Security enhancement method based on multi-core optical fiber quantum noise stream encryption system

Abstract

The invention discloses a security enhancement method based on a multi-core optical fiber quantum noise stream encryption system. A receiving end and a transmitting end share a quantum noise stream encryption key and an optical delay key of each signal channel; the distributed feedback laser generates a homologous local oscillator and an optical carrier of each channel; a transmitting terminal uses a plurality of IQ modulators for modulation to obtain multiple paths of quantum noise stream encrypted optical signals, the quantum noise stream encrypted optical signals are respectively delayed according to an optical delay key, and then the quantum noise stream encrypted optical signals are transmitted to a receiving terminal through a peripheral fiber core of a multi-core optical fiber; homologous local oscillator light is transmitted to a receiving light splitter through an intermediate fiber core, and light delay matching is carried out after light splitting to obtain the local oscillator of each signal channel; carrying out self-coherent detection on the local oscillator and the encrypted optical signal which are matched with each channel in a delay manner through a coherent receiver to obtain an encrypted electric signal of each channel; according to the method, eavesdropping of illegal parties is interfered by means of the physical structure of the multi-core optical fiber and artificially added optical delay, the security is improved, and meanwhile, capacity expansion is realized and the DSP is simplified.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to a security enhancement method based on a multi-core optical fiber quantum noise stream encryption system. Background Art

[0002] With the development of Internet applications, a large amount of user personal information is transmitted through the network every moment. Therefore, the security of the communication network has become a performance indicator that cannot be ignored. However, with the development of quantum computing, traditional cryptographic encryption methods based on computational complexity can no longer guarantee absolute security, and physical layer encryption technology has become its alternative. Compared with classical physical layer encryption technologies such as quantum communication, chaotic secure communication, and optical code division multiplexing, quantum noise stream encryption technology stands out with its excellent compatibility and high-speed and long-distance transmission capabilities, and has become a research hotspot in recent years.

[0003] However, unlike the traditional one-time encryption scheme, the key of quantum noise stream encryption technology is usually obtained by expanding the seed key from the shift register. It is easy to be cracked by brute force when dealing with eavesdropping methods such as fast correlation attacks, so it is very necessary to further improve the security of quantum noise stream encryption. At present, there are mainly the following solutions to enhance the security of quantum noise stream encryption technology: the first is to reduce the signal-to-noise ratio of the system, but this will affect the normal communication performance of the system and shorten the transmission distance; the second is to increase the order of quantum noise stream encryption. This solution puts forward high requirements on the quantization accuracy of the transmitter DAC, and can only improve the cover of the encryption bit of the quantum noise stream encrypted ciphertext. The information bit is still exposed to eavesdropping and is easily cracked by low-order demodulation technology; the third is to add random noise artificially. In order to avoid additional key overhead, this method can only cover the encryption bit, which is similar to the previous case. In short, none of the current solutions can achieve the cover of information bits, and blindly increasing the cover effect of encryption bits will not significantly improve the security of quantum noise stream encryption. Summary of the invention

[0004] In view of the defects and improvement needs of the prior art, the present invention provides a security enhancement method based on a multi-core optical fiber quantum noise stream encryption system.

[0005] The multi-core optical fiber quantum noise stream encryption system of the present invention comprises: Transmitter terminal, multiple transmitter adjustable optical delay devices, distributed feedback laser, transmitter optical splitter, fan-in, multi-core optical fiber, multiple IQ modulators, fan-out, receiver optical splitter, multiple receiver adjustable optical delay devices, coherent receiver, receiver terminal; The transmitting terminal is connected to the receiving terminal; The transmitting terminal is connected to the plurality of transmitting-end adjustable optical delay devices in sequence; The distributed feedback laser is connected to the transmitting optical splitter; The transmitting optical splitter is connected to the fan-in; The fan-in is connected to the middle core of the multi-core optical fiber; The middle fiber core of the multi-core optical fiber is connected to the fan-out device; The transmitting optical splitter is connected to the multiple IQ modulators in sequence; The transmitting terminal is connected to the multiple IQ modulators in sequence; The multiple IQ modulators are connected to the multiple transmitter-end adjustable optical delay devices in sequence; The plurality of transmitter-end adjustable optical delay devices are connected to the fan-in device in sequence; The fan-in is connected to the multiple peripheral cores of the multi-core optical fiber in sequence; The plurality of peripheral cores of the multi-core optical fiber are sequentially connected to the fan-out device; The fan-out device is connected to the receiving optical splitter; The receiving optical splitter is connected to the plurality of receiving-end adjustable optical delay devices in sequence; The multiple receiving-end adjustable optical delay devices are sequentially connected to the coherent receiver; The fan-out is connected to the coherent receiver; The coherent receiver is connected to the receiving terminal; The number of the adjustable optical delay device at the transmitting end, the peripheral core of the multi-core optical fiber, the IQ modulator, and the adjustable optical delay device at the receiving end are all the same; The security enhancement method specifically comprises the following steps: Step 1: The transmitting terminal and the receiving terminal share the quantum noise stream encryption key and the optical delay key of each signal channel, and transmit the optical delay key of each signal channel to each transmitting end adjustable optical delay device; Step 2: The distributed feedback laser generates a homologous local oscillator optical signal and transmits it to the fan-out device, which generates an optical carrier for each signal channel and transmits it to each IQ modulator; Step 3: The transmitting terminal generates a high-order encrypted analog signal, which is further modulated to obtain a quantum noise stream encrypted optical signal for each signal channel; Step 4: Generate a delayed quantum noise stream encrypted optical signal for each signal channel and transmit it to the fan-out device; Step 5: Couple the homologous local oscillator optical signal to the receiving optical splitter, and couple the delayed quantum noise stream encrypted optical signal of each signal channel to the coherent receiver; Step 6: Generate a local oscillator optical signal of the signal channel and transmit it to the adjustable optical delay device at the receiving end; Step 7: Generate a local oscillator optical signal with optical delay matching for each signal channel through each receiving end adjustable optical delay device, and transmit it to the coherent receiver for self-coherent detection to obtain the quantum noise stream encrypted electrical signal of each signal channel, and output it to the receiving end terminal; Step 8: The receiving terminal combines the quantum noise stream encrypted electrical signal of each signal channel with the quantum noise stream encryption key through the quantum noise stream decryption method to obtain the decrypted plaintext signal.

[0006] Preferably, the step 1 is as follows: The transmitting terminal generates a plaintext signal, generates a quantum noise stream encryption key and an optical delay key for each signal channel through a pseudo-random number generator, and transmits the quantum noise stream encryption key and the optical delay key for each signal channel to the receiving terminal for sharing; the number of bits of quantum noise stream encryption is set, and a high-order encrypted signal is obtained through quantum noise stream encryption in combination with the noise stream encryption key, and the optical delay key for each signal channel is transmitted to each transmitting terminal adjustable optical delay device.

[0007] Preferably, the step 2 is as follows: The laser signal output by the distributed feedback laser is divided into multiple original optical signals by the transmitting optical splitter, one of which is coupled into the middle core of the multi-core optical fiber through the fan-in as a homologous local oscillator optical signal. The middle core of the multi-core optical fiber transmits the homologous local oscillator optical signal to the fan-out device, and each of the remaining original optical signals is used as the optical carrier of each signal channel, and the optical carrier of each signal channel is transmitted to each IQ modulator through the optical fiber.

[0008] Preferably, the step 3 is as follows: The transmitting terminal converts the high-order encrypted signal into a high-order encrypted analog signal through digital-to-analog conversion, and further transmits it to each IQ modulator. Each IQ modulator modulates the high-order encrypted analog signal on the optical carrier of each signal channel to obtain the quantum noise stream encrypted optical signal of each signal channel, and transmits the quantum noise stream encrypted optical signal of each signal channel to the adjustable optical delay device of each signal channel.

[0009] Preferably, the step 4 is as follows: Each transmitting end adjustable optical delay device optically delays the modulated quantum noise stream encrypted optical signal of each signal channel according to the optical delay key of each signal channel to obtain the delayed quantum noise stream encrypted optical signal of each signal channel; the delayed quantum noise stream encrypted optical signal of each signal channel is coupled into each outer fiber core of the multi-core optical fiber through the fan-in device, and each outer fiber core of the multi-core optical fiber transmits the delayed quantum noise stream encrypted optical signal of each signal channel to the fan-out device.

[0010] Preferably, the step 5 is as follows: The fan-out couples the homologous local oscillator optical signal out of the multi-core optical fiber and transmits it to the receiving optical splitter, and couples the delayed quantum noise stream encrypted optical signal of each signal channel out of the multi-core optical fiber and transmits it to the coherent receiver.

[0011] Preferably, the step 6 is as follows: The receiving optical splitter splits the homologous local oscillator optical signal into local oscillator optical signals of multiple signal channels. The number of paths of the optical splitter is the same as the number of peripheral cores of the multi-core optical fiber. The local oscillator optical signal of each signal channel is transmitted to the adjustable optical delay device at the receiving end.

[0012] Preferably, the step 7 is as follows: The delay corresponding to the local oscillator optical signal of each signal channel of each adjustable optical delay device at each receiving end is set in combination with the optical delay key of each signal channel, and the local oscillator optical signal of each signal channel is optically delayed and matched through the adjustable optical delay device at each receiving end to obtain the local oscillator optical signal with optical delay matching of each signal channel, and the local oscillator optical signal with optical delay matching of each signal channel and the delayed quantum noise stream encrypted optical signal of each signal channel are input into the coherent receiver for self-coherent detection to obtain the quantum noise stream encrypted electrical signal of each signal channel, which is output to the receiving terminal.

[0013] The advantages of the present invention are: The use of self-coherent detection can simplify the digital signal processing process at the receiving end.

[0014] Space division multiplexing based on multi-core optical fiber can expand transmission capacity.

[0015] Relying on the physical properties of multi-core optical fibers and artificially added optical delays, the quantum noise masking range can be effectively improved, and not only the encryption bits can be masked, but also the signal bits.

[0016] Even if the eavesdropper obtains the quantum noise stream encryption key, it cannot decrypt the plaintext normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 : A flow chart of a method according to an embodiment of the present invention; Figure 2 : Transmission performance and security performance diagram in the experiment of the embodiment of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In specific implementation, the method proposed in the technical solution of the present invention can be implemented by technical personnel in this field using computer software technology to realize automatic operation process. System devices for implementing the method, such as computer-readable storage media storing the corresponding computer program of the technical solution of the present invention and computer equipment running the corresponding computer program, should also be within the scope of protection of the present invention.

[0020] The example experiment of the present invention is carried out in a laboratory and can simulate high-speed optical fiber communication within a data center or between data centers.

[0021] Combine the following Figure 1 to Figure 2 The specific implementation mode of the present invention is a security enhancement method based on a multi-core optical fiber quantum noise stream encryption system.

[0022] The specific implementation of the system of the present invention is a multi-core optical fiber quantum noise stream encryption system, which is as follows: Transmitter terminal, multiple transmitter adjustable optical delay devices, distributed feedback laser, transmitter optical splitter, fan-in, multi-core optical fiber, multiple IQ modulators, fan-out, receiver optical splitter, multiple receiver adjustable optical delay devices, coherent receiver, receiver terminal; The transmitting terminal is connected to the receiving terminal; The transmitting terminal is connected to the plurality of transmitting-end adjustable optical delay devices in sequence; The distributed feedback laser is connected to the transmitting optical splitter; The transmitting optical splitter is connected to the fan-in; The fan-in is connected to the middle core of the multi-core optical fiber; The middle fiber core of the multi-core optical fiber is connected to the fan-out device; The transmitting optical splitter is connected to the multiple IQ modulators in sequence; The transmitting terminal is connected to the multiple IQ modulators in sequence; The multiple IQ modulators are connected to the multiple transmitter-end adjustable optical delay devices in sequence; The plurality of transmitter-end adjustable optical delay devices are connected to the fan-in device in sequence; The fan-in is connected to the multiple peripheral cores of the multi-core optical fiber in sequence; The plurality of peripheral cores of the multi-core optical fiber are sequentially connected to the fan-out device; The fan-out device is connected to the receiving optical splitter; The receiving optical splitter is connected to the plurality of receiving-end adjustable optical delay devices in sequence; The multiple receiving-end adjustable optical delay devices are sequentially connected to the coherent receiver; The fan-out is connected to the coherent receiver; The coherent receiver is connected to the receiving terminal; The number of the adjustable optical delay device at the transmitting end, the peripheral core of the multi-core optical fiber, the IQ modulator, and the adjustable optical delay device at the receiving end are all the same; The model of the transmitting terminal is: Keysight M8195A The models of the multiple transmitter adjustable optical delay devices are: MDL-002-1-35-33-SS-FC-APC The model of the distributed feedback laser is: SWLD-1550100122-02 The model of the emission optical splitter is: 1:7 optical splitter The model of the fan-in is: 7-core fan-in The model of the multi-core optical fiber is: 10km 7-core fiber The models of the multiple IQ modulators are: FTM7977 The model of the fan-out device is: 7-core fan-out The model of the receiving optical splitter is: 1:7 optical splitter The models of the multiple receiving-end adjustable optical delay devices are: MDL-002-1-35-33-SS-FC-APC The model of the coherent receiver is: FUJITSU-FIM24706 / 301 The model of the receiving terminal is: Tektronix DPO-73304D The embodiments of the method of the present invention are as follows: Step 1: The transmitting terminal and the receiving terminal share the quantum noise stream encryption key and the optical delay key of each signal channel, and transmit the optical delay key of each signal channel to each transmitting end adjustable optical delay device; The step 1 is specifically as follows: The transmitting terminal generates a plaintext signal, generates a quantum noise stream encryption key and an optical delay key for each signal channel through a pseudo-random number generator, and transmits the quantum noise stream encryption key and the optical delay key for each signal channel to the receiving terminal for sharing; the number of bits of quantum noise stream encryption is set, and a high-order encrypted signal is obtained through quantum noise stream encryption in combination with the noise stream encryption key, and the optical delay key for each signal channel is transmitted to each transmitting terminal adjustable optical delay device.

[0023] Step 2: The distributed feedback laser generates a homologous local oscillator optical signal and transmits it to the fan-out device, which generates an optical carrier for each signal channel and transmits it to each IQ modulator; The step 2 is specifically as follows: The laser signal output by the distributed feedback laser is divided into multiple original optical signals by the transmitting optical splitter, one of which is coupled into the middle core of the multi-core optical fiber through the fan-in as a homologous local oscillator optical signal. The middle core of the multi-core optical fiber transmits the homologous local oscillator optical signal to the fan-out device, and each of the remaining original optical signals is used as the optical carrier of each signal channel, and the optical carrier of each signal channel is transmitted to each IQ modulator through the optical fiber.

[0024] Step 3: The transmitting terminal generates a high-order encrypted analog signal, which is further modulated to obtain a quantum noise stream encrypted optical signal for each signal channel; The step 3 is as follows: The transmitting terminal converts the high-order encrypted signal into a high-order encrypted analog signal through digital-to-analog conversion, and further transmits it to each IQ modulator. Each IQ modulator modulates the high-order encrypted analog signal on the optical carrier of each signal channel to obtain the quantum noise stream encrypted optical signal of each signal channel, and transmits the quantum noise stream encrypted optical signal of each signal channel to the adjustable optical delay device of each signal channel.

[0025] Step 4: Generate a delayed quantum noise stream encrypted optical signal for each signal channel and transmit it to the fan-out device; The step 4 is specifically as follows: Each transmitting end adjustable optical delay device optically delays the modulated quantum noise stream encrypted optical signal of each signal channel according to the optical delay key of each signal channel to obtain the delayed quantum noise stream encrypted optical signal of each signal channel; the delayed quantum noise stream encrypted optical signal of each signal channel is coupled into each outer fiber core of the multi-core optical fiber through the fan-in device, and each outer fiber core of the multi-core optical fiber transmits the delayed quantum noise stream encrypted optical signal of each signal channel to the fan-out device.

[0026] Step 5: Couple the homologous local oscillator optical signal to the receiving optical splitter, and couple the delayed quantum noise stream encrypted optical signal of each signal channel to the coherent receiver; The step 5 is specifically as follows: The fan-out couples the homologous local oscillator optical signal out of the multi-core optical fiber and transmits it to the receiving optical splitter, and couples the delayed quantum noise stream encrypted optical signal of each signal channel out of the multi-core optical fiber and transmits it to the coherent receiver.

[0027] Step 6: Generate a local oscillator optical signal of the signal channel and transmit it to the adjustable optical delay device at the receiving end; The step 6 is specifically as follows: The receiving optical splitter splits the homologous local oscillator optical signal into local oscillator optical signals of multiple signal channels. The number of paths of the optical splitter is the same as the number of peripheral cores of the multi-core optical fiber. The local oscillator optical signal of each signal channel is transmitted to the adjustable optical delay device at the receiving end.

[0028] Step 7: Generate a local oscillator optical signal with optical delay matching for each signal channel through each receiving end adjustable optical delay device, and transmit it to the coherent receiver for self-coherent detection to obtain the quantum noise stream encrypted electrical signal of each signal channel, and output it to the receiving end terminal; The step 7 is specifically as follows: The delay corresponding to the local oscillator optical signal of each signal channel of each adjustable optical delay device at each receiving end is set in combination with the optical delay key of each signal channel, and the local oscillator optical signal of each signal channel is optically delayed and matched through the adjustable optical delay device at each receiving end to obtain the local oscillator optical signal with optical delay matching of each signal channel, and the local oscillator optical signal with optical delay matching of each signal channel and the delayed quantum noise stream encrypted optical signal of each signal channel are input into the coherent receiver for self-coherent detection to obtain the quantum noise stream encrypted electrical signal of each signal channel, which is output to the receiving terminal.

[0029] Step 8: The receiving terminal combines the quantum noise stream encrypted electrical signal of each signal channel with the quantum noise stream encryption key through the quantum noise stream decryption method to obtain the decrypted plaintext signal.

[0030] The output of the transmitting laser is split by an optical splitter, part of which is transmitted through the central fiber core as the self-coherent optical carrier of the receiving end, and the rest is used to modulate the quantum noise stream encryption signal. The outer core of the multi-core optical fiber is used to transmit the ciphertext signal, and the middle core is used to transmit the homologous local oscillator.

[0031] For each signal channel, an optical delay is artificially added to introduce a mismatch length, thereby preventing the eavesdropper from achieving ideal self-coherent detection after successfully intercepting the homologous optical carrier in the middle fiber core.

[0032] At the receiving end, the optical carrier received from the middle fiber core is divided into n parts, where n is the number of outer fiber cores. Then, the split homologous optical carrier is loaded with the same optical delay as the corresponding channel at the transmitting end. After that, the homologous carrier loaded with optical delay and the quantum noise stream encrypted signal transmitted through the channel are input into the coherent optical transmitter for coherent detection. Assuming that the initial phase of the laser is 0, the signal light before entering the coherent receiver can be expressed as: , in, t is a certain moment of signal transmission defined by s ( t )for t The quantum noise stream encrypts the signal at each moment. f and φ is the frequency and phase noise of the laser, τ A is the optical delay added by the transmitter in the signal path, t-τ A Indicates the time after the delay at the transmitter. Similarly, the same source local oscillator can be expressed as: , in τ B The optical delay added by the receiving end in the optical carrier path, f and φ is the frequency and phase noise of the laser, t-τ B Indicates the time after the delay at the receiving end. For the legal receiver, the phase noise carried by the signal can be expressed as: .

[0033] Since the first two parties have shared the optical delay key, τ A = τ B , so the phase noise is 0. No phase noise compensation is required at the receiving end.

[0034] For the eavesdropper, firstly, it is difficult for him to intercept the optical carrier in the middle fiber core. Secondly, even if he succeeds in intercepting, he cannot match the optical path because he does not know the optical delay artificially added by the transmitter, and the received signal still carries phase noise.

[0035] The present invention provides a preferred implementation mode, in which the transmitter first maps the 35GBaud signal to be transmitted into a 16QAM modulation format, and then QNSC encrypts the 16QAM signal according to the key A, and then inputs it into an arbitrary waveform generator after upsampling and roll-off filtering. The transmitter uses a DFB laser as a light source, and divides its output into two, one as a co-source local oscillator, and the other as a carrier of the modulated signal. The output signal of the arbitrary waveform generator is modulated onto an optical carrier through a dual-polarization IQ modulator, and then input into an outer core of a seven-core optical fiber for transmission. The co-source local oscillator light is coupled into the middle core for transmission. After optical fiber transmission, the receiver performs self-coherence detection on the signal, and then inputs it into an oscilloscope for offline signal processing. In the signal processing process, roll-off filtering and downsampling are first performed, and then the RDE equalizer is used for channel equalization, and then the non-ideal characteristics of the transceiver are compensated by the 4x2 MIMO equalizer. Finally, QNSC decryption is performed according to the key A to obtain a 16QAM plaintext signal.

[0036] Figure 2 The figure on the left shows the transmission performance of different channels. It can be seen that the signal quality of each peripheral fiber core is not much different. Through space division multiplexing of multi-core optical fiber, the transmission capacity can be effectively improved.

[0037] Figure 2 The figure on the right shows the noise masking number and bit error rate performance under different mismatch lengths. The noise masking number (NMS) is usually used to quantitatively measure the security of quantum noise stream encryption systems and is defined as: .

[0038] in, NMS I represents the quantum noise masking number of path I, NMS Q represents the quantum noise masking number of the Q path, σ I and σ Q They represent the noise standard deviation of I and Q paths respectively, and Δ represents the adjacent level difference of quantum noise stream encrypted signals.

[0039] It can be seen that when the mismatch length reaches 3m, NMS is improved to 6 times that of the case without mismatch length. At the same time, the bit error rate under different mismatch lengths shows that even if the eavesdropper obtains the key of quantum noise stream encryption, it is completely unable to obtain the correct plaintext through decryption when the mismatch length is greater than 6m.

[0040] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0041] It should be understood that the above description of the embodiments is relatively detailed and cannot be regarded as limiting the scope of patent protection of the present invention. Under the enlightenment of the present invention, ordinary technicians in this field can also make substitutions or modifications without departing from the scope of protection of the claims of the present invention, which all fall within the scope of protection of the present invention. The scope of protection requested by the present invention shall be based on the attached claims.

Claims

1. A security enhancement method based on a multi-core optical fiber quantum noise stream encryption system, characterized in that: The multi-core optical fiber quantum noise stream encryption system comprises: Transmitter terminal, multiple transmitter adjustable optical delay devices, distributed feedback laser, transmitter optical splitter, fan-in, multi-core optical fiber, multiple IQ modulators, fan-out, receiver optical splitter, multiple receiver adjustable optical delay devices, coherent receiver, receiver terminal; The transmitting terminal is connected to the receiving terminal; The transmitting terminal is connected to the plurality of transmitting-end adjustable optical delay devices in sequence; The distributed feedback laser is connected to the transmitting optical splitter; The transmitting optical splitter is connected to the fan-in; The fan-in is connected to the middle core of the multi-core optical fiber; The middle fiber core of the multi-core optical fiber is connected to the fan-out device; The transmitting optical splitter is connected to the multiple IQ modulators in sequence; The transmitting terminal is connected to the multiple IQ modulators in sequence; The multiple IQ modulators are connected to the multiple transmitter-end adjustable optical delay devices in sequence; The plurality of transmitter-end adjustable optical delay devices are connected to the fan-in device in sequence; The fan-in is connected to the multiple peripheral cores of the multi-core optical fiber in sequence; The plurality of peripheral cores of the multi-core optical fiber are sequentially connected to the fan-out device; The fan-out device is connected to the receiving optical splitter; The receiving optical splitter is connected to the plurality of receiving-end adjustable optical delay devices in sequence; The multiple receiving-end adjustable optical delay devices are sequentially connected to the coherent receiver; The fan-out is connected to the coherent receiver; The coherent receiver is connected to the receiving terminal; The number of the adjustable optical delay device at the transmitting end, the peripheral core of the multi-core optical fiber, the IQ modulator, and the adjustable optical delay device at the receiving end are all the same; The security enhancement method specifically comprises the following steps: Step 1: The transmitting terminal and the receiving terminal share the quantum noise stream encryption key and the optical delay key of each signal channel, and transmit the optical delay key of each signal channel to each transmitting end adjustable optical delay device; Step 2: The distributed feedback laser generates a homologous local oscillator optical signal and transmits it to the fan-out device, which generates an optical carrier for each signal channel and transmits it to each IQ modulator; Step 3: The transmitting terminal generates a high-order encrypted analog signal, which is further modulated to obtain a quantum noise stream encrypted optical signal for each signal channel; Step 4: Generate a delayed quantum noise stream encrypted optical signal for each signal channel and transmit it to the fan-out device; Step 5: Couple the homologous local oscillator optical signal to the receiving optical splitter, and couple the delayed quantum noise stream encrypted optical signal of each signal channel to the coherent receiver; Step 6: Generate a local oscillator optical signal of the signal channel and transmit it to the adjustable optical delay device at the receiving end; Step 7: Generate a local oscillator optical signal with optical delay matching for each signal channel through each receiving end adjustable optical delay device, and transmit it to the coherent receiver for self-coherent detection to obtain the quantum noise stream encrypted electrical signal of each signal channel, and output it to the receiving end terminal; Step 8: The receiving terminal combines the quantum noise stream encrypted electrical signal of each signal channel with the quantum noise stream encryption key through the quantum noise stream decryption method to obtain the decrypted plaintext signal.

2. The security enhancement method based on the multi-core optical fiber quantum noise stream encryption system according to claim 1 is characterized in that: The step 1 is specifically as follows: The transmitting terminal generates a plaintext signal, generates a quantum noise stream encryption key and an optical delay key for each signal channel through a pseudo-random number generator, and transmits the quantum noise stream encryption key and the optical delay key for each signal channel to the receiving terminal for sharing; The number of bits of quantum noise stream encryption is set, and the high-order encrypted signal is obtained by quantum noise stream encryption in combination with the noise stream encryption key, and the optical delay key of each signal channel is transmitted to each transmitter adjustable optical delay device.

3. The security enhancement method based on the multi-core optical fiber quantum noise stream encryption system according to claim 2 is characterized in that: The step 2 is specifically as follows: The laser signal output by the distributed feedback laser is divided into multiple original optical signals by the transmitting optical splitter, one of which is coupled into the middle core of the multi-core optical fiber through the fan-in as a homologous local oscillator optical signal. The middle core of the multi-core optical fiber transmits the homologous local oscillator optical signal to the fan-out device, and each of the remaining original optical signals is used as the optical carrier of each signal channel, and the optical carrier of each signal channel is transmitted to each IQ modulator through the optical fiber.

4. The security enhancement method based on the multi-core optical fiber quantum noise stream encryption system according to claim 3 is characterized in that: The step 3 is as follows: The transmitting terminal converts the high-order encrypted signal into a high-order encrypted analog signal through digital-to-analog conversion, and further transmits it to each IQ modulator. Each IQ modulator modulates the high-order encrypted analog signal on the optical carrier of each signal channel to obtain the quantum noise stream encrypted optical signal of each signal channel, and transmits the quantum noise stream encrypted optical signal of each signal channel to the adjustable optical delay device of each signal channel.

5. The security enhancement method based on the multi-core optical fiber quantum noise stream encryption system according to claim 4 is characterized in that: The step 4 is specifically as follows: Each transmitting end adjustable optical delay device optically delays the modulated quantum noise stream encrypted optical signal of each signal channel according to the optical delay key of each signal channel to obtain the delayed quantum noise stream encrypted optical signal of each signal channel; the delayed quantum noise stream encrypted optical signal of each signal channel is coupled into each outer fiber core of the multi-core optical fiber through the fan-in device, and each outer fiber core of the multi-core optical fiber transmits the delayed quantum noise stream encrypted optical signal of each signal channel to the fan-out device.

6. The security enhancement method based on the multi-core optical fiber quantum noise stream encryption system according to claim 5 is characterized in that: The step 5 is specifically as follows: The fan-out couples the homologous local oscillator optical signal out of the multi-core optical fiber and transmits it to the receiving optical splitter, and couples the delayed quantum noise stream encrypted optical signal of each signal channel out of the multi-core optical fiber and transmits it to the coherent receiver.

7. The security enhancement method based on the multi-core optical fiber quantum noise stream encryption system according to claim 6 is characterized in that: The step 6 is specifically as follows: The receiving optical splitter splits the homologous local oscillator optical signal into local oscillator optical signals of multiple signal channels. The number of paths of the optical splitter is the same as the number of peripheral cores of the multi-core optical fiber. The local oscillator optical signal of each signal channel is transmitted to the adjustable optical delay device at the receiving end.

8. The security enhancement method based on the multi-core optical fiber quantum noise stream encryption system according to claim 7 is characterized in that: The step 7 is specifically as follows: The delay corresponding to the local oscillator optical signal of each signal channel of each adjustable optical delay device at each receiving end is set in combination with the optical delay key of each signal channel, and the local oscillator optical signal of each signal channel is optically delayed and matched through the adjustable optical delay device at each receiving end to obtain the local oscillator optical signal with optical delay matching of each signal channel, and the local oscillator optical signal with optical delay matching of each signal channel and the delayed quantum noise stream encrypted optical signal of each signal channel are input into the coherent receiver for self-coherent detection to obtain the quantum noise stream encrypted electrical signal of each signal channel, which is output to the receiving terminal.

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