CN111342953B

CN111342953B - Demonstration system for quantum channel eavesdropping attacks on quantum key distribution devices

Info

Publication number: CN111342953B
Application number: CN201811549300.XA
Authority: CN
Inventors: 聂际敏; 陈昊泽
Original assignee: Cas Quantum Network Co ltd
Current assignee: Cas Quantum Network Co ltd
Priority date: 2018-12-18
Filing date: 2018-12-18
Publication date: 2025-09-30
Anticipated expiration: 2038-12-18
Also published as: CN111342953A

Abstract

The invention provides a demonstration system for quantum channel eavesdropping attacks of quantum key distribution equipment, which comprises a quantum key distribution transmitting end Alice, a quantum key distribution eavesdropping end Eve, a quantum key distribution detecting end Bob, a transmission light path, a control end and a demonstration end, wherein the Alice end is arranged to be capable of outputting single photon signals, the Eve end and the Bob end are arranged to be capable of detecting the single photon signals and outputting detection electric signals, the transmission light path is arranged to realize light path connection of the Alice end and the Bob end or light path connection of the Alice end and the Eve end according to control signals provided by the control end, and the demonstration end is arranged to demonstrate quantum channel eavesdropping attacks according to detection results of the Bob end and/or the Eve end.

Description

Demonstration system for quantum key distribution equipment quantum channel eavesdropping attack

Technical Field

The invention relates to the field of quantum communication, in particular to a demonstration system for quantum channel eavesdropping attack of quantum key distribution equipment.

Background

Quantum Key Distribution (QKD) systems can theoretically generate consistent quantum keys unconditionally securely for both legitimate communicating parties. At present, most attacks aiming at the system are demonstrated as attacks of a data layer, namely, an attacker cannot crack a data message encrypted by a quantum key. Other attack experiments aiming at the quantum channel aiming at the system loopholes are complex, and the aim is to highlight the security loopholes possibly existing in the QKD system and cannot play a role in demonstrating the security distribution key of the quantum key distribution system. These existing systems cannot be well demonstrated for single quantum inseparability on which quantum key distribution security is based.

Disclosure of Invention

The invention provides a demonstration system for quantum channel eavesdropping attack of quantum key distribution equipment, which comprises a quantum key distribution transmitting end Alice, a quantum key distribution eavesdropping end Eve, a quantum key distribution detecting end Bob, a transmission light path, a control end and a demonstration end, wherein the Alice end is arranged to be capable of outputting single photon signals, the Eve end and the Bob end are arranged to be capable of detecting the single photon signals and outputting detection electric signals, the transmission light path is arranged to realize light path connection of the Alice end and the Bob end or light path connection of the Alice end and the Eve end according to control signals provided by the control end, and the demonstration end is arranged to demonstrate quantum channel eavesdropping attack according to detection results of the Bob end and/or the Eve end.

Preferably, the transmission optical path may include an optical switch, a first optical path a, a second optical path B, a beam splitting unit, and a beam combining unit. The optical switch may be configured to switch optical path connection between the Alice terminal and the first optical path a or the second optical path B according to the control signal, the beam combining unit may be configured to combine optical signals input via the first optical path a and the second optical path B to output, and the beam splitting unit may be configured to split optical signals input via the second optical path B to output.

Further, the Alice terminal is connected with the Bob terminal through the first light path A and the beam combination unit, the Alice terminal is connected with the Eve terminal through the second light path B and the beam combination unit, and the Alice terminal is connected with the Bob terminal through the second light path B, the beam combination unit and the beam combination unit.

Preferably, the beam combining unit may be a beam splitter, and/or the beam splitting unit is a beam splitter or a clamp.

Preferably, the control terminal may include a first counter for counting the detection electric signal output from the Bob terminal and a second counter for counting the detection electric signal output from the Eve terminal. Further, the control end may further include a third counter, a signal delay adjuster, and a coincidence gate unit, where the signal delay adjuster is configured such that, in one period, the detected electrical signal output by the Bob end and the detected electrical signal output by the Eve end arrive at the coincidence gate unit at the same time, the coincidence gate unit is configured to perform an and operation on the detected electrical signal output by the Bob end and the detected electrical signal output by the Eve end, and the third counter is configured to count valid electrical signals output by the coincidence gate unit.

Preferably, the control terminal may further include a clock source for outputting synchronous clock signals to the Alice terminal, the Bob terminal, and the Eve terminal.

Preferably, the control end may further include a discriminator, configured to discriminate and shape the detected electrical signal output by the Bob end and/or the detected electrical signal output by the Eve end.

Preferably, the Alice terminal may have a low frequency intense light emission mode and a high frequency single photon emission mode, and be configured to be switchable between the low frequency intense light emission mode and the high frequency single photon emission mode based on control of the control terminal.

Preferably, the presentation end may include an input interface allowing a user to input instructions to determine whether the presentation system operates in a normal mode or a eavesdropping mode, and a display interface for system status presentation.

Drawings

FIG. 1 illustrates the principle of the present invention for a presentation system for quantum channel eavesdropping attacks by a quantum key distribution device, and

Fig. 2 shows an exemplary embodiment of a presentation system of the present invention for a quantum key distribution device quantum channel eavesdropping attack.

Detailed Description

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are provided by way of illustration to fully convey the spirit of the invention to those skilled in the art to which the invention pertains. Thus, the present invention is not limited to the embodiments disclosed herein.

Fig. 1 is a diagram for illustrating the principles of a presentation system for quantum channel eavesdropping attacks by a quantum key distribution device of the present invention. As shown in fig. 1, the presentation system may include a quantum key distribution transmitting terminal (Alice), a quantum key distribution eavesdropping terminal (Eve), a quantum key distribution detecting terminal (Bob), a transmission light path, a control terminal (not shown), and a presentation terminal (not shown).

The quantum key distribution transmitting terminal Alice transmits a single photon signal and is used for simulating the generation of a quantum key signal. By way of example, the quantum key distribution emitter may be any light source capable of providing a single photon signal, or a light source implemented based on a weak coherent laser source.

The quantum key distribution detection end Bob can receive and detect the existence of single photon signals and is used for simulating the reception of quantum key signals. The quantum key distribution eavesdropper Eve can receive and detect the existence of single photon signals and is used for simulating an eavesdropper of the quantum key signals. In the present invention, the quantum key distribution detecting terminal Bob and the quantum key distribution eavesdropping terminal Eve may preferably have the same detecting structure. As an example, bob and Eve ends may comprise single photon detectors, preferably avalanche detectors or superconducting detectors.

The transmission light path realizes the light path connection between the Alice end and the Bob end or between the Alice end and the Eve end according to the control signal provided by the control end.

An embodiment of a transmission light path according to the invention is also exemplarily depicted in fig. 1. As shown, the transmission optical path may include an optical switch, a first optical path a, a second optical path B, a beam splitting unit, and a beam combining unit. The output end of Alice has the optical path to be connected with the input of optical switch, and first optical path A and second optical path B are connected respectively to the first and second output of optical switch for optical switch can make the single photon signal that Alice's end sent get into first optical path A or second optical path B according to control signal.

The beam combining unit comprises a first/second input end and an output end, and is used for combining optical signals input through the first input end and the second input end and then outputting the optical signals outwards through the output end. As an example, the first input end of the beam combining unit may be in optical path connection with the first output end of the optical switch via the first optical path a, and the output end of the beam combining unit is in optical path connection with the Bob end. As an example, the beam combining unit may be a Beam Splitter (BS), as shown in fig. 1.

The beam splitting unit is disposed on the second optical path B, and includes an input end and a first/second output end, and is configured to split an optical signal input through the input end and output the split two beams through the first/second output end. As an example, the input end of the beam splitting unit may be in optical path connection with the second output end of the optical switch, the first output end of the beam splitting unit may be in optical path connection with the Eve end, and the second output end of the beam splitting unit may be connected with the second input end of the beam splitting unit via the second optical path B. As an example, the beam splitting unit may be a Beam Splitter (BS) or a clamp, as shown in fig. 1. Those skilled in the art will appreciate that the clamp can achieve splitting of an optical signal in an optical fiber by disrupting the total reflection effect of the fiber without disrupting the fiber.

Under the structure, a single photon signal is emitted from the Alice end, and enters two paths, namely a first optical path A and a second optical path B through an optical switch. When the optical switch is turned on the first optical path A, the single photon signal emitted by Alice is directly input to the Bob end to demonstrate the non-eavesdropped state. When the optical switch is connected with the second optical path B, a single photon signal emitted by the Alice end propagates towards the Eve/Bob end under the action of the beam splitting unit so as to demonstrate the eavesdropped state. It should be noted that due to the indivisible nature of single photons, it is not possible for the same single photon signal from Alice to be detected by both Bob and Eve, thus proving that single photon signals are used in the quantum key distribution system.

Fig. 2 shows an exemplary embodiment of a presentation system for quantum key distribution device quantum channel eavesdropping attacks, for specifying the structure of the control side and the presentation side. As shown in fig. 2, the control terminal may be provided with a clock source, which outputs clock signals to Alice terminal, bob terminal and Eve terminal, so that clocks of the three terminals are synchronized.

The Alice end generates and outputs a single photon signal, and the single photon signal enters two paths, namely a first optical path A and a second optical path B through an optical switch. When the optical switch is turned on the first optical path a, a single photon signal emitted by Alice is directly input to the Bob terminal via a beam combining unit (e.g., BS). At the Bob end, the input single photon signal is detected and a corresponding electrical signal is output. The probe electrical signal output by Bob terminal is then input to the control terminal. In the control end of the present invention, a first discriminator may be preferably provided to discriminate and shape the input probe electrical signal, and then the shaped effective electrical signal is input to a first counter to count, thereby recording the number of signals used in communication (not subject to eavesdropping).

When the optical switch is turned on the second optical path B, a single photon signal emitted from Alice end enters the second optical path B, and reaches the beam splitting unit (e.g., a clamp). Because of the indivisible nature of the single photon signal, the single photon signal will, with a certain probability, enter the Eve end directly via the first output end of the beam splitting unit or enter the Bob end via the second output end of the beam splitting unit, the second input end of the beam combining unit and the output end.

When the single photon signal enters the Eve end, the Eve end detects the input single photon signal and outputs a corresponding electric signal. The probe electrical signal output by the Eve terminal is then input to the control terminal. Similarly, a second discriminator may be preferably provided in the control end of the present invention to discriminate and shape the incoming probe electrical signal and then input the shaped effective electrical signal to a second counter for counting statistics to record the number of signals not used for communication (subject to eavesdropping).

The control end of the invention is also provided with a signal delay regulator which is used for enabling the detection electric signal output by the Bob end and the detection electric signal output by the Eve end to reach the coincidence gate unit simultaneously in one period. As an example, a signal delay adjuster may be disposed between the second discriminator and the coincidence gate unit. The coincidence gate unit performs AND gate operation on the input electric signals, namely, outputs an effective electric signal when two paths of signals are input at the same time. The valid electrical signal output by the coincidence gate unit is input to a third counter for counting statistics, thereby recording the number of signals used for communication (and subject to eavesdropping).

The three count results from the three counters are input to the control unit for processing and storage.

The demonstration end comprises an input interface and a display interface. The input interface allows a user to input instructions to determine whether the system is operating in a normal mode or in a eavesdropping mode, for example, by controlling an optical switch via a control terminal. The display interface will be used for system status demonstration, for example to display the non-eavesdroppability of the quantum communication according to the counting results of the three counters.

In the invention, in order to ensure the accuracy of the delay adjustment of the signal delay adjuster, the control end is set to enable the Alice end to have two working modes, namely a low-frequency strong light emission mode and a high-frequency single photon emission mode.

The low-frequency intense light emission mode is used under a debugging working condition, and can have a light emitting frequency of 10kHz and average photon number per pulse of 10. In this mode, since the line delay error cannot be greater than one transmission period (e.g., a frequency of 10kHz for a time interval of 100us, which corresponds to a cable length of 10000 meters), the desired delay value can be found correctly. The high frequency single photon emission mode is used under working conditions, and can have a light emitting frequency of 40MHz, for example, and the average photon number per pulse is in the range of 0.5. In this mode, the single photon indivisible characteristic can be demonstrated, and the counting rate per second is kept at a high level, and a good demonstration effect is maintained.

By means of the demonstration system, the demonstration problem of the single photon indivisible characteristic of the quantum key distribution system is solved. The quantum key distribution system is subjected to beam splitting attack through the beam splitting unit, and counting statistics is carried out by combining with the coincidence gate unit, so that the single photon signal which visually shows that effective codes are formed between Alice and Bob can not be obtained by Eve, namely, effective detection electric signals can not appear at the Bob end and the Eve end at the same time in one period, and the method has remarkable significance for technical science popularization and application and popularization.

The above description is not intended to limit the invention, nor is the invention limited to the examples described above, and the various alternatives described above may be used in combination with one another without contradiction. Variations, modifications, additions, or substitutions that would be within the spirit and scope of the invention are also within the scope of the invention, which is defined by the following claims.

Claims

1. A demonstration system for quantum channel eavesdropping attacks on a quantum key distribution device, comprising a quantum key distribution transmitter Alice, a quantum key distribution eavesdropper Eve, a quantum key distribution detector Bob, a transmission optical path, a control terminal, and a demonstration terminal, wherein:

The Alice terminal is configured to output a single photon signal;

The Eve terminal and the Bob terminal are configured to detect the single photon signal and output a detection electrical signal;

The transmission optical path is configured to realize an optical path connection between the Alice end and the Bob end or an optical path connection between the Alice end and the Eve end according to a control signal provided by the control end; and

The demonstration end is configured to demonstrate a quantum channel eavesdropping attack based on the detection results of the Bob end and/or the Eve end;

The transmission optical path includes an optical switch, a first optical path A, a second optical path B, a beam splitting unit, and a beam combining unit; the optical switch is configured to switch the optical path connection between the Alice end and the first optical path A or the second optical path B according to the control signal; the beam combining unit is configured to combine and output the optical signals input through the first optical path A and the second optical path B; the beam splitting unit is configured to split and output the optical signal input through the second optical path B;

The Alice end is connected to the Bob end via the first optical path A and the beam combining unit; the Alice end is connected to the Eve end via the second optical path B and the beam splitting unit, and is connected to the Bob end via the second optical path B, the beam splitting unit and the beam combining unit.

2. The demonstration system according to claim 1, wherein the beam combining unit is a beam splitter; and/or the beam splitting unit is a beam splitter or a clamp.

3. The demonstration system as claimed in claim 1, wherein the control end includes a first counter and a second counter; the first counter is used to count the detection electrical signal output by the Bob end, and the second counter is used to count the detection electrical signal output by the Eve end.

4. The demonstration system as claimed in claim 3, wherein the control end further includes a third counter, a signal delay adjuster and a coincidence gate unit, the signal delay adjuster is configured so that within one cycle, the detection electrical signal output by the Bob end and the detection electrical signal output by the Eve end reach the coincidence gate unit at the same time; the coincidence gate unit is configured to perform an AND gate operation on the detection electrical signal output by the Bob end and the detection electrical signal output by the Eve end; and the third counter is used to count the valid electrical signals output by the coincidence gate unit.

5 . The demonstration system according to claim 3 , wherein the control end further comprises a clock source for outputting a synchronous clock signal to the Alice end, the Bob end, and the Eve end.

6. The demonstration system according to claim 3, wherein the control end further comprises a discriminator for discriminating and shaping the detection electrical signal output by the Bob end and/or the detection electrical signal output by the Eve end.

7. A demonstration system as described in any one of claims 1, 3-6, wherein the Alice end has a low-frequency strong light emission mode and a high-frequency single-photon emission mode, and is configured to be able to switch between the low-frequency strong light emission mode and the high-frequency single-photon emission mode based on the control of the control end.

8. The demonstration system as claimed in claim 1, wherein the demonstration end includes an input interface and a display interface, the input interface allows a user to input instructions to determine whether the demonstration system operates in normal mode or eavesdropping mode, and the display interface is used for system status demonstration.