Quantum key distribution system and method based on end-to-end loss control

Abstract

The invention relates to quantum key distribution, in particular to a quantum key distribution system and method based on end-to-end loss control and enhanced Alice, and is characterized in that on the basis of traditional Alice, an OTDR (Optical Time Domain Reflectometer) transmitting unit and a transmission measurement transmitting unit are integrated; according to the enhanced Bob, on the basis of a traditional Bob, an OTDR receiving unit and a transmission measurement receiving unit are integrated; the data processing and control unit is used for generating an OTDR reflectogram and a loss tomogram, calculating a total effective leakage value, optimizing signal strength and privacy amplification parameters according to the latest effective leakage value, performing information coordination and privacy amplification, continuously performing channel fingerprint authentication and safely terminating when abnormity occurs under the cooperation of the enhanced Alice and the enhanced Bob; the inherent physical structure of the optical fiber quantum channel serves as a physical unclonable function; according to the invention, the defect of sharp contradiction among the key rate, the transmission distance and the actual security can be overcome.

Description

Technical Field

[0001] This invention relates to quantum key distribution, and more specifically to a quantum key distribution system and method based on end-to-end loss control. Background Technology

[0002] Quantum key distribution (QKD) is the most promising technology in quantum cryptography. Its security is based on quantum mechanical principles, such as Heisenberg's uncertainty principle and the quantum no-cloning theorem, theoretically providing information-theoretably provable security. However, in practical engineering, especially in long-distance fiber optic channels, QKD faces the following fundamental challenges that severely restrict its large-scale application:

[0003] 1) The fundamental contradiction between channel loss and key rate versus transmission distance: Optical signals undergo exponential attenuation during transmission in optical fibers due to Rayleigh scattering, absorption, and other factors. The well-known PLOB (Pirandola-Laurenza-Ottaviani-Banchi) limit theoretically proves that the secure key rate of point-to-point repeaterless QKD increases exponentially with channel transmission efficiency. Linear scaling ( This leads to an exponential decrease in key rate over long distances, creating a "ceiling" that is difficult to overcome.

[0004] 2) Eavesdropping attack threat targeting channel loss: The traditional QKD security model assumes that the eavesdropper (Eve) can obtain and exploit all channel loss, which gives rise to two main types of attacks:

[0005] o Photon Number Splitting Attack (PNS Attack): For protocols that use weakly coherent light sources (such as the BB84 protocol), Eve intercepts extra photons from a multiphoton pulse and forwards the remaining part through a lossless channel, thereby obtaining key information without loss.

[0006] o-beam splitting attack: For coherent state protocols (such as COW protocol), Eve steals the signal portion that is "expected to be lost" through a beam splitter without introducing obvious bit errors;

[0007] 3) Limitations of existing solutions:

[0008] o Decoy state method: Although it can effectively defend against PNS attacks, it is essentially an indirect statistical estimation. The security key still comes only from single-photon events and cannot utilize multi-photon pulses, resulting in a low key rate limit.

[0009] o Quantum repeater-independent measurement device (QKD): These solutions are technically very difficult, and the systems are complex and costly, making them difficult to put into practical use in the short term;

[0010] 4) The gap between the security model and the engineering reality: the existing security proof is based on the worst-case assumption, which leads to an overly conservative privacy amplification process, assuming that Eve obtains information proportional to the total channel loss, thereby excessively compressing the length of the final key, causing performance waste.

[0011] In summary, the existing technology has a sharp contradiction between the key rate, transmission distance and actual security, and urgently needs an innovative solution that can fundamentally break through the PLOB limit while maintaining high security and practicality. SUMMARY

[0012] (I) Technical problems to be solved

[0013] In view of the above-mentioned defects of the prior art, the present application provides a quantum key distribution system and method based on end-to-end loss control, which can effectively overcome the defects of the prior art that there is a sharp contradiction between the key rate, transmission distance and actual security.

[0014] (II) Technical solutions

[0015] In order to achieve the above-mentioned purposes, the present application is realized by the following technical solutions:

[0016] A quantum key distribution system based on end-to-end loss control, comprising an enhanced Alice, an enhanced Bob, a data processing and control unit, and an optical fiber quantum channel;

[0017] The enhanced Alice integrates an OTDR transmitting unit and a transmission measurement transmitting unit on the basis of the traditional Alice;

[0018] The enhanced Bob integrates an OTDR receiving unit and a transmission measurement receiving unit on the basis of the traditional Bob;

[0019] The data processing and control unit generates an OTDR reflection map and a loss tomography map under the cooperation of the enhanced Alice and the enhanced Bob, calculates the total effective leakage value, optimizes the signal strength and privacy amplification parameters according to the latest effective leakage value, and performs information coordination and privacy amplification, while continuously performing channel fingerprint authentication and safely terminating when an exception occurs;

[0020] The inherent physical structure of the optical fiber quantum channel serves as a physical unclonable function, constituting a security cornerstone.

[0021] Preferably, the data processing and control unit generates an OTDR reflection map and a loss tomography map under the cooperation of the enhanced Alice and the enhanced Bob, and calculates the total effective leakage value, including:

[0022] Inject high-intensity monitoring test pulses into the quantum channel of the optical fiber, analyze the time delay and intensity of the backscattered light, generate the OTDR reflection map, and obtain the loss tomography map through algorithm processing, so as to accurately locate the position and size of the local leakage;

[0023] At the same time, by comparing the intensities of the transmitted and received monitoring test pulses, the total effective leakage value r E .

[0024] Preferably, the data processing and control unit optimizes the signal intensity and privacy amplification parameter according to the latest effective leakage value, and performs information coordination and privacy amplification, including:

[0025] According to the real-time calculated effective leakage value r E , the average photon number of the quantum signal pulse of the authorized legitimate user is increased from 1 to the range of 10~1000, so that the multi-photon pulse is transformed from a security burden to a resource that contributes to the key;

[0026] Perform information coordination and privacy amplification. In the process of privacy amplification, only the corresponding accurate information leakage amount is compressed according to the effective leakage value r E , rather than based on the total loss.

[0027] Preferably, the data processing and control unit continuously performs channel fingerprint authentication and safely terminates when an exception occurs, including:

[0028] The initialized OTDR reflection map is used as the unique reference fingerprint of the quantum channel of the optical fiber. During the key distribution process, the real-time OTDR reflection map is continuously compared with the reference fingerprint.

[0029] Any global attack will cause significant changes in the real-time OTDR reflection map. When the real-time OTDR reflection map is inconsistent with the reference fingerprint, the system is triggered to safely terminate.

[0030] A quantum key distribution method based on end-to-end loss control, applied to the quantum key distribution system based on end-to-end loss control of claim 1, characterized in that it comprises the following steps:

[0031] S1, initialization and fingerprint registration: perform the first optical fiber quantum channel scanning in a secure environment, establish the initialized OTDR reflection map and loss tomography map, and use the initialized OTDR reflection map as the unique reference fingerprint of the quantum channel of the optical fiber;

[0032] S2, concurrent transmission and monitoring: quantum signal pulses and monitoring test pulses are transmitted concurrently, and OTDR and transmission measurement are continuously working;

[0033] ​S3, Real-time analysis and decision: optimize signal strength and privacy amplification parameters according to the latest effective leakage value;

[0034] S4, Security key generation and verification: coordinate information and privacy amplification, while continuously conducting channel fingerprint authentication, and safely terminating when abnormalities occur.

[0035] (Three) beneficial effects

[0036] Compared with the prior art, the quantum key distribution system and method based on end-to-end loss control provided by the application has the following beneficial effects:

[0037] 1) Breakthrough improvement of key rate and transmission distance: by using high-intensity signals and precise privacy amplification, the key rate is improved by 10-100 times compared with the original BB84 and COW protocols at a transmission distance of 200km, and the PLOB limit under a quantum repeater is broken;

[0038] 2) Substantial security enhancement: through physical channel authentication, PNS, BS and other global attacks are effectively prevented, and Eve is limited to a controllable local perturbation range, and the system has permanent security;

[0039] 3) High practicability and compatibility: the application is an enhancement of the existing mainstream QKD protocol, without replacing the core quantum device, and only by adding a monitoring unit and updating the algorithm, it can be realized, and it is easy to deploy and upgrade to the existing system;

[0040] 4) Robustness to equipment flaws: even at a higher bit error rate (such as 10%), the application can still maintain a much higher key rate than traditional protocols, indicating that it has good tolerance to equipment imperfections in actual engineering. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0042] Figure 1 To enhance the traditional BB84 protocol, the system diagram of the enhanced BB84 protocol is obtained;

[0043] Figure 2 To enhance the traditional COW protocol, the system diagram of the enhanced COW protocol is obtained;

[0044] Figure 3OTDR reflection graph and loss tomography graph in the application;

[0045] Figure 4 The relationship graph between the optimal average photon number of quantum signal pulses and the transmission distance obtained on the basis of the BB84 protocol in the application;

[0046] Figure 5 The relationship graph between the optimal average photon number of quantum signal pulses and the transmission distance obtained on the basis of the COW protocol in the application;

[0047] Figure 6 The relationship graph between the key rate and the transmission distance obtained on the basis of the BB84 protocol in the application;

[0048] Figure 7 The relationship graph between the key rate and the transmission distance obtained on the basis of the COW protocol in the application. DETAILED DESCRIPTION

[0049] To make the objects, technical solutions and advantages of the embodiments of the application clearer, the technical solutions in the embodiments of the application will be described below in connection with the drawings of the embodiments of the application. Obviously, the described embodiments are some but not all of the embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the application.

[0050] The specific functional modules (as shown in Figure 1 and Figure 2 ) and technical effects of the quantum key distribution system based on end-to-end loss control provided by the application will be introduced below in connection with specific examples. The system functional modules include: enhanced Alice, enhanced Bob, data processing and control unit, and optical fiber quantum channel.

[0051] The enhanced Alice integrates an OTDR transmitting unit and a transmission measurement sending unit on the basis of a traditional Alice.

[0052] The enhanced Bob integrates an OTDR receiving unit and a transmission measurement receiving unit on the basis of a traditional Bob.

[0053] The data processing and control unit generates an OTDR reflection graph and a loss tomography graph in cooperation with the enhanced Alice and the enhanced Bob, calculates the total effective leakage value, optimizes the signal strength and privacy amplification parameters according to the latest effective leakage value, and performs information coordination and privacy amplification, while continuously performing channel fingerprint authentication and safely terminating when an exception occurs.

[0054] Optical fiber quantum channel, its inherent physical structure as a physical unclonable function, constitutes a security cornerstone.

[0055] Figure 1 The application enhances the traditional BB84 protocol to obtain a system schematic diagram of the enhanced BB84 protocol, and the OTDR unit, the transmission measurement unit and the data processing and control unit are added on the basis of the original BB84 protocol, and the local beam splitter attack of Eve is shown. Figure 1 In the application,

[0056] Alice: the sending end / Alice end;

[0057] Bob: the receiving end / Bob end;

[0058] laser: laser;

[0059] PR (Polarization Rotator): polarization controller;

[0060] PM (Phase Modulator): phase modulator;

[0061] OTDR (Optical Time-Domain Reflectometer): optical time-domain reflectometer;

[0062] switch: optical switch;

[0063] Eve: eavesdropper;

[0064] original quantum channel: original quantum channel;

[0065] PBS (Polarizing Beam Splitter): polarization beam splitter;

[0066] D1, D2: single-photon detectors 1 and 2.

[0067] Figure 2 The application enhances the traditional COW protocol to obtain a system schematic diagram of the enhanced COW protocol, and the OTDR unit and the transmission measurement unit are added on the basis of the original COW protocol, and the local beam splitter attack of Eve is shown. Figure 2 In the application,

[0068] AM (Amplitude Modulator): amplitude modulator / intensity modulator;

[0069] D B : data detector.

[0070] I. Integrated line chromatographic monitoring

[0071] o Implementation: Adopt the monitoring scheme of fusion of optical time domain reflectometer (OTDR) and transmission measurement.

[0072] The data processing and control unit generates the OTDR reflection diagram and loss profile under the cooperation of the enhanced Alice and the enhanced Bob, and calculates the total effective leakage value, including:

[0073] Inject high-intensity monitoring test pulses (such as 10 11 photons / pulse) into the optical fiber quantum channel, generate the OTDR reflection diagram (such as Figure 3 indicated by the upper diagonal line in the middle), and obtain the loss profile (such as Figure 3 indicated by the lower column chart in the middle) through algorithm processing, so as to accurately locate the position and size of the local leakage;

[0074] At the same time, by comparing the intensities of the sent and received monitoring test pulses, the total effective leakage value r E is calculated.

[0075] Figure 3 The OTDR reflection diagram and the loss profile in the present application show the natural loss baseline and the local leakage peak. Figure 3

[0076] Backscattered power: backscattered power;

[0077] Reflectogram: reflection diagram;

[0078] Loss profile: loss profile;

[0079] Contributions to r E : contribution to the effective leakage value r E ;

[0080] Distance: transmission distance.

[0081] o Technical effect: Direct physical measurement of channel state is realized, which replaces the traditional indirect statistical estimation mode of decoy state, and provides accurate data basis for subsequent optimization.

[0082] II. Adaptive optimization mechanism based on real-time monitoring data

[0083] o Implementation: Use the effective leakage value r E calculated in real time to dynamically adjust the system core parameters.

[0084] ​The data processing and control unit optimizes the signal strength and privacy amplification parameter according to the latest effective leakage value, and performs information coordination and privacy amplification, including:

[0085] According to the effective leakage value r calculated in real time E , the average photon number of the quantum signal pulse of the authorized legal user is increased from 1 to the range of 10-1000 (the optimal average photon number is shown in and Figure 4 ), so that the multi-photon pulse is transformed from a security burden to a resource that contributes to the key; Figure 5 Perform information coordination and privacy amplification. In the process of privacy amplification, only the corresponding accurate information leakage amount is compressed according to the effective leakage value r E , and not based on the total loss.

[0086] o Technical effect: fundamentally breaks through the key rate limit of traditional protocols that can only utilize single-photon events, and greatly reduces the key waste in the privacy amplification process, thereby achieving a key rate order of magnitude improvement (as shown in

[0087] and Figure 6 ). Figure 7

[0088] Figure 4 The figure showing the relationship between the optimal average photon number of the quantum signal pulse and the transmission distance in the enhanced BB84 protocol proposed in the application, shows that the average photon number of the quantum signal pulse can reach dozens to hundreds, while the original BB84 protocol is always 1. Figure 4 In the application:

[0089] BB84: BB84 protocol;

[0090] Optimal average photon number : optimal average photon number ;

[0091] Distance D AB : transmission distance;

[0092] original: original protocol.

[0093] Figure 5 The figure showing the relationship between the optimal average photon number of the quantum signal pulse and the transmission distance in the enhanced COW protocol proposed in the application, shows that the average photon number of the quantum signal pulse can reach dozens to hundreds, far exceeding the original COW protocol.

[0094] ​III. Global attack defense mechanism based on physically unclonable channel

[0095] o Implementation: The initialized OTDR reflection map is used as the unique reference fingerprint of the fiber quantum channel.

[0096] The data processing and control unit continuously performs channel fingerprint authentication and safely terminates when an anomaly occurs, including:

[0097] The initialized OTDR reflection map is used as the unique reference fingerprint of the fiber quantum channel, and the real-time OTDR reflection map is continuously compared with the reference fingerprint during the key distribution process.

[0098] Any global attack (such as channel replacement required by PNS attack, large-scale signal blocking, etc.) will cause significant changes in the real-time OTDR reflection map, and when the real-time OTDR reflection map is inconsistent with the reference fingerprint, the system is triggered to safely terminate.

[0099] o Technical effect: Limit Eve's ability to local perturbations that can be monitored, forcing her attack pattern to be reduced from "omnipotent" to "locally controllable", thereby laying the foundation for the security of the entire system.

[0100] Based on the above disclosure of a quantum key distribution system based on end-to-end loss control, the technical scheme of the present application also discloses a quantum key distribution method based on end-to-end loss control, comprising the following steps:

[0101] S1, initialization and fingerprint registration: perform the first fiber quantum channel scanning in a secure environment, establish the initialized OTDR reflection map and loss tomography map, and use the initialized OTDR reflection map as the unique reference fingerprint of the fiber quantum channel;

[0102] S2, concurrent transmission and monitoring: quantum signal pulses and monitoring test pulses are transmitted concurrently, and OTDR and transmission measurement are continuously operated;

[0103] S3, real-time analysis and decision: optimize signal strength and privacy amplification parameters according to the latest effective leakage value;

[0104] S4, secure key generation and verification: perform information coordination and privacy amplification, and continuously perform channel fingerprint authentication and safely terminate when an anomaly occurs.

[0105] In order to better illustrate the technical scheme of the present application, two specific experiments will be described in detail below.

[0106] Experiment 1: Performance of enhanced BB84 protocol under long transmission distance

[0107] • Experimental conditions: transmission distance D AB= 200km, effective leakage value r E = 0.005.

[0108] • Operation process: As shown in Figure 1 , the OTDR unit and the transmission measurement unit work in real time, and the data processing and control unit optimizes the signal intensity to the average photon number = 100.

[0109] • Experimental results and conclusions: As shown in Figure 6 , the key rate (L f / L) of the present application reaches about 10 -2 , which is about 100 times higher than the original BB84 protocol (10 -4 ), and breaks the PLOB limit.

[0110] Figure 6 The figure in the present application shows the relationship between the key rate and the transmission distance based on the BB84 protocol, which shows the performance improvement of the enhanced BB84 protocol proposed in the present application compared with the original BB84 protocol and the PLOB limit under different effective leakage values r E . Figure 6 In the figure:

[0111] Normalized key rate L f / L: normalized key rate L f / L;

[0112] PLOB: PLOB limit (or PLOB capacity limit).

[0113] Experiment two: performance of the enhanced COW protocol under a transmission distance of 150km

[0114] • Experimental conditions: transmission distance D AB = 150km, effective leakage value r E = 0.01.

[0115] • Operation process: As shown in Figure 2 , the OTDR unit and the transmission measurement unit work in real time, and the data processing and control unit optimizes the signal intensity to the average photon number = 50.

[0116] • Experimental results and conclusions: As shown in Figure 7 , the key rate (L f / L) of the present application reaches about 8×10 -4 , which is about 80 times higher than the original COW protocol (1×10 -5 ).

[0117] Figure 7To get the relationship graph between the key rate and the transmission distance in the COW protocol in the application, the enhanced COW protocol proposed in the application is demonstrated in different effective leakage values r E Next, the key rate is compared between the original COW protocol and the PLOB limit, and the performance improvement is shown.

[0118] The above examples are only used to illustrate the technical solutions of the application, but not limit the application; although the application is described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced equivalently; and these modifications or replacements will not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A quantum key distribution system based on end-to-end loss control, characterized in that: This includes an enhanced Alice, an enhanced Bob, a data processing and control unit, and a fiber optic quantum channel; The enhanced Alice integrates an OTDR transmitter unit and a transmission measurement transmitter unit on the basis of the traditional Alice. The enhanced Bob integrates an OTDR receiver unit and a transmission measurement receiver unit on the basis of the traditional Bob. The data processing and control unit, in cooperation with enhanced Alice and enhanced Bob, generates OTDR reflection maps and loss tomography maps, calculates the total effective leakage value, optimizes signal strength and privacy amplification parameters based on the latest effective leakage value, performs information coordination and privacy amplification, continuously performs channel fingerprint authentication, and securely terminates when an anomaly occurs. Fiber optic quantum channels, with their inherent physical structure as physically unclonable functions, form the cornerstone of security.

2. The quantum key distribution system based on end-to-end loss control according to claim 1, characterized in that: The data processing and control unit, in cooperation with enhanced Alice and enhanced Bob, generates OTDR reflection maps and loss tomography maps, and calculates the total effective leakage value, including: High-intensity monitoring and testing pulses are injected into the fiber quantum channel. By analyzing the time delay and intensity of the backscattered light, an OTDR reflection map is generated, and a loss tomography map is obtained through algorithm processing, thereby accurately locating the location and size of local leakage. Simultaneously, by comparing the intensity of the transmitted and received monitoring test pulses, the total effective leakage value r is calculated. E .

3. The quantum key distribution system based on end-to-end loss control according to claim 2, characterized in that: The data processing and control unit optimizes signal strength and privacy amplification parameters based on the latest effective leakage value, and performs information coordination and privacy amplification, including: Based on the effective leakage value r obtained through real-time calculation E Authorized legitimate users will have access to the average number of photons in the quantum signal pulse. The range from 1 to 10 to 1000 transforms multiphoton pulses from a security burden into a resource that contributes to the key; Information coordination and privacy amplification are carried out, and in the process of privacy amplification, only the effective leakage value r is considered. E The key is compressed based on the precise amount of information leakage, rather than pessimistically based on the total loss.

4. The quantum key distribution system based on end-to-end loss control according to claim 3, characterized in that: The data processing and control unit continuously performs channel fingerprint authentication and securely terminates upon encountering an anomaly, including: The initialized OTDR reflection map is used as the unique reference fingerprint of the fiber quantum channel. During the key distribution process, the real-time OTDR reflection map is continuously compared with the reference fingerprint. Any global attack will cause a significant change in the real-time OTDR reflection map. When the real-time OTDR reflection map is inconsistent with the baseline fingerprint, the system will be terminated securely.

5. A quantum key distribution method based on end-to-end loss control, applied to the quantum key distribution system based on end-to-end loss control as described in claim 1, characterized in that: Includes the following steps: S1. Initialization and fingerprint registration: Perform the first fiber quantum channel scan in a secure environment, establish the initial OTDR reflection map and loss tomography map, and use the initial OTDR reflection map as the unique reference fingerprint of the fiber quantum channel. S2. Concurrent transmission and monitoring: Quantum signal pulses and monitoring test pulses are transmitted concurrently, while OTDR and transmission measurement continue to operate. S3. Real-time analysis and decision-making: Optimize signal strength and privacy amplification parameters based on the latest effective leakage values; S4. Secure Key Generation and Verification: Performs information coordination and privacy amplification, while continuously performing channel fingerprint authentication and securely terminating in case of anomalies.

Images