Continuous variable quantum secret sharing method with high actual safety

Abstract

The invention discloses a continuous variable quantum secret sharing method with high practical safety, which belongs to the technical field of quantum communication, and specifically comprises the following steps: firstly, establishing a communication scene formed by an untrusted measurement party, a distribution party and n participants; the n participants and the distributor distribute and prepare respective quantum states, and transmit the quantum states to the measuring party through a quantum channel; the measurement party performs Bell state measurement on the quantum states from the participant and the distributor, and discloses a measurement result; then, the distributor and the participant randomly select part of quantum state data respectively, and all channel transmittances are calculated in combination with the public measurement result of the measurement party; then, the distributor carries out classical post-processing with each participant in sequence to obtain respective secret keys; and finally, the participant and the distributor carry out key verification by using a hash function. According to the method, the untrusted third party performs quantum state measurement and discloses the measurement result, so that security vulnerabilities caused by non-ideality of the detector are avoided.

Description

Technical Field

[0001] The present invention relates to the field of quantum communication technology, and in particular to a continuous variable quantum secret sharing method with high practical security. Background Art

[0002] In recent years, with the development of high-performance computer technology, the security of classical cryptography based on computational complexity has been greatly threatened. Quantum cryptography is an interdisciplinary subject based on quantum physics and classical information theory. It uses the principles of quantum physics to ensure unconditional security in the communication process and has received extensive attention and research.

[0003] Quantum Secret Sharing (QSS) is a relatively practical multi-party quantum communication technology, in which the distributor (dealer) distributes its secret share to the participants (players) through quantum means, and the latter need to cooperate with each other to recover the secret.

[0004] The earliest quantum secret sharing protocol was first proposed by Hillery et al. in 1999 (Phys. Rev. A 59, 1829). The protocol uses GHZ entangled states to achieve secure secret sharing. However, entanglement-based protocols face problems such as difficulty in preparing entangled states, complex experimental equipment, and low tolerable loss, which greatly affects their practicality.

[0005] In the field of continuous variables, this problem was solved by Grice et al. (Phys. Rev. A 100, 02233) in 2018. Instead of using the entanglement property, they generated security keys separately between the distributor and multiple participants, thereby realizing (n,n) threshold quantum secret sharing, improving the tolerance to noise and loss, and being able to be extended to the case of a large number of participants, increasing the practicality of quantum secret sharing. Summary of the invention

[0006] In order to overcome the defect of the existing continuous variable quantum secret sharing technology that is easily attacked by the detector, the present invention provides a continuous variable quantum secret sharing method with high practical security. The distributor and all participants prepare the quantum state through the quantum module (including lasers, modulators and other equipment) in the local security station, and the untrusted third party as the measuring party completes the quantum state measurement. Then the distributor performs the classical post-processing process with each participant respectively, and provides a verification mechanism for the security key finally recovered. It can resist the hacker attack of the eavesdropper on the detector and the deception attack of the dishonest participants, thereby improving the security of quantum secret sharing.

[0007] The above-mentioned high practical security continuous variable quantum secret sharing method comprises the following specific steps:

[0008] Step 1: Build a communication scenario consisting of an untrusted measurement party, a distribution party, and n participants;

[0009] The distributor and all participants are connected via quantum channels and are also connected to the measuring party;

[0010] The distributor and each participant prepare their own quantum states through lasers and modulators respectively. The participants except the first participant add their own quantum states to the channel through a highly asymmetric beam splitter. Finally, the quantum states from the distributor and all participants enter the 50:50 beam splitter of the measuring party, and the measuring party performs Bell state measurement.

[0011] Step 2: n participants prepare their own quantum states through lasers and modulators in their respective security stations, and couple them together to join the quantum channel to transmit to the measuring party;

[0012] Specifically:

[0013] First, the first participant P 1 Prepare quantum states locally |x 1 +ip 1 > and send it to the quantum channel;

[0014] Quantum state modulation includes Gaussian modulation and discrete modulation;

[0015] x 1 and p 1 The mean is 0 and the variance is V 1 Gaussian distribution of , i is the imaginary part of the complex number.

[0016] Then, the second party P 2 Prepare quantum states locally |x 2 +ip 2 > and combines it with the transmitted quantum state |x in the channel through a highly asymmetric beam splitter 1 +ip 1 > coupling and sending to the quantum channel again.

[0017] Starting from the third participant, repeat the steps of the second participant, and eventually all participants complete the quantum state preparation process.

[0018] Finally, the measuring party receives the quantum states of all participants as

[0019] Where T k is the channel transmittance of the quantum state of the kth participant transmitted in the channel.

[0020] Step 3: The distributor also prepares its own quantum state locally |xD +ip D > and sends it to the measuring party through the quantum channel.

[0021] The channel transmittance of the distributor transmitting quantum states in the channel is T D .

[0022] Step 4: The measuring party performs Bell state measurement on the quantum states from the participating party and the distributor, and makes the measurement results public;

[0023] The measurement results are expressed as: and

[0024] x M and p M They are the results of two homodyne detections on the measuring side.

[0025] Step 5: The distributor and the participant each randomly select part of the quantum state data and combine it with the public measurement result x of the measuring party. M and p M , calculate the transmittance of all channels {T 1 ,T 2 ,...,T n} and T D .

[0026] Step 6: The distributor performs classical post-processing with each participant in turn to obtain the keys of the distributor and all the participants;

[0027] The specific steps are as follows:

[0028] Step 601: The distributor assumes that P 1 is an honest participant, and the other participants are dishonest. Then the distributor randomly selects part of the data and requires other participants to disclose their corresponding original data. At the same time, the measuring party discloses its own measurement results.

[0029] Step 602: The distributor uses the public results of the measuring party and removes P 1 The original data of the remaining participants except 1 The estimated value of {x N ,p N};

[0030] Specifically:

[0031]

[0032] Step 603: The distributor uses its own quantum state to 1 The estimated value of {x N ,p N} to obtain the corrected data {x1 ′,p 1 '};

[0033] The correction formula is:

[0034] x 1 ′=x D +k·x N , p 1 ′=p D -k·p N ;

[0035] in is the magnification factor.

[0036] Step 604: Distributor and participant P 1 Using the original data {x 1 ,p 1} and the modified data {x 1 ′,p 1 ′} performs parameter estimation, data coordination and private key amplification, and finally obtains the participant P 1 The security key K 1 .

[0037] Key K 1 The corresponding security code rate is R 1 ;

[0038] Step 605: Return to step 601, the distributor selects the next participant as the honest participant, repeats the above steps, and finally obtains the independent keys {K 1 ,K 2 ,...,K n};

[0039] The minimum value among all security code rates is selected as the final security code rate for all keys, that is, R = min{R 1 ,R 2 ,...,R n}.

[0040] Step 606: The distributor performs XOR on the n strings of keys to obtain the final security key. Each of the n participants holds a string of keys, and only by cooperating with each other can the final key be recovered.

[0041] Step 7. The participants and distributors use hash functions to verify their respective final keys and compare the output results.

[0042] Specifically, all participants perform XOR operations on their own keys and determine whether the output result is the same as the K output of the distributor. If so, the security key is used as the communication key to transmit the secret. Otherwise, the key is abandoned.

[0043] Compared with the prior art, the advantages of the present invention are:

[0044] 1) A highly practically secure continuous variable quantum secret sharing method that uses a measurement device-independent method in which an untrusted third party performs quantum state measurement and makes the measurement results public, thereby being able to resist hacker attacks on the detector and avoiding security vulnerabilities in quantum secret sharing caused by the non-ideality of the detector.

[0045] 2) A highly practically secure continuous variable quantum secret sharing method that uses a hash function to verify the final security key to resist deception attacks by dishonest participants, further improving security. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram of a communication scenario constructed for the present invention;

[0047] Figure 2 The present invention is a flow chart of a continuous variable quantum secret sharing method with high practical security. DETAILED DESCRIPTION

[0048] The present invention will be further described in detail below with reference to the accompanying drawings and implementation examples.

[0049] The present invention first builds a quantum secret sharing communication scenario that is independent of measurement equipment, including an untrusted measurement party, a distributor and n participants, wherein the distributor and all participants prepare Gaussian modulated coherent states through their own lasers, modulators and other equipment, and the other participants except the first participant add their own coherent states to the channel through a highly asymmetric beam splitter. Finally, the coherent states from the distributor and all participants enter the 50:50 beam splitter of the measurement party, and the measurement party performs Bell state measurement.

[0050] In the corresponding quantum secret sharing method that is independent of the measurement device, the distributor and each participant use the measurement results published by the measuring party to generate independent keys. The distributor performs an XOR operation on the n strings of keys it holds to obtain the final key. Only when the n participants cooperate honestly with each other can the final key be recovered.

[0051] like Figure 2 As shown, the specific steps are as follows:

[0052] Step 1: Build a communication scenario consisting of an untrusted measurement party, a distribution party, and n participants;

[0053] like Figure 1 As shown, the distributor and all participants are connected through quantum channels and are also connected to the measuring party;

[0054] The distributor and each participant prepare their own quantum states through lasers and modulators respectively. The participants except the first participant add their own quantum states to the channel through a highly asymmetric beam splitter. Finally, the quantum states from the distributor and all participants enter the 50:50 beam splitter of the measuring party, and the measuring party performs Bell state measurement.

[0055] Step 2: n participants prepare their own quantum states through lasers and modulators in their respective security stations, and couple them together to join the quantum channel to transmit to the measuring party;

[0056] Specifically:

[0057] First, the first participant P 1 Prepare quantum states locally |x 1 +ip 1 > and send it to the quantum channel;

[0058] Quantum state modulation includes Gaussian modulation and discrete modulation;

[0059] x 1 and p 1 The mean is 0 and the variance is V 1 Gaussian distribution of , i is the imaginary part of the complex number. x represents the "position" regular component of the phase space; p represents the "momentum" regular component of the phase space.

[0060] Then, the second party P 2 Prepare quantum states locally |x 2 +ip 2 > and combines it with the transmitted quantum state |x in the channel through a highly asymmetric beam splitter 1 +ip 1 > coupling and sending to the quantum channel again.

[0061] Starting from the third participant, repeat the steps of the second participant n-1 times, and eventually all participants complete the quantum state preparation process.

[0062] Finally, the measuring party receives the quantum states of all participants as

[0063] Where T k is the total channel transmittance of the kth participant’s quantum state transmitted in the channel, including the losses caused by the channel and the beam splitter.

[0064] Step 3: The distributor also prepares its own quantum state locally |x D +ip D > and sends it to the measuring party through the quantum channel.

[0065] The overall channel transmittance of the distributor transmitting quantum states in the channel is TD .

[0066] Step 4: The measuring party performs Bell state measurement on the quantum states from the participating party and the distributor, and makes the measurement results public;

[0067] The measurement results are expressed as: and

[0068] x M and p M They are the results of two homodyne detections on the measuring side.

[0069] Step 5: The distributor and the participant each randomly select part of the quantum state data and make it public, combined with the public measurement result x of the measuring party M and p M , calculate the total channel transmittance {T 1 ,T 2 ,...,T n} and T D .

[0070] Public data will be deprecated.

[0071] Step 6: The distributor performs classical post-processing with each participant in turn to obtain the keys of the distributor and all the participants;

[0072] The specific steps are as follows:

[0073] Step 601: The distributor assumes that P 1 is an honest participant, and the other participants are dishonest. Then the distributor randomly selects part of the data and requires other participants to disclose their corresponding original data. At the same time, the measuring party discloses its own measurement results.

[0074] Step 602: The distributor uses the public results of the measuring party and removes P 1 The original data of the remaining participants except 1 The estimated value of {x N ,p N};

[0075] Specifically:

[0076]

[0077]

[0078] Step 603: The distributor uses its own quantum state to 1 The estimated value of {x N ,p N} to obtain the corrected data {x 1 ′,p1 '};

[0079] The correction formula is:

[0080] x 1 ′=x D +k·x N , p 1 ′=p D -k·p N ;

[0081] in is the magnification factor.

[0082] Step 604: Distributor and participant P 1 Using the original data {x 1 ,p 1} and the modified data {x 1 ′,p 1 ′} to perform parameter estimation, data coordination and private key amplification, and finally obtain 1 The same security key K 1 .

[0083] Key K 1 The corresponding security code rate is R 1 ;

[0084] Step 605: Return to step 601, the distributor selects the next participant as the honest participant, repeats the above steps, and finally obtains the independent keys {K 1 ,K 2 ,...,K n};

[0085] The minimum value among all security code rates is selected as the final security code rate for all keys, that is, R = min{R 1 ,R 2 ,...,R n}.

[0086] Step 606: The distributor performs XOR on the n strings of keys to obtain the final security key. Each of the n participants holds a string of keys, and only by cooperating with each other can the final key be recovered.

[0087] Step 7. The participants and distributors use hash functions to verify their respective final keys and compare the output results.

[0088] Specifically, all participants perform XOR operations on their own keys and determine whether the output result is the same as the K output of the distributor. If so, the security key is used as the communication key to transmit the secret. Otherwise, the key is abandoned.

Claims

1. A continuous variable quantum secret sharing method with high practical security, characterized in that: The specific steps are: Step 1: Build a communication scenario consisting of an untrusted measurement party, a distribution party, and n participants; Step 2: n participants prepare their own quantum states through lasers and modulators in their respective security stations, and couple them together to join the quantum channel to transmit to the measuring party; Specifically: First, the first participant P1 prepares the quantum state |x1+ip1> locally and sends it to the quantum channel; x1 and p1 follow a Gaussian distribution with mean 0 and variance V1, and i is the imaginary part of the complex number; Then, the second participant P2 prepares the quantum state |x2+ip2> locally and couples it with the transmitted quantum state |x1+ip1> in the channel through a highly asymmetric beam splitter and sends it to the quantum channel again; Starting from the third participant, repeat the steps of the second participant, and finally all participants complete the quantum state preparation process; Finally, the measuring party receives the quantum states of all participants as Where T k is the channel transmittance of the quantum state of the kth participant transmitted in the channel; Step 3: The distributor also prepares its own quantum state locally |x D +ip D > and send it to the measuring party through the quantum channel; The channel transmittance of the distributor transmitting quantum states in the channel is T D ; Step 4: The measuring party performs Bell state measurement on the quantum states from the participating party and the distributor, and makes the measurement results public; The measurement results are expressed as: and x M and p M They are the results of two homodyne detections by the measuring party respectively; Step 5: The distributor and the participant each randomly select part of the quantum state data and combine it with the public measurement result x of the measuring party. M and p M , calculate the transmittance of all channels {T1,T2,...,T n } and T D ; Step 6: The distributor performs classical post-processing with each participant in turn to obtain the keys of the distributor and all the participants; The specific steps are as follows: Step 601: The distributor assumes that P1 is an honest participant and the other participants are dishonest. Then the distributor randomly selects some data and requires other participants to disclose their corresponding original data. At the same time, the measuring party discloses its own measurement results. Step 602: The distributor uses the public results of the measurement party and the original data of the remaining participants except P1 to calculate the estimated value {x N ,p N }; Specifically: Step 603: The distributor uses its own quantum state to estimate the value of P1 {x N ,p N } to obtain the corrected data {x1′,p1′}; The correction formula is: x1′=x D +k·x N ,p1′=p D -k·p N ; in is the magnification factor; Step 604: The distributor and participant P1 use the original data {x1, p1} and the modified data {x1′, p1′} to perform parameter estimation, data coordination, and private key amplification, and finally obtain the security key K1 of participant P1; The security code rate corresponding to the key K1 is R1; Step 605: Return to step 601, the distributor selects the next participant as the honest participant, repeats the above steps, and finally obtains the independent keys {K1, K2, ..., K n }; The minimum value among all security code rates is selected as the final security code rate for all keys, that is, R = min{R1, R2, ..., R n }; Step 606: The distributor performs XOR on the n strings of keys to obtain the final security key. Each of the n participants holds a string of keys, and only by cooperating with each other can the final key be recovered; Step 7. The participants and distributors use hash functions to verify their respective final keys and compare the output results.

2. A continuous variable quantum secret sharing method with high practical security as claimed in claim 1, characterized in that: In the step 1, the distributor is connected to all participants through a quantum channel and is also connected to the measurement party; The distributor and each participant prepare their own quantum states through lasers and modulators respectively. The participants except the first participant add their own quantum states to the channel through a highly asymmetric beam splitter. Finally, the quantum states from the distributor and all participants enter the 50:50 beam splitter of the measuring party, and the measuring party performs Bell state measurement.

3. A continuous variable quantum secret sharing method with high practical security as claimed in claim 1, characterized in that: In the step 2, the quantum state modulation includes Gaussian modulation and discrete modulation.

4. A continuous variable quantum secret sharing method with high practical security as claimed in claim 1, characterized in that: The specific step seven is: all participants perform XOR operation on their own keys and determine whether it is the same as the K output result of the distributor. If so, the security key is used as a communication key to transmit the secret; otherwise, the key is abandoned.

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