Information leakage-free quantum dialogue method based on Grover quantum search

Abstract

The invention provides an information-leakage-free quantum dialogue method based on Grover quantum search, so that two communication parties realize mutual exchange of secret messages by utilizing transmission of quantum signals. According to the method, the auxiliary initial two-particle product state is directly transmitted from one user to the other user, so that the problem of information leakage is eliminated. Security analysis proves that the method can resist interception-retransmission attacks, measurement-retransmission attacks, entanglement-measurement attacks and Trojan horse attacks initiated by external eavesdroppers. According to the method provided by the invention, the quantum bit efficiency is up to 2 / 3 after the eavesdropping detection process is ignored. According to the method, only the product state of the two particles is used as an initial quantum resource, only single particle measurement is needed, and quantum entanglement swapping does not need to be executed.

Description

Technical Field

[0001] The present invention relates to the field of quantum cryptography and designs a quantum dialogue method without information leakage based on Grover quantum search, so that two communicating parties can exchange secret messages by transmitting quantum signals. Background Art

[0002] As early as 2002, Long and Liu [1] The concept of quantum secure direct communication (QSDC) is innovatively proposed, aiming to use the transmission of quantum signals to directly transmit secret messages from the sender to the receiver without establishing a key in advance. In other words, the classical message transmission of QSDC is one-way, that is, the one-way message transmission from the sender to the receiver. However, in daily life, conversations are inevitable. How to use the transmission of quantum signals to achieve the mutual exchange of secret messages between two communicators is a topic worth studying.

[0003] In 2004, two research groups [2-4] The concept of quantum dialogue (QD) was independently and innovatively proposed to achieve the above goals. However, in 2008, two other research groups [5,6] Independent pointed out that the early QD methods basically had the problem of information leakage, that is, an external eavesdropper could use public information to infer part of the secret messages of the two communicators without launching an active attack. Since then, QD research has turned to how to design a more secure QD method that can eliminate the problem of information leakage. A series of QD methods without information leakage [7-25] They have been designed by researchers using various quantum technologies. The existing QD methods without information leakage have more or less shortcomings, such as the need to use quantum entangled states as initial quantum resources, the need to measure quantum entangled states, the need to perform quantum entangled exchange, and the low efficiency of quantum bits.

[0004] Quantum computing, based on the basic principles of quantum mechanics, has powerful parallel computing capabilities. It has shown speeds far exceeding classical computing in prime factorization, combinatorial optimization, database search, etc., and has attracted the attention of many scholars in recent years. Grover quantum search algorithm

[26] It is one of the most famous quantum computing algorithms, which can be used to The search - time complexity for finding the target item far exceeds the O(N) search - time complexity required by traditional computers to complete this task, where N is the data size of the database. Moreover, Grover's quantum search algorithm has extensive applications in the design of quantum cryptographic methods and has been used to design quantum secret sharing (QSS) methods based on Grover's quantum search

[27] , controlled deterministic secure quantum communication (CDSQC) methods

[28] , quantum private comparison (QPC) methods

[29] , QD methods [18,23] , quantum key agreement (QKA) methods

[30] etc.

[0005] Based on the above analysis, different from the QD methods in references [18, 23], the present invention proposes a novel information - leakage - free QD method based on Grover's quantum search, which eliminates the information - leakage problem by directly transmitting the auxiliary initial two - particle product state from one user to another. The QD method of the present invention has a quantum - bit efficiency as high as 2 / 3 after ignoring the eavesdropping detection process. The QD method of the present invention only requires two - particle product states as the initial quantum resources, only requires single - particle measurements, and does not require quantum entanglement swapping

[0006] References

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[39] Cabello A. Quantum key distribution in the Holevo limit. Phys Rev Lett, 2000, 85: 5635 Summary of the Invention

[0046] The object of the present invention is to design a quantum dialogue method without information leakage based on Grover quantum search, enabling two communicating parties to exchange secret messages through the transmission of quantum signals.

[0047] A quantum dialogue method without information leakage based on Grover quantum search includes the following five processes:

[0048] S1) Alice's secret message is {a 1 , a 2 , …, a N}, and Bob's secret message is {b 1 , b 2 , …, b N}, where a j , b j ∈ {00, 01, 10, 11}, j = 0, 1, …, N. Bob generates a sequence P = {|C 1 >, |C′ 1 >, |C 2 >, |C′ 2 >, …, |C N >, |C′ N >} consisting of 2N two-particle product states, where |C j > and |C' j > are in the same quantum state, and C j , C' j ∈ {++, -+, +-, --}, j = 0, 1, …, N. Then, Bob prepares γ b single decoy particles randomly in {|0>, |1>, |+>, |->} and inserts them randomly into the sequence P to form a new sequence P'. Then, Bob transmits the sequence P' to Alice.

[0049] S2) Alice installs a wavelength filter and a photon number splitter in front of her device to resist invisible photon eavesdropping attacks and delayed photon Trojan horse attacks respectively [31,32] . To determine whether there is eavesdropping on the Bob-Alice quantum channel, Alice and Bob conduct the following eavesdropping detection together: (1) Bob tells Alice the positions and preparation bases of γ b decoy single particles in the sequence P'; (2) Alice measures the γ b decoy single particles in the sequence P' using the correct measurement basis and tells Bob the corresponding measurement results; (3) Bob compares Alice's measurement results with the initial preparation states of the γ b decoy single particles in the sequence P' to determine whether there is eavesdropping on the Bob-Alice quantum channel. If there is eavesdropping on the Bob-Alice quantum channel, the communication will be terminated; otherwise, the communication will continue.

[0050] S3) After completing the eavesdropping detection in step S2, the sequence P' in Alice's hand is restored to the sequence P. Alice divides the sequence P into two subsequences P 1 and P 2 , where P 1 = {|C 1 >, |C 2 >, …, |C N >} and P 2 = {|C' 1 >, |C' 2 >, …, |C' N >}. Then, Alice applies 1 to the j-th quantum state of the sequence P to convert the sequence P 1 into the sequence . Then, Alice prepares γ a decoy single particles randomly in {|0>, |1>, |+>, |->} and inserts them randomly into the sequence P' 1 to form a new sequence P″ 1 . Finally, Alice sends the sequence P″ 1 to Bob.

[0051] S4) Bob installs a wavelength filter and a photon number splitter in front of his device to resist invisible photon eavesdropping attacks and delayed photon Trojan horse attacks respectively [31,32] . To determine whether there is eavesdropping on the Alice-Bob quantum channel, Bob and Alice conduct the following eavesdropping detection together: (1) Alice tells Bob the γ 1 in the sequence P″ aInform Bob of the positions and preparation bases of the decoy single particles; (2) Bob measures the sequence P″ using the correct measurement basis 1 for the γ in a decoy single particles and inform Alice of the corresponding measurement results; (3) Alice compares Bob's measurement results with the γ in the sequence P″ 1 for the a decoy single particles to determine whether there is eavesdropping on the Alice-Bob quantum channel. If there is eavesdropping on the Alice-Bob quantum channel, the communication will be terminated; otherwise, the communication will continue.

[0052] S5) After completing the eavesdropping detection in step S4, the sequence P″ in Bob's hand 1 is restored to the sequence P′ 1 . Then, Bob applies 1 to the j-th quantum state of the sequence P′ so as to transform the sequence P′ 1 into the sequence Then, Bob measures in the X basis (i.e., {|+>, |->}) and announces his measurement results to Alice, where j = 0, 1, …, N. According to |C j >, and his own X-basis measurement results of , Bob can easily decrypt a j by virtue of Property 2 in Part 2, where j = 0, 1, …, N. Alice measures |C′ j > in her hand in the X basis. Since |C j > and |C′ j > are in the same quantum state, according to her own X-basis measurement results of |C′ j >, and Bob's X-basis measurement results of , Alice can easily decrypt b j by virtue of Property 2 in Part 2, where j = 0, 1, …, N. Detailed implementation manners

[0053] The technical solutions of the present invention will be further described below in conjunction with embodiments.

[0054] 1 Method description

[0055] 1.1 Properties of Grover's quantum search algorithm

[0056] Grover's quantum search algorithm is one of the most famous quantum search algorithms, and its database is generally a multi-particle product state. Here, the two-particle product state |S w > is defined as

[0057]

[0058] wherein Define two unitary operations as

[0059]

[0060] where \(w\in\{00,01,10,11\}\), \(S\ w \in\{++, -+, +-, --\}\).

[0061] The Grover quantum search algorithm has the following two important properties:

[30]

[0062] Property 1: Assume that \(n\) is a positive integer and an odd number, and \(w, v, w i \in\{00,01,10,11\}\), where \(i = 0, 1, \ldots, n\). Then, if and only if holds, there exists

[0063] Property 2: Assume that \(n\) is a positive integer and an even number, and \(w, w i \in\{00,01,10,11\}\), where \(i = 0, 1, \ldots, n\). Then, if and only if holds, there exists

[0064] 1.2 Description of the method of the present invention

[0065] Alice and Bob intend to conduct a secure conversation using a quantum channel. Alice's secret message is \(\{a 1 , a 2 , \ldots, a N \}\), and Bob's secret message is \(\{b 1 , b 2 , \ldots, b N \}\), where \(a j , b j \in\{00,01,10,11\}\), \(j = 0, 1, \ldots, N\). Inspired by the literature [7, 8, 16, 18, 23, 30], the present invention proposes the following QD method without information leakage based on Grover quantum search to achieve the goal of secure quantum conversation between Alice and Bob.

[0066] S1) Bob generates a sequence \(P = \{|C 1 >, |C' 1 >, |C 2 >, |C' 2 >, \ldots, |C N >, |C' N>}, where |C j > and |C' j > are in the same quantum state, and C j , C' j ∈{++, -+, +-, --}, j = 0, 1, …, N. Next, Bob prepares γ b randomly prepared single photons in {|0>, |1>, |+>, |->} and inserts them randomly into the sequence P to form a new sequence P'. Then, Bob sends the sequence P' to Alice.

[0067] S2) Alice installs a wavelength filter and a photon number splitter in front of her device to resist invisible photon eavesdropping attacks and delayed photon Trojan horse attacks respectively [31,32] . To determine whether there is eavesdropping on the Bob - Alice quantum channel, Alice and Bob perform the following eavesdropping detection together: (1) Bob tells Alice the positions and preparation bases of the γ b randomly prepared single photons in the sequence P'; (2) Alice measures the γ b randomly prepared single photons in the sequence P' using the correct measurement bases and tells Bob the corresponding measurement results; (3) Bob compares Alice's measurement results with the initial preparation states of the γ b randomly prepared single photons in the sequence P' to determine whether there is eavesdropping on the Bob - Alice quantum channel. If there is eavesdropping on the Bob - Alice quantum channel, the communication will be terminated; otherwise, the communication will continue.

[0068] S3) After completing the eavesdropping detection in step S2, the sequence P' in Alice's hand is restored to the sequence P. Alice divides the sequence P into two subsequences P 1 and P 2 , where P 1 = {|C 1 >, |C 2 >, …, |C N >} and P 2 = {|C' 1 >, |C' 2 >, …, |C' N >}. Next, Alice applies 1 to the j - th quantum state of the sequence P to transform the sequence P 1 into the sequence Then, Alice prepares γ a randomly prepared single photons in {|0>, |1>, |+>, |->} and inserts them randomly into the sequence P' 1 to form a new sequence P'' 1Finally, Alice transmits the sequence P″ 1 to Bob.

[0069] S4) Bob installs a wavelength filter and a photon number splitter in front of his device to resist the stealth photon eavesdropping attack and the delayed photon Trojan horse attack respectively [31,32] To determine whether there is eavesdropping on the Alice-Bob quantum channel, Bob and Alice jointly perform the following eavesdropping detection: (1) Alice tells Bob the positions and preparation bases of the γ 1 decoy single particles in the sequence P″ a ; (2) Bob measures the γ 1 decoy single particles in the sequence P″ a using the correct measurement basis and tells Alice the corresponding measurement results; (3) Alice compares Bob's measurement results with the initial preparation states of the γ 1 decoy single particles in the sequence P″ a to determine whether there is eavesdropping on the Alice-Bob quantum channel. If there is eavesdropping on the Alice-Bob quantum channel, the communication will be terminated; otherwise, the communication will continue.

[0070] S5) After completing the eavesdropping detection in step S4, the sequence P″ 1 in Bob's hand is restored to the sequence P′ 1 . Then, Bob applies 1 to the j-th quantum state of the sequence P′ to convert the sequence P′ 1 into the sequence Then, Bob performs an X-basis (i.e., {|+>, |->}) measurement on and announces his measurement results to Alice, where j = 0, 1,..., N. According to |C j >, and his own X-basis measurement results on , Bob can easily decrypt a j by virtue of Property 2 in Part 2, where j = 0, 1,..., N. Alice performs an X-basis measurement on the |C′ j > in her hand. Since |C j > and |C′ j > are in the same quantum state, according to her own X-basis measurement results on |C′ j >, and Bob's X-basis measurement results on , Alice can easily decrypt b j by virtue of Property 2 in Part 2, where j = 0, 1,..., N.

[0071] Security Analysis against Active Attacks by External Eavesdroppers

[0072] In step S1, Bob sends the sequence P' to Alice; in step S3, Alice sends the sequence P″ 1 to Bob. In both of these two quantum state transmissions, decoy particles are used to detect whether there is eavesdropping. This eavesdropping detection method is called the decoy particle eavesdropping detection method [34,35] , which is essentially a variant of the unconditionally secure BB84 method [36,37] for eavesdropping detection. Here, taking the example of Bob sending the sequence P' to Alice, the security of the method of the present invention against active attacks by external eavesdroppers is demonstrated below.

[0073] ① Measurement - resending attack

[0074] When Bob sends the sequence P' to Alice, Eve randomly measures the quantum states of the sequence P' using the Z - basis or X - basis and sends the obtained quantum state sequence to Alice. Since the preparation basis of the decoy particles by Bob and the measurement basis used by Eve for the decoy particles may not be the same, this attack by Eve will be detected by Alice and Bob with a probability of in step S2.

[38] When γ b approaches infinity, this probability will be 0. Here, the Z - basis is {|0, |1}.

[0075] ② Interception - resending attack

[0076] When Bob sends the sequence P' to Alice, Eve intercepts the sequence P' and replaces it with a pre - generated random sequence of fake particles in the Z - basis or X - basis and sends it to Alice. Since the initial prepared state of the decoy particles by Bob may not be consistent with the measurement results of the fake particles prepared by Eve by Alice, this attack by Eve will be detected by Alice and Bob with a probability of in step S2.

[38] When γ b approaches infinity, this probability will be 0.

[0077] ③ Entanglement - measurement attack

[0078] Proposition 1: When Bob sends the sequence P' to Alice, in order to obtain useful information, Eve attempts to entangle his auxiliary particle |ρ> and the particles of P' by applying a unitary operation to them. In order for this attack not to be detected by Alice and Bob in step S2, the final state of Eve's auxiliary particle should be independent of the particles of P'.

[0079] Proof: The unitary operation applied by Eve to her ancillary particle |ρ> and the particle of P' has the following effects:

[0080]

[0081] where |κ 00 >, |κ 01 >, |κ 10 > and |κ 11 > are Eve's detection states, |α| 2 + |λ| 2 = 1 and |β| 2 + |δ| 2 = 1. It is easy to obtain from Eqs. (4) and (5)

[0082]

[0083] In order for this attack not to be detected by Alice and Bob in step S2, from Eqs. (4 - 7), we have

[0084] λ = β = 0, (8)

[0085] α|κ 00 > + β|κ 10 > - λ|κ 01 > - δ|κ 11 > = 0, (9)

[0086] α|κ 00 > - β|κ 10 > + λ|κ 01 > - δ|κ 11 > = 0. (10)

[0087] From Eqs. (8 - 10), we have

[0088] α|κ 00 > = δ|κ 11 > = |υ>. (11)

[0089] Substituting Eqs. (8) and (11) into Eqs. (4 - 7), we get

[0090]

[0091]

[0092] According to Eqs. (12 - 15), in order for this attack not to be detected by Alice and Bob in step S2, the final state of Eve's ancillary particle should be independent of the particle of P', so that Eve obtains no useful information.

[0093] Example:

[0094] 1 Application Example of the Method of the Present Invention

[0095] Here, take |C 1 > and |C' 1 > as an example for illustration. Without loss of generality, assume a 1 = 10, b 1 = 11 and |C 1 > = |C' 1 > = |++>. According to the process of the method of the present invention, |C 1 > will go through the process, that is, there exists

[0096] |++> → U 10 |++> → V ++ U 11 U 10 |++> = -|-+>. (16) Bob performs an X - basis measurement on and announces his measurement result as |-+> to Alice. According to |C 1 >, and his own X - basis measurement result of , Bob can easily decrypt a 1 = 10 by virtue of Property 2. Alice performs an X - basis measurement on the |C' 1 > in her hand. Since |C 1 > = |C' 1 > = |++>, according to her own X - basis measurement result of |C' 1 >, and Bob's X - basis measurement result of , Alice can easily decrypt b 1 = 11 by virtue of Property 2.

[0097] 2 Discussion

[0098] 2.1 Security Against Information Leakage Problem

[0099] Here, the above example is used to analyze whether there is an information leakage problem in the method of the present invention. When Bob announces his X - basis measurement result of to Alice, Eve may also receive relevant information. Since Eve doesn't know the initial state of |C 1 >, she has to make a random guess about it. According to Property 2, there exists where |C 1 > and have the corresponding relationship shown in Equation (1). When Eve guesses the initial state of |C 1 > as |++>, it exactly corresponds to At this time, there is That is, (a1 , b 1 ) There are four possibilities: {(00, 01), (01, 00), (10, 11), (11, 10)}; when Eve guesses that the initial state of |C 1 > is |-+>, it corresponds to At this time, there is That is, (a 1 , b 1 ) There are four possibilities: {(00, 00), (01, 01), (10, 10), (11, 11)}; when Eve guesses that the initial state of |C 1 > is |+->, it corresponds to At this time, there is That is, (a 1 , b 1 ) There are four possibilities: {(00, 11), (01, 10), (10, 01), (11, 00)}; when Eve guesses that the initial state of |C 1 > is |-->, it corresponds to At this time, there is That is, (a 1 , b 1 ) There are four possibilities: {(00, 10), (01, 11), (10, 00), (11, 01)}. According to Shannon's information theory

[33] , these 16 uncertainties contain a total of bits of information for Eve, which is exactly equal to the total number of bits of the secret messages of Alice and Bob. It can be concluded that there is no information leakage problem in the method of the present invention because Bob directly transmits the equivalent auxiliary quantum state |C′ j > of |C j > to Alice, so that Eve cannot know the initial state of |C j .

[0100] 2.2 Quantum bit efficiency

[0101] The quantum bit efficiency of the quantum dialogue method is defined as

[39]

[0102]

[0103] where ρ d is the number of secret bits exchanged between the two communication parties, ρ q is the number of consumed quantum bits, and ρ c is the number of consumed classical bits. All quantum and classical resources consumed for wiretap detection are not considered here. The method of the present invention can successfully exchange a 1 and b using |C 1 > and |C′ 1 and b1 , while 2 bits are required for Bob to announce the X-basis measurement result of . Therefore, the qubit efficiency of the method of the present invention is 2.3 Comparison

[0104] After ignoring the eavesdropping detection process, the information-leakage-free QD methods in references [7, 8, 16 - 18, 23] are compared with the method of the present invention, and the comparison results are summarized in Table 1. The QD method in reference [7] successfully exchanges 2 bits of information of Alice and Bob respectively by using 2 polarized Bell states, while 2 bits are required for Bob to announce the results of his Bell measurement, so that the qubit efficiency of this method is The QD method in reference [8] successfully exchanges 1 bit of information of Alice and Bob respectively by using 2 polarized single photons, while 2 bits are required for Bob to announce the results of his single-particle measurement, so that the qubit efficiency of this method is The QD method in reference

[16] successfully exchanges 2 bits of information of Alice and Bob respectively by using 2 single particles with two degrees of freedom of polarization and spatial mode, while 4 bits are required for Bob to announce the results of his single-particle measurement, so that the qubit efficiency of this method is The QD method in reference

[17] successfully exchanges 2 bits of information of Alice and Bob respectively by using 2 single particles with two degrees of freedom of polarization and spatial mode, while 2 bits are required for Bob to announce the measurement basis of the auxiliary single particle and 4 bits are required for Bob to announce the results of his single-particle measurement, so that the qubit efficiency of this method is After ignoring the quantum resources and classical resources required for sharing keys between participants, the QD method in reference

[18] successfully realizes the transmission of 2 bits from Alice to Bob by using 1 polarized two-particle product state and successfully realizes the transmission of 2 bits from Bob to Alice by using 1 polarized two-particle product state, while 4 bits are required for Charlie to announce the allowed sequence bits, so that the qubit efficiency of this method is After ignoring the quantum resources and classical resources required for sharing keys between participants, the QD method in reference

[23] can successfully exchange 2 bits of information of Alice and Bob respectively by using 1 polarized two-particle product state, while 4 bits are required for Charlie to announce the allowed sequence bits and the initial quantum state and 2 bits are required for Bob to announce the results of his single-particle measurement, so that the qubit efficiency of this method is

[0105] According to Table 1, the conclusion can be drawn that since the preparation of Bell states is more difficult than that of single-particle states, the method of the present invention outperforms the methods in References [7] and

[23] in terms of quantum resources; since the implementation of Bell basis measurement is more difficult than that of single-particle measurement, the method of the present invention outperforms the methods in References [7] and

[23] in terms of quantum measurement; the method of the present invention for eliminating information leakage is different from the methods in References

[18] and

[23] ; since there is no need to perform quantum entanglement swapping, the method of the present invention outperforms the method in Reference

[23] in terms of the use of quantum entanglement swapping; the method of the present invention is superior to the methods in References [8, 16 - 18, 23] in terms of qubit efficiency.

[0106] 3 Conclusion

[0107] The present invention proposes a novel information-leakage-free QD method based on Grover quantum search, enabling two communicating parties to exchange secret messages with each other by using the transmission of quantum signals. The method of the present invention directly transfers the auxiliary initial two-particle product state from one user to another user, thus eliminating the problem of information leakage. Security analysis confirms that the method of the present invention can resist intercept-resend attacks, measure-resend attacks, entangle-measure attacks, and Trojan horse attacks launched by external eavesdroppers. The qubit efficiency of the method of the present invention is as high as 2 / 3 after ignoring the eavesdropping detection process. The method of the present invention only requires two-particle product states as the initial quantum resources, only requires single-particle measurement, and does not need to perform quantum entanglement swapping.

[0108] Table 1 Comparison between the method of the present invention and previous information-leakage-free QD methods

[0109]

Claims

1. A quantum dialogue method without information leakage based on Grover quantum search, which enables two communicating parties to exchange secret messages by transmitting quantum signals; the auxiliary initial two-particle product state is directly transmitted from one user to another, thereby eliminating the problem of information leakage; the quantum bit efficiency after ignoring the eavesdropping detection process is as high as 2 / 3; only the two-particle product state is required as the initial quantum resource, only single-particle measurement is required, and there is no need to perform quantum entanglement exchange; it includes the following five processes: S1) Alice’s secret message is {a1,a2,…,a N }, Bob’s secret message is {b1,b2,…,b N }, where a j ,b j ∈{00,01,10,11}, j=0,1,…,N; Bob generates a sequence P={|C1>,|C1'>,|C2>,|C'2>,…,|C N >,|C' N >}, where |C j > and |C' j > are in the same quantum state, and C j ,C' j ∈{++,-+,+-,--}, j=0,1,…,N; then, Bob prepares γ b decoy particles randomly located at {|0>,|1>,|+>,|->}, and randomly insert them into the sequence P to form a new sequence P'; then, Bob transmits the sequence P' to Alice; S2) Alice installs a wavelength filter and a photon number divider in front of her device to resist the invisible photon eavesdropping attack and the delayed photon Trojan attack respectively. In order to determine whether there is eavesdropping in the Bob-Alice quantum channel, Alice and Bob perform the following eavesdropping detection together: (1) Bob replaces the γ in the sequence P' b Alice informs Alice of the position and preparation basis of the decoy single particle; (2) Alice uses the correct measurement basis to measure the γ in the sequence P' b (3) Bob compares Alice’s measurement result with the γ in the sequence P’. b The initial preparation state of a decoy single particle is used to determine whether there is eavesdropping on the Bob-Alice quantum channel; if there is eavesdropping on the Bob-Alice quantum channel, the communication will be terminated, otherwise, the communication will continue; S3) After completing the eavesdropping detection in step S2, the sequence P' in Alice's hand is restored to the sequence P; Alice divides the sequence P into two subsequences P1 and P2, where P1 = {|C1>, |C2>, ..., |C N >} and P2={|C1'>,|C'2>,…,|C' N >}; Then, Alice applies U to the jth quantum state of sequence P1 aj , thereby converting the sequence P1 into the sequence Then, Alice prepares γ a decoy single particles randomly located at {|0>,|1>,|+>,|->}, and randomly insert them into the sequence P1' to form a new sequence P1". Finally, Alice transmits the sequence P1" to Bob. S4) Bob installs a wavelength filter and a photon number divider in front of his device to resist the invisible photon eavesdropping attack and the delayed photon Trojan attack respectively. In order to determine whether there is eavesdropping in the Alice-Bob quantum channel, Bob and Alice perform the following eavesdropping detection together: (1) Alice replaces the γ in the sequence P1” a (2) Bob uses the correct measurement basis to measure the γ in the sequence P1”. a (3) Alice compares Bob’s measurement result with the γ in sequence P1”. a The initial preparation state of a decoy single particle is used to determine whether there is eavesdropping on the Alice-Bob quantum channel; if there is eavesdropping on the Alice-Bob quantum channel, the communication will be terminated, otherwise, the communication will continue; S5) After completing the eavesdropping detection in step S4, the sequence P1" in Bob's hand is restored to the sequence P1'; then, Bob applies V to the jth quantum state of the sequence P1' Cj U bj , thereby converting the sequence P1' into the sequence Then, Bob Perform X-basis measurement and publish the measurement result to Alice, where X-basis is {|+>,|->}, j=0,1,…,N; according to |C j >、 With yourself The X-based measurement result, Bob can easily decrypt a j , where j = 0, 1, ..., N; Alice has |C' j >Perform X-based measurement; due to |C j > and |C' j > are in the same quantum state, according to their own |C' j > X-based measurement results, and Bob Alice can easily decrypt b j , where j = 0, 1,…, N.

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