A Multi-Party Quantum Identity Authentication Method Based on Multi-Party Quantum Secure Direct Communication

Abstract

The present invention belongs to the technical field of quantum secure communication, and discloses a multi-party quantum identity authentication method based on multi-party quantum secure direct communication to verify whether multiple parties actually communicating with the verifier are its legitimate collaborators. The present invention applies the multi-party quantum secure direct communication technology to multi-party quantum identity authentication. Among them, the verifier shares a set of keys with multiple target communicators in advance through quantum key distribution. The verifier prepares a series of multi-photon GHZ states and distributes them to itself and multiple parties to be proved. After the parties to be proved perform encoding operations according to the authentication keys shared with the verifier in advance, they return the photons to the verifier, and the verifier performs GHZ state analysis to realize the simultaneous identity verification of multiple parties to be proved. This method can authenticate the identities of multiple users at the same time, effectively improve the authentication efficiency, and is of great significance for promoting the practical application of quantum secure direct communication in the field of quantum authentication.

Description

Technical Field

[0001] The present invention belongs to the technical field of quantum secure communication, and particularly relates to a multi-party quantum identity authentication (QIA) method based on multi-party quantum secure direct communication (multi-party QSDC). Background Art

[0002] Quantum authentication is an important part of quantum secure communication. In quantum secure communication, in order to prevent illegal parties from impersonating communication parties to attack the communication process, it is necessary to first authenticate the identities of the communication parties to determine their legitimacy. Therefore, authenticating the identities of both communication parties in quantum secure communication is a very important step. Different from classical identity authentication based on mathematical difficult problems, quantum identity authentication verifies the identity legitimacy of both communication parties based on the basic principles of quantum mechanics, and theoretically has absolute security, while ensuring the security of the identity authentication key during the identity authentication process.

[0003] In 2000, [Zeng G H, Zhang W P. Identity verification in quantum cryptography. Phys. Rev. A, 2000, 61(2): 022303] proposed a scheme for encoding using shared information corresponding to measurement bases. This scheme uses the properties of entangled states to ensure security, and proposes a random interleaving method and a measurement basis encoding method. Identity authentication is achieved by sharing information corresponding to measurement bases and measuring entangled states. The scheme can achieve key distribution, eavesdropping detection, and identity authentication, but the execution process of the scheme is relatively complex and requires the transmission of a large amount of classical information. Subsequently, several quantum authentication schemes have been proposed. In order to improve efficiency and save resources during the identity authentication process, [Yang, Yu-Guang, Wen, et al. Economical multiparty simultaneous quantum identity authentication based on Greenberger–Horne–Zeilinger states[J]. Chinese Physics B, 2009, 18(8): 3233-3237] proposed a more economical multi-party quantum identity authentication protocol based on GHZ states in 2009. In 2017, [Chang ho Hong, Jino Heo, Jin Gak Jang. Quantum identity authentication with single photon. Quantum Inf. Process. 2017, 16(10), 236] proposed a method for quantum identity authentication using single photons. This protocol can verify two-bit authentication information using only one photon, thus ensuring high efficiency. [Zawadzki, P. Quantum identity authentication without entanglement. Quantum Information Processing, 2019, 18(1), 7.] pointed out the deficiencies of Hong's protocol. During the operation of the protocol, eavesdroppers steal part of the information during each protocol run. After the protocol is executed multiple times, eavesdroppers will obtain more key information. In order to achieve two-way authentication in the process of quantum identity authentication, in 2020, [Zhang Xinglan, Zhao Yijing. Quantum two-way synchronous identity authentication protocol based on single photon[J]. Computer Applications, 2020, v.40: No.361(09): 162-166.] proposed a two-way synchronous quantum identity authentication protocol based on single photons. However, the existing quantum identity authentication methods have characteristics such as complex operation processes, low authentication efficiency, and low security, which limit the practical development of quantum identity authentication. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a multi-party quantum identity authentication method based on multi-party quantum secure direct communication. This solution is simple to operate, can simultaneously authenticate the identities of N parties to be proved, and has high efficiency. The security of each round of photon transmission process is guaranteed by security detection, so that eavesdroppers cannot steal any identity authentication keys of the parties to be proved, ensuring the security of the identity authentication keys.

[0005] The multi-party quantum identity authentication method based on multi-party quantum secure direct communication of the present invention is as follows:

[0006] Step 1: The verifier Alice and the target communication parties Bob1’, Bob2’... Bob N ’ respectively share a set of authentication keys K1’, K2’... K N ’ through the BB84 protocol;

[0007] Step 2: The verifier Alice prepares a series of identical N + 1 photon polarization GHZ states, takes out photon 1 in all GHZ states to form a sequence S A , and stores the photons in sequence S A in a quantum memory; Alice forms a sequence S B1 with photon 2 in all GHZ states, forms a sequence S B2 with photon 3 in all GHZ states, and so on until forming a sequence S BN with photon N + 1 in all GHZ states;

[0008] Step 3: The verifier Alice randomly inserts security detection photons equal in number to the original photons in the sequences S B1 , S B2 ... S BN ; Alice sends the sequences S B1 , S B2 ... S BN inserted with security detection photons to the actual communication parties, namely the parties to be proved Bob1, Bob2... Bob N through N quantum channels;

[0009] Step 4: After receiving the photons, the parties to be proved Bob1, Bob2... Bob N store the photons in a quantum memory. Alice publicly discloses the positions and preparation bases of the security detection photons in each photon sequence. Bob1, Bob2... Bob NExtract the security - detection photons separately and conduct the first - round security detection; each party measures the security - detection photons using the corresponding measurement basis and announces the measurement results. Alice estimates the error rate of each quantum channel based on the results announced by each party. If the error rate of any quantum channel exceeds the pre - set threshold, it indicates that there is eavesdropping by Eve in this channel, and the authentication process is aborted. Each party re - checks the channel. If the error rate of each channel is lower than the pre - set threshold, it indicates that the photon transmission process in all quantum channels is secure, and then proceed to the next step;

[0010] Step 5: The parties to be proved, Bob1, Bob2... Bob N Extract other photons from the quantum memories respectively, and then perform encoding operations according to their respective authentication keys K1, K2... K N simultaneously, Bob1, Bob2... Bob N randomly insert security - detection photons equal in number to the photons in the original sequence into their respective photon sequences. After the operation, each party obtains sequences S B1 ’, S B2 ’... S BN ’. Then, each party sends its photon sequence to the verifier Alice through N quantum channels;

[0011] Step 6: After receiving the photons, the verifier Alice stores the photons of sequences S B1 ’, S B2 ’... S BN ’ into the quantum memories respectively; Bob1, Bob2... Bob N announce the positions and preparation bases of the security - detection photons in the sequences. Alice extracts the corresponding photons at the respective positions and conducts the second - round security detection. If the error of any quantum channel exceeds the threshold, it indicates that there is eavesdropping by Eve when the photons are transmitted in this quantum channel, and the authentication process is aborted. If the error rates of all quantum channels are lower than the set threshold, it indicates that the photon transmission process in all quantum channels is secure, and then proceed to the next step;

[0012] Step 7: The verifier Alice extracts the corresponding photons from the sequences S A and sequences S B1 ’, S B2 ’... S BN ’ in the quantum memories, conducts GHZ - state analysis, and infers the encoding information of Bob1, Bob2... Bob N based on the GHZ - state results, so as to read out the authentication key sequences K1, K2... K N transmitted by Bob1, Bob2... Bob N; By comparing with the authentication keys K1’, K2’ …… K N ’ of the target communication parties, the identities of Bob1’, Bob2’ …… Bob N ’ are verified.

[0013] Furthermore, in step 1, the authentication keys shared by Alice and N target communication parties are different from each other, and are respectively a series of binary bit strings of the same length. For example, K1’ = {1011……1}, K2’ = {1101……0}, ……, K N ’ = {0101……0}. Each target communication party only knows its own shared key sequence with Alice, while Alice knows the key sequences of all target communication parties.

[0014] Furthermore, in step 2, a series of identical polarized N + 1 photon GHZ states prepared by the verifier Alice has the same number as the length of the authentication key sequence, belongs to one of the 2 N+1 N + 1 photon GHZ states; There are 8 different forms of 3 - photon GHZ states, which are respectively

[0015]

[0016] Furthermore, in steps 4 and 6, after each round of photon transmission, the party that receives the photons needs to first store all the photons in the quantum memory, and then extract the security - detection photons for security verification; after the security verification passes, then extract the other photons for operations; At the same time, Alice does not perform any encoding operations on the photon sequence S A she holds.

[0017] Furthermore, in steps 3 and 5, the positions of the security - detection photons are random, and the preparation bases are also randomly selected from the rectangular basis and the diagonal basis; The rectangular basis and the diagonal basis are respectively represented as {H, V} and where H and V respectively represent horizontal polarization and vertical polarization, and + and - respectively represent 45° polarization and 135° polarization; The security - detection photons prepared in this way are randomly in one of the 4 quantum states H, V, +, -.

[0018] Furthermore, in step 5, the verifier uses the bit - encoding method to load the authentication key information onto the entangled photons, and the encoding operation includes two unitary operations {I, σ x}; I = HH + VV (identity operation) represents the key 0, σ x = HV + VH (bit - flip operation) represents the key 1.

[0019] Further, in steps 4 and 6, the positions and preparation bases of the security detection photons in the public sequence are determined by classical communication after the transmission of the photon sequence is completed; single-photon measurement is used for security detection, and an error threshold for each channel is set in advance considering the presence of channel noise.

[0020] Further, in step 7, each prover only performs bit encoding and does not perform phase encoding. The GHZ state after the encoding operations of N provers is one of 2 N cases; after each prover sends the encoded photons to Alice, Alice needs to perform GHZ state analysis and only needs to distinguish 2 N+1 of the 2 N GHZ states. For example, considering a 3-photon GHZ state, in this protocol, Alice only needs to distinguish 4 of the 8 GHZ states, namely

[0021] corresponding to Bob1's key being 0 and Bob2's key being 0;

[0022] corresponding to Bob1's key being 1 and Bob2's key being 0;

[0023] corresponding to Bob1's key being 0 and Bob2's key being 1;

[0024] corresponding to Bob1's key being 1 and Bob2's key being 1.

[0025] Further, in step 7, since the GHZ state analysis result of Alice is not publicly announced, only Alice can obtain the authentication keys of all provers, thereby authenticating the identities of N provers simultaneously; if Bob i , i = 1, 2, 3..., N, sends an authentication key sequence K that is the same as the authentication key sequence K' of the target communication party, then Alice confirms Bob's i identity; any prover Bob i , i = 1, 2, 3..., N, cannot know the authentication keys of other provers.

[0026] The beneficial effects of the present invention are as follows: The present invention needs to prepare an N+1 photon polarization GHZ state. Theoretically, each GHZ state can transmit an N-bit identity authentication key. The operation of the present invention is simple, and it can authenticate the identities of N parties to be proved simultaneously, with high efficiency. The security of each round of photon transmission process is guaranteed by security detection, so that eavesdroppers cannot steal any identity authentication key of the parties to be proved, ensuring the security of the identity authentication key. The method described in the present invention applies the multi-party quantum secure direct communication technology to multi-party quantum identity authentication to verify whether the multi-party actually communicating with the verifier is its legal collaborator, which is of great significance for promoting the practical application of quantum secure direct communication in the field of quantum authentication. Description of the Drawings

[0027] Figure 1 is a flowchart of a multi-party quantum identity authentication method based on multi-party quantum secure direct communication in an embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of the principle of a multi-party quantum identity authentication method based on multi-party quantum secure direct communication in an embodiment of the present invention;

[0029] Figure 3 is a specific example in an embodiment of the present invention, in which the principle of a three-party quantum identity authentication method is specifically demonstrated. Detailed Embodiment

[0030] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments and in conjunction with the drawings.

[0031] In order to describe the purpose, technical solution and advantages of the present invention more clearly, a three-party quantum identity authentication method with N = 2 in this solution is selected for detailed description. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art fall within the scope defined by the appended claims of this application.

[0032] As Figure 1 、 Figure 2 and Figure 3 shown, the present invention provides a multi-party quantum identity authentication method based on multi-party quantum secure direct communication, including:

[0033] The verifier Alice shares a set of authentication keys K1’ and K2’ with the target communication parties Bob1’ and Bob2’ respectively. The two sets of authentication keys are different from each other and are both a series of binary bit strings of the same length, used to confirm the identities of Bob1 and Bob2. The authentication keys can be set as K1’ = {1011……1}, K2’ = {1101……0}. Bob1’ and Bob2’ only know their own shared key sequences with Alice, while Alice knows the key sequences of all target communication parties.

[0034] The verifier Alice prepares a large number of 3-photon GHZ states in the same quantum state, which is one of the 8 GHZ states:

[0035]

[0036] For example, select one of the quantum states for preparation, and the number is equal to the length of the authentication key sequence. The verifier Alice takes out the photons 1 in all GHZ states to form a sequence S1, and stores the photons in the sequence S1 in the quantum memory. Alice forms a sequence S2 with the photons 2 in all GHZ states, and forms a sequence S3 with the photons 3 in all GHZ states.

[0037] The verifier Alice randomly inserts a sufficient number of security detection photons into the sequences S2 and S3 respectively. The positions of the security detection photons are random, and the preparation bases are also randomly selected from the rectangular basis and the diagonal basis. The rectangular basis and the diagonal basis are represented as {H, V} and where H and V represent horizontal polarization and vertical polarization respectively, and + and - represent 45° polarization and 135° polarization respectively. The security detection photons prepared in this way randomly stay in one of the 4 quantum states H, V, +, -.

[0038] The verifier Alice sends the sequences S2 and S3 after inserting security - detection photons to the actual communication parties (the parties to be proved) Bob1 and Bob2 respectively through two quantum channels. After receiving the photons, Bob1 and Bob2 store the photons in quantum memories. Alice discloses the positions and preparation bases of the security - detection photons in the two photon sequences. Bob1 and Bob2 extract the security - detection photons respectively and conduct the first - round security detection. Each party measures the security - detection photons using the corresponding measurement basis and announces the measurement results. Alice estimates the error rate of each quantum channel according to the results announced by each party. If the error rate of any quantum channel exceeds the pre - set threshold, it indicates that there is eavesdropping by Eve in this channel, and the authentication process is aborted, and each party re - checks the channel. If the error rate of each channel is lower than the pre - set threshold, it indicates that the photon - transmission process in all quantum channels is secure, and then the next step is carried out.

[0039] The security detection uses single - photon measurement. Considering the existence of channel noise, the error threshold of each channel is pre - set, for example, 10%. Since the positions of the security - detection photons are random, if there is eavesdropping by Eve in the channel, she will inevitably intercept the security - detection photons. Moreover, the preparation bases of the photons are randomly selected, and Eve does not know the preparation basis of each photon and can only randomly guess a basis to measure the photon. Therefore, Eve has a 50% probability of guessing the preparation basis wrong. In the case where Eve guesses the preparation basis wrong, the single - photon she prepares according to the measurement result is re - sent to the measuring party, and the error rate in the security detection is 50%. Therefore, if there is eavesdropping, theoretically it will lead to an error rate of 25% in the security detection, which is much higher than the set threshold. Therefore, it will surely be detected.

[0040] After the parties to be proved Bob1 and Bob2 confirm the security, they respectively extract the other photons from the quantum memories, and then perform encoding operations according to their respective keys K1 and K2, loading the authentication - key information onto the entangled photons. The encoding operation includes two unitary operations {I, σ x}. I = HH + VV (the identity operation) represents the key 0, and σ x = HV+VH (the bit - flip operation) represents the key 1. At the same time, Bob1 and Bob2 randomly insert a sufficient number of security - detection photons into their respective sequences. After the operation, sequences S2’ and S3’ are obtained respectively. Then, Bob1 and Bob2 send their photon sequences to the verifier Alice through two quantum channels. Here, the preparation bases of the security - detection photons are also randomly selected from the rectangular basis and the diagonal basis and randomly in one of the four quantum states H, V, +, -.

[0041] After the verifier Alice receives the photons, she stores the photons in the sequence S2’ and S3’ into the quantum memory respectively. Bob1 and Bob2 respectively disclose the positions and preparation bases of the security detection photons in the sequence. Alice extracts the corresponding photons at the corresponding positions and conducts the second round of security detection. If the error of any quantum channel exceeds the threshold, it indicates that there is eavesdropping by Eve when the photons are transmitted in this quantum channel, and the authentication process is aborted. If the error rates of all quantum channels are lower than the set threshold, it indicates that the transmission process of the photons in all quantum channels is secure, and then the next step is carried out.

[0042] The verifier Alice extracts the corresponding photons in the sequences S1, S’2 and S’3 in the quantum memory, conducts GHZ state analysis, and infers the encoding information of Bob1 and Bob2 according to the GHZ state results, so as to respectively read out the authentication key sequences K1 and K2 transmitted by Bob1 and Bob2. By comparing with the authentication keys K1’ and K2’ of the target communication party, the identities of Bob1’ and Bob2’ are verified.

[0043] According to the authentication keys K1 and K2 of Bob1 and Bob2, only bit flips are performed without phase flips, and one of the 4 cases of GHZ states exists after encoding. Therefore, Alice only needs to distinguish 4 of the 8 GHZ states, that is For Bob1's key is 0 and Bob2's key is 0;

[0044] For Bob1's key is 1 and Bob2's key is 0;

[0045] For Bob1's key is 0 and Bob2's key is 1;

[0046] For Bob1's key is 1 and Bob2's key is 1.

[0047] Since the GHZ state analysis results of Alice are not publicly announced, only Alice can obtain the authentication keys of all the parties to be proved, so as to authenticate the identities of these 2 parties to be proved at the same time. If the authentication key sequence K1 sent by Bob1 is the same as the authentication key sequence K1’ of the target communication party, then Alice can confirm the identity of Bob1; similarly, if the authentication key sequence K2 sent by Bob2 is the same as the authentication key sequence K2’ of the target communication party, then Alice can confirm the identity of Bob2. The parties to be proved, Bob1 and Bob2, cannot know each other's authentication keys, so neither of them can imitate the identity of the other.

[0048] The above are only the preferred embodiments of the present invention, and are not intended to further limit the present invention. All equivalent changes made by using the content of the specification and drawings of the present invention are within the protection scope of the present invention.

Claims

1. A multi-party quantum identity authentication method based on multi-party quantum secure direct communication, characterized in that The method steps are as follows: Step 1: The verifier Alice and the target communication parties Bob1’, Bob2’ …… Bob N ’ respectively share a set of authentication keys K1’, K2’ …… K N ’ through the BB84 protocol; Step 2: Verifier Alice prepares a series of identical N+1 photon polarization GHZ states, extracts photon 1 from all the GHZ states to form sequence S A , and stores the photons in sequence S A in a quantum memory; Alice forms sequence S B1 with photon 2 from all the GHZ states, forms sequence S B2 with photon 3 from all the GHZ states, and so on until forming sequence S BN with photon N+1 from all the GHZ states; Step 3: Verifier Alice randomly inserts security check photons equal in number to the original photons in the sequence into sequences S B1 , S B2 ... S BN ; Alice sends the sequences S B1 , S B2 ... S BN with security check photons inserted to the actual communication parties, namely the parties to be proved Bob1, Bob2... Bob N respectively; Step 4: The party to be proven, Bob1, Bob2... Bob N After receiving the photons, store the photons in the quantum memory. Alice publicly discloses the positions and preparation bases of the security detection photons in each photon sequence. Bob1, Bob2... Bob N respectively extract the security detection photons and conduct the first round of security detection; each party measures the security detection photons using the corresponding measurement basis and announces the measurement results. Alice estimates the error rate of each quantum channel based on the results announced by each party; If the error rate of any quantum channel exceeds a pre-set threshold, it indicates that there is eavesdropping by Eve in this channel, and the authentication process is aborted, and all parties re-check the channel; if the error rate of each channel is lower than the pre-set threshold, it indicates that the photon transmission process in all quantum channels is secure, and then the next step is carried out; Step 5: The parties to be proved, Bob1, Bob2... Bob N respectively extract other photons from the quantum memories, and then perform encoding operations according to their respective authentication keys K1, K2... K N ; meanwhile, Bob1, Bob2... Bob N randomly insert security detection photons equal in number to the photons in the original sequence into their respective photon sequences; after the operation is completed, each party obtains the sequences S B1 ’, S B2 ’... S BN ’; then, each party respectively sends its own photon sequence to the verifier Alice through N quantum channels; Step 6: After the verifier Alice receives the photons, she stores the photons in sequence S B1 ’, S B2 ’... S BN ’ into the quantum memories respectively; Bob1, Bob2... Bob N discloses the positions and preparation bases of the security detection photons in the public sequence. Alice extracts the photons at the corresponding positions respectively and conducts the second-round security detection; if the error of any quantum channel exceeds the threshold, it indicates that there is Eve's eavesdropping when the photons are transmitted in this quantum channel, and the authentication process is aborted; if the error rates of all quantum channels are lower than the set threshold, it indicates that the transmission processes of the photons in all quantum channels are secure, and then proceed to the next step; Step 7: Verifier Alice extracts the sequence S from the quantum memory A and the sequence S B1 ’, S B2 ’... S BN ’s corresponding photons, performs GHZ state analysis, and infers the encoding information of Bob1, Bob2... Bob N from the GHZ state results analysis, so as to respectively read out the authentication key sequences K1, K2... K N transmitted by Bob1, Bob2... Bob N ; by comparing with the authentication keys K1’, K2’... K N ’ of the target communication party, the identities of Bob1’, Bob2’... Bob N ’ are verified.

2. A multi-party quantum identity authentication method based on multi-party quantum secure direct communication according to claim 1, characterized in that: In step 1, the authentication keys shared by Alice and N target communication parties are different, and are respectively a series of binary bit strings of the same length; Each target communication party only knows its own shared key sequence with Alice, while Alice knows the key sequences of all target communication parties.

3. A multi-party quantum identity authentication method based on multi-party quantum secure direct communication according to claim 1, characterized in that: In step 2, a series of identical polarized N + 1 photon GHZ states prepared by the verifier Alice is equal to the length of the authentication key sequence, belongs to one of the 2 N+1 N + 1 photon GHZ states; there are 8 different forms of 3 - photon GHZ states, which are respectively 4. A multi-party quantum identity authentication method based on multi-party quantum secure direct communication according to claim 1, characterized in that: In steps 4 and 6, after each round of photon transmission, the party that receives the photons needs to first store all the photons in the quantum memory, and then extract the security detection photons for security verification; after the security verification passes, extract the other photons for operations; at the same time, Alice does not perform any encoding operations on the photon sequence S she holds. A Do not perform any encoding operations.

5. A multi-party quantum identity authentication method based on multi-party quantum secure direct communication according to claim 1, characterized in that: In steps 3 and 5, the positions of the security detection photons are random, and the preparation bases are also randomly selected from the rectangular basis and the diagonal basis; the rectangular basis and the diagonal basis are represented as {|H>, |V>} and where |H> and |V> represent horizontal polarization and vertical polarization respectively, and |+> and |-> represent 45° polarization and 135° polarization respectively; the security detection photons prepared in this way are randomly in one of the four quantum states |H>, |V>, |+>, |->.

6. A multi-party quantum identity authentication method based on multi-party quantum secure direct communication according to claim 1, characterized in that: In step 5, the verifier loads the authentication key information onto the entangled photons in the form of bit encoding, and the encoding operation includes two unitary operations {I, σ x}; I = |H><H| + |V><V| represents the key 0, and σ x = |H〉〈V| + |V><H| represents the key 1.

7. A multi-party quantum identity authentication method based on multi-party quantum secure direct communication according to claim 1, characterized in that: In steps 4 and 6, the positions and preparation bases of the security detection photons in the public sequence are determined by classical communication after the photon sequence transmission is completed; the security detection uses single-photon measurement, and considering the existence of channel noise, a pre-set error threshold for each channel is set.

8. A multi-party quantum identity authentication method based on multi-party quantum secure direct communication according to claim 1, characterized in that: In step 7, each prover only performs bit encoding and does not perform phase encoding. The GHZ state after the encoding operations of N provers is one of 2 N cases; after each prover sends the encoded photons to Alice, Alice needs to perform GHZ state analysis and only needs to distinguish 2 N+1 of the 2 N GHZ states.

9. A multi-party quantum identity authentication method based on multi-party quantum secure direct communication according to claim 1, characterized in that: In step 7, since the analysis results of Alice's GHZ state are not publicly announced, only Alice can obtain the authentication keys of all parties to be authenticated, so as to authenticate N parties to be authenticated simultaneously; if Bob i , i = 1, 2, 3..., N, the authentication key sequence K sent is the same as the authentication key sequence K' of the target communication party, then Alice confirms Bob i 's identity; any party to be authenticated Bob i , i = 1, 2, 3..., N, cannot know the authentication keys of other parties to be authenticated.

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