Strong light attack monitoring method, calibration method and equipment in QKD (quantum key distribution) system and QKD system

Abstract

The invention provides a highlight attack monitoring method in a QKD (quantum key distribution) system, which is characterized in that the QKD system adds a delay of a preset time before each calibration process in a calibration stage, and is used for monitoring highlight attacks. The invention also provides a QKD system calibration method of the strong light attack monitoring method in the QKD system, and equipment and a system adopting the method, after the QKD system is started, a preset time delay is added before each calibration process of a calibration stage for monitoring the strong light attack, and after all the calibration processes are completed, the QKD system is calibrated. And the QKD system enters a quantum key generation stage. According to the method, whether the system is attacked by highlight or not can be found in both the equipment calibration stage and the normal quantum key generation stage, the system can carry out exception handling and report the exception to a user in time, system misinformation is avoided in the equipment calibration stage, meanwhile, reasons for calibration failure can be found in time, and the safety of equipment operation is guaranteed.

Description

Technical Field

[0001] The present invention relates to a quantum key distribution (QKD) system, and particularly to a method for monitoring external injected strong light attacks. Background Art

[0002] Currently, the main vulnerability targeted by strong light attacks is the detection characteristic that a single-photon detector may degrade into a linear mode due to strong light injection during actual operation.

[0003] Regarding this vulnerability, an attacker can change the Geiger mode of single-photon detection to a non-single-photon detection linear mode by injecting blinding strong light. The time interval in which the linear mode exists is called the blinding interval. Using the linear mode, the attacker Eve can then use pulsed light, i.e., trigger light, to make the detection part that uses a different basis vector from the measurement basis vector used by the receiving end Bob not be recorded and discovered by the receiving end Bob, thereby eliminating the impact of the attack. Specifically, referring to Figure 1 , the monitoring of strong light attacks and system protection are as follows:

[0004] 1) Eve injects blinding strong light into the detector, causing the avalanche photodiode (APD) to output a large current. A large voltage drop is formed across the resistor in series with the APD, reducing the voltage across the APD and making it lower than the breakdown voltage, causing the APD to exit the Geiger mode and enter the linear mode.

[0005] 2) On this basis, Eve implements an intercept-and-resend attack. By inputting a strong light pulse of appropriate intensity, i.e., trigger light, the response of the detector in the linear mode can be controlled. For example, when the light intensity is adjusted to E, the detector can respond when all of it receives the E light intensity (the generated photocurrent is large enough to be discriminated by the subsequent discrimination circuit). If it receives energy of E / 2, it cannot respond (the generated photocurrent is not large enough to be discriminated by the subsequent discrimination circuit).

[0006] 3) During the process of the sender Alice and the receiver Bob performing the basis, Alice will announce the basis vector information she uses. Since the data corresponding to the parts of the measurement basis vectors used by Bob that are different from Eve will not be recorded, the error rate will not increase, and the attack will not leave a trace. All the recorded data are the data corresponding to the cases where the measurement basis vectors of Bob and Eve are the same. Eve will not be discovered by Bob at all, and Eve can determine which detector of Bob responds, so she can obtain all the key information.

[0007] 4) By detecting the working current of the APD in real time, when the input signal optical power increases, the working current of the APD will increase. When the power value exceeds the set threshold, the APD bias current detection circuit can report a strong light detection alarm. Before the APD degrades to the linear mode, an alarm is issued and the QKD quantum key generation is stopped, so that Eve has no way to obtain the key information.

[0008] The current method for monitoring and protecting against strong light attacks is that after the QKD system enters the quantum key generation stage, in order to prevent Eve from injecting strong light to obtain quantum key information, the system enables strong light attack monitoring. However, during the system calibration stage before the system enters the key generation process, since the calibration light of the system may cause false alarms of strong light attacks, in order to avoid false alarms of the system, the strong light attack monitoring is turned off during the device calibration stage. However, in the actual working environment of the device, a strong light attack may occur during the device calibration stage. If strong light is injected into the system during the device calibration stage, the system cannot detect the strong light attack at this time. Although the system has not entered the quantum key generation stage at this time and will not cause the leakage of quantum key information, the external strong light injection will cause the system noise to increase, and the device calibration process cannot pass and falls into the abnormal processing of a long-term device calibration loop. The device cannot work properly for a long time and the user cannot discover the attacker in time, that is, the real reason for the device failure cannot be discovered in time. Summary of the Invention

[0009] The present invention aims to solve the problem that the QKD system cannot accurately detect strong light attacks during the device calibration stage in the normal working process.

[0010] The present invention realizes the solution to the above technical problems through the following technical means: A method for monitoring strong light attacks in a QKD system, in which a preset time delay is added before each calibration process during the calibration stage of the QKD system for monitoring strong light attacks.

[0011] As a further optimized technical solution, when a calibration process fails, the QKD system restarts the calibration process, and a preset time delay is added before the restart of the calibration process for monitoring strong light attacks.

[0012] As a further optimized technical solution, on the basis that the strong light attack detection threshold of the QKD system is uniformly determined by software configuration, different detection thresholds are calibrated for the differences of different detectors.

[0013] The present invention also provides a QKD system calibration method. After the QKD system is started, a preset time delay is added before each calibration process during the calibration stage for monitoring strong light attacks. After all calibration processes are completed, the QKD system enters the quantum key generation stage.

[0014] As a further optimized technical solution, the equipment calibration stage of the QKD system is mainly divided into the calibration process of the received signal light, the calibration of the quantum state at the receiving end, and the calibration process of the relative position of the signal light. A time delay of a preset time is added before each calibration process to determine whether a strong light attack is received. If no strong light attack is received, the next calibration process is entered.

[0015] As a further optimized technical solution, the QKD system calibration method includes the following steps:

[0016] Step S1, the QKD is started;

[0017] Step S2, start monitoring for strong light attacks within the preset time, and determine whether a strong light attack is received. If a strong light attack is received, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is received, the monitoring of strong light attacks is turned off and the calibration stage is entered;

[0018] Step S3, enter the first calibration stage: calibration of the received signal light;

[0019] Step S4, determine whether the calibration of the received signal light fails. If it fails, return to Step S2, otherwise proceed to the next step;

[0020] Step S5, before the start of the second calibration stage, start monitoring for strong light attacks within the preset time, and determine whether a strong light attack is received. If a strong light attack is received, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is received, the monitoring of strong light attacks is turned off and the next calibration stage is entered;

[0021] Step S6, enter the second calibration stage: calibration of the quantum state at the receiving end;

[0022] Step S7, determine whether the calibration of the quantum state at the receiving end fails. If it fails, return to Step S5, otherwise proceed to the next step;

[0023] Step S8, before the start of the third calibration stage, start monitoring for strong light attacks within the preset time, and determine whether a strong light attack is received. If a strong light attack is received, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is received, the monitoring of strong light attacks is turned off and the next calibration stage is entered;

[0024] Step S9, enter the third calibration stage: calibration of the relative position of the signal light;

[0025] Step S10, determine whether the calibration of the relative position of the signal light fails. If it fails, return to Step S8, otherwise proceed to the next step;

[0026] Step S11: Enable strong light attack monitoring. Determine whether a strong light attack is received. If a strong light attack is received, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is received, proceed to the next stage;

[0027] Step S12: Enter the quantum key generation stage;

[0028] Step S13: Keep strong light attack monitoring enabled during the quantum key generation stage. If a strong light attack is received, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is received, remain in Step S12.

[0029] The present invention also provides a QKD receiver device adopting a QKD system calibration method described in any of the above solutions.

[0030] The present invention also provides a QKD system, including a QKD transmitter device, a QKD receiver device, and a host computer. The QKD transmitter device and the QKD receiver device are connected, and both the QKD transmitter device and the QKD receiver device are connected to the host computer. The QKD receiver device adopts the above QKD receiver device.

[0031] The advantages of the present invention are as follows:

[0032] 1. The present invention adds a delay of a preset time before each process of device calibration to monitor strong light attacks. When a certain calibration process fails, the calibration process is restarted, and a preset time is still waited for strong light attack monitoring before the calibration process is started. When all calibration processes pass, the device enters the normal key generation stage, and at this time, the strong light attack monitoring is always on. Therefore, the present invention can detect whether the system is under strong light attack during device calibration and normal quantum key generation stages. The system can perform anomaly handling and report to the user in a timely manner. While avoiding false alarms of the system during the device calibration stage, it can timely discover the reasons leading to calibration failure and ensure the safety of device operation.

[0033] 2. Monitor the noise data of the device. If the noise increases and causes a certain calibration process to fail, restart the current calibration process.

[0034] 3. Calibrate different detection thresholds for the differences of different detectors, so as to perform more accurate strong light attack detection. Description of the Drawings

[0035] Figure 1 is the existing strong light attack topology diagram;

[0036] Figure 2 is the flowchart of enabling strong light attack monitoring during the device calibration stage of the embodiment of the present invention. Detailed Embodiments

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0038] The method for monitoring strong light attacks in the QKD system of the present invention is to enable strong light attack monitoring and exception handling during the system calibration period. Currently, the calibration stage of the receiving end device in the QKD system mainly includes calibration processes such as signal light calibration of the receiving end, quantum state calibration of the receiving end, and relative position calibration of the signal light. After each calibration process is completed, the system enters the next calibration process. After all calibration processes are completed, the system enters the quantum key generation stage. When a certain calibration process fails continuously, the system will attempt to re - perform this calibration process.

[0039] Therefore, strong light attack monitoring can wait for a preset time (such as 1 second) before each calibration process for strong light attack monitoring, so as to effectively monitor strong light attacks within a preset time before each calibration process starts. If a strong light attack occurs during a calibration process and the strong light causes the calibration to fail, the system will attempt to re - start this calibration process and still wait for a preset time for strong light attack monitoring before the calibration process starts. At this time, the system can still detect the strong light attack before this calibration process; if the device calibration process is not affected by strong light attacks, strong light attacks can still be detected before entering the next calibration process after the current calibration process is completed.

[0040] In addition, to achieve more accurate and effective judgment, the present invention has made necessary rectifications to the detector end. For each detector, due to hardware differences, the detection thresholds for strong light attacks of different detectors are slightly different. On the basis of being uniformly determined by software configuration, different detection thresholds are calibrated for the differences of different detectors, so as to more accurately detect strong light attacks.

[0041] Please refer to Figure 2 , the specific monitoring process of the method for monitoring strong light attacks in the QKD system of the present invention includes:

[0042] Step S1, QKD starts;

[0043] Step S2, enable strong light attack monitoring within a preset time (such as 1 second), determine whether a strong light attack is received. If a strong light attack is received, the system enters the strong light exception handling process and reports to the user. If no strong light attack is received, then turn off the strong light attack monitoring and enter the calibration stage;

[0044] Step S3: Enter the first calibration stage: Receiver signal light calibration;

[0045] Step S4: Determine whether the receiver signal light calibration fails. If it fails, return to Step S2; otherwise, proceed to the next step.

[0046] Step S5: Before the start of the second calibration stage, turn on the strong light attack monitoring within a preset time. Determine whether a strong light attack is received. If a strong light attack is received, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is received, turn off the strong light attack monitoring and enter the next calibration stage.

[0047] Step S6: Enter the second calibration stage: Receiver quantum state calibration;

[0048] Step S7: Determine whether the receiver quantum state calibration fails. If it fails, return to Step S5; otherwise, proceed to the next step.

[0049] Step S8: Before the start of the third calibration stage, turn on the strong light attack monitoring within a preset time. Determine whether a strong light attack is received. If a strong light attack is received, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is received, turn off the strong light attack monitoring and enter the next calibration stage.

[0050] Step S9: Enter the third calibration stage: Signal light relative position calibration;

[0051] Step S10: Determine whether the signal light relative position calibration fails. If it fails, return to Step S8; otherwise, proceed to the next step.

[0052] Step S11: Turn on the strong light attack monitoring and determine whether a strong light attack is received. If a strong light attack is received, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is received, proceed to the next stage.

[0053] Step S12: Enter the quantum key generation stage;

[0054] Step S13: Keep the strong light attack monitoring on during the quantum key generation stage. If a strong light attack is received, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is received, stay in Step S12.

[0055] Before each process of device calibration, the present invention adds a time delay of a preset time for monitoring strong light attacks. When a certain calibration process fails, the calibration process will be restarted, and a preset time is still waited before the start of this calibration process for strong light attack monitoring. When all calibration processes pass, the device enters the normal key generation stage, and at this time, the strong light attack monitoring is always in the open state. Therefore, the present invention can detect whether the system is under strong light attack during both device calibration and normal quantum key generation stages. The system can perform anomaly handling and report to the user in a timely manner. While avoiding false alarms of the system during the device calibration stage, it can timely discover the reasons leading to calibration failure and ensure the security of device operation.

[0056] External strong light injection will cause the system noise to increase, and the increased noise will cause a certain calibration process to fail. The present invention monitors the device noise data. If the calibration process fails, the current calibration process will be restarted, and a preset time is still waited before the start of this calibration process for strong light attack monitoring. At this time, the system can still detect strong light attacks before this calibration process.

[0057] The above-mentioned strong light attack monitoring method or the QKD system calibration method using the above-mentioned strong light attack monitoring method is applicable to QKD receiver devices; the QKD system composed of this QKD receiver device, QKD transmitter device, and upper computer can detect whether the system is under strong light attack during both device calibration and normal quantum key generation stages, ensuring the security of device operation.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for monitoring strong light attacks in a QKD system, characterized in that: The QKD system adds a time delay of a preset duration before each calibration process during the calibration phase to monitor for strong light attacks.

2. The method for monitoring strong light attacks in a QKD system according to claim 1, characterized in that: When a calibration process fails, the QKD system repeats that calibration process and adds a time delay of the preset duration before restarting the calibration process to monitor for strong light attacks.

3. The method for monitoring strong light attacks in a QKD system according to claim 1, characterized in that: Based on being uniformly determined by software configuration, the QKD system calibrates different detection thresholds for the differences of different detectors for the strong light attack detection threshold.

4. A QKD system calibration method adopting the method for monitoring strong light attacks in a QKD system according to any one of claims 1 to 3, characterized in that: After the QKD system starts, a time delay of a preset duration is added before each calibration process when entering the calibration phase to monitor for strong light attacks. After all calibration processes are completed, the QKD system enters the quantum key generation phase.

5. The calibration method of a QKD system according to claim 4, wherein: The device calibration phase of the QKD system is mainly divided into the calibration of the received signal light at the receiving end, the calibration of the quantum state at the receiving end, and the calibration process of the relative position of the signal light. A time delay of a preset duration is added before each calibration process to determine whether a strong light attack is suffered. If no strong light attack is suffered, the next calibration process is entered.

6. The QKD system calibration method according to claim 5, wherein: It includes the following steps: Step S1, the QKD starts; Step S2, during the preset time, turn on the monitoring for strong light attacks, and determine whether a strong light attack is suffered. If a strong light attack is suffered, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is suffered, turn off the monitoring for strong light attacks and enter the calibration phase; Step S3, enter the first calibration phase: calibration of the received signal light at the receiving end; Step S4, determine whether the calibration of the received signal light at the receiving end fails. If it fails, return to Step S2. Otherwise, enter the next step; Step S5, before the start of the second calibration phase, during the preset time, turn on the monitoring for strong light attacks, and determine whether a strong light attack is suffered. If a strong light attack is suffered, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is suffered, turn off the monitoring for strong light attacks and enter the next calibration phase; Step S6, enter the second calibration phase: calibration of the quantum state at the receiving end; Step S7, determine whether the calibration of the quantum state at the receiving end fails. If it fails, return to Step S5. Otherwise, enter the next step; Step S8, before the start of the third calibration phase, during the preset time, turn on the monitoring for strong light attacks, and determine whether a strong light attack is suffered. If a strong light attack is suffered, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is suffered, turn off the monitoring for strong light attacks and enter the next calibration phase; Step S9, enter the third calibration phase: calibration of the relative position of the signal light; Step S10, determine whether the calibration of the relative position of the signal light fails. If it fails, return to Step S8. Otherwise, enter the next step; Step S11, turn on the monitoring for strong light attacks, and determine whether a strong light attack is suffered. If a strong light attack is suffered, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is suffered, enter the next phase; Step S12, enter the quantum key generation phase; Step S13, continuously turn on the monitoring for strong light attacks during the quantum key generation phase. If a strong light attack is suffered, the system enters the strong light anomaly handling process and reports to the user. If no strong light attack is suffered, it remains in Step S12 all the time.

7. A QKD receiver device using the QKD system calibration method according to any one of claims 4-6.

8. A QKD system, comprising a QKD transmitter device, a QKD receiver device and a host computer, the QKD transmitter device and the QKD receiver device are connected, and both the QKD transmitter device and the QKD receiver device are connected to the host computer, characterized in that: The QKD receiver device uses the device according to claim 7.

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