预设的第一数据获取算法，获取第二密钥。
在实施中，可以在处理器中，基于第二子调制光信号的正则分量信息以及预设的第一数据获取算法，获取第二密钥。
步骤S1080，将第二密钥进行存储。其中，第二密钥是将第一密钥调制到第一光源信号时出现误码后的密钥，且第二密钥是与接收端设备进行通信时待使用的密钥。
关于本实施例中的方法，其中具体的操作方式已经在有关该设备的实施例中进行了详细描述，此处将不做详细阐述说明。
通过本申请实施例提供的生成密钥的方法，避免直接将第一密钥作为与接收端设备进行通信的密钥，而是获取调制后的调制光信号携带的密钥，并将其作为与接收端设备进行通信的密钥，获取出的调制光信号携带的密钥与发送端设备实际发送出的调制光信号携带的密钥关联性较高。这样，避免了发送端设备保存的第二密钥和与接收端设备进行通信的密钥的关联性较弱的情况的发生。进一步地，可以提高密钥制备和传输的成功率，从而避免了对系统资源造成浪费。
本领域技术人员在考虑说明书及实践这里公开的公开后，将容易想到本申请的其它实施方案。本申请旨在涵盖本申请的任何变型、用途或者适应性变化，这些变型、用途或者适应性变化遵循本申请的一般性原理并包括本申请未公开的本技术领域中的公知常识或惯用技术手段。说明书和实施例仅被视为示例性的，本申请的真正范围和精神由下面的权利要求指出。
应当理解的是，本申请并不局限于上面已经描述并在附图中示出的精确结构，并且可以在不脱离其范围进行各种修改和改变。本申请的范围仅由所附的权利要求来限制。

Claims (16)

  1. 一种生成密钥的设备，其特征在于，所述设备包括密钥生成器、调制器、光源发生器、第一分束器、数据获取器、衰减器以及存储器，其中：
    所述密钥生成器，用于生成第一密钥；
    所述调制器，用于将所述第一密钥调制到第一光源信号上，得到调制光信号；
    所述第一分束器，用于对所述调制光信号进行分束，得到第一子调制光信号和第二子调制光信号；
    所述衰减器，用于对所述第一子调制光信号进行衰减，以使得所述第一子调制光信号每周期包含的光子数量低于预设值，向所述接收端设备发送衰减后的第一子调制光信号；
    所述数据获取器，用于获取所述第二子调制光信号携带的第二密钥，将所述第二密钥存储在所述存储器中，其中，所述第二密钥是将所述第一密钥调制到所述第一光源信号时出现误码后的密钥，且所述第二密钥是与所述接收端设备进行通信时待使用的密钥。
  2. 根据权利要求1所述的生成密钥的设备，其特征在于，所述设备还包括第二分束器，所述数据获取器包括外差探测器、第一模数转换器以及处理器，其中：
    所述第二分束器，用于对所述光源发生器生成的原始光源信号进行分束，得到所述第一光源信号和第二光源信号；
    所述外差探测器，用于对所述第二子调制光信号和所述第二光源信号进行探测，得到携带所述第二子调制光信号的正则分量信息的第一模拟电信号；
    所述第一模数转换器，用于对所述第一模拟电信号进行模数转换，得到携带所述第二子调制光信号的正则分量信息的第一数字电信号，发送给所述处理器；
    所述处理器，用于基于所述第二子调制光信号的正则分量信息以及预设的第一数据获取算法，获取所述第二密钥。
  3. 根据权利要求2所述的生成密钥的设备，其特征在于，所述处理器，用于：
    基于所述第二子调制光信号的正则分量信息、所述外差探测器的探测效率、所述第二光源信号的强度信息、所述第一分束器的分束比、所述衰减器的透过率、以及预设的第一数据获取算法，获取所述第二密钥。
  4. 根据权利要求3所述的生成密钥的设备，其特征在于，所述预设的第一数据获取算法为：
    Figure PCTCN2018090471-appb-100001
    其中，η D为所述外差探测器的探测效率，I LO为所述第二光源信号的强度信息，k 240为所述第一分束器的分束比，η 310为所述衰减器的透过率，V A为等效纠缠态方差，X和P为所述第二子调制光信号的正则分量信息，x A和p A构成所述第二密钥。
  5. 根据权利要求1所述的生成密钥的设备，其特征在于，所述设备还包括第三分束器、第四分束器和第五分束器，所述数据获取器包括第一光电探测器、第二光电探测器、零差探测器、第二模数转换器以及处理器，其中：
    所述第三分束器，用于对所述光源发生器生成的原始光源信号进行分束，得到所述第一光源信号和第二光源信号；
    所述第五分束器，用于对所述第二子调制光信号进行分束，得到第三子调制光信号以及第四子调制光信号；
    所述第一光电探测器，用于对所述第三子调制光信号进行探测，得到携带所述第三子调制光信号的强度信息的第二模拟电信号；
    所述第四分束器，用于对第二光源信号进行分束，得到第一子光源信号以及第二子光源信号；
    所述零差探测器，用于对所述第一子光源信号和所述第四子调制光信号进行探测，得到携带所述第一子光源信号以及第四子调制光信号相干后的信号的强度信息的第三模拟电信号；
    所述第二光电探测器，用于对所述第二子光源信号进行探测，得到携带所述第二子光源信号的强度信息的第四模拟电信号；
    所述第二模数转换器，用于对所述第二模拟电信号进行模数转换，得到携带所述第三子调制光信号的强度信息的第二数字电信号；对所述第三模拟电信号进行模数转换，得到携带所述第一子光源信号以及第四子调制光信号相干后的信号的强度信息的第三数字电信号；对所述第四模拟电信号进行模数转换，得到携带所述第二子光源信号的强度信息的第四数字电信号，发送给所述处理器；
    所述处理器，用于基于所述第三子调制光信号的强度信息、所述第一子光源信号与第四子调制光信号相干后的信号的强度信息、所述第二子光源信号的强度信息、以及预设的第二数据获取算法，获取所述第二密钥。
  6. 根据权利要求5所述的生成密钥的设备，其特征在于，所述处理器，用于：
    基于所述第三子调制光信号的强度信息、所述第一子光源信号与第四子调制光信号相干后的信号的强度信息、所述第二子光源信号的强度信息、所述第一分束器的分束比、所述衰减器的透过率、以及预设的第二数据获取算法，获取所述第二密钥。
  7. 根据权利要求6所述的生成密钥的设备，其特征在于，所述预设的第二数据获取算法为：
    Figure PCTCN2018090471-appb-100002
    Figure PCTCN2018090471-appb-100003
    其中，I S为所述第三子调制光信号的强度信息，I LR为所述第二子光源信号的强度信息，I BHD为所述第一子光源信号与第四子调制光信号相干后的信号的强度信息，k 240为所述第一分束器的分束比，η 310为所述衰减器的透过率，V A为等效纠缠态方差，x A和p A构成所述第二密钥。
  8. 根据权利要求2或5所述的生成密钥的设备，其特征在于，
    所述处理器，还用于基于在预设次数的确定第二密钥的处理过程中确定的第一密钥和第二密钥，确定第一密钥和第二密钥的转换关系；获取所述密钥生成器生成的第一密钥，基于所述转换关系对应的逆转换关系和所述第一密钥，确定调整后的第一密钥；
    所述调制器，具体用于将调整后的第一密钥调制到第一光源信号上，得到调制光信号。
  9. 一种生成密钥的方法，其特征在于，所述方法包括：
    生成第一密钥；
    将所述第一密钥调制到第一光源信号上，得到调制光信号；
    对所述调制光信号进行分束，得到第一子调制光信号和第二子调制光信号；
    对所述第一子调制光信号进行衰减，以使得所述第一子调制光信号每周期包含的光子数量低于预设值，向所述接收端设备发送衰减后的第一子调制光信号；
    获取所述第二子调制光信号携带的第二密钥，将所述第二密钥进行存储，其中，所述第二密钥是将所述第一密钥调制到所述第一光源信号时出现误码后的密钥，且所述第二密钥是与所述接收端设备进行通信时待使用的密钥。
  10. 根据权利要求9所述的方法，其特征在于，所述获取所述第二子调制光信号携带的第二密钥，包括：
    检测所述第二子调制光信号的正则分量信息；
    基于所述第二子调制光信号的正则分量信息以及预设的第一数据获取算法，获取所述第二密钥。
  11. 根据权利要求10所述的方法，其特征在于，基于所述第二子调制光信号的正则分量信息以及预设的第一数据获取算法，获取所述第二密钥，包括：
    基于所述第二子调制光信号的正则分量信息、对所述第二子调制光信号的正则分量信息进行检测的外差探测器的探测效率、在检测所述正则分量信息时所使用的第二光源信号的强度信息、对所述调制光信号进行分束的分束比、对所述第一子调制光信号进行衰减的透过率、以及预设的第一数据获取算法，获取所述第二密钥，其中，所述第二光源信号与所述第一光源信号具有相同相位。
  12. 根据权利要求11所述的方法，其特征在于，所述预设的第一数据获取算法为：
    Figure PCTCN2018090471-appb-100004
    其中，η D为所述外差探测器的探测效率，I LO为所述第二光源信号的强度信息，k 240为对所述调制光信号进行分束的分束比，η 310为对所述第一子调制光信号进行衰减的透过率，V A为等效纠缠态方差，X和P为所述第二子调制光信号的正则分量信息，x A和p A构成所述第二密钥。
  13. 根据权利要求9所述的方法，其特征在于，所述获取所述第二子调制光信号携带的第二密钥，包括：
    检测所述第三子调制光信号的强度信息、所述第三光源信号的强度信息和所述第四子调制光信号与所述第四光源信号相干后的强度信息，其中，所述第三子调制光信号和所述第四子调制光信号是对所述第二子调制光信号进行分束得到的光信号，所述第三光源信号和第四光源信号与所述第一光源信号具有相同相位；
    基于所述第三子调制光信号的强度信息、所述第三光源信号的强度信息、所述第四子调制光信号与所述第四光源信号相干后的强度信息、以及预设的第二数据获取算法，获取第二密钥。
  14. 根据权利要求13所述的方法，其特征在于，所述基于所述第三子调制光信号的强度信息、所述第三光源信号的强度信息、所述第四子调制光信号与所述第四光源信号相干后的强度信息、以及预设的第二数据获取算法，获取第二密钥，包括：
    基于所述第三子调制光信号的强度信息、所述第三光源信号的强度信息、所述第四子调制光信号与所述第四光源信号相干后的强度信息、对所述调制光信号进行分束的分束比、对所述第一子调制光信号进行衰减的透过率、以及预设的第二数据获取算法，获取第二密钥。
  15. 根据权利要求14所述的方法，其特征在于，所述预设的第二数据获取算法为：
    Figure PCTCN2018090471-appb-100005
    Figure PCTCN2018090471-appb-100006
    其中，I S为所述第三子调制光信号的强度信息，I LR为所述第三光源信号的强度信息，I BHD为所述第四子调制光信号与所述第四光源信号相干后的强度信息，k 240为对所述调制光信号进行分束的分束比，η 310为对所述第一子调制光信号进行衰减的透过率，V A为等效纠缠态方差，x A和p A构成所述第二密钥。
  16. 根据权利要求9所述的方法，其特征在于，所述方法还包括：
    基于在预设次数的确定第二密钥的处理过程中确定的第一密钥和第二密钥，确定第一密钥和第二密钥的转换关系；
    所述将所述第一密钥调制到第一光源信号上，得到调制光信号，包括：
    获取生成的第一密钥，基于所述转换关系对应的逆转换关系和生成的第一密钥，确定调整后的第一密钥；
    将调整后的第一密钥调制到第一光源信号上，得到调制光信号。
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