WO2016093610A1

WO2016093610A1 - Method, apparatus, and system for distributing quantum encryption key

Info

Publication number: WO2016093610A1
Application number: PCT/KR2015/013429
Authority: WO
Inventors: 이준구; 고해신; 임경천
Original assignee: 한국과학기술원
Priority date: 2014-12-09
Filing date: 2015-12-09
Publication date: 2016-06-16
Also published as: KR101767067B1; KR20160070032A

Abstract

The present invention relates to a method, apparatus, and system for distributing a quantum encryption key and, more particularly to, a method, apparatus, and system for distributing a quantum encryption key, in which, when a transmitter (Alice) distributes a quantum encryption key to a receiver (Bob) using a series of light pulses, each of the light pulses is randomly polarized at one of a plurality of predetermined polarization angles or randomly modulated with one of a plurality of predetermined phases, each polarized or modulated light pulse is transmitted, and then information on consecutive light pulses among the series of light pulses is transferred to the receiver so as to verify whether an attacker (Eve) is eavesdropping. Accordingly, the present invention can improve a security problem that may occur in coherent one way (COW) quantum encryption key distribution. In a method, apparatus, and system for distributing a quantum encryption key according to an embodiment of the present invention, since a series of light pulses transmitted by a transmitter for quantum encryption key distribution pass through random polarization or phase modulation, the presence of an attacker can be clearly detected even in a sequential light pulse phase-position detection and attack-type where it is difficult to detect the presence of an attacker in a conventional coherent one way quantum encryption key distribution protocol, and thus security can be improved.

Description

Quantum cryptographic key distribution method, apparatus and system

The present invention relates to a method, apparatus, and system for quantum cryptographic key distribution, and more particularly, to a transmitter using a series of optical pulses to distribute quantum cryptographic keys to a receiver, wherein each optical pulse is a plurality of predetermined polarizations. Randomly polarize to one of the angles, or randomly modulate and transmit to one of a plurality of predetermined phases, and then convey information about successive light pulses in the series of light pulses to the recipient to verify whether the attacker is eavesdropping. Thereby, the present invention relates to a quantum cryptographic key distribution method, apparatus and system that can ameliorate security problems that may arise in coherent unidirectional quantum cryptographic key distribution.

Recently, as the damage cases caused by personal or national interception and interception have been continuously introduced, interest in security has increased greatly. However, the security communication according to the prior art has a considerable risk of exposing the communication contents by an external attack, and as a next-generation security technology to compensate for this, quantum cryptography communication, which can guarantee very high security, has been spotlighted. I am getting it.

In this regard, research on quantum cryptographic key distribution among quantum cryptographic communication technologies has been actively conducted. Quantum cryptographic key distribution technology uses photon quantum mechanical properties to distribute and share cryptographic keys among remote users. In this case, when an attacker attempts to obtain encryption key information distributed between users due to quantum mechanical properties, the encryption key information may be altered, and thus users who send and receive encryption keys may detect the existence of the attacker. Will be.

A representative example of the quantum cryptographic key distribution protocol according to the prior art is a coherent one way (COW) quantum cryptographic key distribution protocol. FIG. 1 illustrates a diagram illustrating the Coherent One Way (COW) quantum cryptographic key distribution protocol. Referring to FIG. 1, the operation principle of the coherent one-way quantum cryptography key distribution protocol is as follows. First, in the coherent unidirectional quantum cryptographic key distribution protocol, the transmitter (Alice) of the cryptographic key generates a coherent laser having a constant phase difference between each pulse, and then uses the two pulses as one information unit (Bob). Will be sent to. In this case, when there is no subsequent pulse among the two pulses and only the preceding pulse is present, the bit information '0' means. On the other hand, when there is no preceding pulse in time and only the following pulse means bit information '1'. In addition, when both pulses are present, the pulses are not used as encryption key information but used to detect the presence of an attacker, and when both pulses are present, they are called decoy data.

When the sender Alice transmits the bait data as f , the probability that the sender Alice transmits the three types of information defined above is (1- f ) / 2, (1- f ) / 2, can be f. The receiver Bob has a data line and a monitoring line in order to detect the distribution of the encryption key and the presence of the attacker. At this time, some of the data transmitted by the sender Alice enters the data line of the receiver Bob and is measured, and the rest enters the monitoring line of the receiver Bob and is measured.

The information measured on the data line is information that can be used to generate an encryption key after undergoing an encryption key distribution procedure. On the other hand, the information transmitted to the monitoring line is used to detect the presence of the attacker (Eve). In this case, the monitoring line may include a delay interferometer for delaying the phase difference ρ used by the sender Alice to generate a coherent laser pulse. In addition, the monitoring line includes two photon detectors D _M1 and D. _M2 ) can be located to detect the occurrence of constructive and destructive interference of the signal, respectively. Accordingly, if two pulses transmitted by the sender Alice are transmitted to the receiver without a change of state in the middle (i.e. without an attacker's attack), the photon detection may be performed only in one photon detector detecting the occurrence of constructive interference. do.

On the other hand, if the attacker (Eve) wants to access the pulse transmitted by the sender Alice to obtain the encryption key information, the attacker (Eve) can know the phase difference between the two pulses, but the absolute phase of each pulse Since the value is not known, the attacker Eve cannot restore and retransmit the same signal transmitted by the sender Alice so that the coherence between the pulses received by the receiver Bob cannot be maintained. do. Therefore, when there is an attack of the attacker (Eve), since the photon detection may occur on the photon detector side where the occurrence of destructive interference is detected, the sender (Alice) or the receiver (Eve) can detect the presence of the attacker (Eve). do.

However, the coherent one-way quantum cryptography key distribution protocol according to the prior art has a limitation that it is difficult to properly detect the presence of the attacker (Eve) for the following attack method. That is, the attacker Eve can easily calculate the phase difference between the pulses by first examining several pulses located in front of the sender Alice. The attacker Alice then only measures the position of every pulse the sender sends without having to measure the phase for each pulse. In this case, since the attacker Eve can know the positions of the remaining pulses except for the first few pulses, the pulses transmitted by the sender Alice can be almost completely understood in consideration of the phase difference information between the pulses previously calculated. Will be. That is, the attacker Eve can obtain complete information about the pulse transmitted by the sender Alice except for the first few pulses, and then the attacker Eve can compare with the pulse transmitted by the sender Alice. Since the same pulse can be reproduced and retransmitted to the receiver Bob, the sender Alice and the receiver Bob can hardly detect the presence of the attacker Eve. Therefore, in the case of the above attack type (hereinafter referred to as "optical pulse phase-position sequential detection attack"), it may be very difficult to detect the presence of an attacker in the existing coherent one-way quantum cryptographic key distribution protocol. As a result, an attacker Eve can effectively obtain the quantum encryption key.

The present invention was devised to solve the above problems of the prior art, and in the coherent one-way quantum cryptographic key distribution protocol according to the prior art, the optical pulse phase-position sequential detection attack type that is difficult to detect an attacker's eavesdropping. It is also an object of the present invention to provide a quantum cryptographic key distribution method, apparatus, and system that can improve the security by allowing the attacker's eavesdropping to be clearly detected.

A quantum cryptographic key distribution method according to an aspect of the present invention for solving the above problems is a method in which a sender distributes a quantum cryptographic key to a receiver by using a series of optical pulses, the sender is a plurality of predetermined light pulses An optical pulse transmission step of randomly polarizing one of the polarization angles and transmitting the polarized light to a receiver; And when the sender delivers information about successive light pulses among the series of light pulses to the receiver, and there is an attacker's eavesdropping in the process of transmitting the series of light pulses using the measurement values for the successive light pulses. Verification information transmission step to verify whether or not; characterized in that it comprises a.

Here, in the verification information transmission step, the sender transmits information on the case where the continuous light pulses have the same polarization to the receiver, wherein the receiver uses the quantum interference effect to polarize the same pulse. It can be determined whether there is an attacker's eavesdropping by determining whether or not there is a.

Further, in the verification information transmission step, the sender transmits information on the case where the successive light pulses have different polarizations to the receiver, wherein the receiver is mutually related to the case where no quantum interference effect occurs. According to the different types of polarizations, it is possible to determine whether there is an attacker's eavesdropping by comparing the previously calculated detection prediction value with the actual measurement value.

In addition, the quantum cryptographic key distribution method according to an aspect of the present invention may further include calculating a quantum cryptographic key using some or all of information on the quantum cryptographic keys included in the series of optical pulses.

A quantum cryptographic key distribution method according to another aspect of the present invention is a method of distributing a quantum cryptographic key using a series of light pulses that a receiver receives from a sender, wherein the receiver receives each light pulse from among a plurality of predetermined polarization angles. An optical pulse receiving step of receiving a series of optical pulses transmitted by randomly polarizing one; And if the receiver receives information about the continuous light pulses from the series of light pulses from the sender, and if there is an attacker's eavesdropping in the process of transmitting the series of light pulses using the measurement values for the continuous light pulses. And tapping verification step of verifying whether or not.

Here, in the tapping verification step, the receiver receives information on the case where the continuous pulses have the same polarization from the transmitter, and determines whether the continuous pulses have the same polarization by using a quantum interference effect. By judging, it can be determined whether there is an attacker's eavesdropping.

In the tapping verification step, the receiver receives information on the case where the consecutive pulses have different polarizations from the sender, so that the receiver does not generate quantum interference effects. Accordingly, it is possible to determine whether there is an attacker's eavesdropping by comparing the previously calculated measurement prediction value with the actual measurement value.

In addition, the quantum cryptographic key distribution method according to another aspect of the present invention may further include calculating a quantum cryptographic key using some or all of information on the quantum cryptographic keys included in the series of optical pulses. .

A quantum cryptographic key distribution method according to another aspect of the present invention is a method in which a sender distributes a quantum cryptographic key to a receiver using a series of light pulses, wherein the sender randomly assigns each light pulse to one of a plurality of predetermined phases. Modulating and transmitting an optical pulse to a receiver; And when the sender delivers information about successive light pulses among the series of light pulses to the receiver, and there is an attacker's eavesdropping in the process of transmitting the series of light pulses using the measurement values for the successive light pulses. Verification information transmission step to verify whether or not; characterized in that it comprises a.

Here, in the verification information transmission step, the transmitter transmits information about the case where the continuous pulse has the same phase or the opposite phase to the receiver, wherein the receiver uses the optical interferometer to perform the continuous It is possible to determine whether there is an attacker's eavesdropping by determining whether the pulse has the same phase or the opposite phase.

A quantum cryptographic key distribution method according to another aspect of the present invention is a method in which a receiver receives a quantum cryptographic key using a series of optical pulses received from a sender, wherein the receiver assigns each optical pulse to one of a plurality of predetermined phases. An optical pulse receiving step of receiving a series of randomly transmitted optical pulses; And the eavesdropping device receives information about the continuous light pulses from the sender and determines whether there was an eavesdropping by an attacker in the process of transmitting the series of light pulses using the measurement values for the continuous light pulses. Verification step; characterized in that it comprises a.

Here, in the tapping verification step, the receiver receives information on the case where the continuous pulses have the same phase or the opposite phase from the sender, and the continuous pulses have the same phase by using an optical interferometer. It can be determined whether there is an eavesdropping by attacker by determining whether or not it has the opposite phase.

In addition, the quantum cryptographic key distribution method according to another aspect of the present invention may further include calculating a quantum cryptographic key using some or all of information on the quantum cryptographic keys included in the series of optical pulses. have.

A transmitting device according to another aspect of the present invention is a transmitting device for distributing a quantum cryptographic key to a receiving device using a series of light pulses, wherein each light pulse is randomly polarized at one of a plurality of predetermined polarization angles, or An optical pulse transmitter which modulates randomly one of a plurality of predetermined phases and transmits the same to a receiving apparatus; And transmitting information about successive light pulses of the series of light pulses to the receiving device to determine whether there was an attacker's eavesdropping in the course of transmitting the series of light pulses using the measurement values for the successive light pulses. Verification information transmission unit for verifying; characterized in that it comprises a.

A receiving apparatus according to another aspect of the present invention is a receiving apparatus that receives a quantum cryptographic key using a series of light pulses received from a transmitting apparatus, and randomly polarizes each light pulse to one of a plurality of predetermined polarization angles. An optical pulse receiver for receiving a series of optical pulses which are randomly modulated with one of a plurality of predetermined phases and transmitted; And receiving information about the continuous light pulses from the series of light pulses from the transmitting device, and checking whether there is an attacker's eavesdropping during the transmission of the series of light pulses using the measurement values for the continuous light pulses. The wiretap verification unit to determine; characterized in that it comprises a.

A quantum cryptographic key distribution system according to another aspect of the present invention is a quantum cryptographic key distribution system in which a transmitting device distributes a quantum cryptographic key to a receiving device using a series of light pulses, wherein each optical pulse is a plurality of predetermined polarizations. An optical pulse transmitter for randomly polarizing one of the angles or randomly modulating one of a plurality of predetermined phases to transmit to a receiving device; And a verification information transmitter for transmitting the information on the successive optical pulses of the series of optical pulses to the receiving apparatus. And an optical pulse receiver configured to receive a series of optical pulses transmitted by the transmitter. And an attacker's eavesdropping in the process of transmitting the series of optical pulses by using the information on the continuous optical pulses among the series of optical pulses received from the transmitting device. And a receiving device including an eavesdropping verification unit for determining whether or not.

In the quantum cryptographic key distribution method and apparatus system according to an embodiment of the present invention, a series of optical pulses transmitted by a transmitter for random quantum cryptographic key distribution undergoes random polarization or phase modulation, thereby cohering according to the prior art. In the runt one-way quantum cryptographic key distribution protocol (Coherent One Way, COW), the presence of the optical pulse phase-position sequential detection attack that is difficult to detect the presence of the attacker can be clearly detected, thereby improving security. Will be.

1 is an explanatory diagram illustrating the operation of a coherent one-way quantum cryptographic key distribution protocol according to the prior art.

2 is an explanatory diagram illustrating an operation of a quantum cryptographic key distribution system according to an embodiment of the present invention.

3 is an explanatory diagram illustrating an operation of a quantum cryptographic key distribution method using polarization according to an embodiment of the present invention.

4 is a flowchart of a quantum cryptographic key distribution method from a transmitter's point of view using random polarization according to an embodiment of the present invention.

5 is a flowchart of a quantum cryptographic key distribution method from a receiver's perspective using random polarization according to an embodiment of the present invention.

6 to 8 are diagrams illustrating a difference in operation according to polarization states in successive optical pulses in a quantum cryptographic key distribution method using random polarization according to an embodiment of the present invention.

9 is an explanatory diagram illustrating a continuous light pulse in the quantum cryptographic key distribution method using random polarization according to an embodiment of the present invention.

10 is an explanatory diagram illustrating an operation of a quantum cryptographic key distribution method using random phase modulation according to an embodiment of the present invention.

11 is a flowchart of a quantum cryptographic key distribution method from a transmitter's point of view using random phase modulation according to an embodiment of the present invention.

12 is a flowchart of a quantum cryptographic key distribution method from a receiver perspective using random phase modulation according to an embodiment of the present invention.

13 to 14 are diagrams illustrating a difference in operation according to phase states in successive optical pulses in a quantum cryptographic key distribution method using random phase modulation according to an embodiment of the present invention.

15 is an explanatory diagram illustrating a continuous light pulse in the quantum cryptographic key distribution method using random phase modulation according to an embodiment of the present invention.

16 is a block diagram of a transmitting device for quantum cryptographic key distribution according to an embodiment of the present invention.

17 is a block diagram of a receiving apparatus for quantum cryptographic key distribution according to an embodiment of the present invention.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be described in detail with reference to the accompanying drawings.

The following examples are provided to assist in a comprehensive understanding of the methods, devices, and / or systems described herein. However, this is only an example and the present invention is not limited thereto.

In describing the embodiments of the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or an operator. Therefore, the definition should be made based on the contents throughout the specification. The terminology used in the description is for the purpose of describing particular embodiments only and should not be limiting. Unless explicitly used otherwise, the singular forms “a,” “an,” and “the” include plural forms of meaning. In this description, expressions such as "comprises" or "equipment" are intended to indicate certain features, numbers, steps, actions, elements, portions or combinations thereof, and one or more than those described. It should not be construed to exclude the presence or possibility of other features, numbers, steps, actions, elements, portions or combinations thereof.

In addition, terms such as first and second may be used to describe various components, but the components are not limited by the terms, and the terms are used to distinguish one component from another component. Only used as

The present invention provides a coherent one-way quantum cryptography key distribution protocol in the commercialization stage of the quantum cryptography key distribution protocol according to the prior art. In view of the problem that an attacker's eavesdropping cannot be detected for a new attack type (hereinafter referred to as "light pulse phase-position sequential detection attack") that measures the position information of an optical pulse, In addition, random polarization or phase encoding enables attackers to be detected even for the optical pulse phase-position sequential detection attack types that could not detect attackers in the coherent one-way quantum cryptographic key distribution protocol according to the prior art.

More specifically, in the present invention, the sender Alice randomly polarizes a series of light pulses to one of a plurality of predetermined polarization angles, or randomly modulates one of a plurality of predetermined phases to transmit to the receiving device.

In one embodiment of the present invention, in order to provide randomness to the phase of the light pulse, the transmitter randomly modulates and transmits the phase of the series of light pulses generated by the light source generating the laser or the like. After the transmission of the series of light pulses, the sender and the receiver can detect the presence of an attacker by comparing the photon detection results on the monitoring line of the receiver through the existing public channel or the like.

Since the attacker cannot measure both the absolute phase of the optical pulse generated by the sender and the position of the optical pulse at the same time, the optical pulse phase-coherent coherent unidirectional quantum cryptographic key distribution protocol could not detect the attacker. Attackers can also be detected for location sequential attack types.

In a similar manner, as a method of imparting randomness to the polarization of light pulses, the sender may randomly polarize a series of light pulses generated by a light source generating a laser or the like. Even in this case, the attacker can be clearly detected, similar to the random phase method described above.

In the following, the theoretical background of the present invention and exemplary embodiments of a novel protocol design method according to the present invention will be described in turn with reference to the accompanying drawings.

First, FIG. 2 is a diagram illustrating an operation of a quantum cryptographic key distribution system according to an embodiment of the present invention. As can be seen in Figure 2 quantum cryptographic key distribution system according to an embodiment of the present invention may be configured to include a sender 110 and a receiver 120, the sender 110 and the receiver 120 It may be connected using an optical communication network 130 including an optical channel capable of delivering optical pulses.

In this case, the transmitter 110 randomly polarizes a series of optical pulses to one of a plurality of predetermined polarization angles, or randomly modulates one of a plurality of predetermined phases to transmit to the receiver 120, and then transmits the series of light pulses to the receiver 120. It transmits information about successive light pulses among the light pulses.

Accordingly, the receiver 120 determines whether there is an eavesdropping of the attacker 140 in the process of transmitting the series of optical pulses by using the measurement value for the consecutive optical pulses of the series of optical pulses. In the case of the coherent unidirectional quantum cryptographic key distribution protocol according to the technology, it is possible to solve the problem that the eavesdropping of the attacker 140 could not be detected in the optical pulse phase-position sequential detection attack type.

Before looking at the present invention in more detail, first, the present invention will be described in general, and then the present invention will be described in more detail with reference to specific embodiments.

The present invention relates to a quantum cryptographic key distribution protocol, which can be said to be a series of appointments for distributing confidential cryptographic keys between sender 110 and receiver 120 using a photon transmission system. The criterion for evaluating the superiority of the protocol according to the present invention depends on how much information a third party, i.e., the attacker 140 can eavesdrop on without being exposed to the sender and receiver, and the sender 110 or the receiver. If the 120 can easily detect the eavesdropping behavior of the attacker 140, it may be determined as an excellent protocol.

The present invention is based on the following assumptions.

A. There is little loss of optical pulses in the optical channel.

B. The dark count of the detector can be ignored.

C. The imperfections of equipment in the system can be ignored.

D. Within each light pulse there is typically one photon.

The above assumptions may be somewhat different from the actual situation, but since there is no big problem in the actual implementation to satisfy the above assumptions, the operation of the present invention will be described based on the above assumptions. .

The present invention has a structure similar to the existing proposed coherent one way (COW) quantum cryptographic key distribution protocol. First, a mode-lock laser can be used as a light source for generating light pulses so that the phase difference between the front and back light pulses is always kept the same. At this time, the average number of photon transmissions (μ) is kept low so that one photon exists in most optical pulses. In addition, information is transmitted in the same manner, and the information transmitted by the sender 110 is 0, 1, and three kinds of decoy data (decoy). Here, each piece of information is represented by the presence or absence of two consecutive light pulses, where only a trailing light pulse is present and a preceding light pulse is empty, and a preceding light pulse is present and a trailing light pulse is present. If empty, 1, and if both light pulses are present, decoy data (decoy). Here, 0 and 1 are information that the sender 110 actually delivers to the receiver 120, and the decoy data (decoy) is data for determining whether the attacker 140 has intercepted in the middle. The transmitter 110 generates and transmits the 0, 1, and decoy data with the probability of convergence to each. In this case, the transmitter 110 generates the information by removing a pulse at a desired position according to the information to be transmitted by the transmitter 110. For this purpose, the transmitter 110 uses a variable attenuator positioned in front of a light source such as the laser. It is also possible to generate a pulse waveform corresponding to the information.

As described above, a series of optical pulses including information such as a quantum cryptographic key is generated through the presence or absence of optical pulses, and then polarization or phase encoding is added to each optical pulse. Hereinafter, a case of performing polarized encoding will be described.

3 is a diagram illustrating an operation of a quantum cryptographic key distribution method using polarization according to an embodiment of the present invention.

Polarization encoding sets the polarization state of a light pulse, and may use two or more bases to randomly polarize one of a plurality of predetermined polarization angles included in the two or more bases. For example, as in the BB84 protocol, using four polarization states forming two bass, each light pulse can be polarized at a polarization angle of one of 0, 45, 90, 135 degrees, wherein 0 and 90 degrees may constitute a first base (+), and 45 and 135 degrees may constitute a second base (×). The encoded light pulses are transmitted to the receiver 120 through the optical channel. The attacker 140 measures the light pulses and extracts information in the middle of the transmission of the light pulses. At this time, when the attacker 140 measures the light pulse transmitted by the transmitter 110, the state of the photons included in the light pulse is derived as a detection result of the detector. At the same time, if a photon is measured, the corresponding photon disappears, and the attacker 140 needs to generate and send the photon to the receiver 120 again based on the measurement result. This is because the receiver 120 may know that the attacker 140 exists in the middle if the receiver 120 does not transmit the message to the receiver 120. Thus, if the attacker 140 can completely measure the state information of the photons transmitted by the sender 110, the attacker 140 may retransmit photons having the same state as the original photons to the receiver 120, and thus the sender 110. And eavesdropping without being exposed to the receiver 12.

However, as described above, the additionally encoded polarization according to the present invention is physically impossible to measure completely, and probable polarization information different from the original polarization may be derived as a measurement result of the detector. Therefore, when the attacker 140 measures and retransmits a photon, the attacker 140 may transmit a state different from the photon state sent by the sender 110.

Accordingly, the receiver 120 receives the photons re-transmitted by the attacker 140 to perform the measurement. As shown in FIG. 3, the photons are divided into data lines and monitoring lines in a splitter. Here, the receiver 120 may determine the presence or absence of the attacker 140 by analyzing photons detected in the monitoring line, and the process is as follows.

A. Receiver 120 records all time slots for which its detector measured photons.

B. After the reception of all transmitted photons, the transmitter 110 transmits two consecutive light pulses in the same polarization state among time slots in which light pulses are continuously present among a series of light pulses transmitted by the sender 110. The receiver 120 is informed of information that can identify the encoded case. The information may be transmitted to the receiver 120 using an authenticated public channel.

C. When the receiver 120 receives the information, the receiver 120 finds a time slot in which successive light pulses may cause interference in the system of its monitoring line, and the time slot Check the detection result in (time slot).

D. If the attacker 140 does not exist and the photon state transmitted by the sender 110 arrives at the receiver 120 as it is, or in rare cases, the attacker 140 retransmits the photon state transmitted by the sender 110. In this position, photons cannot be detected at the detectors D _M1 and D _M2 at the same time by the HOM (Hong Ou Mandel) effect. (See Figure 3)

E. If there is an attacker 140, and if the probability of incorrectly measuring and retransmitting the photon state transmitted by the sender 110, an anti-HOM effect (Coincidence Detection) occurs in the corresponding time slot and the photon It can be detected simultaneously in D _M1 and D _M2 .

F. Therefore, when the anti-HOM effect occurs at the location where the interference is likely to occur, it can be seen that the attacker 140 exists.

G. Alternatively, the transmitter 110 may notify the receiver 120 of two consecutive light pulses encoded in different polarization states among time slots in which light pulses are consecutive among the light pulses transmitted by the sender 110. It may be. The information may also be transmitted to the receiver 120 using an authenticated public channel.

H. At this time, when the receiver 120 receives the above information, the receiver 120 analyzes the measurement results of the detectors D _M1 and D _M2 by finding a time slot in which two consecutive optical pulses are likely to cause interference, as described above.

I. In this case, when there is no eavesdropping of the attacker 140, the detection result by the HOM effect and the Anti-HOM effect is generated with a probability of 0.5, respectively, but when there is an attacker's eavesdropping, the probability that the HOM effect occurs The probability of this 11/16, anti-HOM effect may change to 5/16.

J. Therefore, by analyzing the detection results in the time slots in which the interference is estimated, it is possible to statistically determine whether the attacker 140 exists.

Furthermore, even if the attacker 140 performs an attack different from the above-described attack, since the probability is inconsistent with the case without the eavesdropping attack, the presence of the attacker 140 can be statistically determined by comparing the detection result. Will be.

In addition, the process of performing the quantum cryptographic key distribution protocol between the sender 110 and the receiver 120 including the above-described process is as follows. (Including process above)

A. The sender 110 generates a series of light pulses using a light source such as a mode-locking laser and generates 0, 1, and decoy data (1-f) / 2, (1-). f) / 2, with a probability of convergence to f .

B. Encode and transmit the generated series of light pulses with polarization of one of 0, 45, 90, 135 degrees, respectively.

C. The receiver 120 records all the time slots in which the measurement occurred in the detectors of the data line and the monitoring line.

D. After the transmission of the optical pulses, the transmitter 110 determines a time slot in which consecutive optical pulses exist among the series of optical pulses, respective polarization information and positions of the decoy data. The identifiable information is transmitted to the receiver 120 through an authenticated classical channel or the like.

E. The receiver 120 finds time slots in which the interference occurs in the monitoring line among time slots in which the sender 110 has transmitted a continuous light pulse, Check the detection information in the corresponding time slot.

F. If a coincidence detection occurs at two detectors in a time slot in which a detection result should occur at one detector due to the HOM effect, the receiver 120 determines that the attacker 140 has eavesdropped. The protocol can be aborted.

G. Also, in a time slot in which detection at one detector and coincidence detection at two detectors must occur with a certain probability due to the HOM effect and Anit-HOM effect, according to the detection result in the corresponding time slot. Even when the calculated probability is different from the predetermined predetermined probability, the receiver 120 may stop the protocol by determining that the attacker 140 has eavesdropped.

H. If it is determined that there is no eavesdropping of the attacker 140 in the above process, the receiver 120 may detect error correction and error amplification on the 0 and 1 bits successfully detected in the data line. A quantum cryptographic key may be calculated by applying an amplification technique, and further, valid time slot information may be transmitted to the sender 110 so that the calculated quantum cryptographic key can also be obtained by the sender 110.

I. The sender 110 may calculate the same quantum encryption key as the receiver using the 0 and 1 information transmitted by the receiver 120 in the time slot that the receiver 120 has known to be valid.

4 illustrates a flowchart of a quantum cryptographic key distribution method from a transmitter 110 perspective using random polarization according to an embodiment of the present invention. As can be seen in Figure 4, the quantum cryptographic key distribution method from the perspective of the sender 110 using random polarization according to an embodiment of the present invention, the sender 110 uses a series of light pulses to the receiver 120 As a method for distributing a quantum cryptographic key to a), it may be configured to include an optical pulse transmission step (S410) and verification information transmission step (S420).

Furthermore, in the quantum cryptographic key distribution method from the perspective of the transmitter 110 using random polarization according to an embodiment of the present invention, the transmitter 110 may include a part of information about the quantum cryptographic key included in the series of optical pulses, or It may further include the step (S430) of calculating the quantum encryption key using all.

5 illustrates a flowchart of a quantum cryptographic key distribution method from a receiver 120 perspective using random polarization according to an embodiment of the present invention. As can be seen in Figure 4, the quantum cryptographic key distribution method from the perspective of the receiver 120 using random polarization according to an embodiment of the present invention, a series of light received by the receiver 120 from the sender 110 As a method of receiving a quantum cryptographic key using pulses, the method may include an optical pulse reception step S510 and an eavesdropping verification step S520.

Furthermore, in the quantum cryptographic key distribution method from the perspective of the receiver 120 using random polarization according to an embodiment of the present invention, the receiver 120 may include some or more information about the quantum cryptographic keys included in the series of optical pulses. It may further include the step (S530) of calculating the quantum encryption key using all.

Hereinafter, referring to FIGS. 4 and 5, the quantum encryption key distribution method using random polarization according to an embodiment of the present invention will be described in more detail.

First, in the optical pulse transmission step (S410), the transmitter 110 randomly polarizes each optical pulse to one of a plurality of predetermined polarization angles and transmits the optical pulses to the receiver 120. For example, as shown in FIG. 3, the transmitter 110 randomly polarizes a series of light pulses at polarization angles of one of 0, 45, 90, and 135 degrees, and transmits them to the receiver 120 through the optical channel. can do.

Subsequently, in the verification information transmitting step (S420), the transmitter 110 transmits information about a continuous light pulse among the series of light pulses to the receiver 120, and uses the measurement value for the continuous light pulse to transmit the information. During the transmission of a series of light pulses to determine whether there was an eavesdropping of the attacker 140. For example, in FIG. 3, the transmitter 110 transmits information, such as a time slot for identifying consecutive light pulses, such as decoy, which is a continuous light pulse having the same polarization angle, to the receiver 120. . At this time, the receiver 120 calculates a time slot corresponding to the detection result detected in the monitoring line among the information on the received continuous light pulses, and then examines the detection result in the time slot to attacker 140 It is possible to determine the presence of.

For example, when the continuous light pulses have the same polarization angle, the continuous light pulses should be detected only at one detector D _M1 or D _M2 due to the HOM effect, but here the attacker 140 In the case of intervening, the same polarization state is not maintained and has various polarization angles, and is detected only at one detector or both detectors.

More specifically, when the successive light pulses have the same polarization angle, if there is no eavesdropping of the attacker 140, the photons are detected only at one detector D _M1 or D _{M2 in} the monitoring line of the receiver 120 due to the HOM effect. Be detected (ie, P [O] = 1, P [C] = 0). However, in this case, when the attacker 140 taps to approach the continuous light pulse, in the monitoring line of the receiver 120, as shown in FIG. 6, the photons are detected at one detector D _M1 or D _M2 . Since the probability P [O] to be detected is 3/16, and the probability P [C] of photons is simultaneously detected at both detectors D _M1 and D _M2 , the attacker 140 is selected. The detection result is changed according to whether the user taps, so that the receiver 120 can clearly determine whether the attacker 140 attacks.

In addition, when the continuous light pulses have polarization angles perpendicular to each other, photons may be detected by both detectors D _M1 or D _{M2 in} the monitoring line of the receiver 120 without eavesdropping by the attacker 140. Therefore, both the probability P [O] of photons being detected by one detector D _M1 or D _M2 and the probability P [C] of photons being detected simultaneously by both detectors D _M1 and D _M2 1/2. However, in this case, when the attacker 140 taps to approach the continuous light pulse, in the monitoring line of the receiver 120, as shown in FIG. 7, the photon is detected at one detector D _M1 or D _M2 . Since the probability to be detected at the same time is 5/16 and the probability that photons are detected at both detectors D _M1 and D _M2 is 11/16, the detection result is different depending on whether the attacker 140 is tapped. The receiver 120 can clearly determine whether the attacker 140 attacks.

On the other hand, when the polarization angles of the continuous light pulses have a difference of 45 degrees from each other, if there is no eavesdropping of the attacker 140, photons may be detected at one detector D _M1 or D _M2 in the monitoring line of the receiver 120. The probability P [O] is 3/4, and the probability P [C] at which photons are simultaneously detected at both detectors D _M1 and D _M2 is 1/4. However, in this case, even when the attacker 140 taps to approach the continuous light pulse, as shown in FIG. 8, a photon is detected at one detector D _M1 or D _M2 in the monitoring line of the receiver 120. At the same time, the probability to be detected is 3/4, and the probability that photons are detected at both detectors D _M1 and D _M2 is 1/4, so that the detection result is the same regardless of whether the attacker 140 is tapped. If the polarization angles of consecutive light pulses have a difference of 45 degrees from each other, the receiver 120 may not distinguish whether the attacker 140 attacks.

Accordingly, (A), (D), and (E) in FIG. 9 may be used to detect whether the attacker 140 is tapped according to the present invention as a continuous light pulse having the same polarization angle. 9 (B) and (C) is a case where the polarization angles of consecutive light pulses have a difference of 45 degrees from each other, and according to the present invention, it is difficult to use it to detect whether an attacker 140 is tapped. Furthermore, although not shown in FIG. 9, even when the continuous light pulses have polarization angles perpendicular to each other as described in the example of FIG. 7, the present invention may be used to detect whether the attacker 140 is tapped according to the present invention. Is self explanatory.

In addition, although the optical pulse is detected by the HOM effect or the Anit-HOM effect as one embodiment of the present invention, the present invention is not limited thereto, and more generally, the quantum interference effect is continuous. The present invention can be applied as long as it can detect whether the polarizations of the light pulses are the same or have a constant difference.

Furthermore, in FIG. 3, the transmitter 110 uses a series of optical pulses having a predetermined phase difference, as in the conventional coherent unidirectional (COW) quantum cryptographic key distribution protocol, and the receiver 120 also corresponds to the phase difference. Although it includes a structure to adjust the phase, in the present invention can detect the attacker's eavesdropping using random polarization bar, it is also possible to remove the phase difference generation and adjustment structure in the sender 110 and the receiver 120 Therefore, it is possible to implement a simpler structure.

Next, FIG. 10 illustrates an operation of a quantum cryptographic key distribution method using random phase modulation according to an embodiment of the present invention.

As shown in FIG. 10, when a quantum cryptographic key is distributed using random phase encoding, when a light pulse having the same phase interferes using a Mach-Zehnder interferometer or the like, the first signal may be interfered. If only the detector detects, and if an optical pulse having a predetermined phase difference such as π interferes, it detects only the second detector, and randomly encodes the phase of each optical pulse to determine whether the attacker 140 is eavesdropping. You can do it. In the present invention, it is not necessary to use 0 and π for random phase modulation, but when 0 and π are used, the structure can be simplified, and the case of using 0 and π will be described below. For convenience, a detector in which light pulses having the same phase are detected is called a first detector D _M1 , and a detector in which light pulses having a phase difference of about is detected is called a second detector D _M2 .

In the case of phase encoding, the method of generating 0, 1, and decoy data (decoy) is also the same as in the case of salpin polarized encoding, but in this case, 0 or π phases are encoded in each optical pulse. In this case, since the phase between each optical pulse is generated by a difference of 0 or π, the attacker 140 may determine the difference between each phase only by measuring the phase for each optical pulse. However, when the attacker 140 wants to measure the phase difference, the attacker 140 may not accurately measure the position of each light pulse. Therefore, instead of measuring the position of the pulse in order to increase the probability of attack success, the attacker 140 may advantageously take an attack form that probabilistically estimates the phase.

When the attacker 140 retransmits an optical pulse having a phase different from that of the optical pulse transmitted by the sender 110 to the receiver 120, the receiver 120 may determine whether the attacker 140 exists, The process is as follows.

A. Receiver 120 records all time slots for which its detector measured photons.

B. After reception of all transmitted photons, the transmitter 110 transmits two consecutive light pulses having the same phase among time slots in which light pulses are continuously present among a series of light pulses transmitted by the sender 110. Find the case, and informs the recipient 120 of the information to identify it. The information may be transmitted to the receiver 120 using an authenticated public channel.

C. Upon receiving the information, the receiver 120 finds a time slot in which a consecutive light pulse is likely to have interfered in the Mach-Gender interferometer of its monitoring line, and in a time slot Check the detected detection result.

D. The photon state transmitted by the sender 110 arrives at the receiver 120 as it is because the attacker 140 does not exist, or on rare occasions, the attacker 140 successfully completes the phase state of the photon transmitted by the sender 110. In the case of retransmission by estimating, detection occurs only in the first detector D _M1 .

E. If the attacker 140 is present, and if the sender 110 incorrectly estimates and retransmits the phase state of the photon transmitted by the sender 110, the detection occurs in the first detector D _M1 in the corresponding time slot. do. Accordingly, the receiver 120 can detect the eavesdropping of the attacker 140.

F. Also, the transmitter 110 transmits to the receiver 120 a time slot in which two consecutive light pulses have a phase difference of π among the time slots in which the light pulses are continuously present among the series of light pulses transmitted by the sender 110. I can tell you. The information may also be transmitted to the receiver 120 using an authenticated public channel.

G. At this time, when the receiver 120 receives the above information, as described above, the receiver 120 finds a time slot in which two consecutive light pulses are estimated to cause interference, and thus, the detector first detector D _M1 and the second detector D _M2 . Analyze the measurement results.

H. Also, as described above, if there is no attacker 140 or if the attacker 140 retransmits the same as the original photon state transmitted by the sender 110, detection occurs in the second detector D _M2 . In case of transmitting the wrong photon state, the detection result is generated in the first detector D _M1 . Accordingly, the receiver 120 can detect the eavesdropping of the attacker 140.

Furthermore, even if the attacker 140 attacks in a new way of measuring the position and phase of the pulse, it is impossible to find both the position and the phase, and thus, the first detector D _M1 and the second detector D as described above. _By analyzing the measurement result of _M2 ), it is possible to determine the presence of the attacker 140.

B. Encode and transmit the generated light pulses into one of 0 and π phases, respectively.

D. After the transmission of the optical pulse, the transmitter 110 determines a time slot in which a continuous optical pulse exists among the series of optical pulses, each phase information thereof, and the position of the decoy data. The identifiable information is transmitted to the receiver 120 through an authenticated classical channel or the like.

J. If a time slot should be detected at the first detector D _M1 , a time slot should be detected at the second detector D _M2 or should be detected at the second detector D _M2 . When the detection occurs at the first detector D _M1 , the receiver 120 may stop the protocol by determining that the attacker 140 has eavesdropped.

K. If it is determined that there is no eavesdropping of the attacker 140 in the above process, the receiver 120 may detect error correction and error amplification on the 0 and 1 bits successfully detected in the data line. A quantum cryptographic key may be calculated by applying an amplification technique, and further, valid time slot information may be transmitted to the sender 110 so that the calculated quantum cryptographic key can also be obtained by the sender 110.

L. The sender 110 may calculate the same quantum encryption key as the receiver by using the 0 and 1 information transmitted by the receiver 120 in a time slot that the receiver 120 has known to be valid.

11 illustrates a flow chart of a quantum cryptographic key distribution method from the perspective of the sender 110 using random phase modulation according to an embodiment of the present invention. As can be seen in FIG. 11, in the quantum cryptographic key distribution method from the perspective of the transmitter 110 using random phase modulation according to an embodiment of the present invention, the transmitter 110 uses a series of optical pulses. As a method of distributing the quantum cryptographic key to 120, the method may include an optical pulse transmission step S1110 and verification information transmission step S1120.

Furthermore, in the quantum cryptographic key distribution method from the perspective of the sender 110 using random phase modulation according to an embodiment of the present invention, the sender 110 has a part of information about the quantum cryptographic key included in the series of optical pulses. Alternatively, the method may further include calculating a quantum encryption key using all of them (S1130).

12 illustrates a flowchart of a quantum cryptographic key distribution method from a receiver 120 perspective using random phase modulation according to an embodiment of the present invention. As can be seen in Figure 12, the quantum cryptographic key distribution method from the perspective of the receiver 120 using random phase modulation according to an embodiment of the present invention, the receiver 120 receives a series of received from the sender 110 A method of receiving a quantum cryptographic key using optical pulses may include an optical pulse reception step S1210 and an eavesdropping verification step S1220.

Furthermore, in the quantum cryptographic key distribution method from the perspective of the receiver 120 using random phase modulation according to an embodiment of the present invention, the receiver 120 has a part of information about the quantum cryptographic key included in the series of optical pulses. Alternatively, the method may further include calculating a quantum cryptographic key using all of them (S1230).

Hereinafter, referring to FIGS. 11 and 12, a quantum cryptographic key distribution method using random phase modulation according to an embodiment of the present invention will be described in more detail.

First, in the optical pulse transmission step (S1110), the transmitter 110 randomly modulates each optical pulse into one of a plurality of predetermined phases and transmits the optical pulses to the receiver 120. For example, as shown in FIG. 10, the transmitter 110 may randomly modulate a series of optical pulses into one of 0 and π to transmit to the receiver 120 through the optical channel.

Subsequently, in the verification information transmitting step (S1120), the transmitter 110 transmits information about a continuous light pulse among the series of light pulses to the receiver 120, and uses the measurement value for the continuous light pulse to perform the During the transmission of a series of light pulses to determine whether there was an eavesdropping of the attacker 140. For example, in FIG. 10, the transmitter 110 transmits information, such as a time slot for identifying consecutive optical pulses, such as decoy, which is a continuous optical pulse having the same phase, to the receiver 120. At this time, the receiver 120 calculates a time slot corresponding to the detection result detected in the monitoring line among the information on the received continuous light pulses, and then examines the detection result in the time slot to attacker 140 It is possible to determine the presence of.

For example, when the continuous light pulses have the same phase, the continuous light pulses should be detected only at the first detector D _M1 , but when the attacker 140 intervenes, Since the same phase may not be maintained and have various phases, photons may be detected not only in the first detector D _M1 but also in the second detector D _M2 .

More specifically, when the consecutive light pulses have the same phase, photons are detected only at the first detector D _M1 in the monitoring line of the receiver 120 without the tapping of the attacker 140 (that is, P [ D _M1 ] = 1, P [D _M2 ] = 0). However, in this case, when the attacker 140 taps to approach the continuous light pulse, the probability of the photon being detected by the first detector D _M1 in the monitoring line of the receiver 120 as shown in FIG. 13. Since P [D _M1 ] and the probability P [D _M2 ] of photons are detected by the second detector D _M2 are both 1/2, the detection result is different depending on whether the attacker 140 is tapped. Thus, the receiver 120 can clearly determine whether the attacker 140 attacks.

In addition, when the continuous light pulses have different phases (0, π), photons may be detected only at the second detector D _M2 in the monitoring line of the receiver 120 without eavesdropping by the attacker 140. (Ie P [D _M1 ] = 0, P [D _M2 ] = 1). However, in this case, when the attacker 140 taps to approach the continuous light pulse, the probability of the photon being detected by the first detector D _M1 in the monitoring line of the receiver 120 as shown in FIG. 14. Since P [D _M1 ] and the probability P [D _M2 ] of photons are detected by the second detector D _M2 are both 1/2, the detection result is different depending on whether the attacker 140 is tapped. Therefore, the detection result is changed according to whether the attacker 140 is tapped, and the receiver 120 can clearly determine whether the attacker 140 is attacked.

Accordingly, (A) and (D) in FIG. 15 are continuous light pulses having different phases and may be used to detect whether the attacker 140 is tapped according to the present invention, or FIG. B), (C), (E), and (F) are continuous light pulses having the same phase and can be used to detect whether the attacker 140 is intercepted according to the present invention. D) or (B), (C), (E), (F) can be used to selectively or sequentially overlap to determine whether the attacker 140 is eavesdropping.

In addition, although the case of detecting the light pulse using a Mach-Zehnder interferometer as an embodiment of the present invention has been described above, the present invention is not limited thereto, and more generally, the Mach-gender interferometer The present invention can be applied to any optical interferometer capable of detecting whether phases of successive optical pulses, such as a Mach-Zehnder interferometer or a Michelson interferometer, are the same.

In addition, FIG. 16 illustrates a block diagram of a transmitting device 110 for quantum cryptographic key distribution according to an embodiment of the present invention. As can be seen in Figure 16, the transmitting device 110 for quantum cryptographic key distribution according to an embodiment of the present invention, the transmitting device 110 for distributing the quantum cryptographic key to the receiving device using a series of light pulses As an example, the light pulse transmitter 111 and the verification information transmitter 112 may be configured.

In addition, FIG. 17 illustrates a configuration diagram of a receiving device 120 for quantum cryptographic key distribution according to an embodiment of the present invention. As shown in FIG. 16, the reception device 120 for quantum encryption key distribution according to an embodiment of the present invention receives the quantum encryption key by using a series of optical pulses received from the transmission device 110. As the reception device 120, the optical device may include an optical pulse receiver 121 and an eavesdropping verification unit 122.

Hereinafter, the transmitter 110 and the receiver 120 for quantum encryption key distribution according to an embodiment of the present invention will be described in more detail with reference to FIGS. 16 and 17.

First, the optical pulse transmitter 111 of the transmission device 110 randomly polarizes each optical pulse to one of a plurality of predetermined polarization angles, or randomly modulates one of the plurality of phases to the reception device 120. Done. For example, the pulse transmitter 111 generates a series of optical pulses using a light source such as a mode-locking laser, and then outputs the series of optical pulses to one of 0, 45, 90, and 135 degrees, respectively. Polarized light is randomly polarized by or is randomly modulated by one of 0 and π to be transmitted to the receiving device 120.

In addition, the verification information transmitter 112 of the transmitting apparatus 110 transmits information on the continuous optical pulses of the series of optical pulses to the receiving apparatus 120 to use the measured values of the continuous optical pulses. During the transmission of the light pulses, the attacker may verify whether there is an eavesdropping. For example, time slot information for successive light pulses having the same polarization or vertical polarization among the series of light pulses is transmitted to the receiving device 120 or successive light pulses having the same phase or different phases. Time slot information on the receiver 120 may be transmitted.

In addition, in the optical pulse receiver 121 of the receiver 120, the transmitter 110 randomly polarizes each optical pulse to one of a plurality of predetermined polarization angles, or randomly modulates one of a plurality of predetermined phases. Receive a series of optical pulses.

Subsequently, the tapping verifying unit 122 of the receiving device 120 receives information about a continuous light pulse among a series of light pulses received by the light pulse receiving unit 121 from the transmitting device 110. Measurements of successive light pulses are used to determine whether there has been an eavesdropping of an attacker during the transmission of the light pulses. For example, even though the continuous light pulses have the same polarization angle, photons are not detected only at one detector by the HOM effect in the receiving device 120, and photons are simultaneously detected at both detectors. Is measured at a significant ratio, or even when the consecutive light pulses have the same phase, photons are not detected only at the detector on one side as a result of photon measurement through the Mach-Gender interferometer included in the receiving device 120. Instead, it is possible to discriminate that the attacker 140 has eavesdropped when the ratio of photons detected by both detectors is significant. More specific information about this has been described above in detail, and thus will not be described in detail here.

Furthermore, the quantum cryptographic key distribution system according to an embodiment of the present invention is a quantum cryptographic key distribution system in which the transmitting device 110 distributes the quantum cryptographic key to the receiving device 120 by using a series of optical pulses. The optical pulse transmitter 111 and the series of optical pulses are randomly polarized to one of a plurality of predetermined polarization angles, or are randomly modulated to one of a plurality of predetermined phases and transmitted to the receiving device 120. A transmission device 110 including a verification information transmitter 112 for transmitting information on an optical pulse to the reception device 120 and an optical pulse receiver for receiving a series of light pulses transmitted by the transmission device 110 ( 121) by using the information on the continuous light pulse of the series of light pulses received from the transmitting device 110, by using the measurement value for the continuous light pulse In the course of the pulse transmission it may also be configured to include a reception unit 120 including a wire verification unit 122 which determines whether there is an attacker eavesdropping.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments described in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and are not limited to these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims

A method by which a sender distributes a quantum cryptographic key to a receiver using a series of light pulses,

An optical pulse transmitting step in which the transmitter randomly polarizes each optical pulse to one of a plurality of predetermined polarization angles and transmits the optical pulses to the receiver; And

The sender transmits information about successive light pulses of the series of light pulses to the receiver, and whether there was an attacker's eavesdropping in the course of transmitting the series of light pulses using the measurement of the successive light pulses. Verifying information transmission to verify the verification;

Quantum cryptographic key distribution method comprising a.
The method of claim 1,

In the verification information transmission step,

The sender sends information to the receiver about the case where the consecutive light pulses have the same polarization,

In this case, the receiver uses the quantum interference effect to determine whether the successive pulses have the same polarization to determine whether there was an attacker's eavesdropping.
The method of claim 1,

In the verification information transmission step,

The sender sends information to the receiver about the case where the consecutive light pulses have different polarizations,

In this case, the receiver determines whether an attacker's eavesdropping has been made by comparing the detection prediction value calculated in advance according to the different types of polarization and the actual measurement for the case where the quantum interference effect does not occur. Distribution method.
A method in which a receiver receives a quantum cryptographic key using a series of light pulses received from a sender.

An optical pulse receiving step of receiving, by the receiver, a series of optical pulses transmitted by randomly polarizing each optical pulse to one of a plurality of predetermined polarization angles; And

Whether the receiver has received information about successive light pulses of the series of light pulses from the sender, and there was an attacker's eavesdropping in the process of transmitting the series of light pulses using the measurement values for the successive light pulses. Tapping verification step of verifying;

Quantum cryptographic key distribution method comprising a.
The method of claim 4, wherein

In the tapping verification step,

The receiver receives information about the case where the consecutive pulses have the same polarization, from the sender,

And determining whether or not there is an eavesdropping by an attacker by determining whether the consecutive pulses have the same polarization by using a quantum interference effect.
The method of claim 4, wherein

In the tapping verification step,

The receiver receives information about the case where the consecutive pulses have different polarizations from the sender,

And quantum cryptographic key distribution method for determining whether there is an attacker's eavesdropping by comparing the measured predicted value and the actual measured value according to the different types of polarizations when the quantum interference effect does not occur.
A method by which a sender distributes a quantum cryptographic key to a receiver using a series of light pulses,

An optical pulse transmitting step of the transmitter randomly modulating each optical pulse into one of a plurality of predetermined phases and transmitting the optical pulse to a receiver; And

The sender transmits information about successive light pulses of the series of light pulses to the receiver, and whether there was an attacker's eavesdropping in the course of transmitting the series of light pulses using the measurement of the successive light pulses. Verifying information transmission to verify the verification;

Quantum cryptographic key distribution method comprising a.
The method of claim 7, wherein

In the verification information transmission step,

The sender sends information to the receiver about when the consecutive pulses have the same phase or the opposite phase,

In this case, the receiver uses an optical interferometer to determine whether the continuous pulse has the same phase or the opposite phase to determine whether there is an attacker's eavesdropping. Distribution method.
A method in which a receiver receives a quantum cryptographic key using a series of light pulses received from a sender.

An optical pulse receiving step of receiving a series of optical pulses by which a receiver randomly modulates each optical pulse into one of a plurality of predetermined phases; And

Eavesdropping verification in which the receiver receives information about the continuous light pulses from the sender and determines whether there was an attacker's eavesdropping during the transmission of the series of light pulses using the measurement values for the continuous light pulses. step;

Quantum cryptographic key distribution method comprising a.
The method of claim 9,

In the tapping verification step,

The receiver receives information from the sender when the consecutive pulses have the same phase or the opposite phase,

And determining whether there is an attacker's eavesdropping by determining whether the consecutive pulses have the same phase or the opposite phase by using an optical interferometer.
The method according to any one of claims 1, 4, 7, or 9,

And calculating a quantum cryptographic key using some or all of the information on the quantum cryptographic keys included in the series of light pulses.
A transmitting device for distributing a quantum cryptographic key to a receiving device using a series of light pulses,

An optical pulse transmitter configured to randomly polarize each optical pulse with one of a plurality of predetermined polarization angles, or to randomly modulate one optical pulse with one of a plurality of predetermined phases and transmit the optical pulse to a receiving apparatus; And

Information about successive light pulses of the series of light pulses is transmitted to the receiving device to verify whether there is an attacker's eavesdropping during the transmission of the series of light pulses using the measurement values for the successive light pulses. A verification information transmitter to make it possible;

Transmission device comprising a.
A receiving device that receives a quantum cryptographic key using a series of light pulses received from a transmitting device,

An optical pulse receiver configured to randomly polarize each optical pulse with one of a plurality of predetermined polarization angles or to randomly modulate one optical pulse with one of a plurality of predetermined phases to receive a series of optical pulses; And

Receiving information on a continuous light pulse among the series of light pulses from the transmitting device, and determining whether there is an attacker's eavesdropping in the process of transmitting the series of light pulses by using the measurement values for the continuous light pulses. An eavesdropping verification unit;

Receiving device comprising a.
A quantum cryptographic key distribution system in which a transmitting device distributes a quantum cryptographic key to a receiving device using a series of light pulses,

An optical pulse transmitter configured to randomly polarize each optical pulse with one of a plurality of predetermined polarization angles, or to randomly modulate one optical pulse with one of a plurality of predetermined phases and transmit the optical pulse to a receiving apparatus; And

A transmitting device including a verification information transmitting unit for transmitting information on a continuous light pulse of the series of light pulses to the receiving device; And

An optical pulse receiver for receiving a series of optical pulses transmitted by the transmitter; And

Whether there was an attacker's eavesdropping in the course of transmitting the series of optical pulses by using the information on the continuous optical pulses among the series of optical pulses received from the transmitting apparatus, and using the measurement values for the continuous optical pulses. A receiving device including an eavesdropping verifying unit to determine a;

Quantum cryptographic key distribution system characterized in that it comprises a.