77 results about "Quantum secure direct communication" patented technology

The invention provides a method and a system for anti-interference quantum secure direct communication. The method comprises the following steps that: a sending end performs non-orthogonal state combination coding, randomly expands a bit to two bits, randomly selects two different base combinations, converts the two bits into corresponding quantum states in the base combinations and then sends the two bits through a quantum channel; and a receiving end randomly selects two same base combinations for quantum state measurement so as to realize definite measurement on one bit. The method and the system can effectively solve the problem of quantum secure direct communication under the condition of not accurate measurement on the quantum, and realize point-to-multipoint quantum information distribution.

According to quantum steganography, the classical steganography and quantum secure communication are combined together, and the quantum steganography is popularized in the field of quanta. The quantum steganography aims to realize secret transmission of classified information by utilizing a quantum hidden channel. The invention provides a quantum steganography protocol based on gigahertz (GHZ) state dense coding and entanglement exchange. A hyper-quantum channel of the protocol is formed by establishing the hidden channel on a quantum secure direct communication (QSDC) protocol. The classified information is transmitted by combining the GHZ state dense coding and GHZ state entanglement exchange based on the original QSDC. The capacity of the hyper-quantum channel of the protocol reaches 6-bit per round in covert communication. In addition, the protocol has high imperceptibility and high safety.

At present, information leakage is a serious security threat to bidirectional quantum secure direct communication (BQSDC). The invention provides an information leakage-free bidirectional quantum secure direct communication protocol based on any two gigahertz (GHZ) state / entanglement exchange result collection codes. In the information leakage-free bidirectional quantum secure direct communication protocol, two remote legitimate communication sides, namely, Alice and Bob can exchange their respective secret information without concern on information disclosure required. According to the protocol, a shared secret gigahertz (GHZ) state is utilized to overcome the problem of information disclosure. The shared secret gigahertz (GHZ) state has the following functions in a bidirectional communication process that: on the one hand, the shared secret gigahertz (GHZ) state makes Bob known a configured initial state, and on the other hand, the shared secret gigahertz (GHZ) state can be used by Bob so that Bob can encode secret information; and further, the protocol can transmit six-bit secret information per communication round. Compared with an existing BQSDC protocol, the protocol of the invention has the following advantages that: the protocol can overcome the problem of information disclosure; and on the other hand, the capacity of the protocol can achieve six bit per communication round.

Bi-directional quantum secure direct communication aims at enabling two legal communication parties to exchange secret information of each other simultaneously. The invention provides a controlled bi-directional quantum secure direct communication protocol free of information leakage. In the protocol, two legal communication parties Alice and Bob are controlled by a controller Charlie to achieve exchange of the secret information of each other without information leakage. The protocol utilizes measuring relevancy after entanglement swapping of 3 Bell states to solve an information leakage problem. In addition, the protocol only uses the Bell states as quantum resources, only Bell measuring is required to be conducted, and the controlled bi-directional quantum secure direct communication protocol is convenient to achieve.

The invention discloses a controlled quantum security direct communication method based on four particle cluster states. Alice and Bob respectively serve as a legal information sender and a legal information receiver during a quantum communication process, and Charlie serves as a credible scheme control party; information security is achieved by randomly inserting a single photon to perform measurement-based comparison detection, and communication starts after security detection; Alice uniformly divides the prepared four particle cluster states into two groups, after being subjected to an XOR operation with a pseudorandom sequence, the sent information is encoded on the two particles reserved by Alice via unitary transformation. Alice performs Bell-based measurement on reserved particles, and sends measurement information to Bob, and Bob recovers the original sequence via an initial state sent by Charlie after the measurement information is compared. The four particle cluster states used by the method has good entanglement, connectivity and damage resistance, only the receiver Bob in the method gets the permission of the controller Charlie, Bob can recover the original information, so that the information can be effectively prevented from being attacked during a transmission process, and an implementation process is simple.

The invention discloses a quantum secure direct communication protocol based on the three-particle GHZ entangled state. Alice prepares N groups of particles in the GHZ entangled state, and a sequence C'2 is sent to Bob; the Bob conducts single practical measurement on a sequence A21 and a sequence B21, the Alice conducts single practical measurement on a sequence C21, and it is determined that wiretapping exists if results of two measurements do not meet the corresponding relation; if the results of the two measurements meet the corresponding relation, A1 and B1 are encoded, particles in a sequence A22 and a sequence B22 are inserted into the A1 and the B1, the order of the particles is disrupted, and a sequence C'3 is generated and sent to the Bob; the Bob conducts single practical measurement on the sequence A22 and the sequence B22, the Alice conducts single practical measurement on a sequence C22, and it is determined that wiretapping exists if results of two measurements do not meet the corresponding relation; if the results of the two measurements meet the corresponding relation, the Bob conducts combined measurement on the A1, the B1 and a C1, and the information sent by the Alice is obtained. According to the quantum secure direct communication protocol based on the three-particle GHZ entangled state, the QSDC communication safety can be effectively improved, and the error detection rate reaches up to 62.5%.

The invention discloses a three-party quantum secure direct communication method based on a hyper-entangled Bell state, including the following steps: a user 1 randomly prepares N hyper-entangled Bellstates and splits the Bell states into two sequences; the user 1 encodes a first sequence path and sends the path to a user 2; the user 2 encodes the path after confirming that no eavesdropping exists and sends the path to a user 3; the user 3 notifies the user 1 to send a second sequence after confirming that no eavesdropping exists; the user 1 performs polarization encoding on the second sequence and sends the second sequence to the user 3; the user 3 performs polarization encoding on the second sequence, performs joint hyper-entangled Bell state measurement on the two sequences, and publishes measurement results; the user 1 acquires encoding information of the user 2 and the user 3 respectively; the user 1 announces an initial state Ri and the encoding information R of the user 3 on XOR of the user 2; and the users 2 and 3 acquire the encoding information of the other two parties. According to the scheme of the invention, the transmission is only performed for three times, the probability of photon loss caused by channel loss can be greatly reduced, the security detection can be provided, and the security of transmission can be fully improved.

The invention belongs to the field of quantum security communication, and discloses a semi-quantum secure direct communication method and system based on a Bell state. Two users participate in the execution of a present protocol, the first participating user has advanced quantum functions, can prepare the Bell state, and can use a Bell base to measure a quantum state and has a quantum storage function; the second participating user only has basic quantum functions, specifically: measurement: using a classical base {|0), |1)} to measure quanta, generating a quantum |1) (|0)) in an opposite state according to a measurement result |0) (|1) ), and sending the quantum; reflection: after receiving the quantum, directly sending the quantum to a sender without any modification; and disorder: disturbing the sending sequence of the quantum sequence by using the delay technology. The protocol proposed by the invention is a semi-quantum secure direct communication protocol, which improves the communication efficiency of the protocol while ensuring the absolute security of secret information transmission.

The invention belongs to the technical field of quantum block chains. The invention discloses a quantum block chain network anonymous election method and system based on trust evaluation. The method comprises the following steps: identity trust evaluation of voters among miner nodes is completed by using a quantum secure direct communication technology, then voters calculate commitment values of voter election contents by using a quantum bit commitment protocol, and broadcast the commitment values to all miner nodes in a block chain; and then the miner nodes are combined with a quantum honestyByzantine protocol to complete voting statistics. The security model analysis of the protocol proves that the protocol has the advantages of anonymity, tamper resistance, verifiability and the like;according to the invention, the honesty quantum Byzantine protocol is adopted, so that the blockchain system can achieve a consistency protocol, and the protocol efficiency is better.

The invention belongs to the technical field of safety communication, and discloses a controlled quantum safe and direct communication method and system for preventing tampering. A receiving end is controlled to obtain secret information of a sending end, and the sending end sends SC* to a control end; the control end disorganizes photons in SC*; then the control end sends rearranged SC* to the receiving end; if the control end does not tell the accurate sequence of the photons to the receiving end, the receiving end cannot resume SC and decrypt the secret information; the control end cannot know the secret information encrypted through K(k1, k2, ..., kN). The premise that a controller is honest is not needed; even under the condition that the controller is dishonest, the proposed protocolis still safe, and any tampering of the secret information can be easily found. By means of the controlled quantum safe direct communication method and system for preventing tampering, attack of fakephotons based on quantum teleportation can be resisted, and meanwhile, identities of two participants, namely, the sender and the receiver, can also be verified.

The invention discloses a controlled quantum secure direct communication method based on Huffman compression coding, which is characterized in that a sender Alice and a receiver Bob design the same sequence generator, a control party Charlie enables the two communication parties to generate the same pseudo-random sequence through sending the initial state of the sequence generators; the sender Alice performs compression on the original information by using Huffman compression coding, and carries out an exclusive-or operation on the compressed sequence and the pseudo-random sequence to form a sequence S1; the sender Alice sends a sequence SB to the receiver Bob to detect the channel security, if the channel is secure, the sender Alice divides the sequence S1 into an odd sequence and an even sequence, and the odd sequence the even sequence are differently coded, then loaded to remaining particles SA and sent to the receiver Bob; and if not, the communication is abandoned. The receiver Bob measures decoding and recovers the sequence S1 after detecting the channel security, and performs an exclusive-or operation on the sequence S1 and the pseudo-random sequence to obtain a compressed sequence, and the receiver Bob decompresses the compressed sequence to acquire the original information. The transmission efficiency of quantum secure direct communication can be effectively improved according to the method disclosed by the invention.

The invention discloses a dual-channel information transmission method oriented to quantum key distribution. The method comprises the following steps: based on the quantum secret key distribution protocol, storing the secret keys generated by a sending end and a receiving end in the secret key pool; when the sending end receives the request for transmitting the confidential information, the sending end judges whether the quantum channel is free or not according to the channel identification, if yes, a similar quantum safe direct communication mode is adopted on the quantum channel, and the confidential information is jointly transmitted on a classical channel by adopting a one-time encryption mode; and if not, the confidential information in a one-time encryption mode on the classic channel. By means of the method, the function of transmitting the confidential information at the same time through the quantum channel and the classic channel is achieved, the transmission efficiency of confidential information is improved, the transmission time is saved, and the maximization of the utilization rate of the channel resources is realized. In addition, the invention further provides an expansion coding scheme, so that more confidential information can be carried by the quantum state, and the communication efficiency is further improved.

The invention discloses a quantum dialogue method irrelevant to measuring equipment based on super-entanglement. The method comprises the following steps that two communication parties randomly prepare a super-entanglement state and a single photon respectively to form corresponding photon sequences; the third detection party performs hyper-entangled Bell state measurement on the photon sequence sent by the communication party and publishes a measurement result, and the communication party performs security detection according to the measurement result; two communication parties simultaneouslyencode information at different degrees of freedom and randomly perform security detection encoding, and the process is similar to quantum secure direct communication at different degrees of freedom;and the two communication parties send the coded photon sequence to the detection party, the detection party performs hyper-entangled Bell state measurement again and publishes a result, and the communication party decodes information according to the result to complete dialogue. According to the method, bidirectional quantum secure direct communication can be realized, communication efficiency is effectively improved, meanwhile, security holes related to measurement equipment and information leakage can be eliminated, and the method has relatively high flexibility, i.e., information codes ondifferent degrees of freedom do not influence each other.

The invention discloses a multi-degree-of-freedom-based quantum secure direct communication method irrelevant to measurement equipment. The method comprises the steps pf preparing quantum states of asending user and a receiving user; performing hyper-entangled Bell state measurement on the quantum states of the sending user and the receiving user to obtain an error bit rate; judging whether eavesdropping exists or not according to the error bit rate and the error rate threshold, and if not, encoding the quantum state of the sending user; and carrying out security detection on the encoded quantum state, judging whether the encoded quantum has wiretapping or not, and if not, obtaining the code of the sending user by the receiving user. Compared with the original MDI-QSDC, the protocol provided by the invention has larger channel capacity, and can ensure the communication security at the same time so as to prevent all possible attacks on a detector end.

The invention relates to fault tolerance single photon communication technology, and in particular to a multi-channel frequency coding technology based on single photon detection with laser light as an information carrier. Laser light undergoes frequency modulation at a transmitting end and is loaded with information. After channel transmission, the intensity of the laser light attenuates to a single photon magnitude, and the laser light is measured by a single photon detector at a receiving party, and the detected single photon pulse sequence undergoes Fourier transformation so as to extract frequency information. According to the invention, the system has very strong fault tolerance in terms of channel loss and noise. The system addresses the problem of information loss and errors that are caused by channel loss and noise in long-distance laser communication and quantum communication, and provides technical means for the realization of satellite-ground laser communication and quantum secure direct communication.

The embodiment of the invention provide a quantum secure direct communication system irrelevant to a measurement device. The quantum secure direct communication system comprise a transmitting end, a receiving end, and a third party, wherein the transmitting end and the receiving end respectively prepare a first photon sequence and a third photon sequence for security detection and send the first photon sequence and the third photon sequence to the third party for measurement, then the transmitting end and the receiving end perform security detection according to the measurement results, afterthe security detection is passed, the transmitting end loads information to be transmitted into a pre-constructed second photon sequence and sends the information to be transmitted to the third party,the receiving end sends a fourth photon sequence to the third party, and the third party sends the measurement results of the second photon sequence and the fourth photon sequence to the receiving end to complete a communication process, wherein the first photon sequence and the second photon sequence comprise mutually entangled photon pairs; and the third photon sequence and the fourth photon sequence comprise mutually entangled photon pairs. The quantum secure direct communication system provided by the invention can avoid security vulnerabilities caused by a detection device under the premise of ensuring the communication security.

The invention discloses a quantum secure direct communication method based on photon orbital angular momentum coding, comprising the following steps: constructing two unitary operators and giving two groups of complete intrinsic quantum states; when quantum secure direct communication is carried out, based on an intrinsic quantum state space, randomly preparing, by a receiving party, a group of photon sequences, and sending to a sending party; randomly choosing, by the sending party, a check photon from the photon sequences to measure Z<^>p or X<^>p and comparing a measurement basis and a measurement result by a public channel; judging whether a communication channel is secure according to an error rate of the measurement result; if the channel is secure, carrying out coding operation on the photons by the sending party; measuring the received photons by the receiving party, comparing an initial state and a final state of a photon orbital angular momentum, obtaining the coding operation carried out by the sending party and constructing coded logic bit information sent by the sending party. According to the method disclosed by the invention, by using the photon orbital angular momentum coding, the communication capacity and the spectral efficiency of the quantum secure direct communication are improved.

The invention provides a continuous variable-based two-step quantum secure direct communication method. The method comprises the steps that a sending party selects a squeezed operator S(r) randomly toprepare two-mode squeezed light S and S, sends detection light S to a receiving party to perform channel detection and identity authentication; after the channel is confirmed secure and identity authentication is finished, the sending party codes information on signal light S through block transmission and sends the signal light to the receiving party, and the receiving party comparesdetection bits in information blocks so as to recover an original information sequence. Identity authentication is finished during channel detection, so that attach by an intermediary is prevented effectively; and in the information transmission stage, the receiving party determines eavesdropping through detection bits, secret information can be obtained in amplitude and phase of a beam through joint measurement, and the communication efficiency reaches 100%.

The embodiment of the invention provides a synchronization method and device suitable for an extremely low receiving rate. The method comprises the steps that each spread spectrum bit in a spread spectrum sequence of current information bits is compared with each spread spectrum code word sequence obtained after specific code word space spread spectrum, the number of the same bits is recorded to serve as a set of count values, and whether the current information bits are synchronous positions or not is determined. According to the synchronization method and device suitable for the extremely low receiving rate provided by the embodiment of the invention, rapid complete synchronization is realized in a short spread spectrum period, information loss and errors of transmission symbols in a quantum channel can be effectively corrected, and therefore, the problem of reliable transmission of information in quantum secure direct communication is solved.

The invention discloses a practical quantum secure communication method, which mainly solves the practical problem of quantum secure direction communication of the given data. According to the practical quantum secure communication method in the invention, a classic error correcting code is used to perform error correcting coding on a message and a random number is used to carry out encryption protection; the obtained ciphertext is used as a state selecting sequence to carry out non-orthogonal quantum state coding, and the obtained quantum state is used as a signal state; then, a certain number of non-orthogonal quantum states are randomly generated and used as a detection state; the detection state or the signal state is randomly sent according to a synchronous clock; a receiving end carries out random measurement and estimates quantum error rate and quantum response rate according to the detection result of the detection state; the correlation between the measurement result of the signal state and the state selecting sequence of a sending end is used for carrying out error correcting decoding and obtaining a target message. The practical quantum secure communication method in theinvention has unconditional security, can be implemented by using a current single-photon or weak coherent state quantum communication system and has a good application prospect in the field of network security and secure communication.

The invention discloses a free-space quantum secure direct communication method for real-time selection of preset thresholds. The method comprises the following steps: a sender of the communication prepares N-to-Bell state photon pulses, and sends one of the pulses to a receiver; the receiver randomly selects some photons for measurement to determine whether there is an eavesdropper; then the sender randomly selects some photons as detection states to perform unitary transformation; the receiver performs measurement to evaluate an error code rate; and finally, the receiver measures the remaining encoded Bell states and obtains the information. The method has a lower quantum bit error rate and a higher signal to noise ratio.

The invention discloses a symmetrically parallel controlled bidirectional quantum secure direct communication method in which a multi-particle GHZ state tensor product is used as a quantum channel, a central server is responsible for distributing particles for building the quantum channel and utilizes eavesdropping detection to ensure secure transmission of the particles, two parties of a conversation and control parties use two multi-particle GHZ state tensor products as the quantum channels, and only all the control parties say yes, the two parties of the legal communication can safely exchange respective secret information. According to the method provided by the invention, the parallel controlled conversation method is used, one of all the parties having the GHZ state particles can serve as the party or the control party of the conversation, so that status of all the parties participating in the conversation is completely symmetrical and equivalent, once the two parties of the conversation are determined, the other participating parties serving as the control parties can independently complete a control operation and control information transmission in parallel, and consumption of minimum time can be ensured by parallel control operation.

The invention belongs to the technical field of network communication, and discloses a semi-quantum secure direct communication method and system based on a Bell state, and the method comprises the steps: a strong quantum party randomly selecting from four sets of Bell states and preparing Bell state particles, and a semi-quantum party randomly selecting measurement or reflection operation on eachparticle after receiving a sequence sent by the strong quantum party; the strong quantum party temporarily storing the particle sequence reflected by the semi-quantum party through quantum memory equipment, and informing the strong quantum party that the particles reflected by the semi-quantum party are completely received through a classical channel; and the strong quantum party measuring the remaining sequence particles to obtain a measurement result. By using the protocol provided by the invention, secret information can be directly transmitted to a common user with weak quantum capacity under relatively good efficiency transmission, so that quantum secure direct communication is completed. Based on the semi-quantum theory, the protocol can be applied to a quantum communication networkcloser to reality.

The invention belongs to the technical field of network communication, two semi-quantum secure direct communication schemes based on Bell states are proposed, through the session of the protocol, thereceiver of the semi-quantum secret information only needs to measure the two columns of sequences sent by the sender of the quantum information with the classical measurement bases {|0>, |1>}, and then obtains the n-bit secret information or the 2n-bit secret information by comparing the two cases in which the initial Bell state may collapse. The invention provides two semi-quantum secure directcommunication schemes based on Bell states, which can allow semi-quantum users to participate in communication. On the one hand, it reduces the cost of users; on the other hand, it reduces the difficulty of protocol implementation because of the simple and easy implementation of semi-quantum operation; both protocols only use Bell states as quantum information carriers and do not require additional decoy photons to participate in eavesdropping detection. It reduces the complexity of the protocol and promotes the implementation of the quantum secure direct communication protocol.

The invention provides a quantum dialogue protocol with collective-dephasing noise resisting robustness based on logic qubits and CNOT operation. A preparation party produces the logic qubits serving as a transmission state to resist collective-dephasing noise. The other party knows the initial preparation state of the logic qubits by the aid of the CNOT operation and acquires secret information of the preparation party through decoding with the help of a classic information sequence transmitted by the preparation party. The preparation party reads secret information of the other party by the aid of quantum secure direct communication. In this way, the risk of information leakage is effectively avoided. In the protocol, only single-photon measurement is required for quantum measurement. Compared with a noise-resistant quantum dialogue protocol in the past, the protocol has the highest information theory efficiency. Compared with the recent quantum dialogue protocol that two adjacent logic qubits need to be prepared to be in the same quantum state, the protocol is easier to execute experimentally because the protocol does not have the special request.

The invention provides a QSDC protocol of a quantum secure direct communication method based on an Omega state and ultra dense coding. Assigning a key is a very important research topic in the cryptography, unlike the traditional encryption algorithms based on mathematical difficulties, a quantum secure transmission protocol is based on the physics and can be proved to be theoretically secure, theoriginal QSDC protocol divides entangled particles into two sequences, a check sequence is used for detecting an intrusion behavior, a message coding sequence is used for transmitting a ciphertext, however, the efficiency of the intrusion detection mode is worse, and to improve the efficiency of the intrusion detection, a QSDC protocol based on the Omega state is proposed. A sender forms a message qubits sequence by using particles in a Bell state so as to transmit security information, inserts a check sequence C into the qubits sequence, and records the location of the check sequence C to obtain a sequence data block T, and a receiver extracts the check sequence C and a quantum bit sequence A from the T, performs Omega measurement on the check sequence C, and compares a measured value with a threshold to judge whether the current environment is secure.

The invention provides an information-disclosure-free two-way quantum secure direct communication protocol based on the Bell state and the control-not-operation. According to the protocol, firstly, a rule generated when the control-not-operation is performed on the Bell state is found, and namely, after the control-not-operation is performed on one Bell state, the Bell state will collapse to form two independent particles without any tangle. According to the rule, a communication making party can automatically know the state of the two independent particles after the control-not-operation. Another communication party can also know the state of the two independent particles after the control-not-operation through X-base or Z-base measurement. Thus, the two communication parties can secretly share the state of the two independent particles after the control-not-operation, and no information is disclosed to Eve. The efficiency of the theory of information of the protocol reaches 100% and is higher than that of a previous information-disclosure-free two-way quantum secure direct communication protocol. The protocol has another advantage that only single-particle measurement needs to be carried out.

The invention provides a device-independent quantum secure direct communication method based on a single photon source. Two communication parties use a single photon source to generate a single photon, the two parties send the single photon to a third party for Bell state measurement, and a measurement result can indicate whether the two parties successfully establish an entanglement channel or not. And then, the information sender encodes the photons in the hand and sends the photons to an information receiver for Bell state measurement so as to read the secret information transmitted by the sender. The security of the two rounds of photon transmission process is ensured by an equipment-independent security detection method. Due to the fact that the probability that the single photon source generates the single photon is far higher than the probability that the entanglement source generates the photon entanglement state, the method can effectively improve the actual safety information capacity of the DI-QSDC, meanwhile, the influence of photon transmission loss on communication safety can be eliminated through an indication method, the information loss rate and the error rate are reduced, and the communication distance is effectively prolonged. In addition, the Bell state measurement equipment is based on linear optics and can be realized under the current experiment condition.

The invention provides an error correcting coding and decoding method suitable for quantum secure direct communication, and belongs to the technical field of quantum secure direct communication. The method comprises the following steps of firstly, at a receiving end and a sending end, replacing a parity check code constraint in a Tanner representing graph of an LDPC code with quantum random numbersequence constraints in order to obtain a Tanner representing graph of an LDPC-QRS code; at the sending end, coding a sending information sequence by utilizing the Tanner representing graph of the LDPC-QRS code in order to obtain a corresponding sending code word, sending the sending code word to a quantum channel for transmission, and receiving a corresponding receiving code word by the receiving end; and at the receiving end, decoding the receiving code word by utilizing the Tanner representing graph of the LDPC-QRS code in order to obtain a corresponding receiving information sequence. Themethod provided by the invention has excellent error correction performance which is close to a Shannon theoretical limitation, and the reliable transmission of information in a quantum secure directcommunication system can be effectively realized.

According to the two-degree-of-freedom-based three-party quantum secure direct communication method irrelevant to the measurement equipment, coding communication is carried out by virtue of two degrees of freedom of photons, so that the channel capacity is doubled; due to the fact that the two degrees of freedom of the hyper-entangled state are completely independent, codes on the two degrees of freedom do not affect each other, detection or transmission errors on one degree of freedom do not affect the second degree of freedom, and therefore the method is more flexible and has higher anti-error capacity compared with a scheme of coding on one degree of freedom. According to the method, all detection devices are placed on the fourth party, all security holes from the detection end are blocked, and all attacks on the detector end can be completely resisted; the method has a wide application prospect in the field of quantum communication in the future.