A measurement-device-independent quantum dialogue method with bidirectional identity authentication function

Abstract

The application discloses a kind of measurement equipment independent quantum conversation methods with bidirectional identity authentication function, the method is mutually authenticated whether communication two sides are legal collaborators, then directly utilize quantum channel to mutually converse each other.Communication two sides Alice and Bob mutually share a set of identity keys by BB84 protocol, Alice and Bob are only responsible for preparing entangled photon pair and single photon, and performing encoding operation to photon, all measurement tasks are completed by third party measurement end Charlie.Alice and Bob can verify the identity of two sides according to the Bell state analysis result of Charlie, determine as the legal party of communication, and complete bidirectional communication after that.The application first applies bidirectional identity authentication technology to MDI-QD field, can resist the impersonation attack of eavesdropper, and by completing measurement task by third party, can effectively resist all attacks to imperfect measurement equipment, enhance the security of two-way identity authentication code and communication.The application has very important significance to promote the practical application of quantum conversation.

Description

Technical Field

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

[0002] Quantum dialogue (QD) is an important branch of quantum secure communication. It does not require a key and allows the two parties to transmit secret information directly 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 communication parties be legitimate. Therefore, authenticating the actual communication parties before transmitting information is of great significance to ensuring the security of QD. Quantum identity authentication is based on the basic principles of quantum mechanics to authenticate the identity of the communication parties. Theoretically, it can guarantee the absolute security of the identity authentication code. 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 practical quantum dialogue and authentication processes, eavesdroppers may exploit imperfections in experimental equipment to launch attacks and steal information and identity codes transmitted by the communicating parties, threatening the security of the actual quantum dialogue and the identity information of legitimate communicating parties. Since most attacks targeting experimental equipment are aimed at the detectors, such as blinding attacks, time-shifting attacks, and dead-time attacks, this invention, for the first time, introduces the concept of Device Independence (MDI) into quantum dialogue with authentication functionality to enhance the security of quantum dialogue under actual experimental conditions and plug security vulnerabilities originating from detectors. This invention delegates all measurement tasks to a third-party measurement terminal, and all measurement results are publicly available; only the legitimate communicating parties can decipher the secret information transmitted by the other party. This invention can resist eavesdropping attacks and all attacks targeting imperfect detectors, allowing the communicating parties to eliminate the influence of the measurement terminal and achieve highly secure quantum dialogue. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings and deficiencies of existing technologies by proposing a measurement-device-independent quantum dialogue method with bidirectional authentication. This method achieves bidirectional quantum authentication between two communicators before they can communicate. This invention effectively resists all attacks from the measurement end, ensuring the security of bidirectional quantum authentication and dialogue even under conditions of imperfect detection devices.

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

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

[0007] Step 2: Alice and Bob, the actual communicators to be authenticated, each prepare a series of entangled photon pairs, all in the same quantum state. Alice (Bob) arranges the entangled photon pairs into photon sequences S in order. A1 ,S A2 (S B1 S B2 Alice (Bob) randomly prepared a large number of single photons in Z-based (right-angled) and X-based (diagonal) substrates as security detection photons. Alice and Bob then randomly inserted the security detection photons into S-based substrates. A2 and S B2 in sequence;

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

[0009] Step 4: Alice and Bob publish S via a classic channel A2 and S B2 The positions and preparation basis of single photons in the sequence are determined, and the pairing situation of BSM is analyzed one by one. If both photons undergoing complete BSM originate from entangled photon pairs, then their positions in S... A1 and S B1 The corresponding photons in the sequence establish an entangled channel through entanglement swapping; if one of the two photons performing BSM is a single photon and the other comes from an entangled photon pair, then the BSM result and S A1 or S B1 All corresponding photons in the sequence are discarded. If both photons used for BSM are single photons with different preparation bases, the BSM result is discarded. If the two single photons have the same preparation base, Alice and Bob can perform the first round of security testing based on the BSM result and their quantum states. After the security test is completed, if the error rate exceeds a pre-set threshold, it indicates that this round of photon transmission is insecure, and authentication is terminated. If the error rate is lower than the pre-set threshold, the next step is continued.

[0010] Step 5: After passing the security check, Alice randomly selects S A1 A sufficient number of photons are selected from the sequence as authentication photons, and their locations are published. Both parties extract the authentication photon pairs based on the published locations to form sequence S. AI1 and S BI1 Alice uses her identification code to access S AI1 The photons in the sequence are bit-encoded and their phases are randomly manipulated. Bob then uses his identity code to... BI1 The photons in the sequence are phase-coded, and their bits are randomly manipulated. After encoding, both parties communicate via S... AI1 and S BI1 A sufficient number of randomly prepared single photons based on the Z or X basis are randomly inserted into the sequence to form security detection photons, constituting S. AI1 'and S BI1 'sequence;

[0011] Step 6: Alice and Bob will... AI1 'and S BI1 The sequence of photons is sent via a quantum channel to a third party, Charlie, for measurement, and the results of the BSM are published. Both parties then publish the S... AI1 'and S BI1 The position of the security detection photon in the sequence: If both photons performing BSM are single photons and have the same preparation basis, the single photon states prepared by both parties and the BSM results 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 performing full BSM originate from entangled photon pairs, their BSM results are used to verify each other's identities. If one of the two photons performing BSM is a single photon and the other comes from an entangled photon pair, or if both photons are single photons but have different preparation bases, the corresponding BSM results should be discarded. For the discarded identity code encoded photon pairs, Alice and Bob need to record their positions and re-encode them in the next round of identity authentication to perform bidirectional identity verification until Alice and Bob have completed the transmission of all identity codes. If the identity code of Bob(Alice) obtained by Alice(Bob) matches the identity code of the legitimate communicator Bob'(Alice'), Alice(Bob) can determine that Bob(Alice) is the legitimate communicator Bob'(Alice'). If either party is not a legitimate party to the communication, the communication is terminated.

[0012] Step 7: Alice uses bit encoding on the remaining photons in her hand according to the information to be transmitted, and performs a phase randomization operation on the photon pairs. Bob uses phase encoding on the remaining photons in his hand; he also performs a bit randomization operation on the photons. Both parties randomly prepare a large number of single photons under Z-based or X-based conditions as security detection photons, and randomly insert them into their respective photon sequences to form S. AI3 and S BI3 The sequence involves sending photons from two sequences to a third party, Charlie, via a quantum channel to perform a full BSM.

[0013] Step 8: If both photons performing BSM are single photons and have the same preparation basis, the single photon states prepared by both parties and the BSM results are used for the third round of security testing. If both photons performing full BSM originate from entangled photon pairs, Alice and Bob read the information transmitted by each other based on their own random coding operations and the BSM results. If one photon performing BSM is a single photon and the other comes from an entangled photon pair, or if both photons are single photons but have different preparation basis, 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 the information to each other.

[0014] Furthermore, in step 1 of this invention, the identity authentication key shared by the legitimate communicating parties Alice and Bob is composed of a series of binary bit strings of identity authentication codes K. A and K B Composition. 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] Where n is a large number.

[0018] Furthermore, in step 2 of this invention, both Alice and Bob prepare a state in maximally entangled state |φ + > Entangled photon pairs, φ + The number of > is greater than the length of the authentication key sequence, |φ + It 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 steps 2, 5, and 7 of this invention are randomly prepared under Z-based and X-based conditions, respectively denoted as:

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

[0023]

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

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

[0026] If both single photons are Z-based, they can be in one of four quantum states: |H>|V>, |V>|H>, |H>|H>, or |V>|V>. 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 of the X basis, the two photons can be in one of four quantum states: |+>|+>, |+>|->, |->|+>, or |->|->. If a result different from the above formula is obtained, both parties determine that an error has occurred;

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

[0029]

[0030] At this point, it is impossible to determine whether an error has occurred based on the complete BSM result, so both parties discard the BSM result.

[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 ​​​​​​​​​​​​​​​​​​​​​​​Furthermore, in the method described in this invention, Alice and Bob first determine whether the other party is a legitimate communicator based on the measurement results of the second and third rounds of full BSM before transmitting information. The security detection also ensures that eavesdroppers cannot obtain the information transmitted by both parties, protecting the absolute security of the identities and dialogue information of both parties.

[0035] Beneficial effects:

[0036] 1. This invention can perform two-way authentication of the legitimate identities of both parties before communication, which can effectively resist eavesdropping attacks.

[0037] 2. By entrusting all measurement tasks to an untrusted third-party measurement terminal, this invention can effectively resist all attacks targeting imperfect measurement devices during identity authentication and quantum dialogue, ensuring the security of both parties' identity authentication codes and transmitted information. Attached Figure Description

[0038] Figure 1 This is a flowchart of a measurement device-independent quantum dialogue method with two-way authentication function according to an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram illustrating the principle of a measurement device-independent quantum dialogue method with two-way authentication function in an embodiment of the present invention. Detailed Implementation

[0040] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention by those skilled in the art in various equivalent forms fall within the scope defined by the appended claims.

[0041] Example 1

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

[0043] The process of this invention will be analyzed below with specific examples:

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

[0045] Alice, the 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 all are in the same initial state. and All a1 photons are arranged in sequence to form S A1 Similarly, the sequence consists of a2 photons forming S. A2 Sequence, b1 photons form S B1 Sequence, b2 photons form S B2 sequence. and All belong to the following four polarization Bell states

[0046]

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

[0048] Alice and Bob are in S respectively A2 and S B2 A sufficient number of randomly prepared single photons in Z- or X-based methods are randomly inserted into the sequence, denoted as Z-based and X-based, respectively.

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

[0050]

[0051] Wherein, \+> and |-> represent the 45° and 135° polarization of the photon, respectively; thus, the security detection photon is randomly in one of the four quantum states \H>, \V>, \+>, and |->.

[0052] Alice and Bob are in S respectively A2 and S B2 A new sequence, after inserting a security detection single photon into the sequence, is sent to a third party, Charlie, via different quantum channels. Charlie performs the first round of Bell state measurements (BSM) on each of the received photon pairs (a2, b2) and publishes the results. Alice and Bob publish the S sequence via a classical channel. A2 and S B2 The positions and preparation bases of single photons in the sequence are determined, and the BSM (Bipolar Multiphoton Sequence) situation is analyzed one by one. Based on the photon source, the following cases are identified:

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

[0054] (2) When a2 and b2 are a single photon and the other comes from an entangled photon pair, the BSM result and its corresponding entangled photon a1 or b1 are discarded.

[0055] (3) When a2 and b2 are both single photons and the preparation bases are different, the BSM results are 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 security detection.

[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. If both photons are single photons, there are three possibilities:

[0058] If both single photons are Z-based, they can be in one of four quantum states: |H>|V>, |V>|H>, |H>|H>, or |V>|V>. A full BSM can distinguish four Bell states, but a BSM under linear optical conditions can only distinguish ψ. + >| or ψ - In this state, both parties use BSM results for security testing, although BSM under linear optical conditions cannot distinguish |φ + > and |φ - However, it is still possible to determine whether an error has occurred. For example, if the measurement result of |H>|V> or |V>|H> shows |φ ± >, or the measurement results of |H>|H> or |V>|V> appear |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 of the X basis, the two photons can be in one of four quantum states: |+>|+>, |+>|->, |->|+>, or |->|->. Therefore, if a complete BSM is obtained |ψ + >or|ψ - >,|φ + >or|φ - Both parties used the 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 cases cannot be distinguished, and it is also impossible to determine 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 insecure and the authentication is aborted. If the error rate is lower than the pre-set threshold, proceed to the next step. 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 as follows

[0064] Since Charlie can identify four Bell states, the measurement results he announces are or When, correspondingly, the entangled states formed by photons a1 and b1 of Alice and Bob are or <​​​​​​​​​​​​​​​​​​​​​​​​​​​There are four possible scenarios: (1) If Alice and Bob's ID codes are 0 and 0 respectively, then the encoding operations are I and I respectively, and the entangled state remains unchanged. (2) If Alice and Bob's identity codes are 0 and 1 respectively, then 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 respectively, then the encoding operations are σ. x And I, then the entangled state evolves into (4) If Alice and Bob's ID codes are 1 and 1 respectively, then the encoding operations are σ. x and σ z Then the entangled state evolves into

[0068] If the entangled state formed by photons a1 and b1 is Right now There are four possible scenarios: (1) If Alice and Bob's ID codes are 0 and 0 respectively, then the encoding operations are I and I respectively, and the entangled state remains unchanged. (2) If Alice and Bob's identity codes are 0 and 1 respectively, then 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 respectively, then the encoding operations are σ. x And I, then the entangled state evolves into (4) If Alice and Bob's ID codes are 1 and 1 respectively, then the encoding operations are σ. x and σ z Then the entangled state evolves into

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

[0070] After the results of the second round of BSM were announced, Alice and Bob used the BSM results and their own encoding methods to deduce the encoded information for verifying their identity codes. If the verification was correct, they would proceed to the next step: quantum dialogue. After identity verification, Alice and Bob would each send the remaining photon sequence S... AI3 and S BI3 The encoding operation is performed according to the content of the quantum dialogue. Similar to the steps above, Alice uses phase random encoding + bit encoding, and Bob uses bit random encoding + phase encoding. The encoding method is as follows: 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, single photons are randomly inserted as security detection photons, and the security detection photons are randomly in 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 photons in different bases are discarded. Alice and Bob can 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 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 again in sequence, 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 quantum dialogue process with two-way authentication function independent of measurement devices is completed.

[0072] The security of the present invention can be guaranteed by three rounds of security detection. Charlie responsible for BSM may be dishonest and even completely controlled by the eavesdropper Eve. In steps 3, step 6 and step 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 method for quantum dialogue independent of measurement devices with two-way authentication function, and the method includes the following steps:

[0075] Step 1: Alice and Bob, the communicating parties to be authenticated, each prepare a series of entangled photon pairs, all in the same quantum state. The entangled photon pairs are arranged into relational sequences S in order. A1 ,S A2 (S B1 S B2 ), and used a large number of single photons prepared under Z-based and X-based conditions as security detection photons;

[0076] Step 2: Alice (Bob) takes one photon S from each pair of entangled photons. A1 (S B1 The sequence, with the remaining photons arranged in order to form S A2 (S B2 ) sequence. Alice and Bob are respectively in S A2 and S B2 Insert a sufficient number of random single photons prepared in the rectangular basis (Z basis) and diagonal basis (X basis) at random positions in the sequence;

[0077] Step 3: Alice and Bob each put 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 measurements (BSM) on each pair of received photons and publishes the measurement results.

[0078] Step 4: Alice and Bob publish S via a classic channel A2 and S B2 The positions and preparation basis of single photons in the sequence are determined, and the pairing of BSMs is analyzed one by one. If both photons performing BSM originate from entangled photon pairs, and the entangled photon pairs have the same number (e.g., both are number i), then their positions in S... A1 and S B1 The corresponding photons in the sequence establish an entangled channel through entanglement swapping; if both photons originate from entangled photon pairs, but the entangled photon pairs have different numbers (e.g., number i and number j respectively), or one photon 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 two photons are both single photons and have different preparation bases, the BSM result is discarded. If the two single photons have the same preparation base, Alice and Bob can perform the first round of security testing based on the BSM result and their quantum states. After the security test is completed, if the error rate exceeds a pre-set threshold, it indicates that this round of photon transmission is insecure, and authentication is terminated. If the error rate is lower than the pre-set threshold, the next step is continued.

[0079] Step 5: After passing the security check, Alice randomly selects S A1 A sufficient number of photons are randomly selected from the sequence as authentication photons, and their locations are published. Both parties extract the authentication photon pairs to form sequence S. AI1 and S BI1 Alice, using her identity code, performed phase random encoding and bit encoding operations on S. AI1 Bob encodes the photons of S. BI1 The photons in the sequence are subjected to bit-random encoding and phase encoding. After encoding, both parties... AI1 and S BI1 A sufficient number of randomly prepared single photons based on the Z or X basis are randomly inserted into the sequence to form security detection photons, constituting S. AI1 'and S BI1 'sequence;

[0080] Step 6: Alice and Bob will... AI1 'and S BI1 The sequence of photons is sent to a third party, Charlie, for measurement, and the results of the BSM are published. Both parties publish the S... AI1 'and S BI1 The position of the security detection photon in the sequence. After removing the security detection photon, the BSM result of the photons from the entangled photon pairs is used to verify Bob's identity. For the discarded encoded photon pairs, Bob needs to record their positions and re-encode them for authentication.

[0081] Step 7: After Alice and Bob complete their two-way authentication, Alice encodes the remaining photons in her hand using phase random encoding and bit encoding, while Bob uses bit random encoding and phase encoding on the remaining photons in his hand. Single photons randomly prepared by both parties under Z-based or X-based architectures are used as security detection photons, forming the S... AI3 and S BI3 The sequence involves sending photons from two sequences to a third party, Charlie, for BSM (Browser-Synthetic Mapping). Alice and Bob can read each other's information based on their own random + bit (phase) encoding operations and the results of BSM. For any discarded encoded photon pairs, their positions need to be recorded and the encoding operation needs to be re-performed until every piece of information in the quantum dialogue is completed.

[0082] Step 8: If some encoded photon pairs in the second and third rounds of BSM are discarded due to BSM pairing errors, resulting in the loss of some information, both parties should record the location of the lost information. Both parties then need to re-authenticate the lost information encoding in steps 2 through 6 and step 7 sequentially. This process continues until all of Alice and Bob's identity codes have been authenticated, all identity codes are correct, and all dialogue information is complete. Only then will Alice and Bob have completed the entire process of two-way identity authentication and dialogue.

[0083] In step 1 of the method described in this invention, Alice and Bob share an authentication key sequence, which is composed of a series of binary bit strings of authentication codes; Alice and Bob share a key sequence.

[0084] In step 2 of the method described in this invention, both Alice and Bob prepare a state in maximally entangled state |φ + > Entangled photon pairs, |φ + The number is greater than the length of the authentication key sequence, |φ + > Belongs to the following four polarization Bell states

[0085]

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

[0087] The single photons used in steps 3, 6, and 7 of the method described in this invention are randomly prepared under Z-based and X-based conditions, respectively denoted as Z-based and X-based.

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

[0089]

[0090] Here, |+> and |-> represent the 45° and 135° polarization of the photon, respectively; thus, the security detection photon is randomly in one of four quantum states: |H>, |V>, |+>, and |->.

[0091] The BSM used in steps 3, 6, and 7 of the method described in this invention is a complete BSM, capable of distinguishing ψ. + > and |ψ - >,|φ + > and |φ - >Four Bell states.

[0092] In steps 4, 6, and 7 of the method described in this 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. 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 full 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 this invention, the phase at Alice is randomly encoded, 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 this invention, analyzing the results of the second and third rounds of complete BSM allows for the deduction of the other party's encoding information. If the identity code at a certain position in Alice's or Bob's identity key sequence is the same as a known identity code, then the identity code at that position is correct. If the identity codes at all positions are the same, it indicates that Alice and Bob's identity authentication keys are correct, and identity authentication is successful. If the result of the second round of complete BSM is correct, it indicates that Alice and Bob's identity authentication codes are correct. Only then can the correct encoding information of Alice and Bob's quantum dialogue be deduced based on the result of the third round of BSM.

[0100] In steps 6 and 7 of the method described in this invention, it is necessary to record the positions and encoding information of the encoded photon pairs discarded due to pairing errors in the second and third rounds of BSM. To complete all the lost codes, steps 2 to 6 and 7 need to be repeated sequentially until all information codes of Alice and Bob have been authenticated.

[0101] This invention allows Alice and Bob to determine each other's legitimacy and the security of their conversations based solely on three full BSM measurements. The security checks also ensure that eavesdroppers cannot obtain either party's identity codes or the content of their conversations. Therefore, this invention theoretically provides absolute security for both parties' identity codes and conversation information.

[0102] The above description is merely a preferred embodiment of the present invention and is not intended to further limit the present invention. All equivalent changes made based on the description and drawings of the present invention are within the protection scope of the present invention.

Claims

1. A measurement-device-independent quantum dialogue method with a bidirectional identity authentication function, characterized in that, The method comprises the following steps: Step 1: A legal communication party Alice' shares two groups of key strings K1, K2 with a legal communication party Bob1', each key string has a length of n, n is a large number, K1 is used as an identity code of Alice', and K2 is used as an identity code of Bob1'; Step 2: Alice and Bob, the actual communication parties to be authenticated, each prepare a series of entangled photon pairs, all in the same quantum state Alice (Bob) arranges the entangled photon pairs in order into photon sequences S A1 , S A2 , (S B1 , S B2 ); Alice (Bob) randomly prepares a large number of single photons in the Z basis (orthogonal basis), X basis (diagonal basis) as security detection photons, and Alice and Bob respectively randomly insert the security detection photons into S A2 and S B2 sequences; Step 3: Alice and Bob send the photons in the sequence S A2 and S B2 to a third party Charlie through quantum channels respectively, Charlie performs the first round of complete Bell state measurement (BSM) on the received photons pair by pair and announces the measurement results; Step 4: Alice and Bob disclose S through a classical channel A2 and S B2 The position of single photons in the sequence and the preparation bases, and analyze the pairing of BSM one by one. If the two photons of the complete BSM are from the entangled photon pair, the corresponding photons in S A1 and S B1 The corresponding photons in the sequence are exchanged by entanglement to establish an entanglement channel; if one of the two photons of the BSM is a single photon and the other is from an entangled photon pair, the BSM result and S A1 or S B1 The corresponding photons in the sequence are discarded; if the two photons of the BSM are both single photons and the preparation bases are different, the result of the BSM is discarded; if the preparation bases of the two single photons are the same, Alice and Bob can perform the first round of security detection according to the BSM result and their quantum states. After the security detection is completed, if the error rate exceeds the threshold set in advance, it means that the round of photon transmission is not safe, the authentication is aborted, and if the error rate is lower than the threshold set in advance, the next step is continued; Step 5: After passing the security check, Alice randomly selects S A1 A sufficient number of photons are selected from the sequence as authentication photons, and their locations are published. Both parties extract the authentication photon pairs based on the published locations to form sequence S. AI1 and S BI1 Alice uses her identification code to access S AI1 The photons in the sequence are bit-encoded and their phases are randomly manipulated. Bob then uses his identity code to... BI1 The photons in the sequence are phase-coded, and their bits are randomly manipulated. After coding, both parties exchange S... AI1 and S BI1 A sufficient number of randomly prepared single photons based on the Z or X basis are randomly inserted into the sequence to form security detection photons, constituting S. AI1 'and S BI1 'sequence; Step 6: Alice and Bob send S AI1 and S BI1 sequences to the third party Charlie through quantum channel for measurement and announcement of BSM results, and announce the positions of security detection photons in S AI1 and S BI1 sequences, if both photons in BSM are single photons and the preparation bases are the same, the single photon states prepared by both parties and BSM results 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 in BSM are from entangled photon pairs, the BSM results are used for both parties to verify the identity of the other party, if one of the photons in BSM is a single photon and the other is from an entangled photon pair, or both photons are single photons but the preparation bases are different, the corresponding BSM results should be discarded, for the identity code encoded photon pairs discarded, Alice and Bob need to record their positions, and in the next round of identity authentication process, re-encode and perform two-way identity authentication operation until Alice and Bob complete 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 legal communication party Bob' (Alice'), Alice (Bob) can judge that Bob (Alice) is the legal communication party Bob' (Alice'), if any party is not the legal communication party, the communication is terminated; Step 7: Alice uses bit encoding on the remaining photons in hand according to the information to be transmitted, and performs a phase random operation on the photon pairs. Bob uses phase encoding on the remaining photons in hand; performs a bit random operation on the photons, and randomly prepares a large number of single photons under Z basis or X basis as security detection photons by both parties, which are randomly inserted into the respective photon sequences to form S AI3 and S BI3 sequences, and sends the photons of the two sequences to a third party Charlie through a quantum channel for complete BSM; Step 8: If both photons in the BSM are single photons and the preparation bases are the same, the single photon states prepared by both parties and the BSM results are used for performing the third round of security detection, if both photons in the BSM are derived from an entangled photon pair, Alice and Bob read the information transmitted by the other party according to the random encoding operation and the BSM result of themselves, if one of the two photons in the BSM is a single photon and the other is derived from an entangled photon pair, or both photons are single photons but the preparation bases are different, the corresponding BSM results should be discarded, for the discarded encoding photon pairs, the positions thereof need to be recorded and encoding is performed in the next round of conversation until all the information is transmitted between the two parties.

2. The measurement-device-independent quantum dialogue method with a bidirectional identity authentication function according to claim 1, characterized in that: In step 1, the authentication key shared by the legitimate communication parties Alice and Bob, respectively, consists of a series of binary bit strings of authentication code K A and K B The authentication code string K A ,K B is described as: K A = (K A1 , K A2 , K A3 ,...., K An ) K B = (K B1 ,K B2 ,K B3 ,.........,K Bn ) Wherein, n is a large number.

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

4. The measurement-device-independent quantum dialogue method with a bidirectional identity authentication function according to claim 1, characterized in that: The single photons used in steps 2, 5 and 7 are randomly prepared in Z bases and X bases, and the Z bases and X bases are represented as: Z P = { |H>, |V>} Wherein, |+> and |-> represent 45° direction polarization and 135° direction polarization of the photon respectively; in this way, the security detection photons are randomly in one of four quantum states |H>, |V>, |+> and |->.

5. The measurement-device-independent quantum dialogue method with a bidirectional identity authentication function according to claim 1, characterized in that: In step 4, step 6 and step 7, if both photons are single photons, there are three possibilities: if both single photons are Z-basis, the two photons can be in one of the four quantum states: |H> |V>, |V> |H>, |H> |H> or |V> |V> states, i.e. If the measurement result is |φ ± > like |H> |V> or |V> |H>, or |ψ ± > like |H> |H> or |V> |V>, both parties can determine that an error has occurred. If both single photons are X bases, two photons can be in one of four quantum states: |+> |+>, |+> |->, |-> |+> or |-> |-> state, that is If the result is different from the above formula, both sides determine that an error occurs; If one photon is an X basis and one photon is a Z basis, the two photons can 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 occurs according to the results of the complete BSM, and the two parties discard the results of the BSM.

6. The measurement-device-independent quantum dialogue method with a bidirectional identity authentication function according to claim 1, characterized in that: In step 5 and step 7, the bit encoding operation at Alice is {I, σ x}, I = |H><H| + |V><V| represents identity code 0, σ x = |H><V| + |V><H| represents identity code 1, phase randomly uses I and σ z encoding; the phase encoding operation at Bob is {I, σ z}, I = |H><H| + |V><V| represents identity code 0, σ z = |H><H| - |V><V| represents identity code 1, bit randomly uses I and σ x encoding, 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 bidirectional identity authentication according to claim 1, characterized in that: In step 6, the two communication parties analyze the results of the first round and the second round of BSM, and according to their own random operation, the identity code transmitted by the other party can be inferred, if the identity code at the position in the identity key sequence of Alice and Bob is the same as the known identity code, that is, the identity code at the position is correct, if the error rate of the identity code is lower than the tolerable threshold, it indicates that the identity authentication of Alice and Bob is safe, the key is correct, and the identity authentication is successful, after the identity authentication is successful, the information of the conversation can be inferred according to the encoding information of the user; Similarly, in step 8, both parties analyze the results of the first and third rounds of BSM, combine their own encoding operations, and deduce 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 finally evolves into According to the results of Charlie's BSM, and according to the initial state and their own encoding operations, Alice and Bob can respectively deduce that the information to be transmitted by the other party is 0 and 1.

8. The measurement-device-independent quantum dialogue method with a bidirectional identity authentication function according to claim 1, characterized in that: In steps 6-8, the positions and encoding information of the encoding photon pairs discarded due to pairing errors in each round of BSM need to be recorded, in order to complete all the lost encoding information, the application needs to be re-run until all the identity codes of Alice and Bob are authenticated and the conversation information transmission is completed.

9. The measurement-device-independent quantum dialogue method with a bidirectional identity authentication function according to claim 1, characterized in that: The Alice and Bob first determine whether the other party is a legal communication party according to the measurement results of the second round and the third round of complete BSM, and then perform information transmission, and the security detection also ensures that the eavesdropper cannot obtain the information transmitted by the two parties, thereby protecting the absolute safety of the identity and conversation information of the two parties.

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