A secure magnetic communication method and system based on key index

Abstract

The application discloses a kind of security magnetic communication method and system based on key index, comprising: four-dimensional hyperchaotic model is generated four column chaotic sequence according to the key initial value set;Two chaotic sequences are inserted into original transmission data and then convolutional encryption is carried out to obtain encrypted bit stream, and the encrypted bit stream is converted to obtain data matrix H, and the data matrix H is sequentially subjected to sub-carrier scrambling and symbol scrambling according to the other two chaotic sequences to obtain data matrix P;Key matrix is used as index, and the elements in data matrix P are mapped to QPSK by constellation codebook to obtain constellation points, and a constellation diagram is formed by each constellation point;The constellation diagram is sent to the receiver by the transmitter;In response to the receiver receiving the constellation diagram, the original transmission data is obtained by decrypting the constellation diagram;The application solves the problem that magnetic induction signal is easy to be stolen, and improves the security of communication system.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic communication, and in particular relates to a secure magnetic communication method and system based on key indexing. Background Art

[0002] With the development of modern industry, magnetic communication is a leading candidate for multi-modal communications due to its lack of significant multipath effects, resistance to absorption and scattering, low power consumption, and simple equipment. However, since magnetic induction signals are directly exposed to the air and are easily captured, ensuring the security of signal transmission becomes extremely important.

[0003] Chaotic encryption schemes are currently widely used in communication systems to address security concerns. Traditional chaotic encryption schemes assume that the receiving end knows the key and use a fixed key to generate a chaotic sequence for encryption. Once the key is cracked, all user information is leaked, resulting in significant losses. To further improve the security of communication systems, key-on-the-fly technology has emerged. At the transmitting end, the signal is encrypted using a chaotic sequence generated by the initial key. The key is then superimposed on a high-power signal in a low-power distribution and transmitted along with the information to the user. This significantly improves the encryption efficiency of the communication system. However, in magnetic communication systems, the signal power is low and noise interference is relatively high. Traditional single key-on-the-fly methods increase the complexity of the transmitted signal, resulting in an increased bit error rate at the receiving end. Furthermore, the key, which is generally transmitted at low power, is difficult to decrypt. If the key cannot be correctly decrypted, the transmission security of the communication system will be significantly reduced. Summary of the Invention

[0004] The present invention provides a secure magnetic communication method and system based on key indexing to solve the problem that magnetic induction signals are easily stolen and to improve the security of the communication system.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A first aspect of the present invention provides a secure magnetic communication method based on a key index, comprising:

[0007] Generate chaotic sequence based on the set initial value of key using four-dimensional hyperchaotic model , chaotic sequence , chaotic sequence and chaotic sequences ;

[0008] The chaotic sequence and chaotic sequences After inserting the original transmission data, convolution encryption is performed to obtain the encrypted bit stream, and the encrypted bit stream is converted into a data matrix H according to the chaotic sequence. and chaotic sequences Perform subcarrier scrambling and symbol scrambling on the data matrix H in sequence to obtain the data matrix P;

[0009] Perform binary conversion on the initial key value and repeatedly superimpose it D times to obtain a key matrix; establish a constellation codebook using QPSK constellation A and QPSK constellation B; set a mapping relationship between the cipher bits in the key matrix and the constellation codebook;

[0010] Using the key matrix as an index, QPSK mapping is performed on the elements in the data matrix P through the constellation codebook to obtain constellation points, and the constellation points form a constellation diagram; the constellation diagram is sent to the receiver through the transmitter;

[0011] In response to the receiver receiving the constellation map, the constellation map is decrypted to obtain the original transmission data.

[0012] Furthermore, a four-dimensional hyperchaotic model is used to generate a chaotic sequence according to the set initial value of the key. , chaotic sequence , chaotic sequence and chaotic sequences The process includes:

[0013] The initial value of the key is input into the four-dimensional hyperchaotic model to obtain the state variables X, Y, Z, and W. The expression formula is:

[0014]

[0015]

[0016]

[0017]

[0018] In the formula, and For the Second and The state variables of the output of the sub-cycle calculation ; and For the Second and The state variables of the output of the sub-cycle calculation ; and For the Second and The state variables of the output of the sub-cycle calculation ; and For the Second and The state variables of the output of the sub-cycle calculation ; 、 、 、 and are the coefficients of the four-dimensional hyperchaotic model; 、 、 and State variables , state variables , state variables and state variables The first derivative of ;

[0019] Generate chaotic sequences according to state variables X, Y, Z and W respectively , chaotic sequence , chaotic sequence and chaotic sequences .

[0020] Furthermore, the chaotic sequence and chaotic sequences After inserting the original transmission data, convolution encryption is performed to obtain the encrypted bit stream. The process includes:

[0021] According to the chaotic sequence and chaotic sequences Generate chaotic insertion sequence S, the expression formula is:

[0022]

[0023] In the formula, is the remainder function; is the floor function; and is the intermediate transformation sequence;

[0024] The original transmission data is converted into binary to obtain original bits, and the original bits are grouped; the chaotic bits in the chaotic insertion sequence S are inserted into each group of original bits and then input into the convolution device to obtain the encrypted bit stream.

[0025] Furthermore, the encrypted bit stream is serial-to-parallel converted to obtain the data matrix H. The process includes:

[0026] Convert encrypted bit stream into data matrix ; The data matrix The data matrix H is obtained by merging every two columns of data.

[0027] Furthermore, according to the chaotic sequence and chaotic sequences Subcarrier scrambling and symbol scrambling are performed on the data matrix H in sequence to obtain the data matrix P. The process includes:

[0028] The chaotic sequence and chaotic sequences After sorting in ascending order and taking the inverse, the chaotic sequence and chaotic sequences Multiply to get the scrambled matrix and scrambled matrix ;

[0029]

[0030] In the formula, is the ascending order function; is the matrix transpose;

[0031] By scrambling matrix and scrambled matrix Extract the position of 1 to generate scrambled sequence M and scrambled sequence N;

[0032] The data matrix H is column-transformed according to each column element of the scrambled sequence M, and the scrambled sequence N is transposed and the data matrix H is row-transformed to obtain the data matrix P.

[0033] Furthermore, the constellation diagram is sent to the receiver via the transmitter, and the process includes:

[0034] The constellation points in the constellation diagram are represented by real and imaginary parts to obtain complex constellation points; the complex constellation points are inverse Fourier transformed, and a cyclic prefix and a cyclic suffix are added to obtain a time domain transmission signal, which is then transmitted from the transmitter to the receiver via an optical fiber channel;

[0035] The cyclic prefix and cyclic suffix of the time domain transmitted signal are removed and Fourier transform is performed to obtain the frequency domain received signal, and the constellation diagram received by the receiver is recovered from the frequency domain received signal.

[0036] Furthermore, in response to the receiver receiving the constellation diagram, decrypting the constellation diagram to obtain the original transmission data includes:

[0037] The constellation diagram is converted into a received data matrix through a constellation codebook, and index bit information is extracted from the received data matrix; according to the mapping relationship between the cipher bits and the constellation codebook, the index bit information is key-combined to obtain a key matrix; and the received data matrix is ​​decrypted according to the key matrix to obtain the original transmitted data.

[0038] A second aspect of the present invention provides a secure magnetic communication system based on a key index, comprising:

[0039] The key module uses a four-dimensional hyperchaotic model to generate a chaotic sequence based on the set key initial value. , chaotic sequence , chaotic sequence and chaotic sequences ;

[0040] Interference module, chaotic sequence and chaotic sequences After inserting the original transmission data, convolution encryption is performed to obtain the encrypted bit stream, and the encrypted bit stream is converted into a data matrix H according to the chaotic sequence. and chaotic sequences Perform subcarrier scrambling and symbol scrambling on the data matrix H in sequence to obtain the data matrix P;

[0041] A mapping module performs binary conversion on the initial key value and repeatedly superimposes it D times to obtain a key matrix; establishes a constellation codebook using QPSK constellation A and QPSK constellation B; and sets a mapping relationship between the cipher bits in the key matrix and the constellation codebook;

[0042] The encryption module uses the key matrix as an index and performs QPSK mapping on the elements in the data matrix P through the constellation codebook to obtain constellation points. The constellation points form a constellation diagram; the constellation diagram is sent to the receiver through the transmitter;

[0043] The decryption module decrypts the constellation diagram to obtain original transmission data in response to the receiver receiving the constellation diagram.

[0044] Furthermore, the decryption module decrypts the constellation diagram to obtain the original transmission data, and the process includes:

[0045] The constellation diagram is converted into a received data matrix through a constellation codebook, and index bit information is extracted from the received data matrix; according to the mapping relationship between the cipher bits and the constellation codebook, the index bit information is key-combined to obtain a key matrix; and the received data matrix is ​​decrypted according to the key matrix to obtain the original transmitted data.

[0046] The third aspect of the present invention provides an electronic device, comprising a storage medium and a processor; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the key index-based secure magnetic communication method described in the first aspect.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The present invention performs binary conversion on the initial value of the key and repeatedly superimposes it D times to obtain a key matrix; selects the index bit that appears the most times as the correct key information, and finally extracts the absolutely correct key; because the key is repeated multiple times, the correctness of key transmission can still be guaranteed even in the case of a very low signal-to-noise ratio.

[0049] The present invention utilizes a four-dimensional hyperchaotic model to generate four chaotic sequences according to a set key initial value; two chaotic sequences are inserted into original transmission data and then convolutionally encrypted to obtain an encrypted bit stream; the encrypted bit stream is serial-to-parallel converted to obtain a data matrix H; and subcarrier scrambling and symbol scrambling are sequentially performed on the data matrix H according to the other two chaotic sequences to obtain a data matrix P; the present invention utilizes the four-dimensional hyperchaotic model because of its high sensitivity and unpredictability to initial conditions, thereby improving the security and reliability of the communication system; at the same time, the chaotic encryption method of the present invention can resist external interference and noise to a certain extent, thereby improving the robustness of the communication system.

[0050] In the present invention, the key matrix is ​​used as an index, and QPSK mapping is performed on the elements in the data matrix P through the constellation codebook to obtain constellation points, and the constellation points form a constellation diagram; the constellation diagram is sent to the receiver through a transmitter; hiding the key in the constellation enhances the security of wireless magnetic communication transmission. The method of using the constellation codebook to hide the key does not add extra bits of redundant information to the transmitted information, and is suitable for magnetic communication systems with limited bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a flowchart of a secure magnetic communication method based on key indexing provided in Example 1 of the present invention;

[0052] Figure 2 is a phase trajectory diagram of the 4D hyperchaotic model provided in Example 1 of the present invention;

[0053] Figure 3 This is the principle of the high-security magnetic communication method based on key indexing provided by Example 1 of the present invention;

[0054] Figure 4 is a constellation diagram received by the receiver provided in embodiment 1 of the present invention;

[0055] Figure 5 This is a curve diagram of the signal bit error rate before and after convolution encryption provided by Example 1 of the present invention. DETAILED DESCRIPTION

[0056] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0057] Example 1

[0058] like Figure 1 As shown, this embodiment provides a secure magnetic communication method based on key indexing, including:

[0059] In this embodiment, the initial value of the key is set 、 、 and They are 0.01001498, 0.49978643, 0.80056479 and 0.10078942 respectively. The chaotic sequence is generated by the four-dimensional hyperchaotic model according to the set initial key value. , chaotic sequence , chaotic sequence and chaotic sequences The process includes:

[0060] The initial value of the key is input into the four-dimensional hyperchaotic model to obtain the state variables X, Y, Z, and W. The expression formula is:

[0061]

[0062]

[0063]

[0064]

[0065] In the formula, and For the Second and The state variables of the output of the sub-cycle calculation ; and For the Second and The state variables of the output of the sub-cycle calculation ; and For the Second and The state variables of the output of the sub-cycle calculation ; and For the Second and The state variables of the output of the sub-cycle calculation ; 、 、 、 and are the coefficients of the four-dimensional hyperchaotic model; 、 、 and State variables , state variables , state variables and state variables The first derivative of ;

[0066] The fourth-order Runge-Kutta method is used to solve the partial differential equation of the four-dimensional hyperchaotic model, and the phase trajectory diagram of the four-dimensional hyperchaotic model is obtained, as shown in Figure 2 As shown in the figure, the value ranges of the four chaotic sequences of the 4D hyperchaotic model are (-85,81), (-25,23), (-26,21) and (-31,32).

[0067] Generate chaotic sequences according to state variables X, Y, Z and W respectively , chaotic sequence , chaotic sequence and chaotic sequences .

[0068] The chaotic sequence and chaotic sequences After inserting the original transmission data, convolution encryption is performed to obtain the encrypted bit stream. The process includes:

[0069] According to the chaotic sequence and chaotic sequences Generate chaotic insertion sequence S, the expression formula is:

[0070]

[0071] In the formula, the chaotic sequence and chaotic sequences Each has 1280 elements, is the remainder function; is the floor function; and is the intermediate transformation sequence;

[0072] The original transmission data is converted into binary to obtain original bits. The original transmission data contains a total of 17920 original bits, and each 7 original bits are divided into a group, for a total of 2560 groups; the chaotic bits in the chaotic insertion sequence S are inserted into each group of original bits and then input into the convolution device to obtain a 1×40960 encrypted bit stream. In this embodiment, the size of the convolution device is 2×1×8.

[0073] Convert the 1×40960 encrypted bit stream into an 80×512 data matrix ; The data matrix Every two columns of data are merged to obtain an 80×256 data matrix H.

[0074] According to the chaotic sequence and chaotic sequences Subcarrier scrambling and symbol scrambling are performed on the data matrix H in sequence to obtain the data matrix P. The process includes:

[0075] The chaotic sequence and chaotic sequences After sorting in ascending order and taking the inverse, the chaotic sequence and chaotic sequences Multiply to get the scrambled matrix and scrambled matrix ;

[0076]

[0077] In the formula, is the ascending order function; is the matrix transpose;

[0078] By scrambling matrix and scrambled matrix Extract the position of 1 to generate scrambled sequence M and scrambled sequence N; scrambled sequence M is a 1×256 matrix, and scrambled sequence N is a 1×80 matrix;

[0079] The data matrix H is column-transformed according to each column element of the scrambling sequence M, and the scrambling sequence N is transposed and the data matrix H is row-transformed to obtain an 80×256 data matrix P.

[0080] The initial key value is converted into binary and repeatedly superimposed D times to obtain an 80×128 key matrix, where D is 80 in this embodiment. A constellation codebook is established using QPSK constellation A and QPSK constellation B. As shown in Table 1, a mapping relationship is set between the cipher bits in the key matrix and the constellation codebook.

[0081] Table 1, constellation index mapping rules;

[0082]

[0083] like Figure 3 As shown, the key matrix is ​​used as an index, and the elements in the data matrix P are QPSK mapped through the constellation codebook to obtain constellation points, and the constellation points form a constellation diagram.

[0084] The constellation points in the constellation diagram are represented by real and imaginary parts to obtain complex constellation points; the complex constellation points are inverse Fourier transformed, and a cyclic prefix and a cyclic suffix are added to obtain an 80×1320 time domain transmission signal, where the cyclic prefix length is 128 and the suffix length is 40; the time domain transmission signal is transmitted from the transmitter to the receiver through an optical fiber channel;

[0085] The cyclic prefix and cyclic suffix of the time domain transmitted signal are removed and then Fourier transformed to obtain the frequency domain received signal, such as Figure 4 As shown in FIG, the constellation diagram received by the receiver is recovered from the frequency domain received signal.

[0086] In response to the receiver receiving the constellation diagram, decrypting the constellation diagram to obtain the original transmission data, the process includes:

[0087] The constellation diagram is converted into an 80×256 received data matrix using a constellation codebook. The index bit information is extracted from the received data matrix. Based on the mapping relationship between the cipher bits and the constellation codebook, the index bit information is combined to obtain a key matrix. The key initial value is obtained from the key matrix, and the index bit with the most occurrences is selected as the correct key initial value, ultimately extracting the absolutely correct key. Because the key is repeated multiple times, the correctness of key transmission can be guaranteed even in low signal-to-noise ratio conditions. Once the final extracted key is guaranteed to be completely correct, the key is introduced into a four-dimensional hyperchaotic model to generate a chaotic sequence, which is then used to decrypt the received data matrix to obtain the original transmitted data.

[0088] For secure key transmission methods, key transmission quality is extremely important. Because the chaotic system itself is very sensitive to the initial value of the key, even slight changes in the initial value will result in the generation of a completely different chaotic sequence, making it impossible to correctly decrypt the signal. To ensure the absolute correctness of key transmission in this embodiment, we repeated the key 80 times, which is equivalent to cyclically sampling the key 80 times. After extracting the key, we also performed information comparison on the key and selected the key with the most occurrences among the 80 groups as the final correct key, thus ensuring error-free key transmission. After simulation, when the signal-to-noise ratio was 5, the bit error rate of the key was zero, proving that error-free key transmission can still be achieved even under very low signal-to-noise ratios.

[0089] Figure 5 Comparative graphs of bit error rate curves after recovering the original data using convolutional encryption (the secure magnetic communication method disclosed in this embodiment), traditional encryption methods, and signals from an unauthorized receiver are shown. The graph shows that the bit error rate for data encrypted using convolutional encryption approaches zero when the signal-to-noise ratio (SNR) exceeds 7. In contrast, the bit error rate for signals using traditional encryption approaches zero only when the SNR reaches 13. Unauthorized receivers, unable to obtain the correct key information, are unable to decrypt the encrypted signal. This demonstrates that the encryption method proposed by this invention offers high information security and excellent information transmission performance.

[0090] Example 2

[0091] This embodiment provides a secure magnetic communication system based on a key index. The secure magnetic communication system of this embodiment can be used to execute the secure magnetic communication method described in Example 1. The secure magnetic communication system includes:

[0092] The key module uses a four-dimensional hyperchaotic model to generate a chaotic sequence based on the set key initial value. , chaotic sequence , chaotic sequence and chaotic sequences ;

[0093] Interference module, chaotic sequence and chaotic sequences After inserting the original transmission data, convolution encryption is performed to obtain the encrypted bit stream, and the encrypted bit stream is converted into a data matrix H according to the chaotic sequence. and chaotic sequences Perform subcarrier scrambling and symbol scrambling on the data matrix H in sequence to obtain the data matrix P;

[0094] A mapping module performs binary conversion on the initial key value and repeatedly superimposes it D times to obtain a key matrix; establishes a constellation codebook using QPSK constellation A and QPSK constellation B; and sets a mapping relationship between the cipher bits in the key matrix and the constellation codebook;

[0095] The encryption module uses the key matrix as an index and performs QPSK mapping on the elements in the data matrix P through the constellation codebook to obtain constellation points. The constellation points form a constellation diagram; the constellation diagram is sent to the receiver through the transmitter;

[0096] The decryption module decrypts the constellation diagram to obtain original transmission data in response to the receiver receiving the constellation diagram.

[0097] The decryption module decrypts the constellation diagram to obtain the original transmission data, and the process includes:

[0098] The constellation diagram is converted into a received data matrix through a constellation codebook, and index bit information is extracted from the received data matrix; according to the mapping relationship between the cipher bits and the constellation codebook, the index bit information is key-combined to obtain a key matrix; and the received data matrix is ​​decrypted according to the key matrix to obtain the original transmitted data.

[0099] This embodiment utilizes the four-dimensional hyperchaotic model because of its high sensitivity and unpredictability to initial conditions, thereby improving the security and reliability of the communication system. At the same time, the chaotic encryption method in this embodiment can resist external interference and noise to a certain extent, thereby improving the robustness of the communication system.

[0100] This embodiment hides the key in the constellation to enhance the security of wireless magnetic communication transmission. The method of using the constellation codebook to hide the key does not add extra bits of redundant information to the transmitted information and is suitable for magnetic communication systems with limited bandwidth.

[0101] Example 3

[0102] This embodiment provides an electronic device, including a storage medium and a processor; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the secure magnetic communication method described in Example 1.

[0103] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take 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.) containing computer-usable program code.

[0104] 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 block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks 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 processes in the flowchart and / or block diagram. 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.

[0105] 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.

[0106] 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.

[0107] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A secure magnetic communication method based on key indexing, characterized in that: include: Generate chaotic sequence based on the set initial value of key using four-dimensional hyperchaotic model , chaotic sequence , chaotic sequence and chaotic sequences ; The chaotic sequence and chaotic sequences After inserting the original transmission data, convolution encryption is performed to obtain the encrypted bit stream, and the encrypted bit stream is converted into a data matrix H according to the chaotic sequence. and chaotic sequences Perform subcarrier scrambling and symbol scrambling on the data matrix H in sequence to obtain the data matrix P; Perform binary conversion on the initial key value and repeatedly superimpose it D times to obtain a key matrix; establish a constellation codebook using QPSK constellation A and QPSK constellation B; set a mapping relationship between the cipher bits in the key matrix and the constellation codebook; Using the key matrix as an index, QPSK mapping is performed on the elements in the data matrix P through the constellation codebook to obtain constellation points, and the constellation points form a constellation diagram; the constellation diagram is sent to the receiver through the transmitter; In response to the receiver receiving the constellation map, the constellation map is decrypted to obtain the original transmission data.

2. The secure magnetic communication method according to claim 1, wherein: Generate chaotic sequence based on the set initial value of key using four-dimensional hyperchaotic model , chaotic sequence , chaotic sequence and chaotic sequences ; The process includes: The initial value of the key is input into the four-dimensional hyperchaotic model to obtain the state variables X, Y, Z, and W. The expression formula is: ； ； ； ； In the formula, and For the Second and The state variables of the output of the sub-cycle calculation ; and For the Second and The state variables of the output of the sub-cycle calculation ; and For the Second and The state variables of the output of the sub-cycle calculation ; and For the Second and The state variables of the output of the sub-cycle calculation ; 、 、 、 and are the coefficients of the four-dimensional hyperchaotic model; 、 、 and State variables , state variables , state variables and state variables The first derivative of ; Generate chaotic sequences according to state variables X, Y, Z and W respectively , chaotic sequence , chaotic sequence and chaotic sequences .

3. The secure magnetic communication method according to claim 1, wherein: The chaotic sequence and chaotic sequences After inserting the original transmission data, convolution encryption is performed to obtain the encrypted bit stream. The process includes: According to the chaotic sequence and chaotic sequences Generate chaotic insertion sequence S, the expression formula is: ； In the formula, is the remainder function; is the floor function; and is the intermediate transformation sequence; The original transmission data is converted into binary to obtain original bits, and the original bits are grouped; the chaotic bits in the chaotic insertion sequence S are inserted into each group of original bits and then input into the convolution device to obtain the encrypted bit stream.

4. The secure magnetic communication method according to claim 1, wherein: The encrypted bit stream is converted from serial to parallel to obtain the data matrix H. The process includes: Convert encrypted bit stream into data matrix ; The data matrix The data matrix H is obtained by merging every two columns of data.

5. The secure magnetic communication method according to claim 1, wherein: According to the chaotic sequence and chaotic sequences Subcarrier scrambling and symbol scrambling are performed on the data matrix H in sequence to obtain the data matrix P. The process includes: The chaotic sequence and chaotic sequences After sorting in ascending order and taking the inverse, the chaotic sequence and chaotic sequences Multiply to get the scrambled matrix and scrambled matrix ; ； In the formula, is the ascending order function; is the matrix transpose; By scrambling matrix and scrambled matrix Extract the position of 1 to generate scrambled sequence M and scrambled sequence N; The data matrix H is column-transformed according to each column element of the scrambled sequence M, and the scrambled sequence N is transposed and the data matrix H is row-transformed to obtain the data matrix P.

6. The secure magnetic communication method according to claim 1, wherein: The constellation diagram is sent from the transmitter to the receiver. The process includes: The constellation points in the constellation diagram are represented by real and imaginary parts to obtain complex constellation points; the complex constellation points are inverse Fourier transformed, and a cyclic prefix and a cyclic suffix are added to obtain a time domain transmission signal, which is then transmitted from the transmitter to the receiver via an optical fiber channel; The cyclic prefix and cyclic suffix of the time domain transmitted signal are removed and Fourier transform is performed to obtain the frequency domain received signal, and the constellation diagram received by the receiver is recovered from the frequency domain received signal.

7. The secure magnetic communication method according to claim 1, wherein: In response to the receiver receiving the constellation diagram, decrypting the constellation diagram to obtain the original transmission data, the process includes: The constellation diagram is converted into a received data matrix through a constellation codebook, and index bit information is extracted from the received data matrix; according to the mapping relationship between the cipher bits and the constellation codebook, the index bit information is key-combined to obtain a key matrix; and the received data matrix is ​​decrypted according to the key matrix to obtain the original transmitted data.

8. A secure magnetic communication system based on key indexing, characterized in that: include: The key module uses a four-dimensional hyperchaotic model to generate a chaotic sequence based on the set key initial value. , chaotic sequence , chaotic sequence and chaotic sequences ; Interference module, chaotic sequence and chaotic sequences After inserting the original transmission data, convolution encryption is performed to obtain the encrypted bit stream, and the encrypted bit stream is converted into a data matrix H according to the chaotic sequence. and chaotic sequences Perform subcarrier scrambling and symbol scrambling on the data matrix H in sequence to obtain the data matrix P; A mapping module performs binary conversion on the initial key value and repeatedly superimposes it D times to obtain a key matrix; establishes a constellation codebook using QPSK constellation A and QPSK constellation B; and sets a mapping relationship between the cipher bits in the key matrix and the constellation codebook; The encryption module uses the key matrix as an index and performs QPSK mapping on the elements in the data matrix P through the constellation codebook to obtain constellation points. The constellation points form a constellation diagram; the constellation diagram is sent to the receiver through the transmitter; The decryption module decrypts the constellation diagram to obtain original transmission data in response to the receiver receiving the constellation diagram.

9. The secure magnetic communication system according to claim 8, wherein: The decryption module decrypts the constellation diagram to obtain the original transmission data, and the process includes: The constellation diagram is converted into a received data matrix through a constellation codebook, and index bit information is extracted from the received data matrix; according to the mapping relationship between the cipher bits and the constellation codebook, the index bit information is key-combined to obtain a key matrix; and the received data matrix is ​​decrypted according to the key matrix to obtain the original transmitted data.

10. An electronic device comprising a storage medium and a processor; the storage medium is used to store instructions; characterized in that, The processor is configured to operate according to the instructions to execute the key index-based secure magnetic communication method according to any one of claims 1 to 7.

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