Key following transmission system and method based on dynamic window encryption

Abstract

The invention discloses a secret key following transmission system and method based on dynamic window encryption, and the system comprises a transmitting end which is configured to obtain a chaotic initial value and an original signal to be transmitted; processing the chaotic initial value through a public key encryption module and a first constellation mapping module to obtain encryption key information; the original signal is processed by a bit stream encryption module, a second constellation mapping module and a symbol encryption module to obtain encrypted information, the bit stream encryption module realizes bit stream encryption by using a disturbance sequence generated by a chaotic initial value, and the symbol encryption module realizes symbol-level scrambling by using a'dynamic window structure '; superposing the encrypted information and the encrypted key information by using a power division multiplexing module to obtain to-be-transmitted composite information; the composite information is converted into a time domain signal through fast inverse Fourier transform (IFFT), and signal transmission is carried out through a channel; and dual improvement of communication safety and communication efficiency is realized.

Description

Technical Field

[0001] The present application belongs to the field of secure coding technology, and specifically relates to a key transmission system and method based on dynamic window encryption. Background Art

[0002] In recent years, with the widespread popularization and application of emerging technologies such as big data, cloud computing, and the Internet of Things, the transmission boundaries of information have been unprecedentedly broadened, and the mobility and accessibility of data have been significantly enhanced. However, it has also brought unprecedented challenges to data security and privacy protection. What is more complicated is that with the continuous advancement of technology, attackers' methods are also constantly upgrading, making attack behaviors more intelligent, covert, and diversified. Traditional security protection measures are often unable to effectively respond to the latest attack methods, making the security risks faced by network communications more and more significant, and more advanced and comprehensive security protection strategies are urgently needed to deal with them.

[0003] In order to cope with the increasingly severe data security challenges, physical layer encryption technology has emerged and has developed rapidly. This technology implements encryption measures at the physical medium level of data storage and transmission to ensure the security of data during transmission. In optical communications, physical layer encryption covers technologies such as Rivest-Shamir-Adleman (RSA) encryption algorithm and bit scrambling. However, although these technologies have shown excellent performance in data security, they also face problems that cannot be ignored, namely, the RSA algorithm and bit scrambling technology have high computational complexity in the implementation process, which to a certain extent limits their practical application scope and efficiency.

[0004] Therefore, how to reduce computational complexity while ensuring data security has become an urgent problem to be solved in the development of current physical layer encryption technology. Summary of the invention

[0005] Purpose: In view of at least one of the above technical problems, the present application provides a key transmission system and method based on dynamic window encryption, which adopts dynamic window technology to reduce the computational complexity, thereby finding a balance between information security and encryption efficiency, and achieving a dual improvement in communication security and communication efficiency.

[0006] The technical solution adopted in this application is:

[0007] In a first aspect, the present application provides a key transmission method based on dynamic window encryption, comprising:

[0008] The transmitting end is configured to: obtain a chaotic initial value and an original signal to be sent; process the chaotic initial value through a public key encryption module and a first constellation mapping module to obtain encryption key information; process the original signal through a bitstream encryption module, a second constellation mapping module, and a symbol encryption module to obtain encrypted information, wherein the bitstream encryption module uses a disturbance sequence generated by the chaotic initial value to realize bitstream encryption, and the symbol encryption module uses a "dynamic window structure" to realize symbol-level scrambling; use a power division multiplexing module to superimpose the encrypted information and the encryption key information to obtain composite information to be transmitted; convert the composite information into a time domain signal through a fast inverse Fourier transform IFFT, and transmit the signal through a channel;

[0009] The receiving end is configured as follows: after the time domain signal is transmitted through the channel, it is converted into a frequency domain signal through fast Fourier transform FFT; the frequency domain signal is demodulated by using a power division multiplexing module to separate the encrypted information and the encryption key information; the encrypted key information that has passed through the first constellation demapping module is decrypted by using a private key decryption module to restore the chaotic initial value, and a disturbance sequence is generated according to the chaotic initial value; the encrypted information is processed by a symbol decryption module, a second constellation demapping module, and a bit stream decryption module to obtain the original data; wherein the symbol decryption module uses a "dynamic window structure" to perform symbol descrambling on the encrypted information; and the bit stream decryption module uses the disturbance sequence to realize bit stream decryption.

[0010] In a second aspect, the present application provides a key transmission method based on dynamic window encryption, comprising:

[0011] Obtain the initial value of chaos and the original signal to be sent;

[0012] The chaotic initial value is processed by a public key encryption module and a constellation mapping to obtain encryption key information;

[0013] generating a disturbance sequence according to the chaotic initial value;

[0014] The original signal is processed by a bitstream encryption module, a constellation mapping module, and a symbol encryption module to obtain encrypted information; wherein the bitstream encryption module uses the perturbation sequence to implement bitstream encryption, and the symbol encryption module uses a "dynamic window structure" to implement symbol-level scrambling;

[0015] Using a multiplexing module to superimpose the encryption information and the encryption key information to obtain composite information to be transmitted;

[0016] Converting the composite information into a time domain signal by means of an inverse fast Fourier transform (IFFT), and transmitting the signal through a channel;

[0017] After the time domain signal is transmitted through the channel, it is converted into a frequency domain signal through fast Fourier transform FFT;

[0018] Demodulate the frequency domain signal using the power division multiplexing module to separate the encrypted information and the encryption key information;

[0019] Decrypting the encrypted key information using a private key decryption module to recover the chaotic initial value, and generating a disturbance sequence according to the chaotic initial value;

[0020] The encrypted information is processed by a symbol decryption module, a constellation demapping module, and a bit stream decryption module to obtain original data; wherein the symbol decryption module uses a "dynamic window structure" to perform symbol descrambling on the encrypted information; and the bit stream decryption module uses the perturbation sequence to implement bit stream decryption.

[0021] Beneficial effects: The key transmission system and method based on dynamic window encryption provided by the present application have the following advantages: in terms of key management, chaotic keys are encrypted by RSA to simplify calculations while combining its high security with the complex characteristics of chaotic encryption; in terms of encryption, chaotic XOR operation and dynamic window technology are used to balance information security and encryption efficiency to ensure safe and efficient communication; in terms of key distribution, power division multiplexing technology is used to achieve synchronous transmission of keys and ciphertexts, further improving the security performance of the communication system. The present application uses RSA algorithm, chaotic encryption, power division multiplexing and dynamic window technology on the basis of optical communication system to improve communication security and communication efficiency. First, the chaotic key is encrypted by RSA algorithm instead of directly processing the plaintext, which not only avoids the complexity of calculations, but also combines the high security of RSA algorithm with the complex and unpredictable characteristics of chaotic encryption technology. Then, chaotic XOR and dynamic window technology are used to scramble bits and symbols respectively, and an optimal balance is found between information security and encryption efficiency, thereby ensuring that the security of the communication process and the communication efficiency can be doubled. Finally, the power division multiplexing technology is used to realize the synchronous transmission of the key and the ciphertext, thereby improving the overall security of information transmission. By combining the RSA algorithm with chaotic encryption, the chaotic key is encrypted using the RSA algorithm, which not only reduces the data processing pressure of traditional RSA encryption, but also combines the high security of the RSA algorithm with the complex characteristics of chaotic encryption. In the encryption process, the dynamic window technology is further introduced to encrypt the symbols, while ensuring the communication security, the encryption efficiency is also improved as much as possible, thereby improving the communication efficiency. Therefore, the present invention can achieve the dual guarantee of communication security and communication efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a key transmission system based on dynamic window encryption according to an embodiment of the present application;

[0023] Figure 2 A schematic diagram of a process for generating a public key and a private key according to an embodiment of the present application;

[0024] Figure 3 A schematic diagram of a bit stream encryption process according to an embodiment of the present application;

[0025] Figure 4 A schematic diagram of constellation superposition according to an embodiment of the present application;

[0026] Figure 5 Schematic diagram of group processing in a symbol encryption module according to an embodiment of the present application;

[0027] Figure 6 A schematic diagram of dynamic window encryption according to an embodiment of the present application;

[0028] Figure 7 The figure is a schematic diagram of the decryption process at the receiving end according to an embodiment of the present application. DETAILED DESCRIPTION

[0029] The present application is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and cannot be used to limit the protection scope of the present application.

[0030] In the description of this application, "several" means more than one, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0031] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0032] The term "and / or" is only a description of the association relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " generally indicates that the related objects are in an "or" relationship.

[0033] Embodiment 1: This embodiment provides a key transmission system based on dynamic window encryption, such as Figure 1 As shown, including:

[0034] The transmitting end is configured to: obtain a chaotic initial value and an original signal to be sent; process the chaotic initial value through a public key encryption module and a first constellation mapping module to obtain encryption key information; process the original signal through a bitstream encryption module, a second constellation mapping module, and a symbol encryption module to obtain encrypted information, wherein the bitstream encryption module uses a disturbance sequence generated by the chaotic initial value to realize bitstream encryption, and the symbol encryption module uses a "dynamic window structure" to realize symbol-level scrambling; use a power division multiplexing module to superimpose the encrypted information and the encryption key information to obtain composite information to be transmitted; convert the composite information into a time domain signal through a fast inverse Fourier transform IFFT, and transmit the signal through a channel;

[0035] The receiving end is configured as follows: after the time domain signal is transmitted through the channel, it is converted into a frequency domain signal through fast Fourier transform FFT; the frequency domain signal is demodulated by using a power division multiplexing module to separate the encrypted information and the encryption key information; the encrypted key information that has passed through the first constellation demapping module is decrypted by using a private key decryption module to restore the chaotic initial value, and a disturbance sequence is generated according to the chaotic initial value; the encrypted information is processed by a symbol decryption module, a second constellation demapping module, and a bit stream decryption module to obtain the original data; wherein the symbol decryption module uses a "dynamic window structure" to perform symbol descrambling on the encrypted information; and the bit stream decryption module uses the disturbance sequence to realize bit stream decryption.

[0036] In some embodiments, the public key and private key of the system are generated according to the Rivest-Shamir-Adleman (asymmetric encryption RSA) algorithm: randomly select two unequal prime numbers p and q, and calculate their product n, that is, n=p*q; calculate the Euler function φ(n) of n, which is the number of numbers that are coprime to n among positive integers less than or equal to n; for n=p*q, then φ(n)=(p−1)(q−1); then select an integer u less than φ(n) so that u and φ(n) are coprime, that is, gcd(u,φ(n))=1; calculate the modular inverse element v through the extended Euclidean algorithm so that the remainder of u*v divided by φ(n) is 1, that is, (v*u) mod ((p-1)*(q-1))=1, where mod is the remainder function; finally, obtain the public key (n,u) and private key (n,v).

[0037] Furthermore, in some embodiments, in the public key encryption module, the public key (n, u) is used to perform an encryption operation on the chaotic initial value m to generate a ciphertext c; the encryption process is specifically as follows:

[0038] ,

[0039] Then, the ciphertext c is converted into a binary sequence [C1, C2, C3, …C i ], where i represents the number in the binary sequence.

[0040] Furthermore, in some embodiments, in the private key decryption module, the demodulated binary sequence [C1, C2, C3, ... C i ] is restored to ciphertext c; then, the ciphertext c is decrypted using the private key (n,v) to restore the original chaotic initial value m; the specific steps of decryption are:

[0041] .

[0042] In some embodiments, the bitstream encryption module implements bitstream encryption using a disturbance sequence generated by a chaotic initial value, including:

[0043] The disturbance sequence is generated by using the three-dimensional Lorenz chaotic map according to the chaotic initial value; the chaotic map is expressed as follows:

[0044] ,

[0045] Among them, σ, ρ, β are system parameters, x, y, z are state variables, and together they constitute the key (σ, ρ, β, x, y, z); through the chaotic mapping, a disturbance sequence (x n ,y n , z n ); x n ,y n , z n are the three components of the disturbance sequence respectively;

[0046] like Figure 3 As shown, select x in the perturbation sequence n As the masking sequence, use the masking sequence x n The bit stream is encrypted by performing an XOR operation with the original bit sequence to obtain an encrypted bit sequence.

[0047] In some embodiments, in a first constellation mapping module, encryption key information is mapped into two independent quadrature phase shift keying (QPSK) signals; in a second constellation mapping module, encryption information is mapped into two independent quadrature phase shift keying signals to facilitate subsequent power division multiplexing (PDM) processing.

[0048] After the signal enters the power division multiplexing module, the system generates an efficient 16-quadrature amplitude modulation (16QAM) signal by superimposing the two orthogonal phase shift keying (QPSK) signals, such as Figure 4 shown.

[0049] Furthermore, in some embodiments, in the power division multiplexing module, superimposing the encryption information with the encryption key information includes:

[0050] ,

[0051] Among them, S i represents the ith signal, P i represents the power of the i-th signal; S1 represents the encryption information, and S2 represents the encryption key information.

[0052] Next, these symbols carrying the encrypted information are sent to the symbol encryption module. In some embodiments, in the symbol encryption module, the symbols mapped by the second constellation mapping module are grouped, the total number of symbols is N, and the symbols are evenly divided into W groups, the length of each group of symbols is L=N / W, and the size of L can be dynamically adjusted according to the total number of symbols N; it should be noted that the size of L is directly related to and affects the scale and scope of subsequent operations, which means that there are multiple grouping methods, such as L=2, L=3, L=4, L=5, etc. Figure 5 These diverse grouping options provide great flexibility, and you can choose the most appropriate grouping strategy based on specific application scenarios and requirements.

[0053] In the symbol encryption module, the present invention introduces an innovative dynamic window encryption technology. Its principle is inspired by pinhole imaging - when light passes through a pinhole, an inverted real image is formed on the other side of the pinhole. In this encryption technology, symbols, like light, need to be transmitted through a "dynamic window structure".

[0054] The symbol encryption module uses a "dynamic window structure" to achieve symbol-level scrambling, including: the symbol is transmitted through a "dynamic window structure", and the "dynamic window structure" determines whether the symbol is transformed or kept as it is according to the current state; the state of the "dynamic window structure" includes "0" and "1" states; if the state of the dynamic window is "0", the corresponding symbol is transformed; if the state of the dynamic window is "1", the corresponding symbol remains as it is. In this embodiment, the state of the "dynamic window structure" is determined by the y in the disturbance sequence. n Decisions provide random and unpredictable "0" and "1" states.

[0055] Specifically, if the state of the dynamic window is "0", a transformation similar to pinhole imaging will be performed on the corresponding symbol. This transformation actually inverts the symbol, similar to the inverted real image formed after light passes through a pinhole, such as Figure 6As shown in FIG. 3 , the grouping of L=3 is taken as an example. If the state of the dynamic window is "1", the corresponding symbol will remain unchanged.

[0056] At the same time, the "dynamic" characteristics of the "dynamic window" are not only reflected in the change of its state, but also in the change of the length L of each group of symbols. Here, L not only represents the length of each group of symbols, but also represents the length of the corresponding window. The length of L has a direct impact on encryption performance: when L is longer, the computational complexity of encryption will be reduced accordingly, because the number of symbols to be processed is reduced, but this also means that the security of the system will be weakened to a certain extent; on the contrary, when L is shorter, although the computational complexity of encryption will increase, the security of the system will be significantly improved.

[0057] Therefore, in order to ensure communication security while also improving encryption efficiency as much as possible, the system needs to dynamically adjust the size of L according to the actual amount of information, that is, the total number of symbols N. Through this flexible encryption technology, an optimal balance can be found between information security and encryption efficiency, thereby ensuring that both the security of the communication process and the communication efficiency can be improved.

[0058] In some embodiments, in the demultiplexing module, the received signal is processed using the serial interference cancellation SIC technology, such as Figure 7 As shown, specifically including:

[0059] Estimate channel response and implement channel equalization to extract encrypted information (high-power signal);

[0060] Remodulating the encrypted information (high-power signal) and adjusting it by applying an estimated value of a channel response to obtain an adjusted signal;

[0061] The adjusted signal is subtracted from the original received signal to separate the encryption key information (low-power signal).

[0062] Finally, through the above-mentioned SIC technology, high-power encryption information and low-power encryption key information are obtained respectively.

[0063] Subsequently, in the decryption process at the receiving end, the "dynamic window structure" is used to perform reverse processing on the high-power encrypted information to complete the symbol descrambling of the encrypted information. At the same time, the private key is used to decode the low-power encryption key information and restore it to the original chaotic initial value. Based on these chaotic initial values, the system can generate the corresponding perturbation sequence, and then perform bit-level descrambling on the encrypted information, and finally restore the original information.

[0064] Embodiment 2: Based on Embodiment 1, this embodiment provides a key transmission method based on dynamic window encryption, including:

[0065] Obtain the initial value of chaos and the original signal to be sent;

[0066] The chaotic initial value is processed by a public key encryption module and a constellation mapping to obtain encryption key information;

[0067] generating a disturbance sequence according to the chaotic initial value;

[0068] The original signal is processed by a bitstream encryption module, a constellation mapping module, and a symbol encryption module to obtain encrypted information; wherein the bitstream encryption module uses the perturbation sequence to implement bitstream encryption, and the symbol encryption module uses a "dynamic window structure" to implement symbol-level scrambling;

[0069] Using a multiplexing module to superimpose the encryption information and the encryption key information to obtain composite information to be transmitted;

[0070] Converting the composite information into a time domain signal by means of an inverse fast Fourier transform (IFFT), and transmitting the signal through a channel;

[0071] After the time domain signal is transmitted through the channel, it is converted into a frequency domain signal through fast Fourier transform FFT;

[0072] Demodulate the frequency domain signal using the power division multiplexing module to separate the encrypted information and the encryption key information;

[0073] Decrypting the encrypted key information using a private key decryption module to recover the chaotic initial value, and generating a disturbance sequence according to the chaotic initial value;

[0074] The encrypted information is processed by a symbol decryption module, a constellation demapping module, and a bit stream decryption module to obtain original data; wherein the symbol decryption module uses a "dynamic window structure" to perform symbol descrambling on the encrypted information; and the bit stream decryption module uses the perturbation sequence to implement bit stream decryption.

[0075] 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 a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, 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 disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0076] 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 and the combination of the 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.

[0077] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0078] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0079] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A key transmission system based on dynamic window encryption, characterized in that: include: The transmitting end is configured to: obtain a chaotic initial value and an original signal to be sent; process the chaotic initial value through a public key encryption module and a first constellation mapping module to obtain encryption key information; process the original signal through a bit stream encryption module, a second constellation mapping module, and a symbol encryption module to obtain encrypted information, wherein the bit stream encryption module uses a disturbance sequence generated by the chaotic initial value to realize bit stream encryption, and the symbol encryption module uses a "dynamic window structure" to realize symbol-level scrambling; use a power division multiplexing module to superimpose the encrypted information and the encryption key information to obtain composite information to be transmitted; convert the composite information into a time domain signal through a fast inverse Fourier transform IFFT, and transmit the signal through a channel; The receiving end is configured to: after the time domain signal is transmitted through the channel, it is converted into a frequency domain signal through a fast Fourier transform FFT; The frequency domain signal is demodulated by a power division multiplexing module to separate the encrypted information and the encryption key information; the encrypted key information after the first constellation demapping module is decrypted by a private key decryption module to recover the chaotic initial value, and a disturbance sequence is generated according to the chaotic initial value; the encrypted information is processed by a symbol decryption module, a second constellation demapping module, and a bit stream decryption module to obtain the original data; wherein the symbol decryption module uses a "dynamic window structure" to perform symbol descrambling on the encrypted information; and the bit stream decryption module uses the disturbance sequence to realize bit stream decryption.

2. The system according to claim 1, characterized in that The public and private keys of the system are generated according to an asymmetric encryption algorithm: randomly select two unequal prime numbers p and q, and calculate their product n, that is, n=p*q; calculate the Euler function φ(n) of n, which is the number of positive integers less than or equal to n that are relatively prime to n; For n=p*q, then ϕ(n)=(p−1)(q−1); then choose an integer u less than ϕ(n) so that u and ϕ(n) are coprime, that is, gcd(u,ϕ(n))=1; calculate the modular inverse element v through the extended Euclidean algorithm so that the remainder of u*v divided by ϕ(n) is 1, that is, (v*u)mod ((p-1)*(q-1))=1, where mod is the remainder function; finally, obtain the public key (n,u) and private key (n,v).

3. The system according to claim 2, characterized in that In the public key encryption module, the public key (n,u) is used to encrypt the chaotic initial value m to generate the ciphertext c. The encryption process is as follows: ， Then, the ciphertext c is converted into a binary sequence [C1, C2, C3, …C i ], where i represents the number in the binary sequence.

4. The system according to claim 2, characterized in that In the private key decryption module, the demodulated binary sequence [C1, C2, C3, ... C i ] is restored to ciphertext c; then, the ciphertext c is decrypted using the private key (n,v) to restore the original chaotic initial value m; the specific steps of decryption are: 。 5. The system according to claim 1, characterized in that The bitstream encryption module realizes bitstream encryption by using a disturbance sequence generated by a chaotic initial value, including: The disturbance sequence is generated by using the three-dimensional Lorenz chaotic map according to the chaotic initial value; the chaotic map is expressed as follows: ， Among them, σ, ρ, β are system parameters, x, y, z are state variables, and together they constitute the key (σ, ρ, β, x, y, z); through the chaotic mapping, a disturbance sequence (x n ,y n , z n ); x n ,y n , z n are the three components of the disturbance sequence; Choose x in the perturbation sequence n As the masking sequence, use the masking sequence x n The bit stream is encrypted by performing an XOR operation with the original bit sequence.

6. The system according to claim 1, characterized in that In the first constellation mapping module, the encryption key information is mapped into two independent quadrature phase shift keying signals; And / or, in the second constellation mapping module, the encrypted information is mapped into two independent orthogonal phase shift keying signals.

7. The system according to claim 1, characterized in that In the power division multiplexing module, superimposing the encryption information with the encryption key information includes: ， Among them, S i represents the ith signal, P i represents the power of the i-th signal; S1 represents the encryption information, and S2 represents the encryption key information.

8. The system according to claim 1, characterized in that In the symbol encryption module, the symbols mapped by the second constellation mapping module are grouped, the total number of symbols is N, and the symbols are evenly divided into W groups, the length of each group of symbols is L=N / W, and the size of L can be dynamically adjusted according to the total number of symbols N; The symbol encryption module uses a "dynamic window structure" to achieve symbol-level scrambling, including: the symbol is transmitted through a "dynamic window structure", and the "dynamic window structure" determines whether the symbol is transformed or kept as it is according to the current state; The states of the "dynamic window structure" include "0" and "1" states; if the state of the dynamic window is "0", the corresponding symbol is transformed; if the state of the dynamic window is "1", the corresponding symbol remains the same.

9. The system according to claim 1, characterized in that In the demultiplexing module, the received signal is processed using the serial interference cancellation (SIC) technology, including: Estimate channel response and implement channel equalization to extract encrypted information; remodulating the encrypted information and adjusting it by applying an estimated value of a channel response to obtain an adjusted signal; The adjusted signal is subtracted from the original received signal to separate the encryption key information.

10. A key transmission method based on dynamic window encryption, characterized in that: include: Obtain the initial value of chaos and the original signal to be sent; The chaotic initial value is processed by a public key encryption module and a constellation mapping to obtain encryption key information; generating a disturbance sequence according to the chaotic initial value; The original signal is processed by a bitstream encryption module, a constellation mapping module, and a symbol encryption module to obtain encrypted information; wherein the bitstream encryption module uses the perturbation sequence to implement bitstream encryption, and the symbol encryption module uses a "dynamic window structure" to implement symbol-level scrambling; Using a multiplexing module to superimpose the encryption information and the encryption key information to obtain composite information to be transmitted; Converting the composite information into a time domain signal by means of an inverse fast Fourier transform (IFFT), and transmitting the signal through a channel; After the time domain signal is transmitted through the channel, it is converted into a frequency domain signal through fast Fourier transform FFT; Demodulate the frequency domain signal using the power division multiplexing module to separate the encrypted information and the encryption key information; Decrypting the encrypted key information using a private key decryption module to recover the chaotic initial value, and generating a disturbance sequence according to the chaotic initial value; The encrypted information is processed by a symbol decryption module, a constellation demapping module, and a bit stream decryption module to obtain original data; wherein the symbol decryption module uses a "dynamic window structure" to perform symbol descrambling on the encrypted information; and the bit stream decryption module uses the perturbation sequence to implement bit stream decryption.

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