Method and device for real-time coding of free-space quantum key distribution

Abstract

The present invention provides a method and device for real-time coding of quantum key distribution in free space, which can be used in the field of quantum communication. The method includes a transmitting end sending a light quantum flow and a laser signal to a receiving end; the receiving end detects the received light quantum flow to obtain a quantum original detection signal, generates multiple original key information data packets according to the synchronous coding information and the measurement basis vector in the received laser signal, and sends the multiple original key information data packets to the transmitting end through a laser communication channel; the transmitting end obtains basis vector comparison key data and information according to the modulation basis vector and the measurement basis vector in the multiple original key information data packets, processes the basis vector comparison key data using a low-density parity check code to obtain verification data and generate multiple intermediate key information data packets, and sends the multiple intermediate key information data packets to the receiving end; the receiving end obtains verification data from the received multiple intermediate key information data packets, and processes the verification data to obtain the target quantum key.

Description

Technical Field

[0001] The present invention relates to the field of quantum communication technology, and more specifically to a method and device for real-time coding of quantum key distribution in free space. Background Art

[0002] With the development of science and technology, the security of multi-party communications has received increasing attention. As an emerging key communication technology, quantum key distribution technology greatly improves the security of multi-party communications due to its unique randomness, unbreakability and traceability. As a result, quantum keys are often widely used in the process of information transmission. However, the existing technology is to transmit quantum keys through quantum channels and transmit encrypted information through classical channels. Since the wave-micro data transmission station used to process encrypted information and the ground optical station used to process quantum keys are not in the same location, real-time key extraction cannot be achieved.

[0003] In the process of realizing the above-mentioned inventive concept, the inventors found that: in the related technology, since the distribution of quantum keys is transmitted through classical channels and quantum channels respectively, the receiving end is unable to extract the quantum keys in real time and quickly according to the encrypted information. In addition, due to the instability of the spatial channel, the quantum keys and encrypted information have a low coding rate during the transmission using the spatial channel. Summary of the invention

[0004] In view of the above problems, the present invention provides a method and device for real-time coding of quantum key distribution in free space.

[0005] According to a first aspect of the present invention, a method for real-time coding of quantum key distribution in free space is provided, which is applied to a receiving end, comprising: in response to receiving a light quantum stream and a laser signal, detecting the light quantum stream using a plurality of measurement basis vectors to obtain a quantum original detection signal, wherein the light quantum stream and the laser signal are both obtained by a transmitting end through a laser communication channel in free space, and the laser signal includes a plurality of synchronous coding information and a plurality of modulation basis vectors; generating a plurality of original key information data packets based on the plurality of synchronous coding information and the plurality of measurement basis vectors, and sending the plurality of original key information data packets to the transmitting end through the laser communication channel, wherein the transmitting end is used to detect the light quantum stream according to the plurality of modulation basis vectors and the plurality of original key information of the transmitting end. The method comprises the following steps: measuring multiple basis vectors in a data packet, obtaining basis vector comparison key data and basis vector comparison result information, processing the basis vector comparison key data using a low-density parity check code to obtain verification data, and generating multiple intermediate key information data packets according to the verification data and the basis vector comparison result information, wherein the basis vector comparison result information includes privacy amplification information; in response to receiving multiple intermediate key information data packets, obtaining verification data from the multiple intermediate key information data packets; determining a check matrix of a low-density parity check code according to the verification data, iteratively decoding the check data using the check matrix to obtain a verification quantum key; and performing privacy amplification processing on the verification quantum key based on the quantum original detection signal and the privacy amplification information to obtain a target quantum key.

[0006] According to an embodiment of the present invention, in response to receiving a photon flow and a laser signal, a plurality of measurement basis vectors are used to detect the photon flow to obtain a quantum original detection signal, including: in response to receiving a photon flow and a laser signal, a plurality of measurement basis vectors are used to detect the photon states in the photon flow to obtain a first initial quantum detection signal; each measurement basis vector and each modulation basis vector are compared and processed, and when the measurement basis vector and the modulation basis vector are consistent, the first initial quantum detection signal corresponding to the measurement basis vector is determined as the quantum original detection signal.

[0007] According to an embodiment of the present invention, the synchronization coding information includes a synchronization coding sequence number and a check code; based on multiple synchronization coding information and multiple measurement basis vectors, multiple original key information data packets are generated and sent to a sending end through a laser communication channel, including: packing multiple measurement basis vectors to obtain a first key information data packet; subpacketizing the first key information data packet to obtain multiple intermediate original key information data packets with sequential numbers; matching multiple synchronization coding sequence numbers with sequential numbers of multiple intermediate original key information data packets to obtain matching results; based on the matching results, embedding the synchronization coding information corresponding to the sequential numbers into the intermediate original key information data packets to obtain multiple original key information data packets with synchronization coding information; and sending multiple original key information data packets with synchronization coding information to the sending end.

[0008] According to an embodiment of the present invention, in response to receiving multiple intermediate key information data packets, verification data is obtained from the multiple intermediate key information data packets, including: in response to receiving multiple intermediate key information data packets, obtaining a synchronization coding sequence number corresponding to each intermediate key information data packet; filling the intermediate key information data packet into a storage space according to the synchronization coding sequence number corresponding to each intermediate key information data packet, wherein the receiving end includes multiple storage spaces with space numbers; based on the space number of the storage space, verifying the synchronization coding sequence number corresponding to the intermediate key data packet stored in the storage space to obtain a verification result; when the verification result indicates that the verification is passed and the number of intermediate key information data packets stored in the storage space meets a first preset condition, obtaining verification data from the multiple intermediate key information data packets.

[0009] According to an embodiment of the present invention, when the intermediate key information data packet stored in each storage space does not meet the first preset condition, multiple intermediate key information data packets are continuously received until the intermediate key information data packet stored in the storage space meets the first preset condition.

[0010] According to an embodiment of the present invention, a check matrix of a low-density parity check code is determined according to check data, and the check matrix is ​​used to iteratively decode the check data to obtain a verification quantum key, including: obtaining a coding matrix and a coding key from the check data; determining a check matrix of a low-density parity check code according to the coding matrix; according to the state of each quantum bit in the coding key, replacing the non-zero state in the check matrix with a key probability likelihood ratio to construct a variable matrix, wherein the key probability likelihood ratio is obtained by performing a log-likelihood ratio calculation on a priori probability of the key; performing a first calculation operation on the variable matrix and the key probability likelihood ratio to obtain a state probability corresponding to the coding key; and calculating the state probability of the key according to the state of each quantum bit in the coding key. A state determination operation is performed on each quantum bit in the coding key according to the key probability likelihood ratio to obtain an intermediate coding key; a verification operation is performed on the intermediate coding key using a check matrix, and when the verification result does not meet the second preset condition, the variable matrix is ​​iteratively updated to obtain an updated variable matrix, and the first calculation operation, the state determination operation and the verification operation are re-executed on the updated variable matrix until the verification result meets the second preset condition, wherein the second preset condition represents that the matrix result obtained by calculating using the check matrix and the intermediate coding key is a zero vector; when the verification result meets the second preset condition, the intermediate coding key is determined to be a verification quantum key.

[0011] According to an embodiment of the present invention, based on the quantum original detection signal and the privacy amplification information, the verification quantum key is subjected to privacy amplification processing to obtain a target quantum key, including: obtaining the privacy amplification information from the basis vector comparison result information; comparing the verification quantum key and the quantum original detection signal to obtain a comparison result; when the comparison result is characterized as the verification quantum key and the quantum original detection signal are consistent, the verification quantum key is subjected to privacy amplification processing according to the privacy amplification information to obtain the target quantum key; when the comparison result is characterized as the verification quantum key and the quantum original detection signal are inconsistent, the quantum original detection signal is discarded and the comparison result is sent to the sending end.

[0012] The second aspect of the present invention provides a method for real-time coding of quantum key distribution in free space, which is applied to a transmitting end and includes: sending a light quantum stream and a laser signal to a receiving end through a laser communication channel in free space, wherein the laser signal includes multiple synchronous coding information and multiple modulation basis vectors; in response to receiving multiple original key information data packets, obtaining basis vector comparison key data and basis vector comparison result information according to multiple modulation basis vectors of the transmitting end and multiple measurement basis vectors in multiple original key information data packets, wherein the multiple original key information data packets are transmitted through a laser communication channel, and the basis vector comparison result information includes privacy amplification information; processing the basis vector comparison key data using a low-density parity check code to obtain verification data, and generating multiple intermediate key information data packets according to the verification data and the basis vector comparison result information; and sending the multiple intermediate key information data packets to the receiving end through a laser communication channel.

[0013] The third aspect of the present invention provides a device for real-time coding of quantum key distribution in free space, which is applied to a receiving end and includes: a detection module, which is used to detect the light quantum flow using multiple measurement basis vectors in response to receiving a light quantum flow and a laser signal, and obtain a quantum original detection signal, wherein the light quantum flow and the laser signal are both obtained by the transmitting end through a laser communication channel in free space, and the laser signal includes multiple synchronous coding information and multiple modulation basis vectors; a generation module, which is used to generate multiple original key information data packets according to the multiple synchronous coding information and the multiple measurement basis vectors, and send the multiple original key information data packets to the transmitting end through the laser communication channel, wherein the transmitting end is used to generate multiple original key information data packets according to the multiple modulation basis vectors and the multiple original key information data packets of the transmitting end. The method comprises the following steps: measuring a basis vector to obtain basis vector comparison key data and basis vector comparison result information, processing the basis vector comparison key data using a low-density parity check code to obtain verification data, and generating multiple intermediate key information data packets according to the verification data and the basis vector comparison result information, wherein the basis vector comparison result information includes privacy amplification information; an acquisition module for obtaining verification data from multiple intermediate key information data packets in response to receiving multiple intermediate key information data packets; a decoding module for determining a check matrix of a low-density parity check code according to the verification data, and performing iterative decoding processing on the check data using the check matrix to obtain a verification quantum key; and a privacy amplification module for performing privacy amplification processing on the verification quantum key based on a quantum original detection signal and the privacy amplification information to obtain a target quantum key.

[0014] The fourth aspect of the present invention provides a device for real-time coding of quantum key distribution in free space, which is applied to a transmitting end and includes: a first transmitting module, which is used to transmit a light quantum stream and a laser signal to a receiving end through a laser communication channel, wherein the laser signal includes multiple synchronous coding information and multiple modulation basis vectors; an obtaining module, which is used to obtain basis vector comparison key data and basis vector comparison result information in response to receiving multiple original key information data packets, according to multiple modulation basis vectors of the transmitting end and multiple measurement basis vectors in multiple original key information data packets, wherein the multiple original key information data packets are transmitted through the laser communication channel, and the basis vector comparison result information includes privacy amplification information; a processing module, which processes the basis vector comparison key data using a low-density parity check code to obtain verification data, and generates multiple intermediate key information data packets according to the verification data and the basis vector comparison result information; a second transmitting module, which is used to send multiple intermediate key information data packets to the receiving end through the laser communication channel.

[0015] A fifth aspect of the present invention provides an electronic device, comprising: one or more processors; a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors execute the above method.

[0016] The sixth aspect of the present invention also provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, causes the processor to execute the above method.

[0017] The seventh aspect of the present invention also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0018] According to the method and device for real-time coding of quantum key distribution in free space of the present invention, a receiving end responds to receiving a light quantum stream carrying quantum key information and a laser signal carrying encryption information sent from a laser communication channel of a sending end, and uses multiple measurement basis vectors in the receiving end to detect the light quantum stream to obtain a quantum original detection signal. The receiving end generates multiple original key information data packets according to multiple measurement basis vectors and multiple synchronous coding information in the laser signal, and then sends the multiple original key information data packets to the sending end through the laser communication channel. The sending end processes the multiple original key information data packets to generate multiple intermediate key information data packets. The sending end sends the multiple intermediate key information data packets to the receiving end. The receiving end extracts verification data from the received multiple intermediate key information data packets in response to the received multiple intermediate key information data packets, determines a check matrix of a low-density parity check code according to the check data, performs multiple iterative decoding processing on the check data using the check matrix to obtain a verification quantum key, and performs privacy amplification processing on the verification quantum key based on the quantum original detection signal and the privacy amplification information to obtain a target quantum key. It realizes the high-efficiency real-time extraction of quantum key distribution in the environment of unreliable channels, and improves the coding rate of quantum keys through multiple iterations of error correction, reduces the impact of the environment of free space transmission channels on quantum key distribution, and thus improves the reliability and stability of quantum key distribution. Furthermore, by utilizing the high-speed transmission capability and high communication capacity of laser communication and transmitting optical quantum streams and laser signals through laser communication channels, the transmission efficiency and security of encrypted information are improved, and the utilization rate of optical fiber resources is improved. Furthermore, through multiple data packet transmissions, even if data packet loss occurs during the transmission process of unreliable channels, it will not affect the generation and extraction of other keys, thereby improving the transmission efficiency and transmission performance of the system, and realizing real-time coding of quantum key distribution in free environments and unreliable channels with unstable links.

[0019] According to an embodiment of the present invention, in the process of quantum key distribution, by optimizing the quantum key extraction algorithm and process, low-density parity check error correction technology is used to perform error correction on the screened key, thereby reducing the number of interactions between the receiving end and the sending end, reducing the communication cost, and improving the security of interaction. In addition, since the quantum key distribution technology itself has true randomness, undecipherability, communication mode security and traceability, the security of the system is further enhanced.

[0020] According to the embodiments of the present invention, the real-time coding method for quantum key distribution in free space of the present invention can be widely used in different transmission channels and communication scenarios, and has good scalability and adaptability. Whether it is between satellites and ground stations or between satellites, the real-time coding method for quantum key distribution in free space of the present application can provide stable and reliable quantum key distribution services. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above contents and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings.

[0022] Figure 1 An application scenario diagram of a method for real-time coding of quantum key distribution in free space according to an embodiment of the present invention is shown.

[0023] Figure 2 A flow chart of a method for real-time coding of quantum key distribution applicable to free space applied to a receiving end according to an embodiment of the present invention is shown.

[0024] Figure 3 A flow chart of a method for sending multiple original key information data packets according to an embodiment of the present invention is shown.

[0025] Figure 4 A flow chart of a method for acquiring verification data according to an embodiment of the present invention is shown.

[0026] Figure 5 A flow chart of a method for real-time coding of quantum key distribution applicable to free space applied to a transmitting end according to an embodiment of the present invention is shown.

[0027] Figure 6 A structural block diagram of a device for real-time coding of quantum key distribution in free space applied to a receiving end according to an embodiment of the present invention is shown.

[0028] Figure 7 A structural block diagram of a device for real-time coding of quantum key distribution in free space applied to a transmitting end according to an embodiment of the present invention is shown.

[0029] Figure 8 A block diagram of an electronic device applicable to a real-time coding method for quantum key distribution in free space according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0030] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0031] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0032] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0033] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0034] In the technical solution of the present invention, the user information (including but not limited to user personal information, user image information, user device information, such as location information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved are all information and data authorized by the user or fully authorized by all parties, and the collection, storage, use, processing, transmission, provision, invention and application of the relevant data comply with relevant laws, regulations and standards, take necessary confidentiality measures, do not violate public order and good morals, and provide corresponding operation entrances for users to choose to authorize or refuse.

[0035] Today, as network security is increasingly valued, quantum key distribution technology, as an emerging key communication technology, is widely used in network security work with its unique true randomness, unbreakability, communication security and traceability. Free-space quantum key distribution, especially satellite-to-ground quantum key distribution, can effectively achieve global coverage of quantum key distribution. In the existing technology, the quantum channel and classical channel of free-space quantum key distribution are separated. The classical channel uses microwave data transmission. Since the microwave data transmission station and the ground optical station are not in the same location, the two cannot work at the same time, so real-time key extraction cannot be achieved. Key extraction needs to be processed offline afterwards, and due to the limitation of measurement and control resources, a key extraction takes several days to complete and form the final secure code.

[0036] However, in the process of transmitting quantum keys through space channels, due to the complexity of space channels, the influence of factors such as weather, and the instability of links, the synchronization signal may be lost, and there may be multiple errors and interruptions during data transmission. During the research and development process, the researchers found that in the relevant technology, since the distribution of quantum keys is transmitted through classical channels and quantum channels respectively, the receiving end cannot extract the quantum keys in real time and quickly based on the encrypted information. In addition, due to the instability of space channels, the quantum keys and encrypted information have a low code rate when transmitted through space channels.

[0037] In view of this, an embodiment of the present invention provides a real-time coding method for quantum key distribution in free space, which is characterized in that it is applied to a receiving end, including: in response to receiving a light quantum stream and a laser signal, using multiple measurement basis vectors to detect the light quantum stream to obtain a quantum original detection signal, wherein the light quantum stream and the laser signal are both obtained by a transmitting end through a laser communication channel in free space, and the laser signal includes multiple synchronous coding information and multiple modulation basis vectors; based on the multiple synchronous coding information and the multiple measurement basis vectors, multiple original key information data packets are generated and sent to the transmitting end through the laser communication channel, wherein the transmitting end is used to detect the light quantum stream according to the multiple modulation basis vectors and the multiple original key information data packets of the transmitting end. The method comprises the following steps: measuring multiple basis vectors in a key information data packet, obtaining basis vector comparison key data and basis vector comparison result information, processing the basis vector comparison key data using a low-density parity-check code to obtain verification data, and generating multiple intermediate key information data packets according to the verification data and the basis vector comparison result information, wherein the basis vector comparison result information includes privacy amplification information; in response to receiving multiple intermediate key information data packets, obtaining verification data from the multiple intermediate key information data packets; determining a check matrix of a low-density parity-check code according to the verification data, iteratively decoding the check data using the check matrix to obtain a verification quantum key; performing privacy amplification processing on the verification quantum key based on the quantum original detection signal and the privacy amplification information to obtain a target quantum key.

[0038] Figure 1 An application scenario diagram of a method for real-time coding of quantum key distribution in free space according to an embodiment of the present invention is shown.

[0039] like Figure 1 As shown, the application scenario according to this embodiment may include a first terminal device 101, a quantum lightpath channel 102, and a second terminal device 103. The first terminal device 101 is used to send encrypted information or a quantum key to the second terminal device 103 through the quantum lightpath channel 102.

[0040] The user can use the first terminal device 101 to interact with the second terminal device 103 through the quantum optical path channel 102 to obtain corresponding encrypted information, etc. The first terminal device 101 can be a quantum satellite that processes encrypted information or quantum keys.

[0041] The second terminal device 103 may be a ground optical device for processing encrypted information or quantum keys. The second terminal device 103 may analyze and process data such as encrypted information or quantum keys, and compare the processing result with the result obtained by the first terminal device 101 and feed it back through the quantum optical path channel 102.

[0042] It should be noted that the method for real-time coding of quantum key distribution in free space provided in the embodiment of the present invention can generally be executed by the first terminal device 101. Accordingly, the apparatus for real-time coding of quantum key distribution in free space provided in the embodiment of the present invention can generally be arranged in the first terminal device 101. The method for real-time coding of quantum key distribution in free space provided in the embodiment of the present invention can also be executed by a second terminal device 103 or a terminal device cluster different from the first terminal device 101. Accordingly, the apparatus for real-time coding of quantum key distribution in free space provided in the embodiment of the present invention can also be arranged in a second terminal device 103 or a terminal device cluster different from the first terminal device 101.

[0043] It should be understood that Figure 1 The number of first terminal devices, quantum light path channels and second terminal devices in the embodiment is only illustrative. According to the implementation requirements, there may be any number of first terminal devices, quantum light path channels and second terminal devices.

[0044] The following will be based on Figure 1 The scene described by Figure 2~Figure 5 The real-time coding method for quantum key distribution in free space according to an embodiment of the invention is described in detail.

[0045] Figure 2 A flow chart of a method for real-time coding of free-space quantum key distribution applied to a receiving end according to an embodiment of the present invention is shown.

[0046] like Figure 2 As shown, the real-time coding method for free-space quantum key distribution applied to a receiving end of this embodiment includes operations S210 to S250.

[0047] In operation S210, in response to receiving a photon flow and a laser signal, the photon flow is detected using a plurality of measurement basis vectors to obtain a quantum original detection signal.

[0048] According to an embodiment of the present invention, both the optical quantum flow and the laser signal are obtained by the transmitter through a laser communication channel in free space, and the laser signal includes multiple synchronous coding information and multiple modulation basis vectors.

[0049] According to an embodiment of the present invention, a light quantum stream is composed of multiple light quantum states, each light quantum state represents a key bit, and the transmitting end generates multiple random quantum keys, and modulates the multiple random quantum keys using multiple modulation basis vectors to obtain multiple modulated light quantum states.

[0050] According to an embodiment of the present invention, by using laser signals as a carrier for encrypted information transmission, a laser communication link, i.e., a laser communication channel, is established between the satellite-ground station (receiving end) and the satellite (transmitting end). The characteristics of laser signal communication such as high communication capacity, small terminal size, light weight, anti-interference and good confidentiality are utilized to improve the efficiency and security of quantum key distribution.

[0051] According to an embodiment of the present invention, the transmitting end transmits both the optical quantum stream and the laser signal through the laser communication channel in free space by multiplexing the laser communication channel. In the laser communication channel, the optical quantum stream and the laser signal can be switched and transmitted at high speed according to time separation, or can be transmitted sequentially according to a predetermined order, thereby realizing the switching transmission of the optical quantum stream carrying quantum key information and the laser signal carrying encryption information, thereby improving the utilization rate of optical fiber resources.

[0052] For example, the predetermined order can be set to transmit the light quantum stream first and then the laser signal. The transmission time period can also be set to 10s to quickly switch the transmission of the light quantum stream carrying quantum key information and the laser signal carrying encryption information.

[0053] According to an embodiment of the present invention, the synchronization coding information may include a synchronization coding sequence number and a check code. After receiving the laser signal sent by the transmitting end, the receiving end can process the synchronization accuracy and stability between the transmitting end and the receiving end according to the check code, thereby eliminating the need to use additional synchronization light for synchronization between the transmitting end and the receiving end, thereby improving the processing efficiency of the transmitting end and the receiving end, and improving the integration between the transmitting end and the receiving end.

[0054] According to an embodiment of the present invention, the receiving end randomly uses multiple measurement basis vectors to detect each light quantum state in the received light quantum flow, and then uses multiple modulation basis vectors in the laser signal to perform basis vector comparison to obtain the screening key of the receiving end, that is, the quantum original detection signal.

[0055] According to an embodiment of the present invention, the multiple modulation basis vectors at the transmitting end and the multiple measurement basis vectors at the receiving end are not completely the same basis vectors.

[0056] In operation S220, a plurality of original key information data packets are generated according to a plurality of synchronization coding information and a plurality of measurement basis vectors, and the plurality of original key information data packets are sent to a transmitting end through a laser communication channel.

[0057] According to an embodiment of the present invention, the transmitting end is used to perform basis vector comparison based on multiple modulation basis vectors of the transmitting end and multiple measurement basis vectors in multiple original key information data packets to obtain basis vector comparison key data and basis vector comparison result information, process the basis vector comparison key data using a low-density parity-check code to obtain verification data, and generate multiple intermediate key information data packets based on the verification data and the basis vector comparison result information, and the basis vector comparison result information includes privacy amplification information.

[0058] According to an embodiment of the present invention, the receiving end obtains multiple synchronization coding information from the laser signal, and then generates a key information data packet based on multiple measurement basis vectors, divides the key information data packet into multiple data packets and embeds multiple synchronization coding information into each data packet to generate an original key information data packet.

[0059] According to an embodiment of the present invention, since multiple original key information data packets are generated, even if one of the original key information data packets is lost during the transmission of the multiple original key information data packets, the impact on subsequent key extraction and generation can be reduced.

[0060] In operation S230, in response to receiving the plurality of intermediate key information data packets, verification data is acquired from the plurality of intermediate key information data packets.

[0061] According to an embodiment of the present invention, after processing the received multiple original key information data packets, the sending end generates multiple intermediate key information data packets, and sends the multiple intermediate key information data packets to the receiving end through the laser communication channel.

[0062] According to an embodiment of the present invention, the verification data may include a coding screening key obtained by the sending end after processing the basis vector comparison key data using a low-density parity-check code, and may also include a bit error rate calculated by the sending end, but is not limited to the above information.

[0063] According to an embodiment of the present invention, the check data may be used to assist the receiving end in performing error correction and interleaving processing.

[0064] According to an embodiment of the present invention, each intermediate key information data packet includes some verification data, and the receiving end obtains all the verification data from multiple intermediate key information data packets, so as to use the verification data to perform quantum key error correction and interleaving, improve the accuracy and reliability of data transmission, and thus ensure the real-time and coding rate of quantum key distribution.

[0065] In operation S240, a check matrix of a low-density parity-check code is determined according to the check data, and the check matrix is ​​used to iteratively decode the check data to obtain a verification quantum key.

[0066] According to an embodiment of the present invention, the verification quantum key can be characterized as the original quantum key sent by the transmitter obtained by iteratively decoding the coded screening key in the verification data using a check matrix.

[0067] According to an embodiment of the present invention, both the transmitting end and the receiving end can use LDPC (Low Density Parity Check) error correction technology to correct the received verification data, so that in the process of data transmission other than the optical quantum flow, only one encrypted data interaction is performed between the receiving end and the transmitting end, that is, the receiving end sends multiple original key information data packets to the transmitting end, and the transmitting end sends multiple intermediate key information data packets obtained after processing to the receiving end. The communication cost of quantum key distribution is reduced through a single interaction, thereby improving the real-time and efficiency of quantum key distribution.

[0068] According to an embodiment of the present invention, in the process of iterative decoding of the check data using the check matrix, the check data can be iterated dozens of times, so that the calculation amount and memory throughput of the receiving end are both high. A high-speed memory with a read and write rate of 200MB / s can be used, while a quantum key distribution system with an average bit error rate of about 2% can only reach a maximum raw key processing rate of about 300KB / s. For systems with a modulation frequency of gigahertz, if a higher raw key processing capability is required, the parallel computing technology of the field programmable gate array can be used to increase the processing speed, that is, multiple LDPC error correction processing units are used to simultaneously process the coded key. In the case of using multiple LDPC error correction processing units to simultaneously process the coded key, more resources need to be added, such as doubling the number of memories.

[0069] In operation S250, based on the quantum original detection signal and the privacy amplification information, the verification quantum key is privacy amplified to obtain the target quantum key.

[0070] According to an embodiment of the present invention, based on the quantum original detection signal and the privacy amplification information, part of the key information is obtained from the decoded verification quantum key and the quantum original detection signal for verification and comparison to obtain a verification result. According to the verification result, it can be determined whether the transmission of the quantum key is eavesdropped. At the same time, the bit error rate can be calculated again according to the verification result. When the bit error rate calculated at the receiving end exceeds a predetermined security threshold, it indicates that the quantum key transmission has failed, and the next quantum key transmission can be waited for. When the bit error rate calculated at the receiving end does not exceed the predetermined security threshold, it indicates that the quantum key transmission is successful, the verification quantum key and the privacy amplification are processed to obtain the target quantum key.

[0071] According to an embodiment of the present invention, after obtaining the target quantum key, a systematic key pool management may be performed on the target quantum key.

[0072] According to an embodiment of the present invention, the target quantum key is privacy-amplified in order to further reduce potential information leakage and improve the security of the key. During the privacy amplification process, a specific algorithm, such as a hash function, can be used to enhance the privacy of the key.

[0073] According to an embodiment of the present invention, in response to receiving a light quantum stream carrying quantum key information and a laser signal carrying encryption information sent from a laser communication channel at a transmitting end, a receiving end detects the light quantum stream using multiple measurement basis vectors in the receiving end to obtain a quantum original detection signal. The receiving end generates multiple original key information data packets according to multiple measurement basis vectors and multiple synchronous coding information in the laser signal, and then sends the multiple original key information data packets to the transmitting end through the laser communication channel. The transmitting end processes the multiple original key information data packets to generate multiple intermediate key information data packets. The transmitting end sends the multiple intermediate key information data packets to the receiving end. The receiving end extracts verification data from the received multiple intermediate key information data packets in response to the received multiple intermediate key information data packets, determines a check matrix of a low-density parity check code according to the check data, performs multiple iterative decoding processing on the check data using the check matrix to obtain a verification quantum key, and performs privacy amplification processing on the verification quantum key based on the quantum original detection signal and the privacy amplification information to obtain a target quantum key. It realizes the high-efficiency real-time extraction of quantum key distribution in the environment of unreliable channels, and improves the coding rate of quantum keys through multiple iterations of error correction, reduces the impact of the environment of free space transmission channels on quantum key distribution, and thus improves the reliability and stability of quantum key distribution. Furthermore, by utilizing the high-speed transmission capability and high communication capacity of laser communication and transmitting optical quantum streams and laser signals through laser communication channels, the transmission efficiency and security of encrypted information are improved, and the utilization rate of optical fiber resources is improved. Furthermore, through multiple data packet transmissions, even if data packet loss occurs during the transmission process of unreliable channels, it will not affect the generation and extraction of other keys, thereby improving the transmission efficiency and transmission performance of the system, and realizing real-time coding of quantum key distribution in free environments and unreliable channels with unstable links.

[0074] According to an embodiment of the present invention, in the process of quantum key distribution, by optimizing the quantum key extraction algorithm and process, low-density parity check error correction technology is used to perform error correction on the screened key, thereby reducing the number of interactions between the receiving end and the sending end, reducing the communication cost, and improving the security of interaction. In addition, since the quantum key distribution technology itself has true randomness, undecipherability, communication mode security and traceability, the security of the system is further enhanced.

[0075] According to the embodiments of the present invention, the real-time coding method for quantum key distribution in free space of the present application can be widely used in different transmission channels and communication scenarios, and has good scalability and adaptability. Whether it is between satellites and ground stations or between satellites, the real-time coding method for quantum key distribution in free space of the present application can provide stable and reliable quantum key distribution services.

[0076] According to an embodiment of the present invention, in response to receiving a light quantum flow and a laser signal, a plurality of measurement basis vectors are used to detect the light quantum flow to obtain a quantum original detection signal, including:

[0077] According to an embodiment of the present invention, in response to receiving a photon flow and a laser signal, a plurality of measurement basis vectors are used to detect the photon states in the photon flow to obtain a quantum original detection signal.

[0078] According to an embodiment of the present invention, after receiving a light quantum stream carrying quantum key information and a laser signal carrying encryption information, the receiving end randomly obtains multiple measurement basis vectors consistent with the number of light quantum states in the light quantum stream, and uses the multiple measurement basis vectors to detect the multiple light quantum states in the light quantum stream one by one to obtain a first initial quantum detection signal.

[0079] According to an embodiment of the present invention, each measurement basis vector and each modulation basis vector are compared and processed, and when the measurement basis vector and the modulation basis vector are consistent, the first initial quantum detection signal corresponding to the measurement basis vector is determined to be the quantum original detection signal.

[0080] According to an embodiment of the present invention, the receiving end obtains multiple modulation basis vectors used by the transmitting end to modulate the quantum key from the laser signal, performs basis vector comparison between the multiple measurement basis vectors and the multiple modulation basis vectors, and obtains the basis vector comparison result in the receiving end.

[0081] According to an embodiment of the present invention, the basis vector comparison result in the receiving end includes the measurement basis vectors and modulation basis vectors of those bits that are inconsistent, and the measurement basis vectors and modulation basis vectors of those bits that are consistent.

[0082] According to an embodiment of the present invention, based on the basis vector comparison result, the first initial quantum detection signal of the bit whose measurement basis vector and modulation basis vector are consistent is retained as the quantum original detection signal.

[0083] According to an embodiment of the present invention, in response to receiving a photon flow and a laser signal, a plurality of measurement basis vectors are used to detect the photon states in the photon flow to obtain a quantum original detection signal, and then each measurement basis vector and each modulation basis vector are compared and processed. When the measurement basis vector and the modulation basis vector are consistent, the first initial quantum detection signal corresponding to the measurement basis vector is determined to be the quantum original detection signal, thereby realizing detection of the photon flow by using a random measurement basis vector at the receiving end, and then performing basis vector comparison based on a plurality of measurement basis vectors and a plurality of modulation basis vectors, and accurately obtaining the quantum original detection signal at the receiving end according to the result of the basis vector comparison.

[0084] Figure 3 A flow chart of a method for sending multiple original key information data packets according to an embodiment of the present invention is shown.

[0085] like Figure 3 As shown, the method for sending multiple original key information data packets of this embodiment includes operations S310~S350.

[0086] According to an embodiment of the present invention, the synchronization coding information includes a synchronization coding sequence number and a check code.

[0087] According to an embodiment of the present invention, based on multiple synchronization coding information and multiple measurement basis vectors, multiple original key information data packets are generated and sent to a transmitting end through a laser communication channel, including:

[0088] In operation S310, a plurality of measurement basis vectors are packaged to obtain a first key information data packet.

[0089] According to an embodiment of the present invention, the receiving end packages multiple measurement basis vectors for demodulating multiple optical quantum states to obtain a first key information data packet containing all measurement basis vector information.

[0090] In operation S320, the first key information data packet is sub-packetized to obtain a plurality of intermediate original key information data packets with sequential numbers.

[0091] According to an embodiment of the present invention, the first key information data packet may be sub-packetized in sequence according to the capacity of the data packet, or the data packet may be sub-packetized randomly in sequence to obtain a plurality of intermediate original key information data packets with sequential numbers.

[0092] For example, the predetermined capacity of each sub-packet can be pre-set to 100MB, and the first key information data packet can be divided into multiple intermediate original key information data packets with sequential numbers and each having a capacity of 100MB. The first key information data packet can also be divided into 5 intermediate original key information data packets with inconsistent capacities.

[0093] According to an embodiment of the present invention, each intermediate original key information data packet carries a sequence number for subpackaging according to a subpackaging order.

[0094] In operation S330, multiple synchronization code serial numbers are matched with the sequence numbers of multiple intermediate original key information data packets to obtain a matching result.

[0095] According to an embodiment of the present invention, matching is performed based on the sequence number of the intermediate original key information data packet and the synchronization code sequence number to ensure that each intermediate original key information data packet matches a synchronization code sequence number.

[0096] For example, the sequence number of the first intermediate original key information data packet is 1, and the synchronization coding information with the synchronization coding sequence number 1 is determined from multiple synchronization coding information to match the first intermediate original key information data packet. The sequence number of the second intermediate original key information data packet is 2, and the synchronization coding information with the synchronization coding sequence number 2 is determined from multiple synchronization coding information to match the second intermediate original key information data packet.

[0097] In operation S340, based on the matching result, the synchronization coding information corresponding to the sequence number is embedded into the intermediate original key information data packet to obtain a plurality of original key information data packets with the synchronization coding information.

[0098] According to an embodiment of the present invention, by embedding the synchronization coding information corresponding to the sequence number into the intermediate original key information data packet, after the data packet is transmitted to the sending end, the sending end can determine whether all data packets have been received based on the synchronization coding sequence number in each original key information data packet.

[0099] In operation S350, a plurality of original key information data packets with synchronization coding information are sent to the sending end.

[0100] According to an embodiment of the present invention, the receiving end sends a plurality of original key information data packets with synchronization coding information to the sending end through a laser communication channel in free space, so that the sending end can perform subsequent quantum key extraction operations such as basis vector comparison and bit error rate calculation after receiving the plurality of original key information data packets with synchronization coding information.

[0101] According to an embodiment of the present invention, a first key information data packet is obtained by packaging multiple measurement basis vectors, the first key information data packet is subpacketized to obtain multiple intermediate original key information data packets with sequential numbers, multiple synchronization coding numbers are matched with the sequential numbers of multiple intermediate original key information data packets, and the synchronization coding information corresponding to the sequential numbers is embedded into the intermediate original key information data packet to obtain multiple original key information data packets with synchronization coding information, and multiple original key information data packets with synchronization coding information are sent to the sending end through a laser communication channel in free space, thereby realizing subpacketization of encrypted data information, so that multiple original key information data packets can be sent to the sending end at the same time, reducing the pressure of sending encrypted data on the receiving end and the pressure of receiving encrypted data on the sending end, improving the processing efficiency of the sending end and the receiving end, reducing the time cost spent on quantum key extraction, and improving the efficiency of quantum key distribution extraction, so that the sending end and the receiving end can check whether the received data is complete. Even if packet loss occurs during the encrypted data transmission process, it will not affect the subsequent transmission, extraction and generation of keys.

[0102] Figure 4 A flow chart of a method for acquiring verification data according to an embodiment of the present invention is shown.

[0103] like Figure 4 As shown, the method for sending multiple original key information data packets of this embodiment includes operations S410~S440.

[0104] According to an embodiment of the present invention, in response to receiving a plurality of intermediate key information packets, obtaining verification data from the plurality of intermediate key information packets includes:

[0105] In operation S410, in response to receiving a plurality of intermediate key information data packets, a synchronization code sequence number corresponding to each intermediate key information data packet is acquired.

[0106] According to an embodiment of the present invention, the sending end generates multiple intermediate key information data packets after processing the multiple received original key information data packets, and sends the multiple intermediate key information data packets to the receiving end, and the receiving end obtains the synchronization coding sequence number from each intermediate key information data packet.

[0107] According to an embodiment of the present invention, the intermediate key information data packet may include the basis vector comparison result, the syndrome, the security factor, the privacy amplification information and the verification data encoded by the coding matrix of the low-density parity-check code obtained after the sending end performs the basis vector comparison, but is not limited to the above data information.

[0108] In operation S420, the intermediate key information data packets are filled into the storage space according to the synchronization code sequence number corresponding to each intermediate key information data packet.

[0109] According to an embodiment of the present invention, the receiving end includes a plurality of storage spaces with space numbers.

[0110] According to an embodiment of the present invention, the receiving end may set a plurality of storage spaces with space numbers according to the total capacity and total number of intermediate key information data packets to be sent by the sending end.

[0111] According to an embodiment of the present invention, since the laser communication channel may be affected by the free space environment or noise, data loss may occur during data packet transmission. In order to improve reliability, the bandwidth of the quantum optical path channel (the bandwidth of the quantum optical path channel>155M / s transmission rate) and the large encrypted data transmission volume requirement (about 30 M / s) can be used to utilize the bandwidth of the quantum optical path channel. When the sending end does not perform the task of sending the next batch of optical quantum streams carrying quantum keys, multiple intermediate key information data packets can be repeatedly sent to the receiving end according to a predetermined frequency.

[0112] According to an embodiment of the present invention, the synchronization code sequence number corresponding to each intermediate key information data packet is matched with the space number of each storage space, and when the matches are consistent, the intermediate key information data packet is stored in the storage space.

[0113] For example, there are 5 intermediate key information data packets in total, and the synchronization code sequence number of the second intermediate key information data packet is confirmed to be 3, and the second intermediate key information data packet is stored in the storage space with space number 3.

[0114] In operation S430, based on the space number of the storage space, the synchronization code sequence number corresponding to the intermediate key data packet stored in the storage space is verified to obtain a verification result.

[0115] According to an embodiment of the present invention, after all received intermediate key information data packets are stored in the storage space, the synchronization coding serial number corresponding to the intermediate key data packet stored in the storage space is verified to check whether the space number of each storage space and the synchronization coding serial number of the stored intermediate key information data packet are consistent.

[0116] According to an embodiment of the present invention, when the space number of each storage space and the synchronization coding serial number of the stored intermediate key information data packet are consistent, the verification result indicates that the verification is passed; when the space number of each storage space and the synchronization coding serial number of the stored intermediate key information data packet are inconsistent, the verification result indicates that the verification is failed.

[0117] In operation S440, when the verification result indicates that the verification is passed and the number of intermediate key information data packets stored in the storage space meets a first preset condition, verification data is obtained from the plurality of intermediate key information data packets.

[0118] According to an embodiment of the present invention, the sending end may send the total number of intermediate key information packets to the receiving end while sending multiple intermediate key information packets to the receiving end. The first preset condition may be represented by the total number of intermediate key information packets at the receiving end.

[0119] According to an embodiment of the present invention, when the verification result indicates that the verification has passed, it is checked whether an intermediate key information data packet is stored in each storage space.

[0120] According to an embodiment of the present invention, in the case where an intermediate key information data packet is stored in each storage space, verification data is obtained from multiple intermediate key information data packets.

[0121] According to an embodiment of the present invention, when the intermediate key information data packet stored in each storage space does not meet the first preset condition, multiple intermediate key information data packets are continuously received until the intermediate key information data packet stored in the storage space meets the first preset condition.

[0122] According to an embodiment of the present invention, when the intermediate key information data packets are not stored in all storage spaces, the sending end continues to send the intermediate key information data packets, and the receiving end continuously refreshes the storage space by filling in blanks until each storage space contains an intermediate key information data packet. In units of data frames, during the process of the receiving end continuously receiving the intermediate key information data packets, as long as the data frame is correct once, it can be confirmed that the reception is successful, that is, the first preset condition is met.

[0123] According to an embodiment of the present invention, the sending end can send multiple groups of intermediate key information data packets to the receiving end, and one group can include multiple intermediate key information data packets. When the sending end needs to send the next group of intermediate key information data packets to the receiving end, the receiving end can pre-check whether the intermediate key information data packets in the storage space meet the first preset condition. If the first preset condition is still not met, all the intermediate key information data packets in all the storage spaces are discarded, and the transmission of the next group of intermediate key information data packets continues.

[0124] According to an embodiment of the present invention, before the sending end needs to send an optical quantum stream carrying a new quantum key to the receiving end, the receiving end can pre-check whether the intermediate key information data packet in the storage space meets the first preset condition. If the first preset condition is still not met, all intermediate key information data packets in all storage spaces are discarded, and the transmission of the optical quantum stream carrying the new quantum key is continued.

[0125] According to an embodiment of the present invention, in response to receiving a plurality of intermediate key information data packets, a receiving end obtains a synchronization coding sequence number corresponding to each intermediate key information data packet, fills the intermediate key information data packet into a storage space according to the synchronization coding sequence number corresponding to each intermediate key information data packet, verifies the synchronization coding sequence number corresponding to the intermediate key information data packet stored in the storage space based on the space number of the storage space, and obtains a verification result. When the verification result indicates that the verification is passed and the number of intermediate key information data packets stored in the storage space meets a first preset condition, verification data is obtained from the plurality of intermediate key information data packets. When the intermediate key information data packets stored in each storage space do not meet the first preset condition, the plurality of intermediate key information data packets are continuously received until the intermediate key information data packets stored in the storage space meet the first preset condition, thereby achieving retransmission and discarding of the plurality of intermediate key information data packets. By continuously receiving the intermediate key information data packets, it is only necessary to make the intermediate key information data packet stored in the storage space meet the first preset condition once to confirm successful reception, thereby avoiding the loss of data packets during transmission due to the environmental influence of the free space, and improving the reliability and stability of the free space laser communication channel transmission.

[0126] According to an embodiment of the present invention, a check matrix is ​​determined according to check data, and the check matrix of a low-density parity check code is used to iteratively decode the check data to obtain a verification quantum key, including:

[0127] According to an embodiment of the present invention, after receiving the verification data, the receiving end can store the verification data in the on-chip FIFO (First In, First Out, data structure or buffer management method) of the receiving end. When decoding and error correction are required, the receiving end can directly retrieve the verification data from the on-chip FIFO.

[0128] According to an embodiment of the present invention, before performing LDPC error correction on the verification data, the receiving end may first perform deinterleaving processing on the verification data so as to obtain a more accurate verification of the quantum key, improve the security and reliability of communication, and reduce the bit error rate.

[0129] According to an embodiment of the present invention, a coding matrix and a coding key are obtained from verification data.

[0130] According to an embodiment of the present invention, the coding key can be characterized as a key obtained by encoding key data using a coding matrix by a transmitter according to a low-density parity-check code error correction basis vector comparison.

[0131] According to an embodiment of the present invention, a check matrix is ​​determined according to a coding matrix.

[0132] According to an embodiment of the present invention, the transpose multiplication of the check matrix and the encoding matrix is ​​equal to zero, so that the check matrix of the encoding key used for decoding error correction is determined according to the encoding matrix.

[0133] According to an embodiment of the present invention, according to the state of each quantum bit in the encoded key, the key probability likelihood ratio is used to replace the non-zero state in the check matrix to construct a variable matrix.

[0134] According to the embodiment of the present invention, the key probability likelihood ratio is obtained by performing log-likelihood ratio calculation on the key prior probability.

[0135] According to an embodiment of the present invention, based on the preset 0-state key prior probability and 1-state key prior probability, the key probability likelihood ratios corresponding to each state are calculated using the log-likelihood ratio. When the probability that the quantum key is in the 0 state is greater, the 0-state key probability likelihood ratio is a positive number, and the 1-state key probability likelihood ratio is a negative number. When the probability that the quantum key is in the 1 state is greater, the 0-state key probability likelihood ratio is a negative number, and the 1-state key probability likelihood ratio is a positive number.

[0136] According to an embodiment of the present invention, the receiving end determines the key probability likelihood ratio corresponding to the state of each quantum bit in the received encoded key, replaces element 1 in the check matrix with the element value of the 1-state key probability likelihood ratio, and leaves element 0 in the check matrix unchanged, thereby obtaining an intermediate matrix.

[0137] According to an embodiment of the present invention, according to the positive or negative sign of the key probability likelihood ratio corresponding to the state of each quantum bit, the corresponding positive or negative sign is added to each element in the intermediate matrix to obtain a variable matrix.

[0138] For example, when the probability of the quantum key being in the 0 state is greater, the probability likelihood ratio of the 0 state key is a positive number, and the probability likelihood ratio of the 1 state key is a negative number. If the first element in the encoded key is 1, then the elements in the first column of the intermediate matrix are all negative values. If the second element in the encoded key is 0, then the elements in the second column of the intermediate matrix are all positive values.

[0139] According to an embodiment of the present invention, a first calculation operation is performed on the variable matrix and the key probability likelihood ratio to obtain a state probability corresponding to the encoding key.

[0140] According to an embodiment of the present invention, the variable matrix is ​​processed according to a predetermined rule to obtain a probability matrix, and the predetermined rule is characterized by performing logarithmic calculation on non-zero elements in the variable matrix. 3, the third element of the first row is 0, then the first element in the first row is calculated by using the second element and the fourth element to perform logarithmic calculation to obtain the first element of the first row in the probability matrix. The third element of the first row in the probability matrix is ​​consistent with the third element of the first row of the variable matrix, both of which are 0 elements. The other rows in the matrix are calculated as above to obtain the final probability matrix.

[0141] According to an embodiment of the present invention, a first calculation operation is performed on the probability matrix to obtain a state probability corresponding to the encoded key. The first calculation operation is to sum each column in the probability matrix, and then use the key probability likelihood ratio corresponding to the state of each quantum bit in the encoding matrix to add the sum of each column to obtain a positive and negative state probability corresponding to the encoded key.

[0142] According to an embodiment of the present invention, a state determination operation is performed on each quantum bit in the encoded key according to the key probability likelihood ratio to obtain an intermediate encoded key.

[0143] According to an embodiment of the present invention, an intermediate coding key is obtained based on the positive and negative state probabilities corresponding to the coding key and the 0 state or 1 state corresponding to the positive and negative key probability likelihood ratio. For example, if the 0 state key probability likelihood ratio is a positive number, the 1 state key probability likelihood ratio is a negative number, and the first state probability among the positive and negative state probabilities corresponding to the coding key is a negative value, then the first element of the intermediate coding key is determined to be 1; if the first state probability among the positive and negative state probabilities corresponding to the coding key is a positive value, then the first element of the intermediate coding key is determined to be 0.

[0144] According to an embodiment of the present invention, a verification operation is performed on the intermediate coding key using a check matrix. When the verification result does not meet the second preset condition, the variable matrix is ​​iteratively updated to obtain an updated variable matrix. The first calculation operation, state determination operation and verification operation are re-executed on the updated variable matrix until the verification result meets the second preset condition.

[0145] According to an embodiment of the present invention, the second preset condition represents that a matrix result obtained by calculation using a check matrix and an intermediate encoding key is a zero vector.

[0146] According to an embodiment of the present invention, calculations are performed using a check matrix and an intermediate coding key. When the matrix result obtained is not a zero vector, the variable matrix and the probability matrix are iteratively updated to obtain updated variable matrix and probability matrix, and subsequent operations are performed in sequence until the verification result meets the second preset condition.

[0147] According to an embodiment of the present invention, an update number threshold may be set for the number of iterative updates. If the update number threshold is exceeded and the verification result still cannot meet the second preset condition, the decoding fails.

[0148] According to an embodiment of the present invention, when the verification result satisfies the second preset condition, the intermediate encoding key is determined to be a verification quantum key.

[0149] According to an embodiment of the present invention, the receiving end performs random sampling monitoring and calculation based on the verification quantum key and the first quantum key to obtain the receiving bit error rate of the receiving end. The bit error rate threshold can be set. When the receiving bit error rate exceeds the bit error rate threshold, it is confirmed that the decoding has failed, otherwise the decoding is successful.

[0150] According to an embodiment of the present invention, when the decoding is successful, the decoding result can be stored in the on-chip cache FIFO to provide key data for subsequent privacy amplification.

[0151] According to an embodiment of the present invention, since a coding matrix and a coding key are obtained from verification data, a check matrix is ​​determined according to the coding matrix, and according to the state of each quantum bit in the coding key, a non-zero state in the check matrix is ​​replaced by a key probability likelihood ratio to construct a variable matrix, a first calculation operation is performed on the variable matrix and the key probability likelihood ratio to obtain a state probability corresponding to the coding key, a state determination operation is performed on each quantum bit in the coding key according to the key probability to obtain an intermediate coding key, and a verification operation is performed on the intermediate coding key using the check matrix. When the verification result does not meet the second preset condition, the variable matrix is ​​iteratively updated to obtain an updated variable matrix, and the first calculation operation, the state determination operation and the verification operation are re-performed on the updated variable matrix until the verification result meets the second preset condition. When the verification result meets the second preset condition, it is determined that the intermediate coding key is a verification quantum key, and decoding and error correction processing of the coded screening key received by the receiving end is realized, thereby obtaining an accurate screening key, and according to the set number of iterations and the bit error rate threshold, it can help to judge whether the decoding and error correction of the receiving end are successful, and further improve the reliability and security of the real-time coding system of free space quantum key distribution.

[0152] According to an embodiment of the present invention, based on the quantum original detection signal and the privacy amplification information, the verification quantum key is subjected to privacy amplification processing to obtain the target quantum key, including:

[0153] According to an embodiment of the present invention, privacy amplification information is obtained from basis vector comparison result information.

[0154] According to an embodiment of the present invention, the privacy amplification information may include a predetermined privacy amplification length.

[0155] According to an embodiment of the present invention, the verification quantum key and the quantum original detection signal are compared to obtain a comparison result. According to an embodiment of the present invention, when the comparison result is characterized as the verification quantum key and the quantum original detection signal being consistent, a hash function is used to perform privacy amplification processing on the verification quantum key according to the privacy amplification information to obtain a target quantum key.

[0156] According to an embodiment of the present invention, when the comparison result is characterized as inconsistency between the verified quantum key and the quantum original detection signal, the quantum original detection signal is discarded and the comparison result is sent to the transmitting end.

[0157] According to an embodiment of the present invention, the verification quantum key may include a check code, and the quantum original detection signal may include a measurement code. The check code and the measurement code are compared. If the check code and the measurement code are consistent, it means that the transmission of the quantum key has not been eavesdropped. The quantum key other than the check code in the verification quantum key is used as the target quantum key, and key pool management is performed. If the check code and the measurement code are inconsistent, it means that the transmission of the quantum key has been eavesdropped. The receiving end may discard the verification quantum key and the quantum original detection signal, and the sending end may send the key extraction result to facilitate the adjustment of the transmission of the quantum key to improve security.

[0158] According to an embodiment of the present invention, privacy amplification information is obtained from basis vector comparison result information, and the verification quantum key and the quantum original detection signal are compared. When the verification quantum key and the quantum original detection signal are compared and consistent, the verification quantum key is privacy amplified according to the privacy amplification information to obtain the target quantum key. When the comparison result is characterized as an inconsistency between the verification quantum key and the quantum original detection signal, the quantum original detection signal is discarded and the comparison result is sent to the sending end, thereby realizing the extraction of the target quantum key from the screened quantum key at the receiving end, and further improving the coding rate and processing efficiency of the quantum key.

[0159] Figure 5 A flow chart of a method for real-time coding of quantum key distribution applicable to free space applied to a transmitting end according to an embodiment of the present invention is shown.

[0160] like Figure 5 As shown, the method for sending multiple original key information data packets of this embodiment includes operations S510~S540.

[0161] In operation S510, a light quantum flow and a laser signal are transmitted to a receiving end through a laser communication channel in free space.

[0162] According to an embodiment of the present invention, the laser signal includes a plurality of synchronous coding information and a plurality of modulation basis vectors.

[0163] According to an embodiment of the present invention, a transmitting end randomly generates a string of original quantum keys, modulates the original quantum keys using multiple modulation basis vectors, and obtains multiple optical quantum states, which form an optical quantum flow.

[0164] According to the embodiment of the present invention, the transmitting end switches and transmits both the optical quantum flow and the laser signal alternately through the quantum light path channel, thereby improving the utilization rate of the optical fiber resources.

[0165] According to an embodiment of the present invention, the quantum laser at the transmitting end can reach a modulation frequency of GHz. The high-speed random numbers obtained from the random number generator are used to generate modulated light quantum states and need to be stored locally. Random number storage requires high throughput and storage depth. Each light quantum state requires 8-bit random number modulation. Calculated at a GHz modulation frequency, the data processing speed during modulation needs to be 1GB / s, so that data processing can be implemented in an ASIC (Application-Specific Integrated Circuit, integrated circuit). FPGA chips can also be used in conjunction with Serdes (Serializer / Deserializer, high-speed data transmission) technology to parallelize serial data and reduce the time frequency. Among them, 4 bits out of 8 bits need to be temporarily stored until the basis vector alignment step is completed, so a storage rate of at least 500MB / s is required. From storage to basis vector comparison, two steps need to be completed: the downlink of the optical quantum state and the reception of the original key. That is, the time for one round trip of data. Calculated based on the high-orbit satellite transmission distance of 30,000 kilometers, the round-trip photon transmission time alone takes about 200ms, including the laser communication data processing time, such as addition and deinterleaving, scrambling, RS encoding and decoding, etc., at least 300ms of random numbers need to be stored, that is, 150MB of data; at the same time, since the modulation process is a continuous flow process, the modulation process will not wait for the previous batch of data to be processed before continuing the modulation, so the memory needs at least a ping-pong mode, which requires at least more than 300MB of high-speed storage space, so that high-speed and large-capacity DDR chips can be used for batch storage.

[0166] In operation S520, in response to receiving multiple original key information data packets, basis vector comparison key data and basis vector comparison result information are obtained according to multiple modulation basis vectors of the transmitter and multiple measurement basis vectors in the multiple original key information data packets.

[0167] According to an embodiment of the present invention, a plurality of original key information data packets are transmitted via a laser communication channel.

[0168] According to an embodiment of the present invention, a sending end receives multiple original key information data packets with synchronization coding information. There may also be multiple cache spaces in the sending end, each cache space may have a space number, and the synchronization coding sequence number in each original key information data packet and the space number of the cache space are matched and stored one by one. The original key information data packet in the cache space of the sending end can be judged to determine whether the synchronization coding sequence number and the space number are consistent, and whether each cache space stores the original key information data packet, so as to facilitate the judgment of whether all data packets have been received and perform subsequent operations such as continuous reception.

[0169] According to an embodiment of the present invention, the transmitting end performs basis vector comparison based on the modulation basis vector and multiple measurement basis vectors received from the receiving end to obtain the screening key of the transmitting end, that is, the basis vector comparison key data, and can use the sampling detection method to calculate the bit error rate of the receiving end.

[0170] In operation S530, the basis vector comparison key data is processed using a low-density parity-check code to obtain verification data, and a plurality of intermediate key information data packets are generated according to the verification data and basis vector comparison result information.

[0171] According to an embodiment of the present invention, before the transmitter uses the LDPC coding matrix to encode the basis vector comparison key data, it can first interleave the basis vector comparison key data to improve the transmission security and reliability.

[0172] According to an embodiment of the present invention, the transmitting end selects an LDPC coding matrix to encode the basis vector comparison key data according to the bit error rate calculated by the on-board payload to obtain the coding key.

[0173] According to an embodiment of the present invention, verification data is generated according to the syndrome, the security factor, the encoding key and the encoding matrix, but is not limited to the above information.

[0174] According to an embodiment of the present invention, the verification data and basis vector comparison result information are packetized to obtain a plurality of intermediate key information data packets, and the synchronization coding information is embedded into each intermediate key information data packet in sequence.

[0175] In operation S540, a plurality of intermediate key information data packets are sent to a receiving end through a laser communication channel.

[0176] According to an embodiment of the present invention, a plurality of intermediate key information data packets are sent to a receiving end via a laser communication channel.

[0177] According to an embodiment of the present invention, by sending a light quantum stream and a laser signal to a receiving end through a laser communication channel in free space, in response to receiving multiple original key information data packets, basis vector comparison key data and basis vector comparison result information are obtained according to multiple modulation basis vectors of the sending end and multiple measurement basis vectors in the multiple original key information data packets, the basis vector comparison key data are processed using a low-density parity check code to obtain verification data, and multiple intermediate key information data packets are generated according to the verification data and the basis vector comparison result information, and the multiple intermediate key information data packets are sent to the receiving end through the laser communication channel, thereby realizing efficient real-time extraction of quantum key distribution, and encoding and transmitting the basis vector comparison key data by selecting a coding matrix according to the bit error rate, thereby improving the transmission security of encrypted information, utilizing the free space laser communication channel, combining the high-speed transmission capability and high communication capacity of laser communication, improving the utilization rate of optical fiber resources, realizing real-time coding and high coding rate of quantum key distribution in a free space environment and in a channel with unstable links, and real-time coding of quantum key distribution in an environmentally unreliable transmission channel.

[0178] Figure 6 A structural block diagram of a device for real-time coding of quantum key distribution in free space applied to a receiving end according to an embodiment of the present invention is shown.

[0179] like Figure 6 As shown, the device for real-time coding of quantum key distribution in free space applied to the receiving end of this embodiment includes: a detection module 610, a generation module 620, an acquisition module 630, a decoding module 640 and a privacy amplification module 650.

[0180] The detection module 610 is used to detect the light quantum flow using multiple measurement basis vectors in response to receiving the light quantum flow and the laser signal, and obtain the quantum original detection signal, wherein the light quantum flow and the laser signal are both obtained by the transmitter through the laser communication channel in free space, and the laser signal includes multiple synchronous coding information and multiple modulation basis vectors. The detection module 610 can be used to perform the operation S210 described above, which will not be repeated here.

[0181] The generation module 620 is used to generate multiple original key information data packets based on multiple synchronous coding information and multiple measurement basis vectors, and send the multiple original key information data packets to the transmitter through the laser communication channel, wherein the transmitter is used to obtain basis vector comparison key data and basis vector comparison result information based on multiple modulation basis vectors of the transmitter and multiple measurement basis vectors in the multiple original key information data packets, process the basis vector comparison key data using a low-density parity check code to obtain verification data, and generate multiple intermediate key information data packets based on the verification data and the basis vector comparison result information, wherein the basis vector comparison result information includes privacy amplification information. The generation module 620 can be used to perform the operation S220 described above, which will not be repeated here.

[0182] The acquisition module 630 is used to acquire verification data from the multiple intermediate key information data packets in response to receiving the multiple intermediate key information data packets. The acquisition module 630 can be used to perform the operation S230 described above, which will not be described in detail here.

[0183] The decoding module 640 is used to determine the check matrix of the low-density parity check code according to the check data, and use the check matrix to iteratively decode the check data to obtain the verification quantum key. The decoding module 640 can be used to perform the operation S240 described above, which will not be repeated here.

[0184] The privacy amplification module 650 is used to perform privacy amplification processing on the verification quantum key based on the quantum original detection signal and the privacy amplification information to obtain the target quantum key. The privacy amplification module 650 can be used to perform the operation S250 described above, which will not be described in detail here.

[0185] According to an embodiment of the present invention, the detection module 610 includes: a first detection submodule and a first comparison submodule.

[0186] The first detection submodule is used to detect the photon state in the photon flow using multiple measurement basis vectors in response to receiving the photon flow and the laser signal, so as to obtain a first initial quantum detection signal.

[0187] The first comparison submodule is used to compare each measurement basis vector and each modulation basis vector, and when the measurement basis vector and the modulation basis vector are consistent, the first initial quantum detection signal corresponding to the measurement basis vector is determined as the quantum original detection signal.

[0188] According to an embodiment of the present invention, the generating module 620 includes: a first packing submodule, a first subpackaging submodule, a first matching submodule, a first embedding submodule and a first sending submodule.

[0189] The first packing submodule is used to pack a plurality of measurement basis vectors to obtain a first key information data packet.

[0190] The first packet sub-module is used to perform packet processing on the first key information data packet to obtain a plurality of intermediate original key information data packets with sequential numbers.

[0191] The first matching submodule is used to match the multiple synchronous coding serial numbers with the sequential numbers of the multiple intermediate original key information data packets to obtain a matching result.

[0192] The first embedding submodule is used to embed the synchronization coding information corresponding to the sequence number into the intermediate original key information data packet based on the matching result, so as to obtain multiple original key information data packets with synchronization coding information.

[0193] The first sending submodule is used to send a plurality of original key information data packets with synchronous coding information to a sending end.

[0194] According to an embodiment of the present invention, the acquisition module 630 includes: a first acquisition submodule, a first filling submodule, a first checking submodule and a second acquisition submodule.

[0195] The first acquisition submodule is used to acquire the synchronization code sequence number corresponding to each intermediate key information data packet in response to receiving multiple intermediate key information data packets.

[0196] The first filling submodule is used to fill the intermediate key information data packet into the storage space according to the synchronous coding sequence number corresponding to each intermediate key information data packet, wherein the receiving end includes a plurality of storage spaces with space numbers.

[0197] The first verification submodule is used to verify the synchronization code sequence number corresponding to the intermediate key data packet stored in the storage space based on the space number of the storage space to obtain a verification result.

[0198] The second acquisition submodule is used to acquire verification data from the plurality of intermediate key information data packets when the verification result indicates that the verification is passed and the number of intermediate key information data packets stored in the storage space meets a first preset condition.

[0199] According to an embodiment of the present invention, the acquisition module 630 further includes: a first continuous receiving submodule.

[0200] The first continuous receiving submodule is used to continuously receive multiple intermediate key information data packets when the intermediate key information data packets stored in each storage space do not meet the first preset condition until the intermediate key information data packets stored in the storage space meet the first preset condition.

[0201] According to an embodiment of the present invention, the decoding module 640 includes: a third acquisition submodule, a first determination submodule, a first replacement submodule, a first calculation submodule, a first judgment submodule, a first verification submodule and a second determination submodule.

[0202] The third acquisition submodule is used to obtain the encoding matrix and the encoding key from the verification data.

[0203] The first determination submodule is used to determine the check matrix of the low-density parity-check code according to the encoding matrix.

[0204] The first replacement submodule is used to replace the non-zero state in the check matrix using the key probability likelihood ratio according to the state of each quantum bit in the encoded key, so as to construct a variable matrix, wherein the key probability likelihood ratio is obtained by calculating the log-likelihood ratio of the key prior probability.

[0205] The first calculation submodule is used to perform a first calculation operation on the variable matrix and the key probability likelihood ratio to obtain a state probability corresponding to the encoding key.

[0206] The first determination submodule is used to perform a state determination operation on each quantum bit in the coded key according to the key probability likelihood ratio to obtain an intermediate coded key.

[0207] The first verification submodule is used to perform a verification operation on the intermediate coding key using a check matrix. When the verification result does not meet the second preset condition, the variable matrix is ​​iteratively updated to obtain an updated variable matrix, and the first calculation operation, state determination operation and verification operation are re-executed on the updated variable matrix until the verification result meets the second preset condition, wherein the second preset condition represents that the matrix result obtained by calculation using the check matrix and the intermediate coding key is a zero vector.

[0208] The second determination submodule is used to determine that the intermediate encoding key is a verification quantum key when the verification result meets the second preset condition.

[0209] According to an embodiment of the present invention, the privacy amplification module 650 includes: a fourth acquisition submodule, a second comparison submodule, a first privacy amplification submodule and a first feedback submodule.

[0210] The fourth acquisition submodule is used to obtain privacy amplification information from the basis vector comparison result information.

[0211] The second comparison submodule is used to compare the verification quantum key and the quantum original detection signal to obtain a comparison result.

[0212] The first privacy amplification submodule is used to perform privacy amplification processing on the verification quantum key according to the privacy amplification information to obtain the target quantum key when the comparison result is characterized as the verification quantum key and the quantum original detection signal are consistent.

[0213] The first feedback submodule is used to discard the quantum original detection signal and send the comparison result to the sending end when the comparison result is characterized by inconsistency between the verification quantum key and the quantum original detection signal.

[0214] According to an embodiment of the present invention, any multiple modules of the detection module 610, the generation module 620, the acquisition module 630, the decoding module 640 and the privacy amplification module 650 can be combined into one module for implementation, or any one of the modules can be split into multiple modules. Alternatively, at least part of the functions of one or more of these modules can be combined with at least part of the functions of other modules and implemented in one module. According to an embodiment of the present invention, at least one of the detection module 610, the generation module 620, the acquisition module 630, the decoding module 640 and the privacy amplification module 650 can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application specific integrated circuit (ASIC), or can be implemented by hardware or firmware such as any other reasonable way of integrating or packaging the circuit, or implemented in any one of the three implementation methods of software, hardware and firmware or in an appropriate combination of any of them. Alternatively, at least one of the detection module 610, the generation module 620, the acquisition module 630, the decoding module 640 and the privacy amplification module 650 may be at least partially implemented as a computer program module, and when the computer program module is executed, the corresponding function may be performed.

[0215] Figure 7 A structural block diagram of a device for real-time coding of quantum key distribution in free space applied to a transmitting end according to an embodiment of the present invention is shown.

[0216] like Figure 7 As shown, the device for real-time coding of quantum key distribution in free space applied to the transmitting end of this embodiment includes: a first sending module 710, an obtaining module 720, a processing module 730 and a second sending module 740.

[0217] The first sending module 710 is used to send a light quantum flow and a laser signal to a receiving end through a laser communication channel in free space, wherein the laser signal includes multiple synchronous coding information and multiple modulation basis vectors. The first sending module 710 can be used to perform the operation S510 described above, which will not be described in detail here.

[0218] The obtaining module 720 is used to obtain the basis vector comparison key data and basis vector comparison result information in response to receiving multiple original key information data packets, according to multiple modulation basis vectors of the transmitting end and multiple measurement basis vectors in the multiple original key information data packets, wherein the multiple original key information data packets are transmitted through the laser communication channel, and the basis vector comparison result information includes the privacy amplification information. The obtaining module 720 can be used to perform the operation S520 described above, which will not be repeated here.

[0219] The processing module 730 is used to process the basis vector comparison key data using a low-density parity check code to obtain verification data, and generate multiple intermediate key information data packets according to the verification data and the basis vector comparison result information. The processing module 730 can be used to perform the operation S530 described above, which will not be repeated here.

[0220] The second sending module 740 is used to send multiple intermediate key information data packets to the receiving end through the laser communication channel. The second sending module 740 can be used to perform the operation S540 described above, which will not be described in detail here.

[0221] According to an embodiment of the present invention, any multiple modules of the first sending module 710, the obtaining module 720, the processing module 730 and the second sending module 740 can be combined into one module for implementation, or any one of the modules can be split into multiple modules. Alternatively, at least part of the functions of one or more of these modules can be combined with at least part of the functions of other modules and implemented in one module. According to an embodiment of the present invention, at least one of the first sending module 710, the obtaining module 720, the processing module 730 and the second sending module 740 can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application specific integrated circuit (ASIC), or can be implemented by hardware or firmware such as any other reasonable way of integrating or encapsulating the circuit, or implemented in any one of the three implementation methods of software, hardware and firmware or in any appropriate combination of any of them. Alternatively, at least one of the first sending module 710, the obtaining module 720, the processing module 730 and the second sending module 740 can be at least partially implemented as a computer program module, and when the computer program module is run, the corresponding function can be executed.

[0222] Figure 8 A block diagram of an electronic device applicable to a real-time coding method for quantum key distribution in free space according to an embodiment of the present invention is shown.

[0223] like Figure 8As shown, the electronic device according to an embodiment of the present invention includes a processor 801, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 802 or a program loaded from a storage part 808 to a random access memory (RAM) 803. The processor 801 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 801 may also include an onboard memory for caching purposes. The processor 801 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present invention.

[0224] In RAM 803, various programs and data required for the operation of the electronic device are stored. The processor 801, ROM 802 and RAM 803 are connected to each other via a bus 804. The processor 801 performs various operations of the method flow according to the embodiment of the present invention by executing the programs in ROM 802 and / or RAM 803. It should be noted that the program can also be stored in one or more memories other than ROM 802 and RAM 803. The processor 801 can also perform various operations of the method flow according to the embodiment of the present invention by executing the programs stored in the one or more memories.

[0225] According to an embodiment of the present invention, the electronic device may further include an input / output (I / O) interface 805, which is also connected to the bus 804. The electronic device 800 may further include one or more of the following components connected to the I / O interface 805: an input portion 806 including a keyboard, a mouse, etc.; an output portion 807 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage portion 808 including a hard disk, etc.; and a communication portion 809 including a network interface card such as a LAN card, a modem, etc. The communication portion 809 performs communication processing via a network such as the Internet. A drive 810 is also connected to the I / O interface 805 as needed. A removable medium 811, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 810 as needed, so that the computer program read therefrom is installed into the storage portion 808 as needed.

[0226] The present invention also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiment; or may exist independently without being assembled into the device / apparatus / system. The above computer-readable storage medium carries one or more programs, and when the above one or more programs are executed, the method according to the embodiment of the present invention is implemented.

[0227] According to an embodiment of the present invention, the computer-readable storage medium may be a non-volatile computer-readable storage medium, for example, it may include but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, the computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, an apparatus or a device. For example, according to an embodiment of the present invention, the computer-readable storage medium may include the ROM 802 and / or RAM 803 described above and / or one or more memories other than ROM 802 and RAM 803.

[0228] The embodiment of the present invention also includes a computer program product, which includes a computer program, and the computer program contains program code for executing the method shown in the flowchart. When the computer program product is run in a computer system, the program code is used to enable the computer system to implement the real-time coding method for quantum key distribution in free space provided by the embodiment of the present invention.

[0229] The computer program executes the above functions defined in the system / device of the embodiment of the present invention when the processor 801 executes the computer program. According to the embodiment of the present invention, the system, device, module, unit, etc. described above can be implemented by a computer program module.

[0230] In one embodiment, the computer program may rely on tangible storage media such as optical storage devices, magnetic storage devices, etc. In another embodiment, the computer program may also be transmitted and distributed in the form of signals on a network medium, and downloaded and installed through the communication part 809, and / or installed from a removable medium 811. The program code contained in the computer program may be transmitted using any appropriate network medium, including but not limited to: wireless, wired, etc., or any suitable combination of the above.

[0231] In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 809, and / or installed from the removable medium 811. When the computer program is executed by the processor 801, the above functions defined in the system of the embodiment of the present invention are performed. According to the embodiment of the present invention, the system, device, means, module, unit, etc. described above can be implemented by a computer program module.

[0232] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present invention may be combined and / or combined in various ways, even if such combinations and / or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention may be combined and / or combined in various ways. All of these combinations and / or combinations fall within the scope of the present invention.

Claims

1. A real-time coding method for quantum key distribution in free space, characterized in that: Applied to the receiving end, including: In response to receiving a light quantum flow and a laser signal, the light quantum flow is detected using a plurality of measurement basis vectors to obtain a quantum original detection signal, wherein the light quantum flow and the laser signal are both obtained by a transmitter through a laser communication channel in the free space, and the laser signal includes a plurality of synchronous coding information and a plurality of modulation basis vectors; Generate multiple original key information data packets according to the multiple synchronous coding information and the multiple measurement basis vectors, and send the multiple original key information data packets to the transmitting end through the laser communication channel, wherein the transmitting end is used to obtain basis vector comparison key data and basis vector comparison result information according to the multiple modulation basis vectors of the transmitting end and the multiple measurement basis vectors in the multiple original key information data packets, process the basis vector comparison key data using a low-density parity check code to obtain verification data, and generate multiple intermediate key information data packets according to the verification data and the basis vector comparison result information, wherein the basis vector comparison result information includes privacy amplification information; In response to receiving the plurality of intermediate key information packets, acquiring the verification data from the plurality of intermediate key information packets; Determine a check matrix of the low-density parity check code according to the check data, and perform iterative decoding processing on the check data using the check matrix to obtain a verification quantum key; Based on the quantum original detection signal and the privacy amplification information, the verification quantum key is subjected to privacy amplification processing to obtain a target quantum key.

2. The method according to claim 1, characterized in that In response to receiving the photon flow and the laser signal, the photon flow is detected using a plurality of measurement basis vectors to obtain a quantum original detection signal, including: In response to receiving the photon flow and the laser signal, detecting the photon state in the photon flow using the multiple measurement basis vectors to obtain a first initial quantum detection signal; A comparison process is performed on each of the measurement basis vectors and each of the modulation basis vectors. When the measurement basis vectors and the modulation basis vectors are consistent, a first initial quantum detection signal corresponding to the measurement basis vector is determined as the quantum original detection signal.

3. The method according to claim 1, characterized in that in, The synchronization coding information includes a synchronization coding sequence number and a check code; The generating a plurality of original key information data packets according to the plurality of synchronous coding information and the plurality of measurement basis vectors and sending the plurality of original key information data packets to the transmitting end through the laser communication channel comprises: Packing the multiple measurement basis vectors to obtain a first key information data packet; Subpackaging the first key information data packet to obtain a plurality of intermediate original key information data packets with sequential numbers; Matching the plurality of synchronization code serial numbers with the sequence numbers of the plurality of intermediate original key information data packets to obtain a matching result; Based on the matching result, the synchronization coding information corresponding to the sequence number is embedded into the intermediate original key information data packet to obtain a plurality of original key information data packets with synchronization coding information; The multiple original key information data packets with synchronous coding information are sent to the sending end.

4. The method according to claim 1, characterized in that: The step of acquiring the verification data from the plurality of intermediate key information packets in response to receiving the plurality of intermediate key information packets comprises: In response to receiving the plurality of intermediate key information packets, acquiring a synchronization code sequence number corresponding to each of the intermediate key information packets; Filling the intermediate key information data packet into a storage space according to the synchronization code sequence number corresponding to each intermediate key information data packet, wherein the receiving end includes a plurality of storage spaces with space numbers; Based on the space number of the storage space, verify the synchronization code sequence number corresponding to the intermediate key data packet stored in the storage space to obtain a verification result; When the verification result indicates that the verification is passed and the number of the intermediate key information data packets stored in the storage space meets a first preset condition, the verification data is obtained from the plurality of intermediate key information data packets.

5. The method according to claim 4, characterized in that Also includes: When the intermediate key information data package stored in each storage space does not satisfy the first preset condition, the plurality of intermediate key information data packages are continuously received until the intermediate key information data package stored in the storage space satisfies the first preset condition.

6. The method according to claim 1, characterized in that The step of determining a check matrix of the low-density parity check code according to the check data, and performing iterative decoding processing on the check data using the check matrix to obtain a verification quantum key comprises: Obtaining a coding matrix and a coding key from the verification data; Determine the check matrix of the low-density parity-check code according to the encoding matrix; According to the state of each quantum bit in the encoded key, a non-zero state in the check matrix is ​​replaced by a key probability likelihood ratio to construct a variable matrix, wherein the key probability likelihood ratio is obtained by calculating the log-likelihood ratio of the key prior probability; Performing a first calculation operation on the variable matrix and the key probability likelihood ratio to obtain a state probability corresponding to the encoding key; Performing a state determination operation on each quantum bit in the encoding key according to the key probability likelihood ratio to obtain an intermediate encoding key; Performing a verification operation on the intermediate encoding key using the check matrix, and when the verification result does not meet a second preset condition, iteratively updating the variable matrix to obtain an updated variable matrix, and re-performing the first calculation operation, the state determination operation, and the verification operation on the updated variable matrix until the verification result meets a second preset condition, wherein the second preset condition indicates that a matrix result obtained by calculating using the check matrix and the intermediate encoding key is a zero vector; When the verification result satisfies the second preset condition, the intermediate encoding key is determined to be the verification quantum key.

7. The method according to claim 1, characterized in that The step of performing privacy amplification processing on the verification quantum key based on the quantum original detection signal and the privacy amplification information to obtain a target quantum key includes: Acquire the privacy amplification information from the basis vector comparison result information; Comparing the verification quantum key with the quantum original detection signal to obtain a comparison result; When the comparison result indicates that the verification quantum key and the quantum original detection signal are consistent, performing privacy amplification processing on the verification quantum key according to the privacy amplification information to obtain the target quantum key; When the comparison result indicates that the verification quantum key and the quantum original detection signal are inconsistent, the quantum original detection signal is discarded and the comparison result is sent to the sending end.

8. A method for real-time coding of quantum key distribution applicable to free space, characterized in that: Applied to the sending end, including: Sending a light quantum flow and a laser signal to a receiving end through a laser communication channel in the free space, wherein the laser signal includes a plurality of synchronous coding information and a plurality of modulation basis vectors; In response to receiving a plurality of original key information data packets, according to a plurality of modulation basis vectors of the transmitting end and a plurality of measurement basis vectors in the plurality of original key information data packets, basis vector comparison key data and basis vector comparison result information are obtained, wherein the plurality of original key information data packets are transmitted through the laser communication channel, the basis vector comparison result information includes privacy amplification information, and the plurality of original key information data packets are data packets generated by the receiving end according to the plurality of synchronization coding information and the plurality of measurement basis vectors; Processing the basis vector comparison key data using a low-density parity check code to obtain verification data, and generating a plurality of intermediate key information data packets according to the verification data and the basis vector comparison result information; The multiple intermediate key information data packets are sent to the receiving end through the laser communication channel, wherein the receiving end obtains the verification data from the multiple intermediate key information data packets in response to the received multiple intermediate key information data packets, determines the check matrix of the low-density parity-check code according to the check data, performs iterative decoding processing on the check data using the check matrix to obtain a verification quantum key, and performs privacy amplification processing on the verification quantum key to obtain a target quantum key.

9. A device for real-time coding of quantum key distribution in free space, characterized in that: Applied to the receiving end, including: A detection module, configured to detect the light quantum flow using a plurality of measurement basis vectors in response to receiving the light quantum flow and the laser signal, and obtain a quantum original detection signal, wherein the light quantum flow and the laser signal are both obtained by a transmitting end through a laser communication channel in the free space, and the laser signal includes a plurality of synchronous coding information and a plurality of modulation basis vectors; A generating module, configured to generate a plurality of original key information data packets according to the plurality of synchronous coding information and the plurality of measurement basis vectors, and to send the plurality of original key information data packets to the transmitting end through the laser communication channel, wherein the transmitting end is configured to obtain basis vector comparison key data and basis vector comparison result information according to the plurality of modulation basis vectors of the transmitting end and the plurality of measurement basis vectors in the plurality of original key information data packets, process the basis vector comparison key data using a low-density parity check code to obtain verification data, and generate a plurality of intermediate key information data packets according to the verification data and the basis vector comparison result information, wherein the basis vector comparison result information includes privacy amplification information; an acquisition module, configured to acquire the verification data from the plurality of intermediate key information packets in response to receiving the plurality of intermediate key information packets; A decoding module, used to determine a check matrix of the low-density parity-check code according to the check data, and perform iterative decoding processing on the check data using the check matrix to obtain a verification quantum key; The privacy amplification module is used to perform privacy amplification processing on the verification quantum key based on the quantum original detection signal and the privacy amplification information to obtain a target quantum key.

10. A device for real-time coding of quantum key distribution in free space, characterized in that: Applied to the sending end, including: A first sending module, used for sending a light quantum flow and a laser signal to a receiving end through a laser communication channel, wherein the laser signal includes a plurality of synchronous coding information and a plurality of modulation basis vectors; an obtaining module, configured to obtain basis vector comparison key data and basis vector comparison result information in response to receiving a plurality of original key information data packets, according to a plurality of modulation basis vectors of the transmitting end and a plurality of measurement basis vectors in the plurality of original key information data packets, wherein the plurality of original key information data packets are transmitted through the laser communication channel, the basis vector comparison result information includes privacy amplification information, and the plurality of original key information data packets are data packets generated by the receiving end according to the plurality of synchronization coding information and the plurality of measurement basis vectors; A processing module, which processes the basis vector comparison key data using a low-density parity check code to obtain verification data, and generates a plurality of intermediate key information data packets according to the verification data and the basis vector comparison result information; A second sending module is used to send the multiple intermediate key information data packets to the receiving end through the laser communication channel, wherein the receiving end obtains the verification data from the multiple intermediate key information data packets in response to the received multiple intermediate key information data packets, determines the check matrix of the low-density parity-check code according to the check data, performs iterative decoding processing on the check data using the check matrix to obtain a verification quantum key, and performs privacy amplification processing on the verification quantum key to obtain a target quantum key.

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