A secure key distribution device, method, and storage medium

Abstract

The present invention discloses a secure key distribution device, method and storage medium, belonging to the technical field of optical key distribution. The secure key distribution device includes: a user A module, an optical fiber channel and a user B module; the user A module and the user B module use a dual polarization state modulation module for polarization multiplexing modulation, and place the modulated signal locally, and perform beat frequency coherent reception with the local oscillator optical signal transmitted through the optical fiber, so that both communication parties obtain a secure key; the local oscillator optical signals transmitted in both directions share the channel environment characteristics of the optical fiber channel at the same moment, and can realize long-distance key distribution with security and high distribution rate, thereby solving the technical problem that the existing key distribution based on coherent reception cannot balance security and high rate. Moreover, the characteristics of the local oscillator optical signal are simple, and it is less affected by optical fiber nonlinearity during transmission, which is convenient for obtaining keys with a high consistency rate from two user terminals.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical key distribution, and more specifically, relates to a secure key distribution device, method, and storage medium. Background Art

[0002] Traditional upper-layer key distribution methods based on cryptographic algorithms rely on computational complexity, but the continuous development of quantum computing poses a risk of being cracked for this method. On the contrary, physical-layer secure key distribution based on physical laws can provide higher security and thus has gradually become a research hotspot. Quantum key distribution is a typical application of physical-layer key distribution. It is based on the uncertainty principle and the no-cloning principle and can provide absolute security in theory, but its distribution efficiency and practical applications are limited. The method based on the reciprocal optical fiber channel has certain technical advantages. The so-called "reciprocity" specifically refers to the characteristic that the energy flows propagating in opposite directions in the transmission medium have symmetry within a certain measurement domain. For a "point-to-point" communication architecture, reciprocity provides a naturally shared measurement target for both parties participating in the communication and ensures that the final channel measurement results have a high degree of similarity. The optical fiber channel is affected by various factors and has an impact on the optical signal in multiple measurement domains. Many of its characteristics have been used to complete key distribution, such as phase noise, polarization mode dispersion, polarization state under Stokes vector representation, etc. However, in reality, ignoring the impact of occasional strong lightning, the optical fiber and its surrounding environment are relatively stable, and telecommunication equipment has the characteristic of slow change. These factors limit the rate of the key distribution system based on the characteristics of the optical fiber channel. Therefore, currently, the key generation rate of conventional reciprocal channel key distribution generally stagnates at the order of kbit / s. Later, research proposed that introducing artificial polarization perturbation or high-speed polarization modulation based on electro-optic modulation can effectively increase the key generation rate to the order of Gbit / s.

[0003] However, the above key distribution system based on the direct modulation and direct detection architecture is limited by the signal-to-noise ratio of the optical signal in the optical fiber channel and the sensitivity of the photoelectric receiver, and cannot achieve a long distribution distance, usually being limited to about 10 km. In the coherent optical communication architecture, relying on the high sensitivity of the coherent receiving module, it is expected to achieve long-distance secure key distribution, but it cannot balance security and high distribution rate. Summary of the Invention

[0004] In view of the above defects or improvement requirements of the prior art, the present invention provides a secure key distribution device, method and storage medium, the purpose of which is that both communication parties use a dual-polarization state modulation module for polarization multiplexing modulation, and place the modulated signal locally, and perform beat-frequency coherent reception with the local oscillator optical signal transmitted through the optical fiber, so that both communication parties obtain a secure key; the local oscillator optical signal transmitted bidirectionally shares the channel environment characteristics of the optical fiber channel at the same moment, which is difficult for eavesdroppers to obtain, and can achieve long-distance key distribution with security and high distribution rate, thereby solving the technical problem that the existing key distribution based on coherent reception cannot balance security and high rate.

[0005] To achieve the above object, according to one aspect of the present invention, a secure key distribution device is provided, including: a user A module, an optical fiber channel and a user B module; both the user A module and the user B module include:

[0006] An optical signal initialization module, configured to provide a linearly polarized optical signal;

[0007] A modulation signal generation module, configured to generate a modulated signal with perturbation;

[0008] A dual-polarization state modulation module, connected to the optical signal initialization module and the modulation signal generation module, and configured to modulate the linearly polarized optical signal with the modulation signal to obtain a modulated polarized light;

[0009] A local oscillator optical module, configured to generate a local oscillator optical signal with a polarization state and transmit it to the optical fiber channel, so that the optical fiber channel rotates the polarization states of the local oscillator optical signals generated by the local oscillator optical modules in both the user A module and the user B module based on the current optical fiber environment at the same time;

[0010] A coherent reception module, connected to the dual-polarization state modulation module and the optical fiber channel, and configured to perform beat-frequency on the modulated polarized light and the rotated local oscillator optical signal from the optical fiber channel to obtain a received signal; wherein, the optical fiber channel transmits the rotated local oscillator optical signal corresponding to the user A module to the coherent reception module of the user B module, and transmits the rotated local oscillator optical signal corresponding to the user B module to the coherent reception module of the user A module;

[0011] A secure key extraction module, connected to the coherent reception module, and configured to perform post-processing on the received signal to extract a secure key.

[0012] In one embodiment, the optical fiber channel includes:

[0013] An A-end optical circulator, connected to the local oscillator optical module of the user A module, and configured to guide the local oscillator optical signal output by the local oscillator optical module of the user A module into the optical fiber transmission channel;

[0014] The B - end optical circulator is connected to the local oscillator optical module of the user B module for bidirectional communication, and is used to guide the local oscillator optical signal output by the local oscillator optical module of the user B module into the optical fiber transmission channel;

[0015] The optical fiber transmission channel is in bidirectional communication with the A - end optical circulator and the B - end optical circulator, and is used to simultaneously rotate the polarization states of the local oscillator lights generated by the local oscillator optical modules in the user A module and the user B module based on the current optical fiber environment, so as to obtain the corresponding rotated local oscillator light of the user A module and the corresponding rotated local oscillator light of the user B module; and transmit the corresponding rotated local oscillator light of the user A module to the coherent receiving module in the user B module through the B - end optical circulator; transmit the corresponding rotated local oscillator light of the user B module to the coherent receiving module in the user A module through the A - end optical circulator.

[0016] In one embodiment, the modulation signal generating module includes:

[0017] An arbitrary waveform generator, which is used to output the digital perturbation signal obtained through offline processing as an analog signal;

[0018] An electrical signal amplifier, which is connected to the arbitrary waveform generator and the dual - polarization state modulation module, and is used to amplify the analog signal to obtain the modulation signal and transmit it to the dual - polarization state modulation module.

[0019] In one embodiment, the offline processing includes: using a digital chaotic signal to perturb the constellation diagram corresponding to the original waveform signal to obtain the perturbation signal.

[0020] In one embodiment, the optical signal initialization module includes:

[0021] A light source, which is used to provide a DC optical signal with a stable linear polarization state;

[0022] A polarization controller, which is arranged on the outgoing optical path of the DC optical signal and is connected to the dual - polarization state modulation module, and is used to adjust the linear polarization state of the DC optical signal to obtain the linearly polarized optical signal and transmit it to the dual - polarization state modulation module.

[0023] In one embodiment, the dual - polarization state modulation module includes:

[0024] A polarization beam splitter, which is connected to the optical signal initialization module and is used to decompose the input linearly polarized optical signal into two orthogonally polarized lights;

[0025] A dual - polarization IQ modulator, which is connected to the polarization beam splitter and the modulation signal generating module, and is used to perform intensity modulation and phase modulation on the two orthogonally polarized lights by using the modulation signal to obtain two modulated lights;

[0026] A polarization beam combiner, connected to the dual-polarization IQ modulator and the coherent receiving module, for combining the two modulated optical beams to obtain the modulated polarized light and transmitting it to the coherent receiving module.

[0027] In one embodiment, the local oscillator optical module includes:

[0028] A local oscillator light source for providing a DC optical signal with a stable linear polarization state;

[0029] A local oscillator polarization controller, disposed on the outgoing optical path of the DC optical signal and connected to the optical fiber channel, for adjusting the polarization state of the linearly polarized optical signal.

[0030] In one embodiment, the received signal includes: the real part information XI in the X polarization state, the imaginary part information XQ in the X polarization state, the real part information YI in the Y polarization state, and the imaginary part information YQ in the Y polarization state; using The security key characterizing the analog state, where R is the sensitivity of the coherent receiver, S is the amplitude of the modulation signal, and L′ is the signal intensity of the local oscillator light.

[0031] According to another aspect of the present invention, a security key distribution method is provided, including:

[0032] S1: Using the user A module to generate a linearly polarized optical signal and a perturbed modulation signal, and modulating the linearly polarized optical signal with the modulation signal to obtain modulated polarized light;

[0033] S2: Using the user B module to provide a linearly polarized optical signal and generate a perturbed modulation signal, and modulating the linearly polarized optical signal with the modulation signal to obtain modulated polarized light;

[0034] S3: Using the optical fiber channel to simultaneously rotate the polarization states of the local oscillator lights generated by the local oscillator optical modules in the user A module and the user B module based on the current optical fiber environment to obtain the corresponding rotated local oscillator light of the user A module and the corresponding rotated local oscillator light of the user B module; and transmitting the corresponding rotated local oscillator light of the user A module to the user B module; transmitting the corresponding rotated local oscillator light of the user B module to the user A module;

[0035] S4: Controlling the user A module to perform beat frequency on the generated modulated polarized light and the corresponding rotated local oscillator light of the user B module to obtain a received signal, and performing post-processing on it to obtain a security key;

[0036] S5: Controlling the user B module to perform beat frequency on the generated modulated polarized light and the corresponding rotated local oscillator light of the user A module to obtain a received signal, and performing post-processing on it to obtain the security key.

[0037] According to another aspect of the present invention, there is provided a computer-readable storage medium having stored thereon a computer program, and when the computer program is executed by a processor, the steps of the method are performed.

[0038] Generally speaking, compared with the prior art by the above technical solution conceived by the present invention, the following beneficial effects can be achieved:

[0039] (1) The present invention provides a secure key distribution device. Among them, both communication parties use a dual-polarization state modulation module for polarization multiplexing modulation, and place the modulated signal locally, and perform beat frequency coherent reception with the local oscillator optical signal transmitted through the optical fiber, so that both communication parties obtain a secure key; the local oscillator optical signals transmitted in both directions share the channel environment characteristics of the optical fiber channel at the same moment, and can realize long-distance key distribution with security and high distribution rate, thereby solving the technical problem that the existing key distribution based on coherent reception cannot balance security and high rate. Moreover, the characteristics of the local oscillator optical signal are simple, and it is less affected by fiber nonlinearity during transmission, which is convenient for obtaining highly consistent keys from two user terminals.

[0040] (2) The optical fiber channel includes: an optical circulator at end A, an optical circulator at end B, and an optical fiber transmission channel. The optical fiber transmission channel rotates the polarization states of the local oscillator optical signals generated by the local oscillator optical modules in the user A module and the user B module based on the current optical fiber environment at the same time, to obtain the corresponding rotated local oscillator optical signal of the user A module and the corresponding rotated local oscillator optical signal of the user B module; the simple structure of the optical fiber channel enables the local oscillator optical signals transmitted in both directions of communication to share the channel environment characteristics of the optical fiber channel at the same moment, and it is difficult for eavesdroppers to obtain, which provides a guarantee for the security of the secure key distribution process.

[0041] (3) Combining chaotic signal perturbation and the polarization reciprocity of the optical fiber channel for secure key distribution, on the basis of ensuring high key distribution rate and high security, long-distance key extraction is realized. In the past, the key distribution system under the direct modulation and direct detection framework was limited by the signal-to-noise ratio and the detector sensitivity, and could not achieve a long distribution distance. The present invention utilizes the polarization reciprocity of the optical fiber channel to achieve higher security and longer distribution distance, and using chaotic signals to perturb the constellation diagram can further improve the key distribution rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is the schematic diagram of the control method of the secure key distribution device provided in Embodiment 1 of the present invention.

[0043] Figure 2 is the structure diagram of the secure key distribution device provided in Embodiment 2 of the present invention.

[0044] Figure 3It is the constellation diagram after the disturbance generated by the first digital generation module of the secure key distribution device provided in Embodiment 4 of the present invention.

[0045] Figure 4 It is the time-domain waveform diagram of the analog key stream signals generated by the user A module and the user B module of the secure key distribution device provided in Embodiment 8 of the present invention.

[0046] Figure 5 It is the spectrogram of the analog key stream signals generated by the user A module and the user B module of the secure key distribution device provided in Embodiment 8 of the present invention.

[0047] Figure 6 It is the correlation scatter diagram of the analog key stream signals generated by the user A module and the user B module of the secure key distribution device provided in Embodiment 8 of the present invention. Detailed implementation manners

[0048] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0049] It should be noted that each embodiment of the present invention describes and differentiates each module in the user A module and the user B module: The user A module includes: a first optical signal initialization module, a first modulation signal generation module, a first dual-polarization modulation module, a first local oscillator optical module, a first coherent reception module, and a first secure key extraction module. The user B module includes: a second optical signal initialization module, a second modulation signal generation module, a second dual-polarization modulation module, a second local oscillator optical module, a second coherent reception module, and a second secure key extraction module.

[0050] Embodiment 1

[0051] As Figure 1 shown, this embodiment provides a secure key distribution device, including: a user A module, an optical fiber channel 7, and a user B module.

[0052] Among them, in the user A module: The first optical signal initialization module 1 is used to provide an optical signal with a specific polarization state and output the optical signal with the specific polarization state to the first input port of the first dual-polarization modulation module. The first modulation signal generation module 3 is used to perform modulation signal processing at the coherent optical communication transmitter end, use a digital chaotic signal to perturb the constellation diagram to obtain an analog signal, and use the amplified analog signal as the modulation signal and transmit it to the second input port of the first dual-polarization modulation module. The first dual-polarization modulation module 2 is used to modulate the optical signal generated by the first optical signal initialization module with the modulation signal generated by the first modulation signal generation module, and output the modulated optical signal to the first input port of the first coherent reception module. The first local oscillator optical module 4 is used to provide an optical signal with a specific polarization state and output the optical signal with the specific polarization state to the first input port of the optical fiber channel 7. The first coherent reception module 5 is used to perform beat frequency on the optical signal after the above modulation and the optical signal after being transmitted through the optical fiber channel 7 to obtain a received signal, and output the received signal to the first secure key extraction module. The first secure key extraction module 6 is used to perform modulation signal processing, sampling quantization, error correction, and other post-processing on the electrical signal obtained by the first coherent reception module to extract the secure key.

[0053] Among them, in the user B module: The second optical signal initialization module 8 is used to provide an optical signal with a specific polarization state and output the optical signal with the specific polarization state to the first input port of the second dual-polarization modulation module. The second modulation signal generation module 10 is used to perform modulation signal processing at the coherent optical communication transmitter end, use a digital chaotic signal to perturb the constellation diagram to obtain an analog signal, and transmit the amplified analog signal to the second input port of the second dual-polarization modulation module. The second dual-polarization modulation module 9 is used to modulate the optical signal generated by the second optical signal initialization module with the modulation signal generated by the second modulation signal generation module, and output the modulated optical signal to the first input port of the second coherent reception module. The second local oscillator optical module 11 is used to provide an optical signal with a specific polarization state and output the optical signal with the specific polarization state to the second input port of the optical fiber channel 7. The second coherent reception module 12 is used to perform beat frequency on the optical signal after the above modulation and the optical signal after being transmitted through the optical fiber channel 7 to obtain a received signal, and output the received signal to the second secure key extraction module. The second secure key extraction module 13 is used to perform modulation signal processing, sampling quantization, error correction, and other post-processing on the electrical signal obtained by the second coherent reception module to extract the secure key.

[0054] Among them, the optical fiber channel 7 is used to transmit the optical signals generated by the first local oscillator optical module and the second local oscillator optical module in the optical fiber channel 7, and is also used to output signals to the second port of the first coherent receiving module and the second port of the second coherent receiving module. Specifically, the optical fiber channel 7 rotates the polarization states of the local oscillator lights generated by the local oscillator optical modules in the user A module and the user B module simultaneously based on the current optical fiber environment. The optical fiber channel 7 transmits the correspondingly rotated local oscillator light of the user A module to the coherent receiving module of the user B module, and transmits the correspondingly rotated local oscillator light of the user B module to the coherent receiving module of the user A module.

[0055] Embodiment 2

[0056] As Figure 2 shown, the optical fiber channel 7 includes: an A-end optical circulator 71, an optical fiber transmission channel 72, and a B-end optical circulator 73.

[0057] Among them, the A-end optical circulator 71 is connected to the local oscillator optical module of the user A module, and is used to guide the local oscillator optical signal output by the local oscillator optical module of the user A module into the optical fiber transmission channel 72.

[0058] Among them, the B-end optical circulator 73 is connected to the local oscillator optical module of the user B module for two-way communication, and is used to guide the local oscillator optical signal output by the local oscillator optical module of the user B module into the optical fiber transmission channel 72.

[0059] Among them, the optical fiber transmission channel 72 communicates with the A-end optical circulator 71 and the B-end optical circulator 73 in both directions, and is used to rotate the polarization states of the local oscillator lights generated by the local oscillator optical modules in the user A module and the user B module simultaneously based on the current optical fiber environment, so as to obtain the correspondingly rotated local oscillator light of the user A module and the correspondingly rotated local oscillator light of the user B module. And it transmits the correspondingly rotated local oscillator light of the user A module to the coherent receiving module in the user B module through the B-end optical circulator 73. It transmits the correspondingly rotated local oscillator light of the user B module to the coherent receiving module in the user A module through the A-end optical circulator 71. Specifically, the optical fiber transmission channel 72 carries the two-way transmission of optical signals and introduces the characteristics caused by the influence of the external environment and the characteristics of the optical fiber itself.

[0060] In this embodiment, the optical fiber channel 7 is connected to and shared by the user A module and the user B module. The A-end optical circulator 71 is used to guide the optical signal generated by the first local oscillator optical module 4 into the optical fiber transmission channel and guide the optical signal generated by the second local oscillator optical module 11 transmitted through the optical fiber into the first coherent receiving module 5. The B-end optical circulator 73 is used to guide the optical signal generated by the second local oscillator optical module 11 into the optical fiber transmission channel and guide the optical signal generated by the first local oscillator optical module 4 transmitted through the optical fiber into the second coherent receiving module 12. The optical fiber transmission channel 72 (50-kilometer standard single-mode optical fiber) is used to carry the bidirectional transmission of optical signals and introduce characteristics caused by external environmental influences and the characteristics of the optical fiber itself. The transmission matrix of the optical fiber transmission channel 72 can be denoted as a unitary matrix U, which is used to represent a series of phase shifts and polarization rotations in the optical fiber. When the optical signals generated by the first local oscillator optical module 4 and the second local oscillator optical module 11 are transmitted bidirectionally in the optical fiber transmission channel 72, they have the reciprocal property, that is, U = U T , where the operator T represents the transpose matrix. Here, the local oscillator optical signal after being transmitted through the optical fiber can be expressed as L′1 = U T *L2 and L′2 = U*L1, that is, L′1 = L′2.

[0061] Embodiment 3

[0062] As Figure 2 shown, the first modulation signal generation module 3 includes a first arbitrary waveform generator 31 and a first electrical signal amplifier 32. The first arbitrary waveform generator 31 is used to output the perturbation signal obtained through offline processing as a modulation signal, and the first electrical signal amplifier 32 is used to amplify the above modulation signal and transmit the modulation signal to the second input port of the first dual-polarization state modulation module 2.

[0063] The second modulation signal generation module 10 includes a second arbitrary waveform generator 101 and a second electrical signal amplifier 102. The second arbitrary waveform generator 101 is used to output the same signal as that in the first modulation signal generation module 3, and the second electrical signal amplifier 102 is used to amplify the above signal and transmit the signal to the second input port of the second dual-polarization state modulation module 9.

[0064] Embodiment 4

[0065] The offline processing includes: using a digital chaotic signal to perturb the constellation diagram corresponding to the original waveform signal to obtain a perturbation signal.

[0066] Specifically, the first modulation signal generation module and the second modulation signal generation module are used to process the modulation signal at the transmitting end of coherent optical communication, perturb the constellation diagram using a digital chaotic signal, and output the modulation signal. The perturbation method is as follows: the chaotic signal is used to multiply and perturb the amplitude and phase of the original signal respectively, which is manifested as the points that are originally scattered in the radial and angular directions on the constellation diagram becoming randomly distributed points.

[0067] Embodiment 5

[0068] As Figure 2 shown, the optical signal generated by the first optical signal initialization module 1 enters the first dual-polarization state modulation module 2, which includes a first polarization beam splitter 21, a first dual-polarization IQ modulator 22, and a first polarization combiner 23. The first polarization beam splitter 21 is used to decompose the input linearly polarized optical signal into two orthogonal polarization modes and output them to two fiber output ends respectively; the first dual-polarization IQ modulator 22 is used to apply deterministic intensity and phase modulation to the optical signal; the first polarization combiner 23 is used to combine the two orthogonal polarization mode optical signals and output them to a single fiber output end. The signal output by the first dual-polarization state modulation module 2 can be expressed as S1. The constellation diagram of this output signal is as Figure 3 shown, presenting a disc-shaped distribution.

[0069] The second optical signal initialization module 8 provided in the embodiment of the present invention includes: a second light source 81 and a second polarization controller 82. Among them, the second light source 81 is used to provide a DC optical signal with a stable linear polarization state. The second polarization controller 82 is used to adjust the polarization state of the linearly polarized optical signal.

[0070] Embodiment 6

[0071] As Figure 2 shown, the optical signal generated by the first optical signal initialization module 1 enters the first dual-polarization state modulation module 2, which includes a first polarization beam splitter 21, a first dual-polarization IQ modulator 22, and a first polarization combiner 23. The first polarization beam splitter 21 is used to decompose the input linearly polarized optical signal into two orthogonal polarization modes and output them to two fiber output ends respectively; the first dual-polarization IQ modulator 22 is used to apply deterministic intensity and phase modulation to the optical signal; the first polarization combiner 23 is used to combine the two orthogonal polarization mode optical signals and output them to a single fiber output end. The signal output by the first dual-polarization state modulation module 2 can be expressed as S1. The constellation diagram of this output signal is as Figure 3 shown, presenting a disc-shaped distribution.

[0072] In the embodiments of the present invention, the second dual-polarization state modulation module 9 and the first dual-polarization state modulation module 2 have similar performance levels and configuration parameters, including that the modulation coefficients of the first dual-polarization IQ modulator 22 and the second dual-polarization IQ modulator 92 are similar, the optical attenuation ratios of the two paths after the optical signal is split are similar, the phase differences introduced after the optical signal is split are similar, and so on. Secondly, the second modulation signal generation module 10 and the first modulation signal generation module 3 have similar performance parameters, including the sampling rate settings of the first arbitrary waveform generator 31 and the second arbitrary waveform generator 101, and the amplification factors of the first electrical signal amplifier 32 and the second electrical signal amplifier 102. In this case, the optical signals output by the first dual-polarization state modulation module 2 and the second dual-polarization state modulation module 9 are almost the same, that is, S1 = S2.

[0073] The second optical signal initialization module 8 includes a second light source 81 and a second polarization controller 82. The second light source 81 is used to provide a DC optical signal with a stable linear polarization state; the second polarization controller 82 is used to adjust the polarization state of the linearly polarized optical signal to ensure that the initial polarization state of the optical signal of the user B module is the same as that of the user A module. In the technical solution disclosed in the embodiments of the present invention, the initial polarization states of the optical signals of the user A module and the user B module are +45-degree linearly polarized states, which ensures the best polarization modulation efficiency when the optical signals enter the first polarization beam splitter 21 and the second polarization beam splitter 91.

[0074] Embodiment 7

[0075] As Figure 2 shown, the first local oscillator optical module 4 includes a third light source 41 and a third polarization controller 42. The third light source 41 generates a DC optical signal with a linear polarization state, and the third polarization controller 42 is used to adjust the polarization state of the DC linearly polarized light to complete the setting of the initial polarization state of the optical signal. The optical signal generated by the first local oscillator optical module 4 can be represented as L1, and this signal is transmitted to the first port of the optical fiber channel 7.

[0076] The second local oscillator optical module 11 includes a fourth light source 111 and a fourth polarization controller 112. The fourth light source 111 generates a DC optical signal with a linear polarization state, and the fourth polarization controller 112 is used to adjust the polarization state of the DC linearly polarized light to complete the setting of the initial polarization state of the optical signal. Ensure that the polarization state of the optical signal output by the second local oscillator optical module 11 is the same as the polarization state of the optical signal output by the first local oscillator optical module 4. The optical signal generated by the second local oscillator optical module 11 can be represented as L2, and this signal is transmitted to the second port of the optical fiber channel 7. In this embodiment, the signal intensities and polarization states of the optical signals generated by the first local oscillator optical module 4 and the second local oscillator optical module 11 are the same, that is, L1 = L2.

[0077] Embodiment 8

[0078] The received signal includes: the real part information XI in the X polarization state, the imaginary part information XQ in the X polarization state, the real part information YI in the Y polarization state, and the imaginary part information YQ in the Y polarization state. Using to characterize the secure key of the analog state.

[0079] Specifically, the first coherent receiving module 5 of user A's module includes a first integrated coherent receiving module 51, which is used to perform beat frequency on the modulated signal and the local oscillator optical signal transmitted through the optical fiber to obtain the received signal. The received signal includes four parts, namely XI, XQ, YI, and YQ. Using as the analog key stream, where R represents the sensitivity of the receiving module. The key stream of user A's module is correspondingly expressed as The first secure key extraction module 6 includes a first data processing unit 61, which is used to perform key extraction processing such as modulation signal processing, sampling quantization, error correction, interleaving, and privacy amplification on the input signal, and output the secure key K1.

[0080] The second coherent receiving module 12 of user B's module includes a second integrated coherent receiving module 121, which is used to perform beat frequency on the modulated signal and the local oscillator optical signal transmitted through the optical fiber to obtain the received signal. The received signal includes four parts, namely XI, XQ, YI, and YQ. Using as the analog key stream, where R represents the sensitivity of the receiving module. The key stream of user B's module is correspondingly expressed as The second secure key extraction module 13 includes a second data processing unit 131, which is used to perform key extraction processing such as modulation signal processing, sampling quantization, error correction, interleaving, and privacy amplification on the input signal, and output the secure key K2. According to the above formula, it can be seen that the analog key stream K2 obtained by user B's module is highly consistent with K1. After the same processing operations of the first data processing unit 61 and the second data processing unit 131, consistent secure keys K1 and K2 can be obtained in user A's module and user B's module.

[0081] The analog key stream signals respectively generated by the secure key distribution device provided by the embodiment of the present invention in user A's module and user B's module are as Figure 4 shown. User A's module (user 1 side) and user B's module (user 2 side) can obtain consistent normalized signal changes. The spectra of the analog key stream signals respectively generated by user A's module (user 1 side) and user B's module (user 2 side) are as Figure 5 shown. The spectra are wide and flat, which is beneficial to extracting high-speed keys. The correlation scatter plots of the analog key stream signals received by user A's module (user 1 side) and user B's module (user 2 side) are as Figure 6As shown, the correlation coefficient between the two is 0.93, approaching the theoretical maximum value of 1, indicating that the analog key stream signals received by User A module and User B module have good consistency, providing a basis for high-quality secure key distribution.

[0082] The first data processing unit 61 and the second data processing unit 131 provided in the embodiments of the present invention sample the analog key stream signal, perform dual-threshold quantization into a binary bit stream, complete random block interleaving, error correction based on BCH coding, and privacy amplification steps based on the SHA-3 algorithm between User A module and User B module to obtain the final secure keys K1 and K2, with a distribution rate of 1.85 Gbit / s. In the case of achieving the same performance level, the data processing methods used by the first data processing unit 61 and the second data processing unit 131 in the embodiments of the present invention are not limited to the processing methods and sequences used in this embodiment.

[0083] Embodiment 9

[0084] According to another aspect of the present invention, a secure key distribution method is provided, including:

[0085] S1: Using User A module to generate a linearly polarized light signal and a perturbed modulation signal, and modulating the linearly polarized light signal with the modulation signal to obtain a modulated polarized light.

[0086] S2: Using User B module to provide a linearly polarized light signal and generate a perturbed modulation signal, and modulating the linearly polarized light signal with the modulation signal to obtain a modulated polarized light.

[0087] S3: Using an optical fiber channel to simultaneously rotate the polarization states of the local oscillator lights generated by the local oscillator light modules in User A module and User B module based on the current optical fiber environment to obtain the corresponding rotated local oscillator light of User A module and the corresponding rotated local oscillator light of User B module. And transmitting the corresponding rotated local oscillator light of User A module to User B module. Transmitting the corresponding rotated local oscillator light of User B module to User A module.

[0088] S4: Controlling User A module to perform beat frequency on the generated modulated polarized light and the corresponding rotated local oscillator light of User B module to obtain a received signal, and performing post-processing on it to obtain a secure key.

[0089] S5: Controlling User A module to perform beat frequency on the generated modulated polarized light and the corresponding rotated local oscillator light of User A module to obtain a received signal, and performing post-processing on it to obtain a secure key.

[0090] Embodiment 10

[0091] According to another aspect of the present invention, there is provided a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the above method.

[0092] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or dedicated designed hardware. Those of ordinary skill in the art can understand that the above devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code is provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuits of programmable hardware devices such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, or can be implemented by a combination of the above hardware circuits and software, such as firmware.

[0093] It is easy for those skilled in the art to understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A secure key distribution device, characterized in that, Comprising: User A module, optical fiber channel, and User B module; Both the User A module and the User B module include: An optical signal initialization module for providing a linearly polarized optical signal; A modulation signal generation module for generating a perturbed modulation signal; A dual-polarization state modulation module connected to the optical signal initialization module and the modulation signal generation module for modulating the linearly polarized optical signal with the modulation signal to obtain a modulated polarized light; A local oscillator optical module for generating a local oscillator optical signal with a specific polarization state and transmitting it to the optical fiber channel, so that the optical fiber channel rotates the polarization states of the local oscillator optical signals generated by the local oscillator optical modules in both the User A module and the User B module based on the current optical fiber environment; A coherent reception module connected to the dual-polarization state modulation module and the optical fiber channel for performing beat frequency on the modulated polarized light and the rotated local oscillator optical signal from the optical fiber channel to obtain a received signal; wherein, the optical fiber channel transmits the rotated local oscillator optical signal corresponding to the User A module to the coherent reception module of the User B module, and transmits the rotated local oscillator optical signal corresponding to the User B module to the coherent reception module of the User A module; A security key extraction module connected to the coherent reception module for post-processing the received signal to extract a security key.

2. The security key distribution device according to claim 1, wherein The optical fiber channel includes: An A-end optical circulator connected to the local oscillator optical module of the User A module for guiding the local oscillator optical signal output by the local oscillator optical module of the User A module into the optical fiber transmission channel; A B-end optical circulator connected to the local oscillator optical module of the User B module for two-way communication, for guiding the local oscillator optical signal output by the local oscillator optical module of the User B module into the optical fiber transmission channel; An optical fiber transmission channel in two-way communication with the A-end optical circulator and the B-end optical circulator for rotating the polarization states of the local oscillator optical signals generated by the local oscillator optical modules in both the User A module and the User B module based on the current optical fiber environment to obtain the rotated local oscillator optical signal corresponding to the User A module and the rotated local oscillator optical signal corresponding to the User B module; and transmitting the rotated local oscillator optical signal corresponding to the User A module to the coherent reception module in the User B module through the B-end optical circulator; transmitting the rotated local oscillator optical signal corresponding to the User B module to the coherent reception module in the User A module through the A-end optical circulator.

3. The secure key distribution device according to claim 1, characterized in that, The modulation signal generation module includes: An arbitrary waveform generator for outputting a digital perturbation signal obtained through offline processing as an analog signal; An electrical signal amplifier connected to the arbitrary waveform generator and the dual-polarization state modulation module for amplifying the analog signal to obtain the modulation signal and transmitting it to the dual-polarization state modulation module.

4. The secure key distribution device according to claim 3, wherein The offline processing includes: Using a digital chaotic signal to perturb the constellation diagram corresponding to the original waveform signal to obtain the perturbation signal.

5. The secure key distribution device according to claim 1, wherein The optical signal initialization module includes: A light source for providing a direct current optical signal with a stable linear polarization state; A polarization controller is arranged on the outgoing optical path of the DC optical signal and connected to the dual-polarization-state modulation module, and is used for adjusting the linear polarization state of the DC optical signal to obtain the linearly polarized optical signal and transmitting it to the dual-polarization-state modulation module.

6. The secure key distribution device according to claim 1, characterized in that, The dual-polarization-state modulation module includes: A polarization beam splitter, connected to the optical signal initialization module, and is used for decomposing the input linearly polarized optical signal into two orthogonally polarized lights; A dual-polarization IQ modulator, connected to the polarization beam splitter and the modulation signal generation module, and is used for intensity modulating and phase modulating the two orthogonally polarized lights by using the modulation signal to obtain two modulated lights; A polarization combiner, connected to the dual-polarization IQ modulator and the coherent receiving module, and is used for combining the two modulated lights to obtain the modulated polarized light and transmitting it to the coherent receiving module.

7. The secure key distribution device according to claim 1, characterized in that, The local oscillator optical module includes: A local oscillator light source, used for providing a DC optical signal with a stable linear polarization state; A local oscillator polarization controller, arranged on the outgoing optical path of the DC optical signal and connected to the optical fiber channel, and is used for adjusting the polarization state of the linearly polarized optical signal.

8. The security key distribution device according to claim 1, characterized in that, The received signal includes: the real part information XI on the X polarization state, the imaginary part information XQ on the X polarization state, the real part information YI on the Y polarization state, and the imaginary part information YQ on the Y polarization state; using K = √XI 2 + XQ 2 + YI 2 + YQ 2 = RSL ′ The security key characterizing the analog state, where R is the sensitivity of the coherent receiver, S is the amplitude of the modulation signal, and L ′ is the signal intensity of the local oscillator light.

9. A secure key distribution method, characterized in that, It includes: S1: Using the user A module to generate a linearly polarized optical signal and a perturbed modulation signal, and using the modulation signal to modulate the linearly polarized optical signal to obtain a modulated polarized light; S2: Using the user B module to provide a linearly polarized optical signal and generate a perturbed modulation signal, and using the modulation signal to modulate the linearly polarized optical signal to obtain a modulated polarized light; S3: Using the optical fiber channel to simultaneously rotate the polarization states of the local oscillator lights generated by the local oscillator optical modules in the user A module and the user B module based on the current optical fiber environment to obtain the corresponding rotated local oscillator light of the user A module and the corresponding rotated local oscillator light of the user B module; and transmitting the corresponding rotated local oscillator light of the user A module to the user B module; transmitting the corresponding rotated local oscillator light of the user B module to the user A module; S4: Controlling the user A module to perform beat frequency on the generated modulated polarized light and the corresponding rotated local oscillator light of the user B module to obtain a received signal, and performing post-processing on it to obtain a security key; S5: Controlling the user B module to perform beat frequency on the generated modulated polarized light and the corresponding rotated local oscillator light of the user A module to obtain a received signal, and performing post-processing on it to obtain the security key.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method described in claim 9.

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