Electromagnetic wave intrinsic orbital angular momentum covert communication system and method

Abstract

This application provides a covert communication system and method based on intrinsic orbital angular momentum of electromagnetic waves, relating to the field of communication technology. The method includes improvements to the communication methods of the signal transmitting subsystem and the signal receiving subsystem in the covert communication system. Specifically, for the signal transmitting subsystem in the covert communication system, the method includes: acquiring an encryption key and a main channel radio frequency signal; wherein the main channel radio frequency signal is the form of encrypted data obtained by encrypting user data using the encryption key; performing keying modulation according to the encryption key to generate electromagnetic wave quantum state orbital angular momentum keying data corresponding to the encryption key; generating electromagnetic wave quantum state orbital angular momentum vortex microwave quantum based on the electromagnetic wave quantum state orbital angular momentum keying data and the main channel radio frequency signal; and radiating the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum to the target space. This application enhances the anti-interception capability of the communication system through the above methods.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a covert communication system and method based on the intrinsic orbital angular momentum of electromagnetic waves. Background Technology

[0002] With the continuous development of electronic technology and its application in the military field, electromagnetic countermeasures technology has become increasingly important. Due to the emergence of various surveillance and detection systems and precision-guided technologies, the importance of electromagnetic stealth technology is growing daily. Electromagnetic stealth technology is mainly divided into target stealth technology and transmission stealth technology. Transmission stealth technology, also known as covert transmission, primarily refers to the ability of a legitimate receiver to effectively receive signals while preventing unauthorized eavesdropping, ensuring the anti-interception nature of data transmission, and thus avoiding attacks and interference.

[0003] Due to the open broadcast nature of wireless channels, security is a critical issue in wireless communication. Traditional encryption techniques are generally implemented at the application layer of Transmission Control Protocol / Internet Protocol (TCP) to ensure data transmission security. Besides traditional encryption techniques, physical layer security techniques have attracted widespread research interest. Among physical layer security techniques, spread spectrum communication or frequency hopping communication is also a method for achieving covert communication. Traditional encryption techniques encrypt the transmitted sequence before transmission; an unauthorized eavesdropper can receive the data, but because they do not know the key, they cannot obtain the correct data. Spread spectrum technology, on the other hand, prevents unauthorized eavesdroppers from detecting the transmitted signal and obtaining the data from the sender. The keys and spreading sequences used in both of these methods can be considered encryption keys.

[0004] Traditional encryption techniques cannot reduce the power of transmitted signals, allowing unauthorized eavesdroppers to still detect them. Spread spectrum communication requires additional bandwidth; using short spreading sequences for spreading and despreading affects the communication system's anti-interception capabilities, while longer sequences require even more bandwidth. Furthermore, the length of the spreading sequence itself influences the concealment effect of the communication. In other words, achieving stronger concealment often necessitates excessive bandwidth. Therefore, under bandwidth constraints, spread spectrum communication presents a trade-off between anti-interception capabilities and transmission rate. In recent years, the 300MHz to 300GHz spectrum has become increasingly congested, necessitating the exploration of new dimensions to develop new technologies that enhance the anti-interception capabilities of communication systems. Summary of the Invention

[0005] This application provides an electromagnetic wave intrinsic orbital angular momentum concealed communication system and method to solve the problem of poor anti-interception in the prior art.

[0006] According to a first aspect of this application, a method for covert communication using intrinsic orbital angular momentum of electromagnetic waves is provided, applied to a signal transmission subsystem in a covert communication system, comprising:

[0007] Obtain the encryption key and the main channel radio frequency signal; wherein, the main channel radio frequency signal is the form of encrypted data obtained by encrypting user data using the encryption key;

[0008] Keying modulation is performed based on the encryption key to generate electromagnetic wave quantum state orbital angular momentum keying data corresponding to the encryption key;

[0009] Based on the electromagnetic wave quantum state orbital angular momentum keying data and the main channel radio frequency signal, an electromagnetic wave quantum state orbital angular momentum vortex microwave quantum is generated.

[0010] The electromagnetic wave quantum state orbital angular momentum vortex microwave quantum radiation is directed into the target space.

[0011] According to a second aspect of this application, another method for covert electromagnetic wave intrinsic orbital angular momentum communication is provided, applied to a signal receiving subsystem in a covert communication system, comprising:

[0012] Receive electromagnetic wave quantum state orbital angular momentum vortex microwave quantum in the target space;

[0013] Based on the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum detection electromagnetic wave quantum state orbital angular momentum keying data, and the main channel radio frequency signal is detected;

[0014] The electromagnetic wave quantum state orbital angular momentum keying data is identified, and the encryption key is demodulated.

[0015] The decryption key corresponding to the encryption key is calculated based on the encryption key, and the decryption key is used to demodulate the main channel radio frequency signal to obtain user data.

[0016] According to a third aspect of this application, an electromagnetic wave intrinsic orbital angular momentum covert communication system is provided, comprising: a signal transmitting subsystem for executing the electromagnetic wave intrinsic orbital angular momentum covert communication method described in the first aspect, and a signal receiving subsystem for executing the electromagnetic wave intrinsic orbital angular momentum covert communication method described in the second aspect. According to a fourth aspect of this application, a computer-readable storage medium is provided, wherein computer-executable instructions are stored therein, which, when executed by a processor, are used to implement the electromagnetic wave intrinsic orbital angular momentum covert communication method described in the first aspect above.

[0017] This application provides an electromagnetic wave intrinsic orbital angular momentum covert communication system and method. By performing keyed modulation based on an encryption key, electromagnetic wave quantum state orbital angular momentum keying data can be generated to encrypt the encryption key. This electromagnetic wave quantum state orbital angular momentum keying data is combined with the main channel radio frequency signal to generate electromagnetic wave quantum state orbital angular momentum vortex microwave quantum, which enables user data to be radiated to the target space in the form of electromagnetic wave quantum state orbital angular momentum vortex microwave quantum. Since the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum realizes secondary encryption of user data, compared with the prior art, this application adds encryption operation to the encryption key, thereby increasing the difficulty for illegal eavesdroppers to decrypt and improving the anti-interception of the communication system.

[0018] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0020] Figure 1 A schematic diagram of the structure of the electromagnetic wave intrinsic orbital angular momentum covert communication system provided in the embodiments of this application;

[0021] Figure 2 A flowchart illustrating an electromagnetic wave intrinsic orbital angular momentum covert communication method provided in this application embodiment;

[0022] Figure 3 A flowchart illustrating a method for selecting the number of quantum state orbital angular momentum modes, provided in an embodiment of this application;

[0023] Figure 4 A flowchart illustrating another electromagnetic wave intrinsic orbital angular momentum covert communication method provided in this application embodiment;

[0024] Figure 5 A schematic diagram of the architecture of an electromagnetic wave intrinsic orbital angular momentum covert communication system submerged in the second-generation standard of satellite digital video broadcasting, provided in an embodiment of this application;

[0025] Figure 6 A schematic diagram of the spectrum and power spectrum of the second-generation standard signal for electromagnetic wave intrinsic orbital angular momentum concealed communication signals and satellite digital video broadcasting under different parameters;

[0026] Figure 7 A flowchart illustrating another electromagnetic wave intrinsic orbital angular momentum covert communication method provided in this application embodiment;

[0027] Figure 8 This is a schematic diagram of another electromagnetic wave intrinsic orbital angular momentum covert communication system provided in an embodiment of this application;

[0028] Figure 9 A flowchart illustrating a statistical OAM mode number selection method provided in this application embodiment;

[0029] Figure 10 The signal logic timing diagram provided for the embodiments of this application;

[0030] Figure 11 This application provides a signal generation subsystem with a delay function as an embodiment.

[0031] Figure 12 A flowchart illustrating another electromagnetic wave intrinsic orbital angular momentum covert communication method provided in this application embodiment;

[0032] Figure 13 This is a schematic diagram of the structure of the signal receiving subsystem provided in an embodiment of this application;

[0033] Figure 14 A flowchart illustrating the demodulation and recovery process of user data and spread spectrum encrypted data is provided in this application embodiment.

[0034] Figure 15 A comparison chart of computational complexity and transmission rate provided for embodiments of this application.

[0035] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0036] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0037] In existing technologies, the orbital angular momentum (OAM) of electromagnetic waves is a physical quantity describing the rotation of energy flux around the propagation direction, and can be expressed as: It is a physical quantity distinct from electric field strength, and also a new dimension of wireless communication. This is achieved by decomposing the displacement vector: r = r (e) +r (i) OAM can be decomposed into external OAM: And intrinsic OAM: Based on the different electromagnetic wave beams used, vortex electromagnetic waves in orbital angular momentum communication systems are currently classified into statistical OAM vortex beams and quantum OAM vortex microwave quanta. Statistical OAM vortex beams are generated through antenna arrays such as uniform circular arrays, and are essentially composed of multiple planar microwave quanta with continuously changing initial phases. Quantum OAM vortex microwave quanta are generated through the interaction between cyclotronic electrons in a magnetic field and microwave quanta (or radiating microwave quanta), transferring the orbital angular momentum of the cyclotrons (i.e., the aforementioned cyclotronic electrons) to the orbital angular momentum of the radiating microwave quanta. From a physical quantity definition perspective, external OAM can form statistical OAM vortex beams, i.e., beams with specific phase planes and amplitudes; while intrinsic OAM refers to quantum OAM vortex microwave quanta, i.e., a single microwave quantum carries OAM, and it is determined that intrinsic and quantum states are the same concept.

[0038] Although anti-interception transmission systems based on statistical state OAM vortex beams already exist, they are essentially still anti-interception transmission systems based on electric field strength, meaning the covert channel lacks physical protection. If an illegal eavesdropper can detect the phase gradient change of the statistical state OAM vortex beam, they are very likely to detect the covert channel, and thus easily complete the monitoring and interception of user data.

[0039] To address at least one of the aforementioned technical problems, this application provides an electromagnetic wave intrinsic orbital angular momentum covert communication system and method, applied in the field of communication, to solve the technical problem of poor anti-interception performance of existing covert systems.

[0040] For ease of understanding, the electromagnetic wave intrinsic orbital angular momentum covert communication system on which the electromagnetic wave intrinsic orbital angular momentum covert communication method of the embodiments of this application depends will be introduced first. Figure 1 A schematic diagram of the structure of the electromagnetic wave intrinsic orbital angular momentum covert communication system provided in this application embodiment. (See diagram below.) Figure 1 As shown, the electromagnetic wave intrinsic orbital angular momentum covert communication system 10 (hereinafter referred to as the covert communication system) includes: a signal generation subsystem 100 and a signal receiving subsystem 200; wherein, the signal generation subsystem 100 includes: a conventional signal generation module 101, a quantum state OAM vortex microwave quantum generation module 102, a keying module 103, and a radiator 104; the signal receiving subsystem 200 includes: a quantum state OAM vortex microwave quantum receiving module 201, a conventional signal receiving module 202, a quantum state OAM demodulation module 203, and a conventional channel decryption module 204.

[0041] Specifically, the conventional signal generation module 101 is used to spread and encrypt user data using an encryption key and generate the corresponding main channel radio frequency signal; the keying module 103 is used to perform keying modulation according to the encryption key and generate the corresponding quantum state OAM keying data (i.e., electromagnetic wave quantum state orbital angular momentum keying data); the quantum state OAM vortex microwave quantum generation module 102 is used to generate the corresponding quantum state OAM vortex microwave quantum (i.e., electromagnetic wave quantum state orbital angular momentum vortex microwave quantum) according to the quantum state OAM keying data; and the radiator 104 is used to radiate the main channel radio frequency signal into free space in the form of quantum state OAM vortex microwave quantum. The quantum state OAM vortex microwave quantum receiving module 201 is used to couple quantum state orbital angular momentum electromagnetic waves (i.e., quantum state OAM vortex microwave quantum) and recover different quantum state OAM mode numbers (i.e., electromagnetic wave quantum state orbital angular momentum keying data); the conventional signal receiving module 202 is used to receive and demodulate the conventional channel signal (i.e., the aforementioned main channel radio frequency signal); the quantum state OAM demodulation module 203 is used to receive and demodulate the recovered different quantum state OAM mode numbers to obtain the corresponding encryption key and calculate the corresponding decryption key; the conventional channel decryption module 204 is used to decrypt the user data transmitted through the conventional main channel using the decryption key to obtain the transmitted user data.

[0042] It should be noted that the signal generation subsystem 100 is also called the signal transmission subsystem. Quantum state orbital angular momentum electromagnetic waves include one or more of the following types: light waves, microwaves, millimeter waves, and terahertz waves. This covert communication system can also add or remove modules according to actual needs to achieve quantum key distribution, quantum direct communication, and the establishment of statistical state OAM keying transmission channels. The radiator 104 is one or more of the following: circular waveguide, rectangular waveguide, array antenna, patch antenna, reflector antenna, and electromagnetic transmission antenna. The quantum state OAM vortex microwave quantum generation module 102 is one or more of the following: cyclotron traveling wave tube, cyclotron oscillator tube, cyclotron klystron, magnetic field undulator, and cyclotron accelerator. The quantum state OAM vortex microwave quantum receiving module 201 is a quantum state OAM sensor, which can perform receiving operations based on one or more of the following: electron diffraction, Stern-Gerlach experiment in a gradient field, and the Hall effect. This covert transmission system has at least two channels: a traditional main channel and a quantum-state OAM vortex microwave quantum index modulation channel. The transmission entity in the quantum-state OAM vortex microwave quantum index modulation channel is a quantum-state OAM vortex microwave quantum with intrinsic OAM. Combined with... Figure 1 It can be seen that the quantum state OAM vortex microwave quantum index modulation channel index Figure 1The line between the keying module 103 and the quantum state OAM vortex microwave quantum generation module 102 is called the line between the traditional signal generation module 101 and the quantum state OAM vortex microwave quantum generation module 102. The traditional channel decryption module 204 can be understood as a receiver demodulator.

[0043] This covert transmission system utilizes intrinsic OAM keying modulation to form a covert channel, transmitting the encryption key from the main channel via this covert channel to enhance the concealment of user data during wireless transmission. At the transmitting end (i.e., at the signal generation subsystem 100), the covert transmission system encrypts the user data transmitted in the traditional main channel using the encryption key, and transmits the encryption key from the traditional main channel by switching the intrinsic OAM mode number. At the receiving end (i.e., at the signal receiving subsystem 200), the system calculates the decryption key by analyzing the encryption key transmitted through the intrinsic OAM covert channel, and then transmits the decryption key to the traditional main channel to complete the decryption operation. During transmission, the encryption key used in the traditional main channel changes in real time due to keying modulation, and is shared at both the transmitting and receiving ends using this covert communication system, achieving a "one-time key" effect, which significantly improves the secure transmission and covert communication capabilities of the encrypted channel.

[0044] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0045] Figure 2 This is a flowchart illustrating a method for covert communication using intrinsic orbital angular momentum of electromagnetic waves, provided as an embodiment of this application. Figure 2 As shown, the method of this embodiment is applied to the signal transmission subsystem of an electromagnetic wave intrinsic orbital angular momentum covert communication system, including:

[0046] S201: Obtain the encryption key and the main channel radio frequency signal; wherein, the main channel radio frequency signal is the form of encrypted data obtained by encrypting user data using the encryption key.

[0047] It should be understood that the encryption method to which the encryption key belongs can be one or more of symmetric encryption, asymmetric encryption, and physical layer encryption. Physical layer encryption may include spread spectrum encryption. In this embodiment, the operation of obtaining the encryption key in S201 is performed by... Figure 1 The traditional signal generation module 101 performs this operation, which is also performed by the keying module 103. Figure 1The quantum state OAM vortex microwave quantum generation module 102 performs this operation. Before acquiring the main channel radio frequency signal, this application also includes the following steps performed by the conventional signal generation module 101: encrypting the user data using an encryption key and generating a main channel radio frequency signal corresponding to the encrypted data. It should be noted that this application does not specifically limit the source of the encryption key or the provider of the user data.

[0048] S202: Perform keying modulation according to the encryption key to generate electromagnetic wave quantum state orbital angular momentum keying data corresponding to the encryption key.

[0049] It should be understood that the result obtained by keying modulation (i.e., electromagnetic wave quantum state orbital angular momentum keying data) corresponds to the encryption key and is used to reflect the determination of the channel selected for transmitting the encryption key. The specific operation is described in steps S2021 to S2022 below, and will not be elaborated here.

[0050] S203: Generate electromagnetic wave quantum state orbital angular momentum vortex microwave quantum based on the electromagnetic wave quantum state orbital angular momentum keying data and the main channel radio frequency signal.

[0051] In this embodiment, compared with the main channel radio frequency signal, the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum adds a selection operation for the transmission channel of the encryption key. This can be simply understood as an additional encryption operation, which is actually an encryption of the main channel radio frequency signal. Therefore, the fusion of the two encryption methods makes the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum more secure and more resistant to interception.

[0052] S204: The electromagnetic wave quantum state orbital angular momentum vortex microwave quantum radiation is directed into the target space.

[0053] In this embodiment, the target space is free space. For ease of understanding, the terms appearing in S201 to S204 are assigned symbols. For example, user data is a, the encryption key obtained in S201 is b, the main channel radio frequency signal is a*=ab, the electromagnetic wave quantum state orbital angular momentum keying data generated in S202 is c, the electromagnetic wave quantum state orbital angular momentum keying data c is related to the encryption key b and is used to represent the transmission channel of the encryption key b, the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum generated in S203 is a*c, and finally it is radiated into free space by radiator 104.

[0054] This application provides an electromagnetic wave intrinsic orbital angular momentum covert communication method. By performing keyed modulation based on an encryption key, electromagnetic wave quantum state orbital angular momentum keying data can be generated to encrypt the encryption key. This electromagnetic wave quantum state orbital angular momentum keying data is combined with the main channel radio frequency signal to generate electromagnetic wave quantum state orbital angular momentum vortex microwave quantum, which enables user data to be radiated to the target space in the form of electromagnetic wave quantum state orbital angular momentum vortex microwave quantum. Since the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum realizes secondary encryption of user data, compared with the prior art, this application adds encryption operation to the encryption key, thereby increasing the difficulty for illegal eavesdroppers to decrypt and improving the anti-interception of the communication system.

[0055] In one possible implementation, to illustrate the feasibility of the keying modulation in this embodiment, this embodiment focuses on refining S202. S202 involves keying modulation based on the encryption key to generate electromagnetic wave quantum state orbital angular momentum keying data corresponding to the encryption key, including the following S2021-S2022, wherein: S2021: The encryption key is used as an electromagnetic wave quantum state orbital angular momentum keying signal for data mapping to obtain a first vector composed of multiple elements; wherein the first vector contains a target element with a value of 1, and the values ​​of all other elements are 0. S2022: The combination of the values ​​of all elements in the first vector is determined as the electromagnetic wave quantum state orbital angular momentum keying data corresponding to the encryption key.

[0056] In this embodiment, the channel corresponding to the target element with a value of 1 represents the channel selected for transmitting the encryption key. Different channel selections can achieve encryption of the encryption key. Through the above method, this embodiment can determine the electromagnetic wave quantum state orbital angular momentum keying data c, preparing for the subsequent generation of electromagnetic wave quantum state orbital angular momentum vortex microwave quantum.

[0057] In one possible implementation, after refining the keying modulation process, to illustrate that the main channel radio frequency signal and electromagnetic wave quantum state orbital angular momentum keying data can be combined in this embodiment, this embodiment focuses on refining the above-mentioned S203. S203, generating electromagnetic wave quantum state orbital angular momentum vortex microwave quantum based on the electromagnetic wave quantum state orbital angular momentum keying data and the main channel radio frequency signal, includes the following S2031 to S2033, wherein: S2031: extracting corresponding encrypted data from the main channel radio frequency signal; S2032: multiplying the element data with the encrypted data for each element data in the electromagnetic wave quantum state orbital angular momentum keying data to obtain a product result; S2033: generating electromagnetic wave quantum state orbital angular momentum vortex microwave quantum based on the second vector formed by the product results corresponding to all element data.

[0058] The above method allows for the fusion of the main channel radio frequency signal and electromagnetic wave quantum state orbital angular momentum keying data, enabling channel selection of the main channel radio frequency signal, i.e., encryption of the main channel radio frequency signal. In this embodiment, the specific descriptions of steps S2021-S2022, S2031-S2033, and... Figure 3 Combining these methods, the generation process of electromagnetic wave quantum state orbital angular momentum vortex microwave quantum is analyzed as follows: In this embodiment, the encryption key can refer to the spreading sequence or its related information in the main channel. When L=2 N When there are multiple selectable OAM modes, N keyed data bits need to be divided into a symbol. Assume the divided data stream is C = [c1, ..., c...]. n , ...c N The resulting symbol can be represented as ] The corresponding OAM mode number is selected based on the formed symbol S, and it is used to carry the main channel radio frequency signal in the traditional main channel. That is, S is the encryption key, and C is a subset used to construct S. Furthermore, this embodiment can further refine the formed user symbol S (i.e.... Figure 3 The OAM keying signal in the data is used for data mapping to form e s e s It is a vector of length L, with only the S-th element being 1 and all other elements being 0. Then, each element of the vector obtained from the data mapping is multiplied by the encrypted data corresponding to the main channel radio frequency signal, and the multiplication results are fed into the quantum state orbital angular momentum generation modules of different mode numbers (i.e.,...). Figure 3The quantum state OAM mode-L generation module, quantum state OAM mode-L+1 generation module, ..., quantum state OAM mode-L-1 generation module and quantum state OAM mode-L generation module in the system generate the quantum state orbital angular momentum corresponding to the mode number. Due to the e-value formed by data mapping... s Only the Sth element is 1, and all other elements are 0. Therefore, in the signal generated after multiplication, only the quantum state orbital angular momentum of the Sth mode number is used to carry the main channel radio frequency signal, while the information carried by the quantum state orbital angular momentum of the other modes number is zero.

[0059] Based on the above embodiments, the technical solution of this application will be described in more detail below with reference to several specific embodiments.

[0060] Figure 4 This is a flowchart illustrating another electromagnetic wave intrinsic orbital angular momentum covert communication method provided in an embodiment of this application. Figure 2 Based on the illustrated embodiment, this embodiment adds a base signal for modifying the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum, submerging the power of the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum below the power of the base signal. In this embodiment, the encryption key can be a spread spectrum sequence.

[0061] like Figure 4 As shown, the method in this embodiment includes: S401: acquiring an encryption key and a main channel radio frequency signal; wherein, the main channel radio frequency signal is the form of encrypted data obtained after encrypting user data using the encryption key. S402: performing keying modulation according to the encryption key to generate electromagnetic wave quantum state orbital angular momentum keying data corresponding to the encryption key. S403: generating electromagnetic wave quantum state orbital angular momentum vortex microwave quantum according to the electromagnetic wave quantum state orbital angular momentum keying data and the main channel radio frequency signal. S404: acquiring a base signal for modifying the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum; S405: modifying the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum using the base signal to obtain a modified electromagnetic wave quantum state orbital angular momentum vortex microwave quantum; S406: radiating the modified electromagnetic wave quantum state orbital angular momentum vortex microwave quantum into a target space.

[0062] It should be understood that the specific implementation methods of S401 to S403 are different from those of S401 and S403. Figure 2 S201 to S203 are similar and will not be elaborated here. The following section combines... Figure 5 The following analysis is performed on S404 to S406:

[0063] like Figure 5 As shown, the second-generation standard (DVB-S2) signal for satellite digital video broadcasting is S. MASPKThe quantum state OAM covert transmission signal (i.e., electromagnetic wave quantum state orbital angular momentum vortex micro quantum) is S OAM In this embodiment, a 16APSK modulated DVB-S2 signal is considered, and its signal form can be expressed as equation (1):

[0064]

[0065] Where, x I (t) represents the in-phase component of the DVB-S2 signal, x Q (t) represents the quadrature component of the DVB-S2 signal, w c Let n represent the carrier frequency, n represent the nth user data, and a represent the carrier frequency. n and b n These represent in-phase component data and quadrature component data, respectively. Indicates the user symbol period.

[0066] At the transmitting end (i.e., the signal transmission subsystem in the covert communication system), this application embodiment uses the quantum state OAM covert transmission method for data transmission, and the frequency point used is the same as that of the DVB-S2 signal. The expression of the covertly transmitted OAM signal (i.e., electromagnetic wave quantum state orbital angular momentum vortex microwave quantum) can be expressed as equation (2):

[0067]

[0068] in, This represents the in-direction component of the spread spectrum main channel user data baseband signal. A represents the orthogonal components of the spread spectrum main channel user data baseband signal. c Indicates the amplitude of the modulated signal. Indicates the phase of the modulated signal. This represents the phase difference between two OAM modes. When a conventional antenna is used for reception, the received signal can be expressed as equation (3):

[0069]

[0070] The spread-spectrum quantum state OAM covert transmission signal will undergo spectral expansion in the traditional frequency domain, affecting the demodulation of the broadcast signal and thus increasing the possibility of detection. Therefore, it is necessary to adjust the transmission system parameters to ensure that the OAM signal can be submerged in the broadcast signal, thus ensuring covertness, while also ensuring that the demodulation of the cover signal is not affected.

[0071] To ensure the concealment of OAM communication in the frequency domain, the OAM signal must be completely submerged in the spectrum of the MAPSK broadcast signal. This requires considering the different power ratios of the OAM covert transmission signal and the DVB-S2 signal. And symbol rate ratio KR =R OAM / R MAPSK The impact on frequency domain concealment is illustrated in the simulation graphs of the spectrum and power spectrum, as shown below. Figure 6 As shown. (Through) Figure 6 It can be seen that under the several simulation parameters given in this embodiment, when the information rate (K) of OAM covert communication is sacrificed... R =1 / 10), and a certain signal power (K P When the frequency response ratio is 1 / 5, the OAM covert communication method has good covertness in the frequency domain, meaning that the occurrence of OAM communication behavior cannot be detected in the frequency domain. Therefore, by adding a base signal, the covertness of OAM communication behavior can be guaranteed in the frequency domain.

[0072] Figure 7 This is a flowchart illustrating another method for covert electromagnetic wave intrinsic orbital angular momentum communication provided in this application. In the above... Figure 2 Based on the illustrated embodiment, this embodiment provides a secondary encrypted covert communication system combining electromagnetic wave quantum state orbital angular momentum vortex microwave quantum and electromagnetic wave statistical state orbital angular momentum vortex beams. This demonstrates that the proposed electromagnetic wave intrinsic orbital angular momentum covert communication system can be combined with other covert communication systems to further enhance the anti-interception performance of the transmission system. In this embodiment, the encryption key is electromagnetic wave statistical state orbital angular momentum keying data.

[0073] like Figure 7 As shown, the method in this embodiment includes:

[0074] S701, acquire electromagnetic wave statistical state orbital angular momentum keying data and main channel radio frequency signal; wherein, the main channel radio frequency signal is the form of encrypted data obtained by encrypting user data using electromagnetic wave statistical state orbital angular momentum keying data.

[0075] S702: Perform keying modulation based on the electromagnetic wave statistical state orbital angular momentum keying data to generate electromagnetic wave quantum state orbital angular momentum keying data.

[0076] S703, Generate an electromagnetic wave quantum state orbital angular momentum vortex microwave quantum to be modified based on the electromagnetic wave quantum state orbital angular momentum keying data and the main channel radio frequency signal;

[0077] S704, Generate an electromagnetic wave statistical state orbital angular momentum vortex beam keying signal based on the electromagnetic wave statistical state orbital angular momentum keying data and the electromagnetic wave quantum state orbital angular momentum keying data;

[0078] S705, based on the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum to be modified and the electromagnetic wave statistical state orbital angular momentum vortex beamkeying signal, generate the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum.

[0079] S706: The electromagnetic wave quantum state orbital angular momentum vortex microwave quantum radiation is directed into the target space.

[0080] Figure 8 This is a schematic diagram of another electromagnetic wave intrinsic orbital angular momentum covert communication system provided in an embodiment of this application; Figure 9 A flowchart illustrating a statistical OAM mode number selection method provided in this application embodiment; Figure 10 The signal logic timing diagram provided for the embodiments of this application; Figure 11 This application provides a signal generation subsystem with a delay function. In this embodiment, the keys of the entire system are the spreading sequence of the main channel and the spread-dimensional sequence in the statistical OAM channel.

[0081] First, this embodiment provides the following data definition within a data frame: the main channel user data can be represented as 'a', with a length of MD and a symbol period of T. u The chip period of the spread spectrum sequence is T. s ; Spread spectrum encrypted data of statistical state OAM beam (i.e. Figure 8 The statistical state OAM keying data in the data is c (1) The length is D, and the symbol period is The chip period of the extended sequence is Quantum state OAM vortex microwave quantum bonding data (i.e. Figure 8 The quantum state OAM keying data in the middle) is c (2) The length is M, and the symbol period is The extended-dimensional signal used for quantum state OAM vortex microwave quantum key transfer is c (3) The length is D 2 The chip cycle is Where M = ND. In this embodiment, all data values ​​are ±1, indicating that the user data uses BPSK modulation, and the spread spectrum and dimension-spreading chips are binary values. Generally, T u >>T s , T u , They are on the same order of magnitude. T s and They are on the same order of magnitude. Figure 8 In one embodiment shown, T s and They are equal, both being the minimum chip period; Tu =DT s ,

[0082] To enhance data anti-interception capabilities, statistical OAM vortex beam keying data is used during transmission. (1) and quantum state OAM vortex microwave quantum bonding data c (2) The signal changes continuously within each data frame and is shared and updated at the receiver via statistical state and quantum state OAM index modulation. The extended-dimensional signal used for vortex microwave quantum key distribution is c. (3) The data was shared at both the sending and receiving ends before the link was established.

[0083] exist Figure 8 In the illustrated embodiment, the main channel user signal can be represented as Statistical OAM vortex beamsing signal 1 D Let D be a column vector of length D, where all elements are 1; the quantum state OAM keying signal can be represented as in It represents the Kronecker product. This represents the i-th signal of the statistical state OAM vortex beam keying signal. This indicates that the modal number is +1 s The statistical vortex beam carries the main channel user signal. This indicates that the modal number is -1 s The statistical vortex beam carries the main channel user signal. In this case, the statistical vortex beam carrying the main channel user signal can be represented as... in The Hada code product is represented by exp, the exponential function is represented by j = -1, and the imaginary part of the complex number is l. s Represents the number of OAM modes. This represents the spatial phase angle. Furthermore, the quantum state OAM index matrix B = f is defined. ind (z (2) ), specifically defined as And there are Indicates a length of MD 2 A vector whose elements are all 1s. Let b represent the i-th signal of the quantum state OAM keying signal. i and They represent b and The i-th element. When b i =1, At that time, the first quantum state OAM mode number is transmitted, when bi =0, At this point, the second quantum state OAM mode number is transmitted. The quantum state OAM carrying the main channel radio frequency signal can then be represented as... S b =[s b s b ] T .

[0084] In one possible implementation, combining Figure 11 It can be seen that this embodiment can refine the above S701. The electromagnetic wave statistical state orbital angular momentum keying data from the previous moment and the main channel radio frequency signal from the current moment are acquired; wherein, the main channel radio frequency signal from the current moment is the encrypted data obtained by encrypting the user data from the previous moment using the electromagnetic wave statistical state orbital angular momentum keying data.

[0085] Specifically, Figure 11 The participation of the delay module can reduce data storage consumption. The number of statistical OAM modes transmitted at the current time l is obtained by expanding the dimension of the quantum OAM keying data transmitted at the previous time l–1. The main channel user signal transmitted at the current time l is obtained by expanding the dimension of the statistical OAM vortex beam keying data transmitted at the previous time l–1. In this application embodiment, the time slot corresponding to the transmitted data frame can be represented by a subscript, such as c. (2)l-1 This represents extended-dimensional encrypted data transmitted via quantum state OAM index modulation in time slot l–1. This embodiment alleviates, to some extent, the problem of illegal eavesdroppers monitoring and intercepting the covert channel of statistical state OAM vortex beams by detecting phase difference changes.

[0086] Figure 12 This is a flowchart illustrating another method for covert electromagnetic wave intrinsic orbital angular momentum communication provided in an embodiment of this application. Figure 1 Based on the illustrated embodiment, this embodiment focuses on detailing the specific operation of the signal receiving subsystem 200. For example... Figure 12 As shown, the method in this embodiment includes:

[0087] S121: Receive electromagnetic wave quantum state orbital angular momentum vortex microwave quantum in target space;

[0088] S122: Based on the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum detection electromagnetic wave quantum state orbital angular momentum keying data, and detect the main channel radio frequency signal;

[0089] S123: Identify the electromagnetic wave quantum state orbital angular momentum keying data and demodulate the encryption key;

[0090] S124: Calculate the decryption key corresponding to the encryption key based on the encryption key, and use the decryption key to demodulate the main channel radio frequency signal to obtain user data.

[0091] To facilitate understanding of the specific operations of S121 to S124, this embodiment can be analyzed based on the symbols appearing in S121 to S124 as follows: S121 receives electromagnetic wave quantum state orbital angular momentum vortex microwave quantum a*c; S122 detects electromagnetic wave quantum state orbital angular momentum keying data c and detects main channel radio frequency signal a*; S123 demodulates encryption key b; S124 calculates decryption key b^ and uses decryption key b^ to demodulate main channel radio frequency signal a* to obtain user data a.

[0092] In an optional embodiment, S121, receiving electromagnetic wave quantum state orbital angular momentum vortex microwave quanta in the target space includes: receiving electromagnetic wave quantum state orbital angular momentum vortex microwave quanta in the target space by using cyclotron coupling of quantum state orbital angular momentum. By executing S121, the following effects can be achieved: at the legitimate receiving end, reception can be performed using cyclotron coupling of quantum state orbital angular momentum. Since angular momentum is conserved during the absorption of orbital angular momentum quanta by cyclotrons, the number of quantum state orbital angular momentum modes transmitted in free space can be detected by detecting the number of vortex electron orbital angular momentum modes.

[0093] In an optional embodiment, step S122: detecting electromagnetic wave quantum state orbital angular momentum keying data based on the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum, includes: S1221: detecting the number of vortex electron orbital angular momentum modes based on the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum; S1222: determining the electromagnetic wave quantum state orbital angular momentum keying data based on the number of vortex electron orbital angular momentum modes.

[0094] In an optional embodiment, S1221: Based on the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum, the number of vortex electron orbital angular momentum modes is detected, including two methods. The first method is: processing the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum using a diffraction crystal combined with an electron fluorescent screen to obtain a fluorescent pattern; determining the number of vortex electron orbital angular momentum modes based on the fluorescent pattern and a preset correspondence between the fluorescent pattern and the number of vortex electron orbital angular momentum modes. It should be noted that the fluorescent patterns after diffraction of vortex electrons with different mode numbers are different. Therefore, the number of vortex electron orbital angular momentum modes carried by the detected vortex electrons can be distinguished by the fluorescent pattern, thereby inferring the number of quantum state orbital angular momentum modes propagating in free space.

[0095] The second method is to determine the fluorescence position by using vortex electrons through a diffraction electron grating; and to determine the vortex electron orbital angular momentum mode number based on the fluorescence position and the pre-defined correspondence between the fluorescence position and the vortex electron orbital angular momentum mode number.

[0096] It should be understood that, in the embodiments of this application, vortex electrons carrying orbital angular momentum of different mode numbers can also be mapped to different positions in space by means of a diffraction electron grating, and the orbital angular momentum of quantum states with different mode numbers can be detected by fluorescence at different positions in space. Therefore, the received signal of the quantum state OAM vortex microwave quantum receiving module 201 can be expressed as Equation (4):

[0097] y = x + n (4)

[0098] in, Indicates the actual received signal. Indicates the theoretical received signal. This represents additive white Gaussian noise. For example, x = [s, 0]. T Let s represent the main channel information transmitted using the first quantum state OAM mode number, where x = [0, s]. T Let s represent the main channel information transmitted using the second quantum state OAM mode number. The main channel information can be understood as encrypted data corresponding to the main channel radio frequency signal.

[0099] In an optional embodiment, S123, the electromagnetic wave quantum state orbital angular momentum keying data is identified, including: identifying the electromagnetic wave quantum state orbital angular momentum keying data using maximum likelihood estimation. In this embodiment, the number of quantum state OAM modes is identified, that is, the positions corresponding to non-zero elements in x; then the received signal in the conventional channel is demodulated, that is, s is demodulated. The identification of the number of quantum state OAM modes can be carried out using the maximum likelihood estimation method, and the formula used for maximum likelihood estimation is Equation (5):

[0100]

[0101] Among them, y H This represents the conjugate transpose of y. Let represent a vector whose i-th element is 1 and all other elements are 0. Furthermore, when the traditional main channel uses BPSK modulation, the above equation is equivalent to equation (6):

[0102]

[0103] Then, the spread spectrum sequence in the traditional main channel is recovered by identifying the quantum state OAM mode number, and the main channel radio frequency signal transmitted in the traditional main channel is despread and demodulated to recover the user data.

[0104] Figure 13 This is a schematic diagram of the structure of the signal receiving subsystem provided in the embodiments of this application, and... Figure 8 The receiver description is consistent with the description in the original text. Figure 8 A quantum state OAM sensor array, comprising at least two quantum state OAM detection devices. For example... Figure 8 As shown, when the legitimate receiver uses two quantum state OAM detection devices, the received signal can be expressed as equation (7):

[0105]

[0106] Where A represents the amplitude value of the valid signal received by the receiver. and Let N represent the spatial location of the two quantum state OAM detection devices, and let N represent the receiver noise. Each element in N is an independent and identically distributed complex Gaussian random variable with variance .

[0107] Next, based on the third embodiment, this embodiment only considers the d-th statistical state OAM vortex beam keying data transmitted in the l-th time slot. The demodulation situation, i.e. The demodulation process is described by analyzing the data demodulation within the time slot. The corresponding received signal can be represented as:

[0108]

[0109] The main channel user signal can be represented as according to Figure 10 The timing logic shown indicates that the number of user data transmitted is M, i.e. The length is M. Statistical state OAM vortex beam keying signal The quantum state OAM vortex microwave quantum key transfer signal can be represented as according to Figure 10 The temporal logic shown indicates that N vortex microwave quantum key transfer data points are transmitted. Based on the maximum likelihood principle, the corresponding estimation method can be expressed as:

[0110]

[0111] in, Denotes the F-norm of matrix X. This judgment method can be simplified to equation (10):

[0112]

[0113] because Therefore, the judgment conditions can be simplified to equation (11):

[0114]

[0115] Figure 14 A flowchart for demodulating and recovering user data and spread spectrum encrypted data is provided for an embodiment of this application. First, the spread spectrum encrypted signal of the current data frame is despread and recovered by using the output of the quantum state OAM sensor in conjunction with the spread spectrum encrypted data buffered in the previous data frame. That is, after demodulating the statistical state OAM vortex beam keying data, the spread spectrum encrypted signal is despread and recovered. Then, as shown in Equation (11), the user signal of the current data frame is despread and recovered by using the spread spectrum encrypted data of the current data frame and the spread spectrum encrypted data buffered in the previous data frame.

[0116] Computational complexity is a crucial metric for evaluating covert transmissions, measuring the difficulty for an unauthorized eavesdropper to recover the covert transmission through blind estimation. Here, we consider a scenario where the unauthorized eavesdropper can receive the signal with a high signal-to-noise ratio and has known the spreading length D, the spread sequence length M, and the number of keying operations N. This presents excellent eavesdropping conditions for the unauthorized eavesdropper, but is extremely demanding for covert transmission. Because c (1) and c (2) The differences exist between different data frames, therefore, for an unauthorized eavesdropper, it is necessary to start from z. (2) Blindly estimate c (3) This is to ensure the interception of user data. Below, we analyze the computational complexity of blind estimation for illegal eavesdropping, using user data transmitted via the main channel as an example.

[0117] The illegal eavesdropper uses a non-overlapping window of length D to analyze the recovered signal x. e The division is shown in equation (12):

[0118]

[0119] Furthermore, it can be based on the cross-correlation matrix. The extended-dimensional sequence is blindly estimated in the form of [formula]. In the cross-correlation matrix C... e In the sequence, two eigenvalues ​​are much larger than the others. Let the eigenvectors corresponding to these two largest eigenvalues ​​be denoted as u1 and u2, respectively. Then the blindly estimated spread spectrum sequence can be expressed as equation (13):

[0120]

[0121] According to equation (13), z can be targeted (1) and z (2) Perform similar busy estimation methods to obtain the extended-dimensional sequence c. (2) and c (3) .

[0122] The computational complexity of eigenvalue decomposition is O(L). 3 ), where L represents the number of rows in the cross-correlation matrix, i.e., the length of the spreading sequence. Therefore, for a traditional direct-sequence spread spectrum system, for the spreading sequence c (1) The computational complexity of blind estimation is O(D). 3 Due to c (1) and c (2) The differences exist between different data frames, therefore, for an unauthorized eavesdropper, it is necessary to start from z. (2) Blindly estimate c (3) To ensure the eavesdropping on user data, different sequences c need to be transmitted during the process. (2) An estimation is performed. In the proposed embodiment, c (3) The length is D 2 The computational complexity of blind estimation is O(D). 6 Estimate the different sequences c transmitted during this process. (2) The computational complexity is O(DM). 3 The total computational complexity of blind estimation is the sum of the two. Simultaneously, the transmission data frame length needs to be carefully designed to ensure the extended dimension sequence c... (1) and c (2) The changes were made before the illegal eavesdropper could make a blind assessment of them.

[0123] Figure 15 This is a comparison chart of computational complexity and transmission rate provided for embodiments of this application. The bandwidth given in this embodiment is assumed to be 31MHz, the spreading sequence length of the traditional main channel data is 31, the spread sequence length of the statistical OAM keying signal is 511, and the spread sequence length of the quantum state OAM keying signal is 961. Figure 15 As can be seen, the proposed quantum state orbital angular momentum covert transmission system achieves a transmission rate of 1 Mbps, while the traditional direct sequence spread spectrum system, under the same computational complexity, achieves a transmission rate of less than 20 kHz, only one-fiftieth of the proposed covert transmission system's rate. Considering the same transmission rate of 1 Mbps, the computational complexity of the proposed covert transmission system is approximately 6 × 10⁹, while the computational complexity of the traditional direct sequence spread spectrum system is 3 × 10⁴. At the same transmission rate, the computational complexity of the anti-interception transmission system based on statistical state OAM vortex beams is approximately 1 × 10⁸, one-sixtieth of the proposed covert transmission system's rate; the computational complexity of using only quantum state OAM keying transmission is less than 10⁹, one-fifth of the proposed covert transmission system's rate. This simulation comparison demonstrates that, given a bandwidth, the proposed electromagnetic wave intrinsic OAM covert transmission system ensures both high transmission rate and anti-interception capability.

[0124] This electromagnetic wave intrinsic OAM covert communication system achieves covert transmission from a new dimension by transmitting spread spectrum encryption sequences or related information from a traditional main channel through a quantum state OAM index modulation channel. Furthermore, the proposed electromagnetic wave intrinsic OAM covert transmission system can be combined with other covert transmission systems. By using intrinsic OAM at the transmitter to spread spectrum scramble the spread spectrum encryption information of other covert communication systems, the anti-interception performance of the transmission system is further enhanced, achieving a further encryption effect.

[0125] The embodiments of this application overcome, to a certain extent, the contradiction between transmission rate and anti-interception performance in covert transmission described in the background, achieving high anti-interception performance while rapidly switching user data. Furthermore, a "secondary encryption" can be formed in the intrinsic OAM channel. At the receiving end, by determining the number of received intrinsic OAM modes, the "secondary encryption" is decrypted to obtain the encryption key in the traditional main channel. After calculating the corresponding decryption key, the information on the traditional main channel is decrypted to obtain the covertly transmitted information.

[0126] The collection, storage, use, processing, transmission, provision, and disclosure of user personal information involved in the technical solution of this application all comply with the provisions of relevant laws and regulations and do not violate public order and good morals.

[0127] This application also provides a computer-readable storage medium storing computer instructions, which, when executed by a processor, implement the steps of the methods described above.

[0128] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this application can be achieved, and this is not limited herein.

[0129] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for covert communication using intrinsic orbital angular momentum of electromagnetic waves, characterized in that, A signal transmission subsystem applied to electromagnetic wave intrinsic orbital angular momentum covert communication systems includes: Obtain the encryption key and the main channel radio frequency signal; wherein, the main channel radio frequency signal is the form of encrypted data obtained by encrypting user data using the encryption key; The encryption key is used as an electromagnetic wave quantum state orbital angular momentum keying signal for data mapping to obtain a first vector consisting of multiple elements; wherein, the first vector contains a target element with a value of 1, and the values ​​of all other elements except the target element are 0; The numerical combination of all elements in the first vector is determined as the electromagnetic wave quantum state orbital angular momentum keying data corresponding to the encryption key; Based on the electromagnetic wave quantum state orbital angular momentum keying data and the main channel radio frequency signal, an electromagnetic wave quantum state orbital angular momentum vortex microwave quantum is generated. The process of generating electromagnetic wave quantum state orbital angular momentum vortex microwave quantum signals based on the electromagnetic wave quantum state orbital angular momentum keying data and the main channel radio frequency signal includes: Extract the corresponding encrypted data from the main channel radio frequency signal; For each element in the electromagnetic wave quantum state orbital angular momentum keying data, the element data is multiplied by the encrypted data to obtain a product result; The electromagnetic wave quantum state orbital angular momentum vortex microwave quantum is generated based on the second vector formed by the product results corresponding to all element data. The electromagnetic wave quantum state orbital angular momentum vortex microwave quantum radiation is directed into the target space.

2. The electromagnetic wave intrinsic orbital angular momentum concealed communication method according to claim 1, characterized in that, After generating the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum based on the electromagnetic wave quantum state orbital angular momentum keying data and the main channel radio frequency signal, the method further includes: Obtain the substrate signal used to modify the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum; The electromagnetic wave quantum state orbital angular momentum vortex microwave quantum is modified using the base signal to obtain the modified electromagnetic wave quantum state orbital angular momentum vortex microwave quantum. The modified electromagnetic wave quantum state orbital angular momentum vortex microwave quantum radiation is directed into the target space.

3. A method for covert communication using intrinsic orbital angular momentum of electromagnetic waves, characterized in that, A signal receiving subsystem used in covert communication systems includes: Receive electromagnetic wave quantum state orbital angular momentum vortex microwave quantum in the target space; The electromagnetic wave quantum state orbital angular momentum vortex microwave quantum detection method detects electromagnetic wave quantum state orbital angular momentum keying data and detects the main channel radio frequency signal; wherein, the electromagnetic wave quantum state orbital angular momentum vortex microwave quantum detection method extracts corresponding encrypted data from the main channel radio frequency signal; for each element data in the electromagnetic wave quantum state orbital angular momentum keying data, the element data is multiplied by the encrypted data to obtain a product result; a second vector is generated based on the product results corresponding to all element data. The electromagnetic wave quantum state orbital angular momentum keying (EMK) data is identified and the encryption key is demodulated. The EMK data is obtained by mapping the encryption key as an EMK signal to obtain a first vector consisting of multiple elements. The first vector contains a target element with a value of 1, and all other elements have values ​​of 0. The vector is determined by combining the values ​​of all elements in the first vector. The decryption key corresponding to the encryption key is calculated based on the encryption key, and the decryption key is used to demodulate the main channel radio frequency signal to obtain user data.

4. The electromagnetic wave intrinsic orbital angular momentum concealed communication method according to claim 3, characterized in that, The process of receiving electromagnetic wave quantum state orbital angular momentum vortex microwave quantum waves in the target space includes: In the target space, electromagnetic wave quantum state orbital angular momentum vortex microwave quantum is received by using cyclotron electron coupling quantum state orbital angular momentum.

5. A covert communication system based on intrinsic orbital angular momentum of electromagnetic waves, characterized in that, include: A signal transmitting subsystem for performing the electromagnetic wave intrinsic orbital angular momentum covert communication method as described in any one of claims 1 to 2, and a signal receiving subsystem for performing the electromagnetic wave intrinsic orbital angular momentum covert communication method as described in any one of claims 3 to 4.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the electromagnetic wave intrinsic orbital angular momentum covert communication method as described in any one of claims 1 to 4.

7. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the electromagnetic wave intrinsic orbital angular momentum covert communication method as described in any one of claims 1 to 4.

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