Measurement equipment independent quantum dialogue method with bidirectional identity authentication function

Abstract

The invention discloses a measurement equipment-independent quantum dialogue method with a bidirectional identity authentication function, which comprises the following steps of: firstly, mutually authenticating whether two communication parties are legal partners or not, and then carrying out mutual dialogue by directly utilizing a quantum channel. Two communication parties Alice and Bob share a group of identity keys through a BB84 protocol, the Alice and Bob are only responsible for preparing entangled photon pairs and single photons and executing encoding operation on the photons, and all measurement tasks are handed over to a third-party measurement end Charlie to be completed. Alice and Bob can mutually verify the identities of the two parties according to the Bell state analysis result of Charlie, and bidirectional communication is completed after the two parties are determined to be legal communication parties. According to the invention, the bidirectional identity authentication technology is applied to the MDI-QD field for the first time, the play attack of an eavesdropper can be resisted, and the measurement task is completed by a third party, so that all attacks aiming at imperfect measurement equipment can be resisted effectively, and the security of identity authentication codes and communication of the two parties is enhanced. The method has very important significance for promoting the practical application of quantum dialogues.

Description

Technical Field

[0001] The invention relates to a measurement device-independent quantum dialogue method with a two-way identity authentication function, belonging to the technical field of quantum secure communication. Background Art

[0002] Quantum dialogue (QD) is an important branch of quantum secure communication. It does not require a key and allows the communicating parties to directly transmit secret information to each other through a quantum channel. In 2004, Nguyen [7] proposed the first QD protocol. Similar to other quantum secure communication protocols, QD requires that both actual communicating parties are legitimate communicating parties. Therefore, it is of great significance to authenticate the actual communicating parties before transmitting information to ensure the security of QD. Quantum identity authentication is based on the basic principles of quantum mechanics to achieve identity authentication of the communicating parties. In theory, the absolute security of the identity authentication code can be guaranteed. In the past few years, researchers have proposed some QD protocols with identity authentication functions. For example, in 2015, Ye et al. proposed a QD protocol with fault tolerance and identity authentication functions based on logical Bell states; in 2018, Qi et al. proposed two QD protocols with identity authentication functions based on three-particle entangled states; in 2020, Zheng et al.

[13] proposed a QD protocol with controlled authentication functions based on GHZ-like states.

[0003] In the actual quantum dialogue and identity authentication process, an eavesdropper may use the imperfection of the actual experimental equipment to launch an attack to steal the information and identity code transmitted by the communication party, threatening the security of the actual quantum dialogue and the identity information of the legitimate communication party. Since most attacks on experimental equipment are attacks on detectors, such as strong light blinding attacks, time shift attacks, dead time attacks, etc. Therefore, in order to enhance the security of quantum dialogue under actual experimental conditions and plug the security loopholes from the detector, the present invention introduces the idea of ​​device independence (MDI) into quantum dialogue with identity authentication function for the first time. The present invention assigns all measurement tasks to a third-party measurement terminal, and the measurement results are all public. Only the legitimate communication parties can interpret the secret information transmitted by the other party. The present invention can resist the impersonation attacks of eavesdroppers and all attacks on imperfect detectors, so that the communication parties can eliminate the influence of the measurement terminal and realize quantum dialogue with high security. Summary of the invention

[0004] The purpose of the present invention is to address the defects and shortcomings of the above-mentioned prior art and propose a measurement device-independent quantum dialogue method with a two-way authentication function, which realizes two-way quantum authentication between two communicators, and then the two parties communicate. The present invention can effectively resist all attacks from the measurement end and ensure the security of two-way quantum authentication and dialogue under the actual imperfect detection device conditions.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a measurement device-independent quantum dialogue method with a two-way identity authentication function, the method comprising the following steps:

[0006] Step 1: The legitimate communication party Alice' first shares two sets of key strings K1 and K2 with the legitimate communication party Bob1'. The length of each key string is n, where n is a large number. K1 is used as Alice's identity identification code, and K2 is used as Bob1's identity identification code.

[0007] Step 2: The actual communication parties to be authenticated, Alice and Bob, respectively prepare a series of entangled photon pairs, all in the same quantum state Alice (Bob) puts the entangled photon pairs into photon sequence S in order A1 ,S A2 (S B1 , S B2 ); Alice (Bob) randomly prepares a large number of single photons in the Z basis (right angle basis) and X basis (diagonal basis) as security detection photons. Alice and Bob randomly insert the security detection photons into S A2 and S B2 in sequence;

[0008] Step 3: Alice and Bob each send S A2 and S B2 The photons in the sequence are sent to the third party Charlie in sequence through the quantum channel. Charlie performs the first round of full Bell state measurement (BSM) on each pair of received photons and publishes the measurement results.

[0009] Step 4: Alice and Bob publicly disclose S through the classical channel A2 and S B2 The position and preparation basis of the single photon in the sequence, and the pairing of BSM are analyzed one by one. If the two photons of the complete BSM are both from entangled photon pairs, then their A1 and S B1 The corresponding photons in the sequence establish an entangled channel through entanglement exchange; if the two photons undergoing BSM are one single photon and one from an entangled photon pair, then the BSM result and S A1 or S B1 The corresponding photons in the sequence are discarded; if the two photons undergoing BSM are both single photons and have different preparation bases, the BSM result is discarded. If the preparation bases of the two single photons are the same, Alice and Bob can perform the first round of security checks based on the BSM results and their quantum states. After the security check is completed, if the error rate exceeds the pre-set threshold, it means that this round of photon transmission is unsafe and the authentication is terminated. If the error rate is lower than the pre-set threshold, proceed to the next step;

[0010] Step 5: After the security check is passed, Alice randomly selects A1 In the sequence, enough photons are selected as authentication photons and their positions are announced. Both parties extract the authentication photon pairs according to the announced positions to form the sequence S AI1 and S BI1 Alice uses her identity code to identify S AI1 The photons of the sequence are encoded with bits and their phases are randomly operated. Bob codes S according to his identity code. BI1 The photons of the sequence are phase-encoded and their bits are randomly operated. After the encoding is completed, both parties AI1 and S BI1 A sufficient number of single photons randomly prepared in the Z basis or X basis are randomly inserted into the sequence for safety detection photons to form S AI1 ' and S BI1 'sequence;

[0011] Step 6: Alice and Bob send S AI1 ' and S BI1 'The sequence of photons is sent to a third party Charlie through a quantum channel for measurement and publication of the BSM results. Both parties publish S AI1 ' and S BI1 'The position of the security detection photon in the sequence. If both photons undergoing BSM are single photons and have the same preparation basis, the single photon states and BSM results prepared by both parties are used for the second round of security detection. The specific process is the same as the security detection process in step 4. If both photons undergoing full BSM are derived from entangled photon pairs, their BSM results are used by both parties to verify each other's identities. If one of the two photons undergoing BSM is a single photon and the other is derived from an entangled photon pair, or both photons are single photons but have different preparation bases, the corresponding BSM results should be discarded. For the discarded identity code encoding photon pairs, Alice and Bob need to record their positions and re-encode them for two-way identity authentication in the next round of identity authentication until Alice and Bob have completed the transmission of all identity codes; if the identity code of Bob (Alice) obtained by Alice (Bob) is consistent with the identity code of the legitimate communication party Bob' (Alice'), Alice (Bob) can determine that Bob (Alice) is the legitimate communication party Bob' (Alice'). If any party is not a legitimate communication party, the communication will be terminated;

[0012] Step 7: Alice uses bit encoding for the remaining photons in her hand according to the information to be transmitted, and performs phase random operations on the photon pairs. Bob uses phase encoding for the remaining photons in his hand; bit random operations are performed on the photons. Both parties randomly prepare a large number of single photons in the Z basis or X basis as security detection photons, and randomly insert them into their respective photon sequences to form S AI3 and S BI3 Sequence, send the two sequences of photons to the third party Charlie through the quantum channel for complete BSM;

[0013] Step 8: If both photons undergoing BSM are single photons and have the same preparation basis, the single photon states and BSM results prepared by both parties are used for the third round of security testing. If both photons undergoing full BSM come from entangled photon pairs, Alice and Bob read the information transmitted by the other party based on their own random coding operations and the results of BSM. If one of the two photons undergoing BSM is a single photon and the other comes from an entangled photon pair, or both photons are single photons but have different preparation bases, the corresponding BSM results should be discarded. For the discarded coded photon pairs, their positions need to be recorded and encoded in the next round of dialogue until both parties have transmitted all information to each other.

[0014] Furthermore, in step 1 of the present invention, the identity authentication key shared by the legitimate communication parties Alice and Bob is respectively composed of a series of binary bit string identity authentication codes K A and K B Identity authentication code string K A ,K B Described as:

[0015] K A =(K A1 ,K A2 ,K A3 ,………,K An )

[0016] K B =(K B1 ,K B2 ,K B3 ,……,K Bn )

[0017] Among them, n is a large number.

[0018] Furthermore, in step 2 of the present invention, Alice and Bob are both prepared in the maximum entangled state |φ + >entangled photon pair, φ + > is greater than the length of the authentication key sequence, |φ + > belongs to one of the following four polarization Bell states:

[0019]

[0020] Here, |H> and |V> represent the horizontal and vertical polarization of the photon, respectively.

[0021] Furthermore, the single photons used in step 2, step 5 and step 7 of the present invention are randomly prepared under the Z base and the X base, and the Z base and the X base are respectively expressed as:

[0022] Z P ={H>,|V>}

[0023]

[0024] Among them, |+>, |-> represent the 45° polarization and 135° polarization of the photon respectively; in this way, the photon used for security detection is randomly in one of the four quantum states |H>, |V>, |+>, |->.

[0025] Furthermore, in step 4, step 6 and step 7 of the present invention, if both photons are single photons, there are three possibilities:

[0026] If both single photons are Z-based, the two photons may be in one of four quantum states: |H>|V>, |V>|H>, |H>|H> or |V>|V>, that is, If the measurement result of |H>|V> or |V>|H> shows |φ ± >, or the measurement result of |H>|H> or |V>|V>| appears |ψ ± >, both parties can determine that an error has occurred;

[0027] If both single photons are X-based, the two photons may be in one of four quantum states: |+>|+>, |+>|->, |->|+> or |->|->, that is, If a result different from the above formula is obtained, both parties will determine that an error has occurred;

[0028] If one photon is X-basis and the other is Z-basis, the two photons may be in one of eight quantum states: |+>|H>, |+>|V>, |H>|+>, |V>|+>, |->|H>, |->|V>, |H>|->, or |V>|->, i.e.

[0029]

[0030] At this time, it is impossible to determine whether an error has occurred based on the results of the complete BSM, and both parties discard the results of the BSM.

[0031] Further, in steps 5 and 7 of the present invention, the bit encoding operation at Alice is {I, σ x}, where I = |H><H| + |V><V| represents the identity code 0, and σ x = |H><V| + |V><H| represents the identity code 1, and the phase is randomly encoded using I and σ z ; the phase encoding operation at Bob is {I, σ z}, where I = |H><H| + |V><V| represents the identity code 0, and σ z = |H><V| - |V><H| represents the identity code 1, and the bit is randomly encoded using I and σ x . After the encoding operation, the original state evolves into one of the following four states: |ψ + >, |ψ - >, |φ + > or |φ - .

[0032] Further, in step 6 of the present invention, the communication parties analyze the BSM results of the first and second rounds. According to their own random operations, they can infer the identity codes transmitted by the other party. If the identity codes at this position in the identity key sequences of Alice and Bob are the same as the known identity codes, that is, the identity codes at this position are correct; if the error rate of the identity codes is lower than the tolerable threshold, it indicates that the identity authentication of Alice and Bob is secure, the key is correct, and the identity authentication is successful; after the identity authentication is successful, they can infer the information of the conversation according to their own encoding information; similarly, in step 8, the communication parties analyze the BSM results of the first and third rounds, combined with their own encoding operations, to infer the secret information transmitted by the other party. The entangled state formed by Alice and Bob is That is If the information transmitted by Alice and Bob to each other is 1 and 0, the entangled state will finally evolve into Based on the BSM results of Charlie by Alice and Bob, and according to the initial state and their own encoding operations, the two can respectively infer that the information to be transmitted by the other party is 0 and 1.

[0033] Further, in steps 6 - 8 of the present invention, it is necessary to record the positions and encoding information of the encoded photon pairs discarded due to pairing errors in each round of BSM. To complete all the lost encoding information, it is necessary to re - run the present invention until all the identity codes of Alice and Bob are authenticated and the conversation information is transmitted.

[0034] Furthermore, in the method of the present invention, Alice and Bob first determine whether the other party is a legitimate communication party based on the measurement results of the second and third rounds of complete BSM and then transmit information. The security detection also ensures that eavesdroppers cannot obtain the information transmitted by both parties, thereby protecting the absolute security of the identities of both parties and the conversation information.

[0035] Beneficial effects:

[0036] 1. The present invention can perform two-way authentication on the legitimate identities of both communicating parties before communication, and can effectively resist the impersonation attack of eavesdroppers.

[0037] 2. The present invention delegates all measurement tasks to an untrusted third-party measurement terminal. During the identity authentication and quantum dialogue process, it can effectively resist all attacks against imperfect measurement devices and ensure the security of the identity authentication codes and transmitted information of both parties. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The present invention is a flow chart of a measurement device-independent quantum dialogue method with a two-way identity authentication function in an embodiment of the present invention.

[0039] Figure 2 Schematic diagram of the principle of a measurement device-independent quantum dialogue method with a two-way identity authentication function in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific implementation cases and in conjunction with the accompanying drawings. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. After reading the present invention, the modifications of various equivalent forms of the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0041] Embodiment 1

[0042] like Figure 1 and Figure 2 As shown, the present invention provides a measurement device-independent quantum dialogue method with a two-way identity authentication function based on entanglement exchange, comprising the following steps:

[0043] The process of the present invention is analyzed below in conjunction with specific examples:

[0044] First, the legitimate communication parties Alice and Bob share a set of identity authentication key sequences K through the BB84 protocol. i , Alice and Bob both know the shared key sequence and their respective identity codes K A and K B , where K A , KB ∈K i The key sequence consists of a series of binary bit string identity authentication codes, where the identity authentication code K i ={0,1},i=1,2,…,m.

[0045] Alice, the communication party to be authenticated, prepares a series of entangled photon pairs (a1, a2), and Bob prepares a series of entangled photon pairs (b1, b2). The number of entangled photon pairs must be greater than the authentication key length m, and they are all in the same initial state. and All a1 photons are sequentially composed of S A1 Sequence, similarly, a2 photons make up S A2 sequence, b1 photons make up S B1 sequence, b2 photons make up S B2 sequence. and All belong to the following four polarized Bell states

[0046]

[0047] Among them, |H> and \V> represent the horizontal polarization and vertical polarization of the photon, respectively.

[0048] Alice and Bob are in S A2 and S B2 A sufficient number of single photons randomly prepared in the Z basis or X basis are randomly inserted into the sequence. The Z basis and X basis are represented as

[0049] Z P ={H>,|V>}

[0050]

[0051] Among them, \+>, |-> represent the 45° polarization and 135° polarization of the photon respectively; in this way, the safety detection photon is randomly in one of the four quantum states \H>, \V>, \+>, |->.

[0052] Alice and Bob are in S A2 and S B2 The new sequence after the security detection single photon is inserted into the sequence is sent to the third party Charlie through different quantum channels. Charlie performs the first round of Bell state measurement (BSM) on the received photon pairs (a2, b2) one by one and publishes the measurement results. Alice and Bob publish S through the classical channel A2 and S B2 The position and preparation basis of single photons in the sequence, and analyze the BSM situation one by one. According to the source of the photon, it is divided into the following situations:

[0053] (1) When a2 and b2 are both entangled photons, photons a1 and b1 establish long-distance entanglement through the entanglement exchange generated during their Bell state measurement;

[0054] (2) When a2 and b2 are a single photon and an entangled photon pair respectively, the BSM result and the corresponding entangled photon a1 or b1 are discarded;

[0055] (3) When a2 and b2 are both single photons and have different preparation bases, the BSM result is discarded;

[0056] (4) When a2 and b2 are both single photons and have the same preparation basis, the BSM results and quantum states are used for the first round of safety testing.

[0057] The complete BSM used in this scheme can distinguish |ψ + > and ψ - >,|φ + > and |φ - >Four Bell states. Alice and Bob first perform a security check. When both photons are single photons, there are three possibilities:

[0058] If both single photons are Z-based, the two photons may be in one of four quantum states: |H>|V>, |V>|H>, |H>|H> or |V>|V>, that is, The four Bell states can be distinguished using the full BSM, but the BSM under linear optics conditions can only distinguish ψ + >|orψ - > state, both parties use BSM results for security testing, although BSM under linear optical conditions cannot distinguish |φ + > and |φ - >, but it is still possible to determine whether an error has occurred. If the measurement result of |H>|V> or |V>|H> shows |φ ± >, or the measurement result of |H>|H> or |V>|V> appears |ψ ± >, both parties can determine that an error has occurred. Therefore, using BSM under linear optical conditions does not affect safety.

[0059] If both single photons are X-based, the two photons may be in one of four quantum states: |+>|+>, |+>|->, |->|+> or |->|->, that is, Therefore, if the complete BSM obtains |ψ + > or |ψ - >,|φ + > or |φ - >, both parties use BSM results for security testing.

[0060] If one photon is in the X basis and one photon is in the Z basis, the two photons can be in one of eight quantum states: |+>|H>, |+>|V>, |H>|+>, |V>|+>, |->|H>, |->|V>, |H>|->, or |V>|->, that is

[0061]

[0062] At this time, these eight situations cannot be distinguished, and it is also impossible to judge whether an error has occurred based on the result of BSM. Therefore, both parties discard the result of BSM.

[0063] After the security detection is completed, if the error rate exceeds the pre-set threshold, it means that the photon transmission in this round is not secure and the authentication is aborted. If the error rate is lower than the pre-set threshold, the next step is carried out. Entanglement swapping occurs during the Bell state measurement of a2 and b2, and long-distance entanglement is established between photons a1 and b1. Then the BSM process is:

[0064] Since Charlie can identify four Bell states, the measurement results he announces are or When, the corresponding entangled states formed by photons a1 and b1 of Alice and Bob are or

[0065] When the result of the first BSM announced by Charlie passes the security check, its encoding method is: Alice performs bit encoding operation with random phase encoding on photon a1 in the S A sequence according to the identity key K A1 she holds, while Bob performs phase encoding operation on photon b1 in the S B sequence according to K B1 with random encoding at the bit position; among them, the bit encoding operation is {I, σ x}, I = |H><H| + |V><V| represents the identity code 0, and σ x = |H><V| + |V><H| represents the identity code 1; the phase encoding operation is {I, σ z}, I = |H><H| + |V><V| represents the identity code 0, and σ z = |H><H| - |V><V| represents the identity code 1.

[0066] The specific encoding operation process is as follows:

[0067] If the entangled state formed by photons a1 and b1 is that is At this time, there are four situations: (1) If Alice and Bob's identity codes are 0 and 0, the encoding operations are I and I respectively, and the entangled state remains unchanged, which is (2) If Alice and Bob’s identity codes are 0 and 1, the encoding operations are I and σ respectively. z , then the entangled state evolves into (3) If Alice and Bob’s identity codes are 1 and 0, the encoding operations are σ respectively. x and I, the entangled state evolves into (4) If Alice and Bob’s identity codes are 1 and 1, the encoding operations are σ respectively. x and σ z , then the entangled state evolves into

[0068] If the entangled state formed by photons a1 and b1 is Right now At this time, there are four situations: (1) If Alice and Bob's identity codes are 0 and 0, the encoding operations are I and I respectively, and the entangled state remains unchanged, which is (2) If Alice and Bob’s identity codes are 0 and 1, the encoding operations are I and σ respectively. z , then the entangled state evolves into (3) If Alice and Bob’s identity codes are 1 and 0, the encoding operations are σ respectively. x and I, the entangled state evolves into (4) If Alice and Bob’s identity codes are 1 and 1, the encoding operations are σ respectively. x and σ z , then the entangled state evolves into

[0069] Regardless of the entangled state formed by photons a1 and b1 still After the encoding operation, the entangled state evolves into one of the four states: or

[0070] After the results of the second round of BSM are announced, Alice and Bob use the BSM results and their own coding methods to deduce the coded information to verify the identity code. If the verification is correct, they proceed to the next step, quantum dialogue. After identity authentication, Alice and Bob respectively send the remaining photon sequence S AI3 and S BI3 According to the content of the quantum dialogue, the encoding operation is performed. Same as the above steps, Alice uses phase random encoding + bit encoding, and Bob uses bit random encoding + phase encoding. The encoding method is: the bit encoding operation is {I, σ x}, I = |H><H| + |V><V| represents the information code 0, σ x = |H><V| + |V><H| represents the information code 1; the phase encoding operation is {I, σ z}, I = |H><H| + |V><V| represents the information code 0, σ z = |H><H| - |V><V| represents the information code 1. After encoding, a single photon is randomly inserted as a security detection photon, and the security detection photon randomly occupies one of the four quantum states |H>, |V>, |+>, |->. Then, Alice and Bob send them to Charlie through different quantum channels. Charlie performs the third round of complete BSM and announces the measurement results. After removing the security detection photons, the complete BSM results of the photons from the entangled photon pairs are used for two-way quantum dialogue, and other entangled photon-single photon pairs and single photon pairs with different bases are discarded. Alice and Bob can mutually read out each other's information according to their own random + bit (phase) encoding operations and the results of the third round of BSM.

[0071] It should be noted that in quantum dialogue, the situation of discarding entangled photons may occur. If both photons are from entangled photon pairs, but the numbers of the entangled photon pairs are different (for example, the i-th and the j-th, i ≠ j), or one photon is a single photon and the other is from an entangled photon pair, then the BSM results and the corresponding entangled photons are discarded. Here, the entangled photons have all undergone encoding operations and carry encoding information, so after discarding, the numbers of the discarded entangled photons must be recorded. After the identity authentication is completed, encoding and adding security detection photons are performed sequentially again, and finally sent to the third party Charlie for complete BSM. According to the results announced by Charlie, they are confirmed one by one until all the dialogue information is safely transmitted, and Alice and Bob respectively obtain all the information of the quantum dialogue. Thus, a measurement device-independent quantum dialogue process with a two-way identity verification function is completed.

[0072] The security of the present invention can be guaranteed by three rounds of security detection. Charlie responsible for BSM can be dishonest and even completely controlled by the eavesdropper Eve. In steps 3, 6, and 7, although Charlie publicly knows the results of these three rounds of BSM, since Charlie cannot infer the encoding operations of Alice and Bob from this, he cannot obtain any information about the identity authentication and quantum dialogue of Alice and Bob.

[0073] Embodiment 2

[0074] The present invention provides a measurement device-independent quantum dialogue method with a two-way identity authentication function, and the method includes the following steps:

[0075] Step 1: Alice and Bob, the communication parties to be authenticated, prepare a series of entangled photon pairs, all in the same quantum state. The entangled photon pairs are organized into a relational sequence S A1 ,S A2 (S B1 , S B2 ), and use a large number of single photons prepared under the Z-base and X-base as safety detection photons;

[0076] Step 2: Alice (Bob) takes out a photon S from each pair of entangled photons A1 (S B1 ) sequence, the remaining photons are sequentially composed of S A2 (S B2 ) sequence. Alice and Bob are in S A2 and S B2 Insert enough single photons randomly prepared in the right angle basis (Z basis) and diagonal basis (X basis) at random positions in the sequence;

[0077] Step 3: Alice and Bob each send S A2 and S B2 The photons in the sequence are sent to a third party, Charlie, through different quantum channels. Charlie performs the first round of Bell state measurement (BSM) on each pair of received photons and publishes the measurement results.

[0078] Step 4: Alice and Bob publicly disclose S through the classical channel A2 and S B2 The position and preparation basis of the single photons in the sequence are analyzed one by one, and the pairing of BSM is analyzed one by one. If the two photons in the BSM are both from entangled photon pairs, and the entangled photon pairs have the same number (for example, both are number i), then they are in S A1 and S B1 The corresponding photons in the sequence establish an entangled channel through entanglement exchange; if both photons come from entangled photon pairs, but the entangled photon pairs have different numbers (for example, No. i and No. j, respectively), or one of the two photons is a single photon and the other comes from an entangled photon pair, then the BSM result and S A1 or S B1 The remaining photons in the sequence are discarded, and the numbers of the discarded entangled photons are recorded; if both photons are single photons and have different preparation bases, the BSM result is discarded. If the preparation bases of the two single photons are the same, Alice and Bob can perform the first round of security checks based on the BSM results and their quantum states. After the security check is completed, if the error rate exceeds the pre-set threshold, it means that this round of photon transmission is unsafe and the authentication is terminated. If the error rate is lower than the pre-set threshold, proceed to the next step;

[0079] Step 5: After the security check is passed, Alice randomly selects A1 Randomly select enough photons in the sequence as authentication photons and publish their positions. Both parties extract the authentication photon pairs to form the sequence S AI1 and S BI1 Alice uses phase random coding + bit coding operation to encode S according to her identity code. AI1 Bob encodes S BI1 The photons of the sequence are randomly encoded with bits and phase encoded. After the encoding is completed, both parties AI1 and S BI1 A sufficient number of single photons randomly prepared in the Z basis or X basis are randomly inserted into the sequence for safety detection photons to form S AI1 ' and S BI1 'sequence;

[0080] Step 6: Alice and Bob send S AI1 ' and S BI1 The photons of the sequence are sent to a third party, Charlie, who measures and publishes the results of BSM. AI1 ' and S BI1 'The position of the safety detection photon in the sequence. After deducting the safety detection photon, the BSM result of the photon from the entangled photon pair is used to verify Bob's identity. For the discarded coded photon pair, Bob needs to record its position and re-encode it for identity authentication;

[0081] Step 7: After Alice and Bob complete the two-way identity authentication, Alice uses phase random coding + bit coding to encode the remaining photons in her hand, and Bob uses bit random coding + phase coding to encode the remaining photons in his hand. Both parties randomly prepare single photons in the Z basis or X basis as security detection photons, forming S AI3 and S BI3 Sequence, send the two sequences of photons to the third party Charlie for BSM. Alice and Bob can read each other's information based on their own random + bit (phase) encoding operations and the results of BSM. For the discarded coded photon pairs, their positions need to be recorded and the encoding operation needs to be performed again until every information of the quantum dialogue is completed.

[0082] Step 8: If some coded photon pairs in the second and third rounds of BSM are discarded due to BSM pairing errors, resulting in partial information loss, both parties will record the location of the lost information, and both parties will need to re-perform steps 2 to 6 and 7 to authenticate the lost information encoding. Until all the identity codes of Alice and Bob are authenticated, all the identity codes are correct, and all the conversation information is complete, then Alice and Bob have completed the entire process of two-way identity authentication and conversation.

[0083] In step 1 of the method of the present invention, the identity authentication key sequence shared by Alice and Bob is respectively composed of a series of identity authentication codes of binary bit strings; Alice and Bob share the key sequence.

[0084] In step 2 of the method of the present invention, Alice and Bob are both prepared in a maximally entangled state |φ + >entangled photon pairs, |φ + The number of is greater than the length of the authentication key sequence, |φ + > belongs to the following four polarized Bell states

[0085]

[0086] Here, |H> and |V> represent the horizontal and vertical polarization of the photon, respectively.

[0087] The single photons used in step 3, step 6 and step 7 of the method of the present invention are randomly prepared under the Z-base and the X-base, and the Z-base and the X-base are respectively represented by

[0088] Z P ={|H>,|V>}

[0089]

[0090] Among them, |+> and |-> represent the polarization of the photon in the 45° direction and 135° direction respectively; in this way, the safety detection photon is randomly in one of the four quantum states: |H>, |V>, |+>, |->.

[0091] The BSM used in step 3, step 6 and step 7 of the method of the present invention is a complete BSM that can distinguish ψ + > and |ψ - >,|φ + > and |φ - >Four Bell states.

[0092] In step 4, step 6 and step 7 of the method of the present invention, if both photons are single photons, there are three possibilities:

[0093] If both single photons are in the Z basis, the two photons can be in one of four quantum states: |H>|V>, |V>|H>, |H>|H>, or |V>|V>. That is, If the measurement end Charlie uses BSM under linear optical conditions, it cannot distinguish between |φ + > and |φ - >, but it can still determine whether an error has occurred. For example, if the measurement result of |H>|V> or |V>|H> shows |φ ± >, or the measurement result of |H>|H> or |V>|V> shows |ψ ± >, both parties can determine that an error has occurred. Therefore, using BSM under linear optical conditions does not affect security.

[0094] If both single photons are in the X basis, the two photons can be in one of four quantum states: |+>|+>, |+>|->, |->|+>, or |->|->. That is, Both parties use the complete BSM results for security detection.

[0095] If one photon is in the X basis and one photon is in the Z basis, the two photons can be in one of eight quantum states: |+>|H>, |+>|V>, |H>|+>, |V>|+>, |->|H>, |->|V>, |H>|->, or |V>|->. That is,

[0096]

[0097] At this time, it is impossible to determine whether an error has occurred based on the BSM results, so both parties discard the BSM results.

[0098] In steps 5 and 7 of the method described in the present invention, the phase is randomly encoded at Alice, and the encoding operation at the bit is {I, σ x}, where I = |H><H| + |V><V| represents the identity code 0, and σ x = |H><V| + |V><H| represents the identity code 1; at Bob, the bit is randomly encoded, and the encoding operation at the phase is {I, σ z}, where I = |H><H| + |V><V| represents the identity code 0, and σ z = |H><H| - |V><V| represents the identity code 1. The state after the encoding operation evolves into one of four states: |ψ + >, |ψ - >, |φ + >, or |φ - >.

[0099] In steps 6 and 7 of the method described in the present invention, the results of the second and third rounds of complete BSM are analyzed to infer the other party's coded information. If the identity code of the position in the identity key sequence of Alice or Bob is the same as the known identity code, that is, the identity code of the position is correct. If the identity codes of all positions are the same, it means that the identity authentication keys of Alice and Bob are correct and the identity authentication is successful. If the result of the second round of complete BSM is correct, it means that the identity authentication codes of Alice and Bob are correct. At this time, the correct coded information of the quantum dialogue between Alice and Bob can be inferred based on the result of the third round of BSM.

[0100] In step 6 and step 7 of the method of the present invention, the position and coding information of the coded photon pairs discarded due to pairing errors in the second and third rounds of BSM need to be recorded. In order to make up for all the lost codes, steps 2 to 6 and step 7 need to be repeated in sequence until all the information codes of Alice and Bob are authenticated.

[0101] In the present invention, Alice and Bob can only judge whether the other party is a legitimate communication party and the security of the conversation information based on the measurement results of three complete BSMs. The security detection also ensures that eavesdroppers cannot obtain the identity codes and conversation contents of both parties. Therefore, the present invention can theoretically protect the absolute security of the identity codes and conversation information of both parties.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to be a further limitation of the present invention. All equivalent changes made using the contents of the present specification and drawings are within the protection scope of the present invention.

Claims

1. A measurement device-independent quantum dialogue method with a two-way identity authentication function, characterized in that: The method comprises the following steps: Step 1: The legitimate communication party Alice' first shares two sets of key strings K1 and K2 with the legitimate communication party Bob1'. The length of each key string is n, where n is a large number. K1 is used as Alice's identity identification code, and K2 is used as Bob1's identity identification code. Step 2: The actual communication parties to be authenticated, Alice and Bob, prepare a series of entangled photon pairs, all in the same quantum state. Alice (Bob) puts the entangled photon pairs into a photon sequence S in order A1 ,S A2 (S B1 , S B2 ); Alice (Bob) randomly prepares a large number of single photons in the Z basis (right angle basis) and X basis (diagonal basis) as security detection photons. Alice and Bob randomly insert the security detection photons into S A2 and S B2 in sequence; Step 3: Alice and Bob each send S A2 and S B2 The photons in the sequence are sent to the third party Charlie in sequence through the quantum channel. Charlie performs the first round of full Bell state measurement (BSM) on each pair of received photons and publishes the measurement results. Step 4: Alice and Bob publicly disclose S through the classical channel A2 and S B2 The position and preparation basis of the single photon in the sequence, and the pairing of BSM are analyzed one by one. If the two photons of the complete BSM are both from entangled photon pairs, then their A1 and S B1 The corresponding photons in the sequence establish an entangled channel through entanglement exchange; if the two photons undergoing BSM are one single photon and one from an entangled photon pair, then the BSM result and S A1 or S B1 The corresponding photons in the sequence are all discarded; if the two photons undergoing BSM are both single photons and have different preparation bases, the BSM result is discarded. If the preparation bases of the two single photons are the same, Alice and Bob can perform the first round of security checks based on the BSM results and their quantum states. After the security check is completed, if the error rate exceeds the preset threshold, it means that this round of photon transmission is unsafe and the authentication is terminated. If the error rate is lower than the preset threshold, proceed to the next step. Step 5: After the security check is passed, Alice randomly selects A1 In the sequence, enough photons are selected as authentication photons and their positions are announced. Both parties extract the authentication photon pairs according to the announced positions to form the sequence S AI1 and S BI1 Alice uses her identity code to identify S AI1 The photons of the sequence are encoded with bits and their phases are randomly operated. Bob codes S according to his identity code. BI1 The photons of the sequence are phase-encoded and their bits are randomly operated. After the encoding is completed, both parties are in S AI1 and S BI1 A sufficient number of single photons randomly prepared in the Z basis or X basis are randomly inserted into the sequence for safety detection photons to form S AI1 ' and S BI1 'sequence; Step 6: Alice and Bob send S AI1 ' and S BI1 'The sequence of photons is sent to a third party Charlie through a quantum channel for measurement and publication of the BSM results. Both parties publish S AI1 ' and S BI1 'The position of the security detection photon in the sequence. If the two photons undergoing BSM are both single photons and have the same preparation basis, the single-photon states and BSM results prepared by both parties are used for the second round of security detection. The specific process is the same as the security detection process in step 4. If the two photons undergoing full BSM are both derived from entangled photon pairs, their BSM results are used by both parties to verify each other's identities. If one of the two photons undergoing BSM is a single photon and the other is from an entangled photon pair, or if both photons are single photons but have different preparation bases, the corresponding BSM results should be discarded. Alice and Bob need to record the position of the identity code-encoded photon pair and re-encode it in the next round of identity authentication to perform a two-way identity authentication operation until Alice and Bob have completed the transmission of all identity codes; if the identity code of Bob (Alice) obtained by Alice (Bob) is consistent with the identity code of the legitimate communication party Bob' (Alice'), Alice (Bob) can determine that Bob (Alice) is the legitimate communication party Bob' (Alice'); if either party is not a legitimate communication party, the communication is terminated; Step 7: Alice uses bit encoding for the remaining photons in her hand according to the information to be transmitted, and performs phase random operations on the photon pairs. Bob uses phase encoding for the remaining photons in his hand; bit random operations are performed on the photons. Both parties randomly prepare a large number of single photons in the Z basis or X basis as security detection photons, and randomly insert them into their respective photon sequences to form S AI3 and S BI3 Sequence, send the two sequences of photons to the third party Charlie through the quantum channel for complete BSM; Step 8: If both photons undergoing BSM are single photons and have the same preparation basis, the single photon states and BSM results prepared by both parties are used for the third round of security testing. If both photons undergoing full BSM come from entangled photon pairs, Alice and Bob read the information transmitted by the other party based on their own random coding operations and the results of BSM. If one of the two photons undergoing BSM is a single photon and the other comes from an entangled photon pair, or both photons are single photons but have different preparation bases, the corresponding BSM results should be discarded. For the discarded coded photon pairs, their positions need to be recorded and encoded in the next round of dialogue until both parties have transmitted all information to each other.

2. According to claim 1, a measurement device-independent quantum dialogue method with a two-way identity authentication function is characterized in that: In step 1, the identity authentication key shared by the legitimate communication parties Alice and Bob is composed of a series of binary bit string identity authentication codes K A and K B Composition, identity authentication code string K A ,K B Described as: K A =(K A1 ,K A2 ,K A3 ,………,K An ) K B =(K B1 ,K B2 ,K B3 ,………,K Bn ) Among them, n is a large number.

3. The measurement device-independent quantum dialogue method with a two-way identity authentication function according to claim 1 is characterized in that: In step 2, Alice and Bob both prepare the maximally entangled state |φ + >entangled photon pairs, |φ + > is greater than the length of the authentication key sequence, |φ + > belongs to one of the following four polarization Bell states: Here, |H> and |V> represent the horizontal and vertical polarization of the photon, respectively.

4. According to claim 1, a measurement device-independent quantum dialogue method with a two-way identity authentication function, wherein The method is characterized in that the single photons used in step 2, step 5 and step 7 are randomly prepared under the Z-base and the X-base, and the Z-base and the X-base are respectively expressed as: From P ={|H>,|V>} in, |+>, |-> represent the 45° polarization and 135° polarization of the photon respectively; in this way, the photon used for security detection is randomly in one of the four quantum states |H>, |V>, |+>, |->.

5. The measurement device-independent quantum dialogue method with a two-way identity authentication function according to claim 1 is characterized in that: In steps 4, 6, and 7, if both photons are single photons, there are three possibilities: If both single photons are Z-based, the two photons may be in one of four quantum states: |H>|V>, |V>|H>, |H>|H> or |V>|V>, that is, If the measurement result of |H>|V> or |V>|H> shows |φ ± >, or the measurement result of |H>|H> or |V>|V> appears |ψ ± >, both parties can determine that an error has occurred; If both single photons are X-based, the two photons may be in one of four quantum states: |+>|+>, |+>|->, |->|+> or |->|->, that is, If a result different from the above formula is obtained, both parties will determine that an error has occurred; If one photon is X-basis and the other is Z-basis, the two photons may be in one of eight quantum states: |+>|H>, |+>|V>, |H>|+>, |V>|+>, |->|H>, |->|V>, |H>|->, or |V>|->, i.e. At this time, it is impossible to determine whether an error has occurred based on the results of the complete BSM, and both parties discard the results of the BSM.

6. The measurement device-independent quantum dialogue method with a two-way identity authentication function according to claim 1 is characterized in that: In steps 5 and 7, the bit encoding operation at Alice is {I, σ x}, where I = |H><H| + |V><V| represents the identity code 0, and σ x = |H><V| + |V><H| represents the identity code 1, and the phase is randomly encoded using I and σ z ; the phase encoding operation at Bob is {I, σ z}, where I = |H><H| + |V><V| represents the identity code 0, and σ z = |H><V| - |V><H| represents the identity code 1, and the bit is randomly encoded using I and σ x . After the encoding operation, the original state evolves into one of the following four states: |ψ + >, |ψ->, |φ + >, or |φ - .

7. The measurement device-independent quantum dialogue method with a two-way identity authentication function according to claim 1 is characterized in that: In step 6, the communicating parties analyze the results of the first and second rounds of BSM, and can infer the identity code transmitted by the other party based on their own random operations. If the identity code at this position in the identity key sequence of Alice and Bob is the same as the known identity code, the identity code at this position is correct; if the error rate of the identity code is lower than the tolerable threshold, it means that the identity authentication of Alice and Bob is secure, the key is correct, and the identity authentication is successful; after the identity authentication is successful, the information of the conversation can be inferred based on their own coded information; Similarly, in step 8, the communicating parties analyze the results of the first and third rounds of BSM, and combine their own encoding operations to infer the secret information transmitted by the other party. The entangled state formed by Alice and Bob is Right now If the information Alice and Bob transmit to each other is 1 and 0, the entangled state will eventually evolve into Based on the results of Charlie's BSM, the initial state and their own coding operations, Alice and Bob can respectively infer that the information the other party wants to convey is 0 and 1.

8. The measurement device-independent quantum dialogue method with a two-way identity authentication function according to claim 1 is characterized in that: In steps 6 to 8, it is necessary to record the positions and coding information of the coded photon pairs discarded due to pairing errors in each round of BSM. In order to make up for all the lost coding information, the present invention needs to be rerun until all the identity codes of Alice and Bob are authenticated and the dialogue information is transmitted.

9. The measurement device-independent quantum dialogue method with a two-way identity authentication function according to claim 1, characterized in that: In the method, Alice and Bob first determine whether the other party is a legitimate communication party based on the measurement results of the second and third rounds of complete BSM and then transmit information. The security detection also ensures that eavesdroppers cannot obtain the information transmitted by both parties, protecting the absolute security of the identities of both parties and the conversation information.

Images