QKD blind negotiation method and system based on polarization code

Abstract

The present invention discloses a polarization code-based QKD blind negotiation method and system. The QKD blind negotiation method comprises: executing preset negotiation steps for each group of post-screening keys until all post-screening keys have completed error correction; the preset negotiation steps include the following sub-steps: performing polarization code processing on the post-screening keys to generate a negotiation key, and sending the negotiation key to a receiving end, so that the receiving end performs polarization code error correction on the negotiation key and feeds back the generated error correction result to the sending end; and updating the running code rate of the next post-screening key to be transmitted based on the error correction result fed back by the receiving end. The present invention can fully utilize error correction information, reduce error correction delay, maximize transmission efficiency, and thus increase the generation rate of quantum secure keys.

Description

Technical Field

[0001] The present invention belongs to the field of quantum secure communication, and in particular relates to a QKD blind negotiation method and system based on polarization codes. Background Art

[0002] Quantum Key Distribution (QKD) is one of the most practical research areas in quantum information science. It enables legitimate parties to communicate over long distances in an unconditionally secure manner. However, due to noise in the quantum channel and eavesdroppers, the post-processing key after basis vector comparison still contains some errors, necessitating classical post-processing to obtain the final secure key.

[0003] Under normal circumstances, the quantum bit error rate (BER) in a smoothly operating QKD system varies little. However, when the channel environment suddenly changes or when the system is eavesdropped on by an eavesdropper (Eve), the BER can fluctuate significantly. Therefore, as the BER fluctuates, the error correction code rate used for error correction must also change accordingly. However, existing negotiation schemes typically use a fixed bit rate design, which is inflexible and results in significant additional communication overhead in high BER scenarios. They also struggle with poor channel conditions, such as time-varying channels and high latency scenarios. Furthermore, existing negotiation schemes typically directly apply reverse encoding of polarization codes to extract frozen bits, which introduces communication delays. Alternatively, they directly apply forward encoding of polarization codes, which eliminates the communication delay introduced by reverse encoding but consumes significant amounts of true random bits and communication resources. Summary of the Invention

[0004] To address the above problems, the present invention proposes a QKD blind negotiation method and system based on polarization codes, which can make full use of error correction information, reduce error correction delay, maximize transmission efficiency, and thus increase the generation rate of quantum security keys.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, the present invention provides a polar code-based QKD blind negotiation method, which is applied to a transmitting end. The QKD blind negotiation method includes:

[0007] The preset negotiation steps are performed for each set of screened keys until all screened keys have completed error correction. The preset negotiation steps include the following sub-steps:

[0008] performing polar code processing on the sieved key to generate a negotiated key, and sending the negotiated key to a receiving end, so that the receiving end performs polar code error correction on the negotiated key and feeds back the generated error correction result to the sending end;

[0009] The running code rate of the next post-screening key to be transmitted is updated based on the error correction result fed back by the receiving end.

[0010] Optionally, before generating a negotiated key after performing polarization code processing on the sieved key, the method further includes setting initialization operation parameters; wherein setting the initialization operation parameters includes the following sub-steps:

[0011] Set the initialization operation parameters, the initialization operation parameters include key length N, variable code rate interval [R min , R max ]、Initial bit rate R0=R max , cyclic check code length C, initial step size δ, number of communication rounds n and continuous error correction code rate update set R ＣRD ;

[0012] Sharing error correction code information with a receiving end through a classical channel, the error correction code information including the initialization operating parameters and polar code shared information; the polar code shared information including a polar code construction index set and frozen bit values ​​corresponding to frozen bit position indexes; the polar code construction index set including frozen bit position indexes and information bit position indexes.

[0013] Optionally, performing polar code processing on the sieved key to generate a negotiated key, and sending the negotiated key to a receiving end, so that the receiving end performs polar code error correction on the negotiated key and feeds back the generated error correction result to the sending end, specifically includes the following sub-steps:

[0014] Select a sieve key x of length N, and perform polarization code encoding on the sieve key x to obtain a bit string u=xG, x=uG, G -1 =G, where G is the polar code generator matrix;

[0015] Set the frozen bit value at the frozen bit position index in the bit string u to 0 to obtain the bit string u′;

[0016] Perform a cyclic redundancy check on the bit string u′ to obtain a cyclic redundancy check value T of length C;

[0017] Polar code the bit string u′ to obtain the bit string v;

[0018] The bit string v is XORed bit by bit with the sieved key x to obtain the negotiated key w, and the negotiated key w and the cyclic redundancy check value T are sent to the receiving end through the classical channel, so that the receiving end performs the following steps:

[0019] The received negotiated key w is XORed bit by bit with the receiver's sieved key y of length N to obtain the bit string z;

[0020] Calculate a channel log-likelihood ratio based on the bit string z, and input the channel log-likelihood ratio, the cyclic redundancy check value T, and the polar code shared information into a polar code decoder;

[0021] The polar code decoder constructs an index set and frozen bit value, cyclic redundancy check value T, and the frozen bit value of the new frozen bit position shared in each round of communication according to the polar code, and decodes to obtain the decoding result.

[0022] Decoding results Perform cyclic redundancy check to obtain the cyclic redundancy check value at the receiving end

[0023] if If the error correction fails, the error correction failure information is fed back to the transmitter. The transmitter converts the least reliable information bits into frozen bits in batches, generates a new frozen bit position index and the frozen bit value of the corresponding position index, and shares the frozen bit value of the new frozen bit position with the receiver. The receiver re-decodes according to the new polar code sharing information until the decoding is successful or the lower bound of the variable code rate R is reached. min ;

[0024] if If the error correction is successful, the decoding result Polar code encoding is performed to obtain Eventually The bit-by-bit XOR with the negotiated key w is used to obtain the secure key after error correction at the receiving end. reserve This decoding is completed;

[0025] According to the error correction result, the corresponding confirmation signal ACK and the current code rate R' are fed back to the sending end.

[0026] Optionally, the channel log-likelihood ratio is calculated as follows:

[0027] LLR(z i )=(1-2z i )[log2(1-p)-log2(p)]

[0028] Where, LLR(z i ) is the log-likelihood ratio corresponding to the i-th channel, z i is the codeword information calculated by the i-th transmitter, and p is the quantum bit error rate.

[0029] Optionally, if the error correction is successful, the negotiated error correction efficiency is:

[0030]

[0031] Where R′ is the current code rate of successful error correction, p is the quantum bit error rate, and h(p) is the binary entropy function. h(p) can be expressed as:

[0032] h(p)=-p log2(p)-(1-p)log2(1-p).

[0033] Optionally, the transmitting end converts the least reliable information bits into frozen bits in batches, generates a new frozen bit position index and a frozen bit value corresponding to the position index, and shares the frozen bit value of the new frozen bit position with the receiving end, so that the receiving end re-decodes according to the new polar code sharing information until the decoding is successful or the lower bound of the variable bit rate R is reached. min , including the following steps:

[0034] The sender checks the number of information bits K′ that have not been disclosed in the bit string u′;

[0035] If the number of undisclosed information bits K′ is less than or equal to the initial step size δ, the error correction fails and all the sieved key bits used for this error correction are discarded; otherwise, the least reliable information bits are converted into frozen bits in batches, and the frozen bit values ​​of the new frozen bit positions are shared with the receiving end, so that the receiving end re-decodes according to the new polar code shared information until the error correction is successful or the set variable rate interval lower bound R is reached. min , the number of communication rounds is updated every time error correction fails.

[0036] Optionally, the information shared between the sender and the receiver is divided into a low-latency mode and a high-latency mode;

[0037] In low-latency mode, the sender only sends a new set of frozen bit values ​​at each frozen bit position, and the receiver re-decodes according to the shared error correction code information until the verification is successful or the lower bound of the variable bit rate R is reached. min , this decoding is completed;

[0038] In high-latency mode, the sender continuously sends new frozen bit values ​​at the frozen bit positions as needed until the receiver feeds back a signal of successful decoding to the sender or reaches the lower bound of the variable bit rate R. min If the signal still fails to be decoded, the decoding ends.

[0039] Optionally, the transmitting end updates the operating bit rate according to the error correction result fed back by the receiving end, specifically:

[0040] If the error correction is successful, the running bit rate is updated to the suboptimal value of the current bit rate;

[0041] If the error correction fails, the running bit rate is updated to the current bit rate.

[0042] Optionally, the calculation formula for the suboptimal value of the current bit rate is:

[0043] R″=min{R CRD >R′,R max}

[0044] Among them, R″ is the suboptimal value of the current bit rate, R′ is the current bit rate, and R max is the upper bound of the variable bit rate.

[0045] In a second aspect, the present invention provides a QKD blind negotiation system based on polar codes, comprising a storage medium and a processor;

[0046] The storage medium is used to store instructions;

[0047] The processor is configured to operate according to the instructions to execute the method according to any one of the first aspects.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The present invention optimizes the polar code rate adaptation mechanism and continuous error correction mechanism, making the code rate change more flexible and adaptable, reducing communication delay, reducing the consumption of true random numbers and communication resources, and ensuring that the post-processing process of quantum key distribution can fully utilize error correction information, maximizing transmission efficiency, and thus increasing the generation rate of quantum secure keys. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings, wherein:

[0051] Figure 1 This is a schematic diagram of a continuous error correction design process for a QKD blind negotiation method based on polar codes according to an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of code rate adaptation design in an error correction module of a polar code-based QKD blind negotiation method according to an embodiment of the present invention;

[0053] Figure 3 This is a diagram showing a specific embodiment of an error correction module of a QKD blind negotiation method based on polar codes in one embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0055] The application principle of the present invention is described in detail below with reference to the accompanying drawings.

[0056] Example 1

[0057] An embodiment of the present invention provides a polar code-based QKD blind negotiation method, which is applied to a transmitting end. The QKD blind negotiation method includes:

[0058] The preset negotiation steps are performed for each set of screened keys until all screened keys have completed error correction. The preset negotiation steps include the following sub-steps:

[0059] performing polarization code processing on the sieved key to generate a negotiated key, and sending the negotiated key to a receiving end, so that the receiving end performs polarization code error correction on the negotiated key and feeds back the generated error correction result to the sending end;

[0060] The running code rate of the next post-screening key to be transmitted is updated based on the error correction result fed back by the receiving end.

[0061] The embodiments of the present invention can fully utilize error correction information, reduce error correction delay, maximize transmission efficiency, and thus increase the generation rate of quantum security keys.

[0062] In a specific implementation of the embodiment of the present invention, before generating a negotiated key after performing polar code processing on the sieved key, the method further includes setting initialization operating parameters. The setting of the initialization operating parameters includes the following sub-steps:

[0063] Set the initialization operation parameters, the initialization operation parameters include key length N, variable code rate interval [R min , R max ]、Initial bit rate R0=R max , cyclic check code length C, initial step size δ, number of communication rounds n and continuous error correction code rate update set R CRD ;

[0064] Sharing error correction code information with a receiving end (preferably, sharing the error correction code information with the receiving end via a classical channel), the error correction code information including the initialization operating parameters and polar code shared information; the polar code shared information including a polar code construction index set and frozen bit values ​​corresponding to frozen bit position indexes; the polar code construction index set including frozen bit position indexes and information bit position indexes.

[0065] In a specific implementation of the embodiment of the present invention, the polarization code processing is performed on the sieved key to generate a negotiated key, and the negotiated key is sent to the receiving end, so that the receiving end performs polarization code error correction on the negotiated key and feeds back the generated error correction result to the sending end, such as Figure 3As shown, it specifically includes the following sub-steps:

[0066] Select a sieve key x of length N, and perform polarization code encoding on the sieve key x to obtain a bit string u=xG, x=uG, G -1 =G, where G is the polar code generator matrix;

[0067] Set the frozen bit value at the frozen bit position index in the bit string u to 0 to obtain the bit string u′;

[0068] Perform a cyclic redundancy check on the bit string u′ to obtain a cyclic redundancy check value T of length C;

[0069] Polar code the bit string u′ to obtain the bit string v;

[0070] The bit string v is XORed bit by bit with the sieved key x to obtain the negotiated key w, and the negotiated key w and the cyclic redundancy check value T are sent to the receiving end through the classical channel, so that the receiving end performs the following steps:

[0071] The received negotiated key w is XORed bit by bit with the receiver's sieved key y of length N to obtain the bit string z;

[0072] Calculate a channel log-likelihood ratio based on the bit string z, and input the channel log-likelihood ratio, the cyclic redundancy check value T, and the polar code shared information into a polar code decoder;

[0073] The polar code decoder constructs an index set and frozen bit value, cyclic redundancy check value T, and the frozen bit value of the new frozen bit position shared in each round of communication according to the polar code, and decodes to obtain the decoding result.

[0074] Decoding results Perform cyclic redundancy check to obtain the cyclic redundancy check value at the receiving end

[0075] if If the error correction fails, the error correction failure information is fed back to the transmitter. The transmitter converts the least reliable information bits into frozen bits in batches, generates a new frozen bit position index and the frozen bit value of the corresponding position index, and shares the frozen bit value of the new frozen bit position with the receiver. The receiver re-decodes according to the new polar code sharing information until the decoding is successful or the lower bound of the variable code rate R is reached. min ;

[0076] if If the error correction is successful, the decoding result Polar code encoding is performed to obtain Eventually The bit-by-bit XOR with the negotiated key w is used to obtain the secure key after error correction at the receiving end. reserve This decoding is completed;

[0077] According to the error correction result, the corresponding confirmation signal ACK and the current code rate R' are fed back to the sending end.

[0078] In a specific implementation of the embodiment of the present invention, the calculation formula of the channel log-likelihood ratio is:

[0079] LLR(z i )=(1-2z i )[log2(1-p)-log2(p)]

[0080] Where, LLR(z i ) is the log-likelihood ratio corresponding to the i-th channel, z i is the codeword information calculated by the i-th transmitter, and p is the quantum bit error rate.

[0081] In a specific implementation of the embodiment of the present invention, if the error correction is successful, the negotiated error correction efficiency is:

[0082]

[0083] Where R′ is the current code rate of successful error correction, p is the quantum bit error rate, and h(p) is the binary entropy function. h(p) can be expressed as:

[0084] h(p)=-p log2(p)-(1-p)log2(1-p).

[0085] In a specific implementation of the embodiment of the present invention, the transmitting end converts the least reliable information bits into frozen bits in batches, generates a new frozen bit position index and a frozen bit value corresponding to the position index, and shares the frozen bit value of the new frozen bit position with the receiving end, so that the receiving end re-decodes according to the new polar code sharing information until the decoding is successful or the lower bound R of the variable bit rate is reached. min , including the following steps:

[0086] The sender checks the number of information bits K′ that have not been disclosed in the bit string u′;

[0087] If the number of undisclosed information bits K′ is less than or equal to the initial step size δ, the error correction fails and all the sieved key bits used for this error correction are discarded; otherwise, the least reliable information bits are converted into frozen bits in batches, and the frozen bit values ​​of the new frozen bit positions are shared with the receiving end, so that the receiving end re-decodes according to the new polar code shared information until the error correction is successful or the set variable rate interval lower bound R is reached. min , each time the error correction fails, the number of communication rounds is updated n=n+1.

[0088] In a specific implementation of the embodiment of the present invention, the information sharing between the sending end and the receiving end is divided into a low-latency mode and a high-latency mode;

[0089] In low-latency mode, the sender only sends a new set of frozen bit values ​​at each communication round, and the receiver re-decodes according to the shared error correction code information until the verification is successful or the lower bound of the variable bit rate R is reached. min , this decoding is completed;

[0090] In high-latency mode, the sender keeps sending new frozen bit values ​​at new frozen bit positions until the receiver feeds back a signal of successful decoding to the sender or reaches the lower bound of the variable bit rate R. min If the signal still fails to be decoded, the decoding ends;

[0091] In a specific implementation of the embodiment of the present invention, the transmitting end updates the operating bit rate according to the error correction result fed back by the receiving end, specifically:

[0092] If the error correction is successful, the running bit rate is updated to the suboptimal value of the current bit rate;

[0093] If the error correction fails, the running bit rate is updated to the current bit rate; the suboptimal value of the current bit rate is calculated as follows:

[0094] R″=min{R ＣRD >R′,R max}

[0095] Among them, R″ is the suboptimal value of the current bit rate, R′ is the current bit rate, and R max is the upper bound of the variable bit rate.

[0096] The following is a specific embodiment, and Figure 1-2 The method in the embodiment of the present invention is described in detail.

[0097] Step 1: Set the initialization operating parameters and determine whether the operating conditions of the error correction module (embodied in the form of a program) are met. If so, proceed to step 2;

[0098] Step 2: Input the initialization operating parameters into the error correction module for error correction, and feed back the correction results to the sending end;

[0099] Step 3: The sending end updates the running code rate of the next post-screening key to be transmitted based on the error correction result fed back by the receiving end, which is used for error correction of the next post-screening key to be transmitted.

[0100] Step 1 specifically includes the following steps:

[0101] Step 1-1: Set the initial operation parameters, including key length N, variable code rate range [R min， R max ]、Initial bit rate R0=R max , cyclic check code length C, initial public step length δ, number of communication rounds n, and continuous error correction code rate update set R CRD The transmitting end and the receiving end share error correction code information via a classical channel. The error correction code information includes initialization operating parameters and polar code sharing information. The polar code sharing information includes a polar code construction index set and frozen bit values ​​corresponding to frozen bit position indexes. The polar code construction index set includes frozen bit position indexes and information bit position indexes.

[0102] In a specific implementation process, the method for constructing the polar code construction index set includes:

[0103] Calculate the information bit length K, Indicates rounding up;

[0104] A polar code index set is constructed using the channel degradation method. Channel reliabilities are sorted from least reliable to most reliable, and the K most reliable sub-channels are selected in sequence as information bits for transmission. The remaining NK sub-channels are used as frozen bits for transmission. The receiver and transmitter share the polar code index set in advance over a classical channel.

[0105] In the specific implementation process, the continuous error correction code rate update set R ＣRD The design method is as follows:

[0106] Set the quantum bit error rate P for continuous error correction CRD Set, P CRD ∈[P min , P max ], where P min P CRD The lower bound of P max P CRD The upper bound of R ＣRD =1-fh(P CRD ), where f is the error correction negotiation efficiency (f≥1 and f=1 is often taken), h(P CRD ) is the binary entropy function.

[0107] Step 1-2: Determine whether the operating conditions of the error correction module are met, that is, determine whether the remaining post-screening key quantity is greater than N. If the remaining post-screening key quantity is greater than N, the operating conditions are met and error correction continues; otherwise, the process ends.

[0108] Step 2 specifically includes the following steps:

[0109] Step 2-1: First, the sending end selects a sieve key x of length N, and performs polarization code encoding on the sieve key x to obtain a bit string u=xG, x=uG, G -1 = G, where G is the polar code generator matrix. Next, the frozen bit values ​​at the frozen bit position indexes in bit string u are set to 0 to obtain bit string u′. A cyclic redundancy check is then performed on bit string u′ to obtain a cyclic redundancy check value T of length C. Polar code encoding is then performed on u′ to obtain bit string v. Finally, v is bitwise XORed with x to obtain the negotiated key w. The negotiated key w and cyclic redundancy check value T are then sent to the receiver via a classical channel.

[0110] Step 2-2: The receiver performs a bit-by-bit XOR operation on the received negotiated key w and the receiver's sieved key y of length N to obtain the bit string z. Based on z, the channel log likelihood ratio (CLR) is calculated and the channel LLR, cyclic redundancy check value T, and polar code shared information are input into the polar code decoder.

[0111] The specific formula for calculating the channel log-likelihood ratio is:

[0112] LLR(z i )=(1-2z i )[log2(1-p)-log2(p)],

[0113] Where, LLR(z i ) is the log-likelihood ratio corresponding to the i-th channel, z i is the codeword information calculated by the i-th transmitter, and p is the quantum bit error rate.

[0114] Step 2-3: The receiving end decodes the shared error correction code information (polar code construction index set and frozen bit value, cyclic redundancy check value T, and the frozen bit value of the new frozen bit position shared in each round of communication) to obtain the decoding result. Decoding results Perform cyclic redundancy check to obtain the cyclic redundancy check value at the receiving end if If the error correction fails, jump to step 2-4; If the error correction is successful, jump to step 2-5;

[0115] Step 2-4: Convert the least reliable information bits into frozen bits in batches, generate new frozen bit position indexes and frozen bit values ​​corresponding to the position indexes, and share the frozen bit values ​​of the new frozen bit positions with the receiver. The receiver re-decodes the polar code information according to the shared polar code information until the decoding is successful or the lower bound of the variable bit rate R is reached. min ; Steps 2-4 are specifically implemented as follows:

[0116] Step 2-4-1: The sender checks the number of undisclosed information bits K' in u'. If the number of undisclosed information bits K' is less than or equal to the initial step size δ, the error correction fails and all the key bits after the error correction are discarded; otherwise, the least reliable information bits are converted into frozen bits in batches, and the frozen bit values ​​of the new frozen bit positions are shared with the receiver (the new frozen bit values ​​are not necessarily 0 at this time). The receiver re-decodes according to the shared error correction code information until the error correction is successful or the lower bound of the variable bit rate interval R is reached. min , each time the error correction fails, the number of communication rounds is updated n=n+1;

[0117] Step 2-4-2: The information sharing between the sender and the receiver can be divided into two modes: low latency mode and high latency mode. In the low latency mode, the sender only sends a new set of frozen bit values ​​of the frozen bit positions disclosed in each round of communication. The receiver re-decodes according to the shared error correction code information until the verification is successful or the lower limit of the variable bit rate R is reached. min , this decoding is completed; in high latency mode, the sender continuously sends the frozen bit value of the new frozen bit position disclosed in each round of communication as needed until the receiver feeds back a signal of successful decoding to the sender or reaches the lower limit R of the variable bit rate set min If the signal still fails to be decoded, the decoding ends.

[0118] Step 2-5: Decoding results Polar code encoding is performed to obtain Eventually The bit-by-bit XOR with the negotiated key w is used to obtain the secure key after error correction at the receiving end. reserve This decoding is finished. At this time, due to the successful error correction, The negotiation error correction efficiency described in steps 2-5 is:

[0119]

[0120] Where R′ is the current code rate of successful error correction, p is the quantum bit error rate, and h(p) is the binary entropy function. h(p) can be expressed as:

[0121] h(p)=-p log2(p)-(1-p)log2(1-p).

[0122] Step 2-6: Based on the error correction results from steps 2-4 and 2-5, the receiving end sends the corresponding acknowledgment signal ACK and the current code rate R' back to the transmitting end. If the error correction is successful, the receiving end returns an acknowledgment signal ACK = 1 and the current code rate R'; if the error correction fails, the receiving end returns an acknowledgment signal ACK = 0 and the current code rate R'.

[0123] The specific steps of step 3 are as follows:

[0124] Step 3-1: If the confirmation signal ACK received by the transmitter is 0, that is, the error correction of the current code block fails, the transmitter updates the running code rate R to the current code rate R′;

[0125] Step 3-2: If the acknowledgement signal ACK=1 received by the transmitter, that is, the error correction of the current code block is successful, the transmitter updates the running code rate R to the suboptimal value R″ of the current code rate R′. The suboptimal value R″ of the current code rate R′ in step 3-2 is selected as follows:

[0126] R″=min{R CRD >R′,R max},

[0127] The formula shows that in R ＣRD Find the smallest value among all values ​​greater than R′ and compare it with R max Compare and take the smaller value and assign it to R".

[0128] In summary, the polar code-based QKD blind negotiation method and system proposed in this invention, through adaptive code rate design, eliminates the communication delay caused by reverse coding and avoids the consumption of true random numbers and communication resources required for forward error correction. Through continuous error correction design, error correction information is maximized to update the initial operating code rate, avoiding the huge communication consumption of fixed code rate schemes under high quantum error rates. Therefore, while ensuring error correction performance, the present invention can flexibly adjust the code rate according to channel conditions, greatly reducing communication delay, maximizing transmission efficiency, and thus increasing the generation rate of quantum secure keys.

[0129] Example 2

[0130] Based on the same inventive concept as Example 1, the present invention provides a QKD blind negotiation system based on polar codes, including a storage medium and a processor;

[0131] The storage medium is used to store instructions;

[0132] The processor is configured to operate according to the instructions to perform the method according to any one of the embodiments 1.

[0133] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0134] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0135] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0136] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0137] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which are all protected by the present invention.

[0138] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A QKD blind negotiation method based on polar codes, characterized in that: Applied to the transmitting end, the QKD blind negotiation method includes: The preset negotiation steps are performed for each set of screened keys until all screened keys have completed error correction. The preset negotiation steps include the following sub-steps: performing polar code processing on the sieved key to generate a negotiated key, and sending the negotiated key to a receiving end, so that the receiving end performs polar code error correction on the negotiated key and feeds back the generated error correction result to the sending end; Update the running code rate of the next post-screening key to be transmitted based on the error correction result fed back by the receiving end; Before generating a negotiated key after performing polarization code processing on the sieved key, the method further includes setting initialization operation parameters; The setting of the initialization operating parameters includes the following sub-steps: Set the initialization operation parameters, the initialization operation parameters include key length N, variable code rate interval [R min ,R max ]、Initial code rate R0=R max , cyclic check code length C, initial step size δ, number of communication rounds n and continuous error correction code rate update set R CRD ; Sharing error correction code information with a receiving end via a classical channel, the error correction code information including the initialization operating parameters and polar code sharing information; the polar code sharing information including a polar code construction index set and frozen bit values ​​corresponding to frozen bit position indexes; the polar code construction index set including frozen bit position indexes and information bit position indexes; The continuous error correction code rate update set R CRD The design method is as follows: Set the quantum bit error rate P for continuous error correction CRD Set, P CRD ∈[P min ,P max ], where P min P CRD The lower bound of P max P CRD The upper bound of R CRD =1-fh(P CRD ), where f is the error correction negotiation efficiency, h(P CRD ) is a binary entropy function; The information shared between the sender and the receiver is divided into low-latency mode and high-latency mode; In low-latency mode, the sender only sends a new set of frozen bit values ​​at each frozen bit position, and the receiver re-decodes according to the shared error correction code information until the verification is successful or the lower bound of the variable bit rate R is reached. min , this decoding is completed; In high-latency mode, the sender continuously sends new frozen bit values ​​at the frozen bit positions as needed until the receiver feeds back a signal of successful decoding to the sender or reaches the lower bound of the variable bit rate R. min If the signal still fails to be decoded, the decoding ends; If the confirmation signal ACK received by the sender is 0, that is, the error correction of the current code block fails, the sender updates the running code rate R to the current code rate R'; If the acknowledgement signal ACK=1 received by the transmitter, that is, the error correction of the current code block is successful, the transmitter updates the running code rate R to the suboptimal value R″ of the current code rate R′. The suboptimal value R″ of the current code rate R′ is selected as follows: R″=min{R CRD >R′,R max }, Indicates that in R CRD Find the smallest value among all values ​​greater than R′ and compare it with R max Compare and take the smaller value and assign it to R".

2. The polar code-based QKD blind negotiation method according to claim 1, wherein: The step of performing polar code processing on the sieved key to generate a negotiated key, and sending the negotiated key to the receiving end, so that the receiving end performs polar code error correction on the negotiated key and feeds back the generated error correction result to the sending end, specifically includes the following sub-steps: Select a sieve key x of length N, perform polarization code encoding on the sieve key x to obtain a bit string u=xG, x=uG,G -1 =G, where G is the polar code generator matrix; Set the frozen bit value at the frozen bit position index in the bit string u to 0 to obtain the bit string u′; Perform a cyclic redundancy check on the bit string u′ to obtain a cyclic redundancy check value T of length C; Polar code the bit string u′ to obtain the bit string v; The bit string v is XORed bit by bit with the sieved key x to obtain the negotiated key w, and the negotiated key w and the cyclic redundancy check value T are sent to the receiving end through the classical channel, so that the receiving end performs the following steps: The received negotiated key w is XORed bit by bit with the receiver's sieved key y of length N to obtain the bit string z; Calculate a channel log-likelihood ratio based on the bit string z, and input the channel log-likelihood ratio, the cyclic redundancy check value T, and the polar code shared information into a polar code decoder; The polar code decoder constructs an index set and frozen bit value, cyclic redundancy check value T, and the frozen bit value of the new frozen bit position shared in each round of communication according to the polar code, and decodes to obtain the decoding result. Decoding results Perform cyclic redundancy check to obtain the cyclic redundancy check value at the receiving end if If the error correction fails, the error correction failure information is fed back to the transmitter. The transmitter converts the least reliable information bits into frozen bits in batches, generates a new frozen bit position index and the frozen bit value of the corresponding position index, and shares the frozen bit value of the new frozen bit position with the receiver. The receiver re-decodes according to the new polar code sharing information until the decoding is successful or the lower bound of the variable code rate R is reached. min ; if If the error correction is successful, the decoding result Polar code encoding is performed to obtain Eventually The bit-by-bit XOR with the negotiated key w is used to obtain the secure key after error correction at the receiving end. reserve This decoding is completed; According to the error correction result, the corresponding confirmation signal ACK and the current code rate R' are fed back to the sending end.

3. The polar code-based QKD blind negotiation method according to claim 2, wherein: The calculation formula of the channel log-likelihood ratio is: LLR(z i )=(1-2z i )[log2(1-p)-log2(p)] Where, LLR(z i ) is the log-likelihood ratio corresponding to the i-th channel, z i is the codeword information calculated by the i-th transmitter, and p is the quantum bit error rate.

4. The polar code-based QKD blind negotiation method according to claim 2, wherein: If the error correction is successful, the negotiated error correction efficiency is: Where R′ is the current code rate of successful error correction, p is the quantum bit error rate, h(p) is the binary entropy function, and h(p) is expressed as: h(p)=-plog2(p)-(1-p)log2(1-p).

5. The QKD blind negotiation method based on polar codes according to claim 2, wherein: The transmitter converts the least reliable information bits into frozen bits in batches, generates new frozen bit position indexes and frozen bit values ​​corresponding to the position indexes, and shares the frozen bit values ​​of the new frozen bit positions with the receiver, so that the receiver re-decodes according to the new polar code sharing information until the decoding is successful or the lower bound of the variable bit rate R is reached. min , including the following steps: The sender checks the number of information bits K′ that have not been disclosed in the bit string u′; If the number of undisclosed information bits K′ is less than or equal to the initial step size δ, the error correction fails and all the sieved key bits used for this error correction are discarded; otherwise, the least reliable information bits are converted into frozen bits in batches, and the frozen bit values ​​of the new frozen bit positions are shared with the receiving end, so that the receiving end re-decodes according to the new polar code shared information until the error correction is successful or the set variable rate interval lower bound R is reached. min , the number of communication rounds is updated every time error correction fails.

6. A QKD blind negotiation system based on polar codes, characterized by: including storage media and processors; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the method according to any one of claims 1-5.

Images