A secure wireless communication system design method based on polarization modulation strategy

Abstract

The application discloses a kind of based on the design method of security wireless communication system of polarization modulation strategy, introduces camouflage image in the process of encoding and decoding and utilizes polarization mask key to encrypt target information, and adopts polarization modulation strategy to send the camouflage image containing encryption information and polarization mask key simultaneously;Target user extracts real target information from the camouflage information received by corresponding decoding strategy, while eavesdropper cannot obtain accurate target information;The method can simultaneously encrypt independent wireless communication in multiple channels with different polarization encoding strategies;By using different polarization mask keys and polarization encoding strategies, the security of the system can be further improved. The encryption scheme proposed integrates computation algorithm encryption and physical layer encryption, has the advantages of high security, large channel capacity, strong camouflage ability, etc., and is expected to play an important role in future secure wireless communication.

Description

Technical Field

[0001] This invention relates to the field of novel artificial electromagnetic materials, and specifically to a design method for a secure wireless communication system based on a polarization modulation strategy. Background Technology

[0002] Metasurfaces, by incorporating active devices such as varactor diodes or PIN diodes, further evolve into programmable metasurfaces, dynamically switching multiple electromagnetic functions in real time to meet different operational requirements. Programmable metasurfaces have been widely applied in fields such as dynamic holograms, reconfigurable smart surfaces, and microwave cloaks. Furthermore, programmable metasurfaces can directly connect with information science and digital signal processing, evolving into information metasurfaces, which are more conducive to building novel wireless communication systems. Compared to traditional wireless communication methods, metasurface-assisted wireless communication schemes have a significantly simplified transmission architecture, enabling direct modulation of object characteristics such as phase, amplitude, or frequency on the metasurface without requiring complex and expensive RF components. Common modulation schemes include On-Off Keying (OOK), Quadrature Phase Shift Keying (QPSK), Binary Frequency Shift Keying (BFSK), and Quadrature Amplitude Modulation (QAM), which are increasingly being applied in metasurface wireless communication systems.

[0003] However, due to the lack of multi-degree-of-freedom programmable metasurface polarization converters, reports on polarization modulation schemes are scarce. Most current work on dynamic metasurface polarization converters is limited to the conversion between homopolarized and crosspolarized waves, or between linearly polarized and circularly polarized waves. Although recently proposed time-varying metasurfaces can achieve more degrees of polarization control by providing time-varying voltage sequences, this harmonic component-based control method wastes significant spectrum resources and increases the difficulty of application. In fact, polarization modulation, as a vector modulation method, can provide an alternative modulation scheme for carrier information and is also a backup option for highly secure wireless communication. Therefore, the development of highly secure metasurface-based wireless communication urgently requires multi-degree-of-freedom dynamic polarization manipulation strategies.

[0004] With the rapid increase in computing power, classical cryptography used in traditional wireless communication is facing significant security threats. Physical layer security technologies, which leverage the physical properties of signals transmitted in wireless channels rather than relying on computational encryption algorithms to ensure wireless communication security, have garnered considerable attention from researchers in recent years. Furthermore, quantum key distribution technology in quantum secure communication, through one-time key encryption, can theoretically achieve unconditional security. However, most current research on metasurface-based physical layer security technologies focuses primarily on theoretical analysis, while quantum key distribution technology, applicable to end-to-end communication, is difficult to implement practically. Summary of the Invention

[0005] The purpose of this invention is to provide a design method for a secure wireless communication system based on a polarization modulation strategy, so as to improve the information security, channel capacity and space utilization of the wireless communication system, and reduce the system complexity.

[0006] To achieve the above functions, this invention designs a secure wireless communication system design method based on a polarization modulation strategy. In at least one channel, the following steps S1-S4 are executed to complete the encryption and transmission of the target image at the transmitting end, and the reception and decryption of the target image at the receiving end:

[0007] Step S1: Based on the orthogonal polarization pairs, establish a polarization mask. Based on the polarization mask K corresponding to the location of the target receiving user, encrypt the target image to obtain an encrypted image. Use least significant bit steganography to hide the encrypted image in the disguised cover image to obtain a disguised image combining the encrypted image and the disguised cover image. The disguised cover image is a deceptive image, and its least significant bit hides the target encrypted information to be transmitted in wireless communication.

[0008] Step S2: Send the camouflaged image to the location of the target receiving user;

[0009] Step S3: The target user receives the camouflage image and polarization mask K;

[0010] Step S4: Extract the encrypted image hidden in the disguised image, decrypt the encrypted image using the polarization mask K, and obtain the target image.

[0011] As a preferred technical solution of the present invention, the specific steps of step S1 are as follows:

[0012] Step S1.1: Encode the polarization state at different positions of the plane longitude coil and the plane latitude coil respectively. The form is an orthogonal polarization pair composed of polarization code and digital code; wherein the polarization code is binary code and the digital code is 0 or 1; according to the location of the target receiving user, form a set of orthogonal polarization pairs corresponding to the plane longitude coil and the plane latitude coil respectively.

[0013] Step S1.2: Construct a polarization mask K based on the orthogonal polarization pair corresponding to the location of the target receiving user. The polarization mask K is a matrix obtained based on the orthogonal polarization pair. The rows of the polarization mask K correspond to P0, and the columns of the polarization mask K correspond to P1. The Mth row and nth column elements in the polarization mask K are obtained by the XOR operation of the Mth element of P0 and the nth element of P1, where P0 and P1 are the combinations of the polarization codes corresponding to the digital codes 0 and 1 in the orthogonal polarization pair, respectively.

[0014] Step S1.3: Divide the target information to be sent into three parts and convert them into three target images respectively. Convert each target image into binary code and perform an XOR operation with the polarization mask K to obtain three encrypted images with the same size as the disguised cover image.

[0015] Step S1.4: Convert the encrypted image into a binary image and hide it in the least significant bits of the R, G, and B channels of the disguised cover image to obtain the disguised image.

[0016] As a preferred embodiment of the present invention, the least significant bit steganography method is as follows:

[0017] Steganography is used to divide the R, G, and B channel images of the disguised cover image into 8 layers. The encrypted image replaces the binary matrix of the first layer of the R, G, and B channel images of the disguised cover image, thereby hiding the encrypted image in the disguised cover image.

[0018] As a preferred technical solution of the present invention: the orthogonal polarization pairs mentioned in step S1.1 are in the form of polarization coding / digital coding. On the plane longitude coil, starting from 0°, the orthogonal polarization pairs in the clockwise direction at 45° intervals are: 0000 / 0, 0001 / 1, 0010 / 1, 0011 / 1, 0100 / 1, 0101 / 0, 0110 / 0, 0111 / 0; on the plane latitude coil, starting from 0°, the orthogonal polarization pairs in the clockwise direction at 45° intervals are: 0000 / 0, 1000 / 0, 1001 / 1, 1010 / 1, 0100 / 1, 1011 / 1, 1100 / 0, 1101 / 0.

[0019] As a preferred technical solution of the present invention: in step S2, the camouflaged image is cut into equal left and right halves, converted into binary code, and the binary code is sent in the order of R, G, B channels of the camouflaged image.

[0020] As a preferred embodiment of the present invention, the specific steps of step S4 are as follows:

[0021] Step S4.1: The target receiving user extracts the encrypted image of the disguised image using least significant bit steganography and converts it into binary code;

[0022] Step S4.2: Perform an XOR operation between the binary code and the obtained polarization mask K to obtain the decrypted image.

[0023] As a preferred technical solution of the present invention: it is implemented based on a secure wireless communication system, including a transmitter and a receiver;

[0024] At the transmitting end, an X-band metamaterial lens antenna, rotated 45°, is fixed 70 cm in front of the polarization modulation information metasurface and connected to a carrier signal generator to generate an incident plane wave with an operating frequency of 10 GHz. At the transmitting end, the target user sends a control signal to the digital voltage control module in real time through the host system according to the predetermined phase-bias voltage mapping relationship, thereby providing a time-varying bias voltage to the varactor diode loaded on the polarization modulation information metasurface. Finally, the polarization modulation wave containing digital information is emitted by the information channel corresponding to the location of the target receiving user.

[0025] At the receiving end, the polarization discrimination antenna is fixed at a straight-line distance of 130 cm from the polarization modulation information metasurface, positioned in the direction of the target receiving user's location, and connected to a four-channel oscilloscope for real-time observation and reception of polarization modulation waves. The received polarization modulation waves are then sent to the host computer via a network cable for data processing and decryption to recover the target image.

[0026] Beneficial effects: Compared with the prior art, the advantages of the present invention include:

[0027] 1. The design method for a secure wireless communication system based on polarization modulation strategy in this invention combines traditional computational encryption algorithms with physical layer encryption. The wireless communication system designed according to this method has the characteristics of information camouflage, multi-channel, and high security.

[0028] 2. The secure wireless communication system design method based on polarization modulation strategy in this invention utilizes the spatial and polarization demultiplexing capabilities of programmable polarization modulation metasurfaces to enable independent encrypted wireless communication in multiple channels simultaneously using different polarization coding strategies.

[0029] 3. The design method for a secure wireless communication system based on polarization modulation strategy in this invention effectively utilizes the real-time control characteristics of programmable metasurfaces. The secure wireless communication system can further improve system security by using different polarization coding strategies or completely different polarization mask keys for each communication.

[0030] 4. The polarization-secure wireless communication system in this invention belongs to metasurface-assisted wireless communication, which can greatly simplify the transmission process. It directly modulates the phase and polarization on the metasurface, eliminating the need for complex and expensive radio frequency (RF) components. Furthermore, the demodulation end is a carefully designed polarization discrimination antenna with a simple structure and high operating frequency. It can not only determine the polarization state but also demodulate the modulated signal. It is manufactured using conventional printed circuit board technology. Attached Figure Description

[0031] Figure 1 This is a conceptual diagram of a programmable polarization modulation metasurface-based wireless communication encryption scheme provided by an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of a Poincaré sphere provided according to an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the polarization states at different positions on the S2S3 plane longitude coil provided according to an embodiment of the present invention.

[0034] Figure 4 This is a schematic diagram of the polarization states at different positions on the S1S2 plane latitude coil provided according to an embodiment of the present invention.

[0035] Figure 5 (a)- Figure 5 (l) is a diagram of a single-channel direct information coding scheme provided according to an embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of the encryption and decryption process in single-channel secure wireless communication according to an embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram illustrating the transmission and reception of a single-channel secure wireless communication scheme provided according to an embodiment of the present invention;

[0038] Figure 8 (a)- Figure 8 (x) is a diagram of a dual-channel direct information coding scheme provided according to an embodiment of the present invention;

[0039] Figure 9 This is a schematic diagram of the encryption and decryption process in dual-channel secure wireless communication provided by an embodiment of the present invention;

[0040] Figure 10 This is a schematic diagram illustrating the transmission and reception of a dual-channel secure wireless communication scheme provided according to an embodiment of the present invention;

[0041] Figure 11 This is an experimental diagram of a single-channel secure wireless communication system provided according to an embodiment of the present invention;

[0042] Figure 12 This is an experimental diagram of a dual-channel secure wireless communication system provided according to an embodiment of the present invention. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0044] This invention provides a design method for a secure wireless communication system based on a polarization modulation strategy. The polarization modulation strategy involves a digital voltage control module modulating the polarization state of an electromagnetic carrier signal at a high rate. Orthogonal polarization states are represented by data "1" and "0". In at least one channel, steps S1-S4 are executed to complete the encryption and transmission of the target image at the transmitting end, and the reception and decryption of the target image at the receiving end.

[0045] Step S1: Based on the orthogonal polarization pairs, establish a polarization mask. Based on the polarization mask K corresponding to the location of the target receiving user, encrypt the target image to obtain an encrypted image. Use least significant bit steganography to hide the encrypted image in the disguised cover image to obtain a disguised image that combines the encrypted image and the disguised cover image.

[0046] The specific steps of step S1 are as follows:

[0047] Step S1.1: Encode the polarization state at different positions of the planar longitude and latitude coils respectively. The form is an orthogonal polarization pair composed of polarization code and digital code. The orthogonal polarization pair is in the form of polarization code / digital code. On the planar longitude coil, starting from 0°, the orthogonal polarization pairs in the clockwise direction at 45° intervals are: 0000 / 0, 0001 / 1, 0010 / 1, 0011 / 1, 0100 / 1, 0101 / 0, 0110 / 0, 0111 / 0. On the planar latitude coil, starting from 0°, the orthogonal polarization pairs in the clockwise direction at 45° intervals are: 0000 / 0, 1000 / 0, 1001 / 1, 1010 / 1, 0100 / 1, 1011 / 1, 1100 / 0, 1101 / 0.

[0048] Based on the location of the target receiving user, the orthogonal polarization pairs corresponding to it on the plane longitude coil and the plane latitude coil are respectively formed into a set of orthogonal polarization pairs;

[0049] Step S1.2: Construct a polarization mask K based on the orthogonal polarization pair corresponding to the location of the target receiving user. The polarization mask K is a matrix obtained based on the orthogonal polarization pair. The rows of the polarization mask K correspond to P0, and the columns of the polarization mask K correspond to P1. The Mth row and nth column elements in the polarization mask K are obtained by the XOR operation of the Mth element of P0 and the nth element of P1, where P0 and P1 are the combinations of the polarization codes corresponding to the digital codes 0 and 1 in the orthogonal polarization pair, respectively.

[0050] Step S1.3: Divide the target information to be sent into three parts and convert them into three target images respectively. Convert each target image into binary code and perform an XOR operation with the polarization mask K to obtain three encrypted images with the same size as the disguised cover image.

[0051] Step S1.4: Convert the encrypted image into a binary image. Use steganography to divide the R, G, and B channel images of the disguised cover image into 8 layers respectively. Replace the binary matrix of the first layer in the R, G, and B channel images of the disguised cover image with the encrypted image, thereby hiding the encrypted image in the disguised cover image.

[0052] Step S2: Cut the spoofed image into equal left and right halves, convert them into binary code, and send the binary code to the target receiving user's location in the order of the R, G, and B channels of the spoofed image.

[0053] Step S3: The target user receives the camouflage image and polarization mask K;

[0054] Step S4: Extract the encrypted image hidden in the disguised image, decrypt the encrypted image using the polarization mask K, and obtain the target image.

[0055] The specific steps of step S4 are as follows:

[0056] Step S4.1: The target receiving user extracts the encrypted image of the disguised image using least significant bit steganography and converts it into binary code;

[0057] Step S4.2: Perform an XOR operation between the binary code and the obtained polarization mask K to obtain the decrypted image.

[0058] The following are specific implementations of a secure wireless communication system design method based on polarization modulation strategy, demonstrating the encryption and transmission of target images in single-channel and dual-channel configurations, as well as the reception and decryption of target images at the receiving end:

[0059] Figure 1 This is a conceptual diagram of a wireless communication encryption scheme based on a programmable polarization modulation metasurface. At the transmitting end, the target information "SEU" and "MMV" are first encrypted and hidden in the least significant bit of two cover images of a bird and a deer, respectively, using least significant bit steganography. The digital information of the disguised images is then converted into a digital encoded bit stream. A self-made digital voltage control module provides different bias voltages to varactor diodes loaded on the metasurface, switching the reflection polarization state of the modulated wave in real time according to a specified polarization modulation scheme. A vertically incident 45° polarized wave, after direct modulation and reflection by the metasurface, simultaneously and independently transmits different encoded information streams to multiple target users at designated locations. At the receiving end, each target user obtains the target image by using the correct decryption protocol. For eavesdroppers, it is difficult to obtain the target information; even if they are at the target location and use the correct polarization modulation scheme to demodulate the received digital signal, they can only reconstruct the disguised image, but cannot obtain the target image information.

[0060] Figure 2This is a schematic diagram of a Poincaré sphere. In a coordinate system based on Stokes parameters (S1, S2, S3), any given |P> on the sphere can be considered as any polarization state, determined by the azimuth angle ψ and the ellipticity angle χ. Therefore, points |R>, |L>, |H>, |V>, |A>, and |D> on the Poincaré sphere correspond to right-hand circular polarization (RHCP), left-hand circular polarization (LHCP), horizontal, vertical, anti-angle, and diagonal polarization states, respectively. Among these, |R> and |L>, |H> and |V>, and |A> and |D> belong to a pair of orthogonal polarization states.

[0061] Figure 3 This is a schematic diagram of the polarization states at different positions on the S2S3 plane longitude coil. Starting from the 45° linear polarization, the codes in a clockwise direction are 0000 / 0, 0001 / 1, 0010 / 1, 0011 / 1, 0100 / 1, 0101 / 0, 0110 / 0, and 0111 / 0. Taking 0010 / 1 as an example, the 0010 before the " / " represents the polarization code, and the 1 after the " / " represents the numerical code.

[0062] Figure 4 This is a schematic diagram of the polarization states at different positions on the S1S2 plane latitude coil. The |A> and |D> polarizations are still encoded as 0000 / 0 and 0100 / 1, respectively, while other polarizations are encoded as 1000 / 0, 1001 / 1, 1010 / 1, 1011 / 1, 1100 / 0, and 1101 / 0. According to... Figure 3 and Figure 4 The polarization encoding and digital encoding indicated in the document are used to establish a polarization codebook, and users who possess the polarization codebook are considered target users.

[0063] Figure 5 (a)- Figure 5 (l) is a diagram of the single-channel direct information coding scheme. In the single-channel secure wireless communication scheme, two sets of orthogonal polarization pairs, 1000 / 0-1011 / 1 and 0000 / 0-0100 / 1, are used, with the propagation direction along the -20° direction on the metasurface normal. By optimizing the polarization matrix on the metasurface, the amplitude and phase of the x-polarized and y-polarized waves are customized, thereby obtaining a highly directional beam with the same deflection angle for different polarization states. Figure (e)- Figure 5 (i) The four sets of corresponding polarization codes M1-M4 shown are polarization matrices generated for the four different polarization states mentioned above, and their corresponding simulation and far-field test radiation patterns, as follows: Figure 5 (i)- Figure 5 As shown in (l). The results show that the simulation results are in good agreement with the experimental results, demonstrating good beam deflection and polarization control performance.

[0064] Figure 6This is a schematic diagram of the encryption and decryption process in single-channel secure wireless communication. The target message to be sent is "SEU," composed of three images: "S," "E," and "U." The cover image is a color picture of a bird, decomposed into R, G, and B channel images. First, an 8×8 matrix polarization mask K is established based on the two sets of orthogonal polarization states. Any element in the polarization mask key K is obtained by XORing the corresponding elements of P0 and P1. P0 consists of polarization codes 1000 and 0000 (digital encoding "0"), and P1 consists of polarization codes 1011 and 0100 (digital encoding "1"). Subsequently, the polarization mask K is cyclically XORed with the binary codes corresponding to the target images "S," "E," and "U" to obtain the corresponding encrypted images. Then, the least significant bit (LSB) of the RGB channels of the cover image is replaced by the encrypted images using LSB steganography.

[0065] Figure 7 This is a schematic diagram of the transmission and reception of a single-channel secure wireless communication scheme. After the camouflaged image is segmented, it is converted into a corresponding binary bit stream. Based on the mapping relationship between the corresponding polarization matrix and the bias voltage, the polarization-modulated metasurface is driven to reflect and modulate electromagnetic waves in real time, which are then received by the target user at the designated location. The polarization mask key and the camouflaged image can be further obtained based on the customized polarization discrimination antenna.

[0066] Figure 8 (a)- Figure 8 (x) is a diagram of a dual-channel direct information coding scheme. For dual-channel secure wireless communication, two types of target information can be independently and simultaneously sent to two different target users, thereby achieving spatial and polarization diversity multiplexing and improving channel capacity in wireless communication. Figure 8 (a)- Figure 8 (h) indicates that channel 1 and channel 2 use two sets of orthogonal polarization pairs: 0101 / 0-0001 / 1 and 0110 / 0-0010 / 1, and 0111 / 0-0011 / 1 and 0110 / 0-0010 / 1, respectively. The corresponding polarization matrices are as follows: Figure 8 (i)- Figure 8 As shown in (p). 8(q)- Figure 8 (x) represents the two channel directions in the wireless communication, which are -20° and 30° respectively. The simulation and test results of the corresponding far-field radiation pattern are in agreement.

[0067] Figure 9This is a schematic diagram of the encryption and decryption process in dual-channel secure wireless communication. Channel 1 points to -20°. Similar to the previous single-channel secure wireless communication, the target images "S", "E", and "U" are hidden in the cover image 1 using the least significant bit algorithm. However, the polarization mask key used here is K1, with corresponding orthogonal polarization pairs of 0101 / 0-0001 / 1 and 0110 / 0-0010 / 1. In channel 2, the target images "M", "M", and "W" are XORed with the polarization mask key K2, which consists of two sets of orthogonal polarization pairs of 0111 / 0-0011 / 1 and 0110 / 0-0010 / 1, and then hidden in the cover image 2.

[0068] Figure 10 This is a schematic diagram of the transmission and reception of a dual-channel secure wireless communication scheme. The target digital information is transformed into a one-dimensional binary bit stream sequence through a simple matrix transformation. Based on the corresponding polarization modulation scheme, it is converted into a corresponding polarization matrix. According to the mapping relationship between the reflection phase and the bias voltage, a digital voltage control module drives a programmable metasurface. The carrier signal containing the digital information is received by a discrimination antenna at a designated location. Based on the polarization modulation scheme and polarization cipherbook, after simple data processing, the corresponding camouflage image and polarization mask key are obtained.

[0069] This invention provides a design method for a secure wireless communication system based on a polarization modulation strategy, implemented using a secure wireless communication system, comprising a transmitter and a receiver.

[0070] Figure 11 This is an experimental diagram of a single-channel secure wireless communication system. At the transmitting end, there is a programmable polarization modulation metasurface, composed of programmable units arranged periodically in space, used to control the arbitrary polarization state of the reflected wave in different deflection directions. Due to the programmable polarization modulation metasurface, different polarization states in multiple radiation beams can be customized, simultaneously and independently radiating different polarized waves to different locations in space. In this embodiment, an X-band metamaterial lens antenna, rotated 45°, is fixed 70cm in front of the polarization modulation information metasurface and connected to a carrier signal generator to generate an incident plane wave with an operating frequency of 10GHz. According to a specified polarization modulation scheme, the transmitting user converts the camouflaged image containing the target images "S", "E", and "U" into corresponding bias voltage sequences in the host system. The system then controls a digital voltage module in real time to drive a programmable metasurface. A carrier signal containing digital information is transmitted along a -20° angle and received by a polarization discrimination antenna at a designated location 130 cm away from the metasurface. This antenna is connected to a four-channel oscilloscope for easy observation and data recording. The oscilloscope is connected to the host system via a network cable, where data processing and target information recovery are performed. This secure wireless communication system, based on a programmable metasurface, features dynamic adjustability, allowing for different polarization modulation strategies and generating different polarization mask keys each time.

[0071] Figure 12 This is an experimental diagram of a dual-channel secure wireless communication system, where channel 1 and channel 2 are along directions of -20° and 30°, respectively. The target information "SEU" and "MMW" are encrypted and hidden to obtain corresponding camouflaged images. After the driving metasurface modulates the carrier wave, the corresponding modulated signal containing digital information is independently and simultaneously received by the discrimination antenna at a designated location, further obtaining the camouflaged images of a bird and a deer, as well as the corresponding polarization mask keys K1 and K2. After simple processing by the host, the target images "S", "E", and "U", as well as "M", "M", and "W", are simultaneously recovered.

[0072] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A design method for a secure wireless communication system based on a polarization modulation strategy, characterized in that, In at least one channel, the following steps S1-S4 are performed to complete the encryption and transmission of the target image at the sending end, and the reception and decryption of the target image at the receiving end: Step S1: Based on the predetermined orthogonal polarization pair, establish a polarization mask key. Based on the polarization mask K corresponding to the location of the target receiving user, encrypt the target image to obtain an encrypted image. Use least significant bit steganography to hide the encrypted image in the disguised cover image to obtain a disguised image that combines the encrypted image and the disguised cover image. The specific steps of step S1 are as follows: Step S1.1: Encode the polarization state at different positions of the plane longitude coil and the plane latitude coil respectively. The form is an orthogonal polarization pair composed of polarization code and digital code; wherein the polarization code is binary code and the digital code is 0 or 1; according to the location of the target receiving user, form a set of orthogonal polarization pairs corresponding to the plane longitude coil and the plane latitude coil respectively. Step S1.2: Construct a polarization mask K based on the orthogonal polarization pair corresponding to the location of the target receiving user. The polarization mask K is a matrix obtained based on the orthogonal polarization pair. The rows of the polarization mask K correspond to P0, and the columns of the polarization mask K correspond to P1. The Mth row and nth column elements in the polarization mask K are obtained by the XOR operation of the Mth element of P0 and the nth element of P1, where P0 and P1 are the combinations of the polarization codes corresponding to the digital codes 0 and 1 in the orthogonal polarization pair, respectively. Step S1.3: Divide the target information to be sent into three parts and convert them into three target images respectively. Convert each target image into binary code and perform an XOR operation with the polarization mask K to obtain three encrypted images with the same size as the disguised cover image. Step S1.4: Convert the encrypted image into a binary image and hide it in the least significant bits of the R, G, and B channels of the disguised cover image to obtain the disguised image; Step S2: Send the spoofed image to the location of the target receiving user; Step S3: The target user receives the camouflage image and polarization mask K; Step S4: Extract the encrypted image hidden in the disguised image, decrypt the encrypted image using the polarization mask K, and obtain the target image.

2. The design method for a secure wireless communication system based on a polarization modulation strategy according to claim 1, characterized in that, The least significant bit steganography method is as follows: Steganography is used to divide the R, G, and B channel images of the disguised cover image into 8 layers. The encrypted image replaces the binary matrix of the first layer of the R, G, and B channel images of the disguised cover image, thereby hiding the encrypted image in the disguised cover image.

3. The design method for a secure wireless communication system based on a polarization modulation strategy according to claim 1, characterized in that, The orthogonal polarization pairs mentioned in step S1.1 are in the form of polarization codes / digital codes. On the plane longitude coil, starting from 0°, the orthogonal polarization pairs in the clockwise direction at 45° intervals are: 0000 / 0, 0001 / 1, 0010 / 1, 0011 / 1, 0100 / 1, 0101 / 0, 0110 / 0, 0111 / 0; on the plane latitude coil, starting from 0°, the orthogonal polarization pairs in the clockwise direction at 45° intervals are: 0000 / 0, 1000 / 0, 1001 / 1, 1010 / 1, 0100 / 1, 1011 / 1, 1100 / 0, 1101 / 0.

4. The design method for a secure wireless communication system based on a polarization modulation strategy according to claim 1, characterized in that, In step S2, the camouflaged image is cut into equal left and right halves, converted into binary code, and sent in the order of the R, G, and B channels of the camouflaged image.

5. The design method for a secure wireless communication system based on a polarization modulation strategy according to claim 1, characterized in that, The specific steps of step S4 are as follows: Step S4.1: The target receiving user extracts the encrypted image of the disguised image using least significant bit steganography and converts it into binary code; Step S4.2: Perform an XOR operation between the binary code and the obtained polarization mask K to obtain the decrypted image.

6. The design method for a secure wireless communication system based on a polarization modulation strategy according to claim 1, characterized in that, Implemented based on a secure wireless communication system, including a transmitter and a receiver; At the transmitting end, an X-band metamaterial lens antenna, rotated 45°, is fixed 70 cm in front of the polarization modulation information metasurface and connected to a carrier signal generator to generate an incident plane wave with an operating frequency of 10 GHz. At the transmitting end, the target user sends a control signal to the digital voltage control module in real time through the host system according to a predetermined phase-bias voltage mapping relationship, thereby providing a time-varying bias voltage to the varactor diode loaded on the polarization modulation information metasurface. Finally, the polarization modulation wave containing digital information is emitted by the information channel corresponding to the location of the target receiving user. At the receiving end, the polarization discrimination antenna is fixed at a straight-line distance of 130 cm from the polarization modulation information metasurface, positioned in the direction of the target receiving user's location, and connected to a four-channel oscilloscope for real-time observation and reception of polarization modulation waves. The received polarization modulation waves are then sent to the host computer via a network cable for data processing and decryption to recover the target image.

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