Secret key code generation method and device and electronic equipment

Abstract

The invention provides a key code generation method and device and electronic equipment, and is applied to the technical field of wireless communication. The method is applied to a transmitting end included in an OFDM-OAM communication system in industrial equipment manufacturing, and comprises the following steps: generating a first pilot signal according to a first transmitting signal; sending a first pilot signal to a receiving end, wherein the first pilot signal is used for the receiving end to determine a first demodulation signal; estimating a channel from the transmitting end to the receiving end according to the first pilot signal and the first demodulation signal to obtain a first channel; performing quantization coding on the first channel to generate a first encryption key of the transmitting end in a communication stage; determining a second demodulation signal according to a second pilot signal sent by the receiving end, wherein the second pilot signal is determined by the receiving end according to the second transmitting signal; and sending a second demodulation signal to the receiving end, wherein the second demodulation signal is used for the receiving end to generate a second encryption key of the receiving end in the communication stage. And the security of data transmission and a communication system is improved.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technology in industrial equipment manufacturing, and in particular to a key coding generation method, device and electronic equipment. Background Art

[0002] As global manufacturing competition enters a three-dimensional game of "technology, standards, and regulations," security challenges in industrial equipment manufacturing (such as high-end equipment manufacturing) are experiencing a systematic escalation. The deep integration of the Industrial Internet and artificial intelligence presents industrial equipment manufacturing with dual challenges: traditional and digital security. Orbital angular momentum (OAM), a new physical dimension of electromagnetic waves, has recently attracted widespread attention in the wireless communications field. Orthogonal frequency division multiplexing (OFDM) technology, with its high spectral efficiency and robustness against multipath interference, has become a key technology in modern communication systems. Combining mature OFDM technology with OAM can create an OFDM-OAM communication system suitable for industrial equipment manufacturing applications. This OFDM-OAM communication system leverages the dual orthogonality of frequency-domain subcarriers and OAM modes, resulting in a wireless communication system with greater information carrying capacity and interference immunity than traditional communication systems.

[0003] While OFDM-OAM communication systems offer extremely high data rates, they still fall within the realm of wireless communications. The broadcast nature of wireless communications means that all data transmitted via these systems can be received by any receiver within the airspace where the OFDM-OAM system resides. This opens the door to both passive and active attacks from potential eavesdroppers. This lowers the security of transmitted data, making these OFDM-OAM communication systems less secure in industrial equipment manufacturing and more vulnerable to potential eavesdroppers.

[0004] Therefore, there is an urgent need for a key coding generation method to encrypt the transmitted data and improve the security of OFDM-OAM communication systems in industrial equipment manufacturing. Summary of the Invention

[0005] The embodiments of the present application provide a key coding generation method, device and electronic device, which are used to address the defects of low security of data transmission in the prior art, which may lead to low security of the above-mentioned OFDM-OAM communication system in industrial equipment manufacturing and susceptibility to attacks by potential eavesdroppers. The method omits part of the key negotiation content in the traditional key coding generation method and is a non-negotiation key coding generation method. In other words, the method avoids the key information leakage caused by information interaction during key negotiation in the traditional key coding generation method by transferring the key negotiation to subsequent communication transmission. The method implicitly "negotiates" a more secure and difficult-to-crack encryption key through the interaction of the pilot signal and the modulation signal, thereby improving the security of subsequent data transmission, thereby enhancing the security of the OFDM-OAM communication system in industrial equipment manufacturing, and making the OFDM-OAM communication system less vulnerable to attacks by potential eavesdroppers.

[0006] In a first aspect, an embodiment of the present application provides a key code generation method, which is applied to an orthogonal frequency division multiplexing-orbital angular momentum OFDM-OAM communication system in industrial equipment manufacturing, including a transmitting end, the OFDM-OAM communication system also including a receiving end, the receiving end being connected to the transmitting end; the method comprising: generating a first pilot signal according to the first transmission signal; and sending the first pilot signal to the receiving end, wherein the first pilot signal is used by the receiving end to determine a first modulation signal; estimating a channel from the transmitting end to the receiving end based on the first pilot signal and the first modulation signal sent by the receiving end to obtain a first channel; quantize and encode the first channel to generate a first encryption key for the transmitting end during the communication phase; A second modulation signal is determined based on a second pilot signal sent by the receiving end, where the second pilot signal is determined by the receiving end based on a second transmission signal; and the second modulation signal is sent to the receiving end, where the second modulation signal is used by the receiving end to generate a second encryption key for the receiving end during the communication phase.

[0007] In a second aspect, an embodiment of the present application provides a key code generation method, which is applied to an orthogonal frequency division multiplexing-orbital angular momentum OFDM-OAM communication system in industrial equipment manufacturing, including a receiving end, the OFDM-OAM communication system also including a transmitting end, the transmitting end being connected to the receiving end; the method comprising: determining a first modulation signal based on a first pilot signal sent by the transmitting end, where the first pilot signal is determined by the transmitting end based on the first transmitting signal; and sending the first modulation signal to the transmitting end, where the first modulation signal is used by the transmitting end to generate a first encryption key of the transmitting end during a communication phase; generating a second pilot signal according to the second transmission signal; and sending the second pilot signal to the transmitting end, where the second pilot signal is used by the transmitting end to determine a second modulation signal; estimating a channel from the receiving end to the transmitting end based on the second pilot signal and the second modulation signal sent by the transmitting end to obtain a second channel; The second channel is quantized and encoded to generate a second encryption key for the receiving end during the communication phase.

[0008] In a third aspect, an embodiment of the present application further provides a key code generation device, which is applied to an orthogonal frequency division multiplexing-orbital angular momentum OFDM-OAM communication system in industrial equipment manufacturing, including a transmitting end, the OFDM-OAM communication system also includes a receiving end, the receiving end is connected to the transmitting end; the device includes A first processing module, configured to generate a first pilot signal according to a first transmission signal, wherein the first pilot signal is used by the receiving end to determine a first modulation signal; A first transceiver module, configured to send the first pilot signal to the receiving end; The first processing module is further configured to estimate a channel from the transmitting end to the receiving end based on the first pilot signal and the first modulation signal sent by the receiving end to obtain a first channel; quantize and encode the first channel to generate a first encryption key for the transmitting end during a communication phase; and determine a second modulation signal based on a second pilot signal sent by the receiving end, where the second pilot signal is determined by the receiving end based on a second transmitting signal; The first transceiver module is further configured to send the second mediation signal to the receiving end, where the second mediation signal is used by the receiving end to generate a second encryption key for the receiving end during the communication phase.

[0009] In a fourth aspect, an embodiment of the present application further provides a key code generation device, which is applied to an orthogonal frequency division multiplexing-orbital angular momentum OFDM-OAM communication system in industrial equipment manufacturing, including a receiving end, the OFDM-OAM communication system also including a transmitting end, the transmitting end being connected to the receiving end; the device includes: a second processing module, configured to determine a first modulation signal according to a first pilot signal sent by the transmitting end, where the first pilot signal is determined by the transmitting end according to the first transmit signal; A second transceiver module is configured to send the first mediation signal to the transmitter, where the first mediation signal is used by the transmitter to generate a first encryption key of the transmitter during a communication phase; The second processing module is further configured to generate a second pilot signal according to the second transmit signal; The second transceiver module is further configured to send the second pilot signal to the transmitting end, where the second pilot signal is used by the transmitting end to determine a second modulation signal; The second processing module is further used to estimate the channel between the receiving end and the transmitting end based on the second pilot signal and the second modulation signal sent by the transmitting end to obtain a second channel; quantize and encode the second channel to generate a second encryption key for the receiving end during the communication phase.

[0010] In the fifth aspect, an embodiment of the present application also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and runnable on the processor, wherein when the processor executes the computer program, it implements the key code generation method as described in any one of the first or second aspects above.

[0011] In a sixth aspect, an embodiment of the present application further provides a non-transitory computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the key code generation method as described in any one of the first or second aspects above is implemented.

[0012] In a seventh aspect, an embodiment of the present application further provides a computer program product, comprising a computer program, which, when executed by a processor, implements the key code generation method as described in any one of the first or second aspects above.

[0013] The key code generation method, device and electronic device provided by the embodiments of the present application are as follows: a transmitting end generates a first pilot signal based on a first transmission signal; and sends the first pilot signal to a receiving end, where the first pilot signal is used by the receiving end to determine a first modulation signal; based on the first pilot signal and the first modulation signal sent by the receiving end, a channel between the transmitting end and the receiving end is estimated to obtain a first channel; the first channel is quantized and encoded to generate a first encryption key of the transmitting end in a communication phase; based on a second pilot signal sent by the receiving end, a second modulation signal is determined, where the second pilot signal is determined by the receiving end based on the second transmission signal; and a second modulation signal is sent to the receiving end, where the second modulation signal is used by the receiving end to generate a second encryption key of the receiving end in a communication phase. This method omits some of the key negotiation content in traditional key coding generation methods and is a non-negotiation key coding generation method. In other words, this method avoids the key information leakage caused by information interaction during key negotiation in traditional key coding generation methods by transferring key negotiation to subsequent communication transmission. Through the interaction of pilot signals and modulation signals, a more secure and difficult-to-crack encryption key is implicitly "negotiated", thereby improving the security of subsequent data transmission, thereby enhancing the security of OFDM-OAM communication systems in industrial equipment manufacturing, making the OFDM-OAM communication system less vulnerable to attacks by potential eavesdroppers. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the present application or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0015] Figure 1 This is one of the flow charts of the key code generation method provided in the embodiment of the present application; Figure 2 Schematic diagram of a UCA antenna at a transmitting end and a UCA antenna at a receiving end provided in an embodiment of the present application; Figure 3 This is a schematic diagram of the encryption key generation phase and the encryption communication phase provided by an embodiment of the present application; Figure 4 This is the second flow chart of the key code generation method provided in the embodiment of the present application; Figure 5 Schematic diagram of a UCA antenna of an eavesdropping terminal provided in an embodiment of the present application; Figure 6 Schematic diagram of the relationship between confidentiality capacity and signal-to-noise ratio (SNR) provided in an embodiment of the present application; Figure 7The bit error rate BER and the offset angle provided in the embodiment of the present application are Schematic diagram of the relationship between Figure 8 This is one of the structural diagrams of the key code generation device provided in the embodiment of the present application; Figure 9 This is the second structural diagram of the key code generation device provided in the embodiment of the present application; Figure 10 It is a structural diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0017] To better understand the embodiments of the present application, the Orthogonal Frequency Division Multiplexing-Orbital Angular Momentum (OFDM-OAM) communication system involved in the embodiments of the present application is first described in detail: The above-mentioned OFDM-OAM communication system is a communication system based on the two-dimensional inverse fast Fourier transform (2-D IFFT) operation / two-dimensional fast Fourier transform (2-D FFT) operation. The modulation points of the 2-D IFFT operation / 2-D FFT operation can be express, is an integer greater than 1.

[0018] The above-mentioned OFDM-OAM communication system adopts the time division duplexing (TDD) mode.

[0019] Optionally, the OFDM-OAM communication system may include a transmitter and a receiver, wherein both the transmitter and the receiver are electronic devices.

[0020] Specifically, the transmitting end and the receiving end each include a uniform circular array (UCA) antenna, and the number of antennas of each UCA antenna is available express, is an integer greater than 1.

[0021] It should be noted that each UCA antenna is a UCA antenna element, also known as UCA antenna array element, each The UCA antenna of the array element produces the most There are vortex waves of different modes, and the OAM mode number of each vortex wave is available. Indicates that, In addition, the total number of OAM modes, that is, the total number of modes available express, is an integer greater than 1.

[0022] Optionally, the transmitting end may include: a computer, a mobile terminal, a wearable device, a mechanical device, etc.

[0023] Optionally, the above-mentioned receiving end may include: a computer, a mobile terminal, a wearable device, a mechanical device, etc.

[0024] It should be noted that the physical layer key generation (PKG) method, as a supplementary method of classical cryptography, has the characteristics of lightweight, resistance to quantum attacks, and strong key dynamics compared to traditional cryptography. The PKG method directly uses the physical characteristics of the wireless channel to generate encryption keys without the need for pre-distribution of key materials, and can be used in the key coding generation method provided in the embodiment of this application.

[0025] Optionally, the above-mentioned OFDM-OAM communication system is a communication system used in high-end equipment manufacturing.

[0026] Optionally, the above-mentioned high-end equipment may include: aerospace equipment, rail transportation equipment, marine engineering equipment and intelligent manufacturing equipment, etc.

[0027] Optionally, the field of high-end equipment manufacturing can include the following application scenarios: 1. Full life cycle management of aerospace equipment (such as satellite on-orbit operation and maintenance and safety protection, aircraft engine health management, etc.); 2. Intelligent operation and maintenance of rail transit equipment (such as high-speed rail bearing remaining life prediction, intelligent train network control system); 3. Extreme environment operation of marine engineering equipment (such as dynamic positioning of deep-sea drilling platforms, submarine pipeline inspection robots, etc.); 4. Extreme condition guarantee of emergency equipment (such as cluster operations of high-rise building fire-fighting robots).

[0028] For example, in the application scenario of on-orbit satellite operation and maintenance and safety protection, the transmitting end is the ground control equipment, and the receiving end is the satellite. When the ground control equipment performs on-orbit operation and maintenance and safety protection for the satellite, the ground control equipment can encrypt the plaintext transmitted data (such as operation and maintenance and protection instructions) to obtain a first ciphertext. The satellite then decrypts the first ciphertext to obtain the target plaintext, and then performs the operation corresponding to the operation and maintenance and protection instruction based on the target plaintext.

[0029] It should be noted that other application scenarios in the field of high-end equipment manufacturing, such as industrial robot control scenarios (such as control applications for industrial robotic arms), CNC system security authentication scenarios (such as authentication of CNC machine tools), and smart factory equipment collaboration scenarios (such as data transmission of smart factory production line equipment clusters), etc., all fall within the scope of protection of this application and will not be described in detail here.

[0030] The key code generation method provided in the embodiment of the present application is described in detail below using the transmitter and receiver execution entities included in the OFDM-OAM communication system in high-end equipment manufacturing: Figure 1 This is a flow chart of the key code generation method provided by the embodiment of the present application. Figure 1 As shown, the method includes the following steps 101 to 112.

[0031] Step 101: A transmitting end generates a first pilot signal according to a first transmitting signal.

[0032] In some embodiments, the first transmit signal is × Dimensional data blocks, and are all integers greater than 1.

[0033] It should be noted that the first transmission signal can be used express, express In the OAM mode The first transmitted signal Depend on The data of each OAM mode is composed of Indicates the number of OFDM subcarriers, where .

[0034] In this way, the transmitting end generates the first pilot signal according to the first transmitting signal, which may include: the transmitting end performs frequency domain shifting on the first transmitting signal The OFDM signal is obtained by performing a 2D IFFT operation on the line. Indicates the number of modulation points in the 2-D IFFT operation, is an integer greater than 1; the transmitter performs OFDM signal transmission in the spatial domain Perform a 2-D IFFT operation on the columns to obtain the OFDM-OAM signal. Indicates the number of antennas of the uniform circular array UCA antenna at the transmitting end. The UCA antenna is a UCA antenna array element. is an integer greater than 1; the transmitting end inserts a cyclic prefix into the OFDM-OAM signal, and then performs up-conversion processing on the RF end to obtain a first pilot signal.

[0035] In the embodiment of the present application, when determining the first pilot signal, the transmitting end may first perform a frequency domain shift on the first transmitting signal. The transmitting end then modulates the OFDM signal into an OFDM signal by performing a 2-D IFFT operation on the rows of the points. A 2-D IFFT operation is performed on the columns, modulating the OFDM signal into an OFDM-OAM signal. To combat multipath and inter-symbol interference (ISI) and improve signal robustness, the transmitter inserts a cyclic prefix (CP) into the OFDM-OAM signal. Finally, the signal undergoes up-conversion at the RF end to generate the first pilot signal, which is then transmitted to the receiver.

[0036] In some embodiments, the expression of the OFDM-OAM signal is: .

[0037] in, Indicates OFDM-OAM signal; represents the antenna power allocation matrix, Indicates the UCA antenna at the transmitter. The power of each antenna; express The Discrete Fourier Transform (DFT) matrix of the point; express The Inverse Discrete Fourier Transform (IDFT) matrix of the point; represents the first transmitted signal, express In the OAM mode OAM mode data; represents the OFDM modulation matrix; Represents the OFDM modulation matrix The inverse matrix of represents the discrete Fourier transform matrix The conjugate transposed matrix of is an OAM modulation matrix; Represents the OFDM modulation matrix The conjugate transposed matrix of .

[0038] In some embodiments, the OAM modulation matrix The expression is: .

[0039] in, , represents the complex exponential term; Indicated by The azimuth angle of the UCA antenna array element composed of antennas, ; Indicates the The number of OAM modes.

[0040] It should be noted that the transmitter can use the IDFT matrix to replace the OAM modulation matrix. When , the number of excited modes is .

[0041] Step 102: The transmitting end sends a first pilot signal to the receiving end.

[0042] The receiving end receives the first pilot signal sent by the transmitting end.

[0043] In some embodiments, the transmitting end sending the first pilot signal to the receiving end may include: the transmitting end sending the first pilot signal to the receiving end through a wireless channel.

[0044] In an embodiment of the present application, when the transmitting end sends the above-mentioned first pilot signal to the receiving end, the first pilot signal can be sent to the wireless channel through the UCA antenna of the transmitting end, and then the first pilot signal is sent to the receiving end through the wireless channel. This can effectively ensure the transmission quality of the first pilot signal in a complex environment.

[0045] It should be noted that the channel model of the wireless channel is a wireless channel model based on the UCA-Multiple-Input Multiple-Output (MIMO) system. The channel matrix of the wireless channel model can be used express.

[0046] In some embodiments, the expression of the first pilot signal sent through the wireless channel is: .

[0047] represents a first pilot signal; Indicates the number of antennas of the UCA antenna at the transmitting end, or the number of array elements of the UCA antenna at the transmitting end; Indicates the number of modulation points in the 2-D IFFT operation; A channel matrix representing a wireless channel; represents the antenna power allocation matrix, Indicates the UCA antenna at the transmitter. The power of each antenna; express The discrete Fourier transform matrix of the point; represents the discrete Fourier transform matrix The conjugate transposed matrix of is an OAM modulation matrix; represents the first transmitted signal, express In the OAM mode OAM mode data; represents the OFDM modulation matrix; Represents the OFDM modulation matrix The conjugate transposed matrix of ; It means the mean is zero and the variance is The complex Gaussian white noise matrix satisfies , express The identity matrix of order.

[0048] Step 103: The receiving end determines a first modulation signal according to the first pilot signal sent by the transmitting end.

[0049] In some embodiments, the receiving end determines the first modulation signal based on the first pilot signal sent by the transmitting end, which may include: the receiving end receives the first pilot signal sent by the transmitting end through a wireless channel, the first pilot signal being obtained after the transmitting end performs a two-dimensional inverse fast Fourier transform 2-D IFFT operation on the first transmission signal; the receiving end first performs down-conversion processing on the first pilot signal at the radio frequency end, and then removes the cyclic prefix at the baseband end to obtain the processed first pilot signal; the receiving end performs a two-dimensional fast Fourier transform 2-D FFT operation on the processed first pilot signal to obtain the first modulation signal.

[0050] In an embodiment of the present application, when determining the first modulation signal, the receiving end may first perform down-conversion processing on the first pilot signal sent by the transmitting end at the RF end, and then remove the cyclic prefix cp (such as cyclic prefix) at the baseband end to obtain a processed first pilot signal, and then perform a two-dimensional fast Fourier transform 2-DFFT operation on the processed first pilot signal to obtain a first modulation signal for subsequent transmission to the transmitting end.

[0051] In some embodiments, based on the first pilot signal received through the wireless channel, the expression of the first modulated signal determined is: .

[0052] in, represents a first mediation signal; express The first sub-modulation signals, each sub-modulation signal corresponds to an OAM mode.

[0053] It should be noted that the above OFDM-OAM signal and the first modulation signal Both are signal models of the above-mentioned OFDM-OAM communication system.

[0054] The channel matrix of the above wireless channel is The construction is elaborated in detail: In the line-of-sight channel, a pair of transmitting antennas (i.e. transmitting array elements) and receiving antennas (i.e. The modeling expression of the transmission function of the receiving array element in free space is: .

[0055] Among them, The transmitting array element is the array element in the UCA antenna at the transmitting end, The receiving array elements are the array elements in the UCA antenna at the receiving end; Indicates the The transmitting element to the Channel gain between receiving array elements; represents a constant related to signal attenuation; Indicates the wavelength of the OAM signal; Indicates the The transmitting element to the The transmission distance between the receiving elements.

[0056] From the above modeling expression, it can be seen that the transfer function Mainly about wavelength and transmission distance function of wavelength. It is generally fixed, so it is particularly important to calculate the distance between the transmitting and receiving antennas in the UCA-MIMO system.

[0057] Considering that it is difficult to strictly align the UCA antenna at the transmitter and the UCA antenna at the receiver in the actual OFDM-OAM communication system, for generalization, the channel matrix of the wireless channel under the condition of misalignment between the transmitter and the receiver can be constructed. .

[0058] Specifically, if Figure 2 FIG2 is a schematic diagram of a UCA antenna at a transmitting end and a UCA antenna at a receiving end provided by an embodiment of the present application. Figure 2 , the radius of the UCA antenna at the transmitting end and the radius of the UCA antenna at the receiving end are both available The center of the UCA antenna at the transmitting end is available Indicates that the center of the UCA antenna at the receiving end is available Indicates. Center with the center The distance between the available express.

[0059] Based on this, for the UCA antenna at the transmitting end, the center is the coordinate origin, and the UCA plane is Surface, build the three-dimensional coordinate system of the transmitter, which can be used express.

[0060] For the UCA antenna at the receiving end, the center As the coordinate origin, construct a three-dimensional coordinate system parallel to Three-dimensional coordinate system , and then the three-dimensional coordinate system Around Axis rotation angle After rotation, we get the three-dimensional coordinate system .

[0061] At this time, the above three-dimensional coordinate system And the above three-dimensional coordinate system The system can simulate the misalignment between the UCA antenna at the transmitting end and the UCA antenna at the receiving end in an OFDM-OAM communication system under actual conditions.

[0062] Assume that The transmitting array elements are in the above three-dimensional coordinate system The coordinates below are , Indicates the The azimuth angle of the transmitting array element in the UCA antenna at the transmitting end. At this time, according to the first coordinate conversion formula, the first The receiving array elements are in the above three-dimensional coordinate system The coordinates below.

[0063] Among them, The transmitting array element can be represented by A; The receiving array element can be represented by B.

[0064] The above first coordinate transformation formula is: .

[0065] Indicates the The receiving array elements are in the above three-dimensional coordinate system The coordinates below; Indicates the The azimuth angle of the receiving array element in the UCA antenna at the receiving end.

[0066] At this time, The transmitting element to the The transmission distance between the receiving elements The expression is: .

[0067] Based on this, the receiving end can obtain the channel matrix of the above wireless channel after determining the channel gain between each pair of transmitting and receiving antennas: The expression is: = .

[0068] It should be noted that the rotation angle In the case of , the UCA antenna at the transmitting end and the UCA antenna at the receiving end are in an ideal alignment state. The receiving array elements are in the above three-dimensional coordinate system The coordinates below are , No. The transmitting element to the The transmission distance between the receiving elements The expression can be simplified to: .

[0069] At the same time, the above channel matrix is a cyclic symmetric matrix that can be decomposed into: .

[0070] in, Represents a diagonal matrix, the diagonal elements of which are channel matrices in eigenvalues.

[0071] Based on this, the first modulation signal The expression can be simplified to: .

[0072] It should be noted that the first modulation signal The simplified expression shows that when the UCA antenna at the transmitting end and the UCA antenna at the receiving end are in an ideal alignment state, the entire channel matrix is equivalent to , the channel matrix is a diagonal matrix, which means that when the UCA antenna at the transmitter and the UCA antenna at the receiver are aligned, the transmission of each OMA mode will not cause interference, and the channels corresponding to each OMA mode can be regarded as independent sub-channels. This also explains why the OAM mode is used as a data transmission channel. The various OAM modes are orthogonal to each other during the transmission process. This diagonal channel matrix can omit the complex equalization operation compensation channel matrix at the receiving end. However, as long as the UCA antenna at the transmitting end and the UCA antenna at the receiving end are not aligned, even with a small offset angle or displacement, the channel matrix They are no longer cyclic symmetric matrices and cannot be simplified as above. As a result, OAM inter-mode crosstalk will appear at the receiving end, and the original data cannot be restored, that is, the first modulation signal cannot be obtained.

[0073] Step 104: The receiving end sends a first modulation signal to the transmitting end.

[0074] The transmitting end receives the first modulation signal sent by the receiving end.

[0075] Optionally, the receiving end sending the first modulation signal to the transmitting end may include: the receiving end sending the first modulation signal to the transmitting end through a wireless channel.

[0076] Optionally, the transmitting end receiving the first modulation signal sent by the receiving end may include: the transmitting end receiving the first modulation signal sent by the receiving end through a wireless channel.

[0077] Step 105: The transmitting end estimates the channel from the transmitting end to the receiving end according to the first pilot signal and the first modulation signal sent by the receiving end to obtain a first channel.

[0078] Optionally, the transmitting end estimates the channel between the transmitting end and the receiving end based on the first pilot signal and the first modulation signal sent by the receiving end to obtain the first channel, which may include: the transmitting end uses the least squares (LS) method to estimate the channel between the transmitting end and the receiving end based on the first pilot signal and the first modulation signal sent by the receiving end to obtain the first channel.

[0079] The least squares method refers to constructing a set of linear equations based on a known transmitted signal (i.e., the first pilot signal) and a received signal (i.e., the first modulation signal) to solve the channel parameters that minimize the sum of squared errors between the received signal and the transmitted signal transmitted through the wireless channel.

[0080] That is, the first channel is a channel parameter.

[0081] Step 106: The transmitting end quantizes and encodes the first channel to generate a first encryption key for the transmitting end in the communication phase.

[0082] Optionally, the transmitting end quantizes and encodes the first channel to generate a first encryption key of the transmitting end in the communication phase, which may include one of the following implementations: Implementation method 1: The transmitting end rounds the first channel and performs binary encoding on the rounded first channel to generate a first encryption key of the transmitting end in the communication phase.

[0083] Optionally, the rounding operation may be rounding up, rounding down, or rounding up, depending on implementation requirements and channel characteristics.

[0084] The above-mentioned implementation method 1 has the advantages of simple implementation, low computational complexity, and is suitable for scenarios with high requirements for key generation speed or limited computing resources.

[0085] Implementation method 2: The transmitting end determines the channel characteristics of the first channel, and quantizes and encodes the channel characteristics to generate a first encryption key of the transmitting end in the communication phase.

[0086] Optionally, the channel characteristics may include: statistical characteristics of channel gain (such as mean and variance), phase distribution, and multipath delay, etc.

[0087] Optionally, a quantization method for quantizing the channel characteristics may include uniform quantization, non-uniform quantization, or clustering-based quantization, etc., depending on the distribution characteristics of the channel characteristics and key generation requirements.

[0088] Implementation 2 above can fully utilize the unique characteristics of the channel to improve the uniqueness and security of the first encryption key. The quantization operation can be optimized based on the distribution characteristics of the channel characteristics to further improve the efficiency of key generation.

[0089] It should be noted that, during the encryption key generation phase, while the transmitting end generates the first encryption key of the transmitting end in the communication phase, the receiving end can also generate the second encryption key of the receiving end in the communication phase. The process of the receiving end generating the second encryption key is the following steps 107-112.

[0090] Since the process of generating the first encryption key at the transmitting end is similar to the process of generating the second encryption key at the receiving end, steps 107 to 112 will not be described in detail below.

[0091] Step 107: The receiving end generates a second pilot signal according to the second transmission signal.

[0092] Step 108: The receiving end sends a second pilot signal to the transmitting end.

[0093] The transmitting end receives the second pilot signal sent by the receiving end.

[0094] Step 109: The transmitting end determines a second modulation signal according to the second pilot signal sent by the receiving end.

[0095] Step 110: The transmitting end sends a second modulation signal to the receiving end.

[0096] The receiving end receives the second modulation signal sent by the transmitting end.

[0097] Step 111: The receiving end estimates the channel from the receiving end to the transmitting end according to the second pilot signal and the second modulation signal sent by the transmitting end to obtain a second channel.

[0098] Step 112: The receiving end quantizes and encodes the second channel to generate a second encryption key for the receiving end during the communication phase.

[0099] It should be noted that, in the encryption key generation stage, both the transmitter and the receiver can generate corresponding encryption keys, and the timing of the transmitter generating the first encryption key and the receiver generating the second encryption key are not limited.

[0100] In the embodiment of the present application, the key code generation method implemented by steps 101 to 112 omits part of the key negotiation content in the traditional key code generation method and is a non-negotiation key code generation method. In other words, this method avoids the key information leakage caused by information interaction during key negotiation in the traditional key code generation method by transferring the key negotiation to subsequent communication transmission. Through the interaction of the pilot signal and the mediation signal, a more secure and difficult-to-crack encryption key is implicitly "negotiated", thereby improving the security of subsequent data transmission, thereby enhancing the security of the OFDM-OAM communication system in industrial equipment manufacturing, and making the OFDM-OAM communication system less vulnerable to attacks by potential eavesdroppers.

[0101] It should be noted that, in addition to the encryption key generation phase, which is steps 101 to 112, the embodiment of the present application also involves an encryption communication phase, which is steps 113 to 118. The wireless channels experienced in these two phases are different. The wireless channel experienced in the encryption key generation phase can be Indicates that the wireless channel experienced during the encryption communication phase is available The above-mentioned OFDM-OAM communication system is Generate encryption keys at all times. Encrypted communication with encryption keys is always achieved, where , represents the coherence time, Represents the Doppler shift. According to the short-time reciprocity of the wireless channel, during the coherence time The channels within can be considered to experience the same channel fading, and vice versa.

[0102] For example, Figure 3 The figure shows a schematic diagram of the encryption key generation phase and the encryption communication phase provided by the embodiment of the present application. Figure 3 , for the encryption key generation phase, assume that the transmitter is the first legitimate communication user, namely Alice; assume that the receiver is the second legitimate communication user, namely Bob. Among them, Alice and Bob communicate in a line of sight (LoS) channel. In the encryption key generation phase, At this moment, Alice and Bob both reach a predetermined time. The pilot signal is sent to each other to detect the channel, wherein the preset time Less than coherence time The entire encryption key generation phase uses channel estimation based on training symbols, that is, the pilot signal is known to both the sender and the receiver. Assuming that Alice knows that the first pilot signal is available Indicates that, at this time, the first modulation signal is , Indicates the first pilot signal The total channel from Alice to Bob’s demodulation; assuming Bob knows that the second pilot signal is available Indicates that, at this time, the second modulation signal is , Indicates the second pilot signal The total channel traversed by demodulation from Bob to Alice.

[0103] Alice's end receives the first pilot signal and the first modulation signal , the least square method is used to estimate the channel Estimate and get the first channel ; Bob's end responds to the second pilot signal and the second modulation signal , the least square method is used to estimate the channel Estimate and get the second channel .

[0104] Due to the short-term reciprocity of the wireless channel, it can be considered that , at this time, you can As the key source on Alice's side, As the key source of Bob's side. Based on this, Alice can Perform quantization encoding to generate the first encryption key of Alice in the communication phase ; Bob's end to the second channel Perform quantization encoding to generate the second encryption key on Bob's side during the communication phase .

[0105] It should be noted that, since the first modulation signal and the second modulation signal There is noise, so the first encryption key and the second encryption key There will be different bits.

[0106] The following is a detailed description of the encrypted communication stage: Figure 4 This is a flow chart of the key code generation method provided by the embodiment of the present application. Figure 4 As shown, after step 112 , the method further includes the following steps 113 and 118 .

[0107] Step 113: The transmitter performs error correction coding on the plaintext of the transmitted data to obtain a first plaintext.

[0108] The plaintext data to be transmitted is the original data to be sent without any encryption or encoding processing, and usually exists in the form of a binary bit stream. In the OFDM-OAM communication system, the plaintext data to be transmitted may optionally contain various types of information such as text, images, and audio. The plaintext data to be transmitted can be used express.

[0109] Error Correction Coding (ECC) adds redundant information to the original data, enabling the receiver to detect and correct errors caused by noise or interference during transmission. The core goal of ECC is to improve data transmission reliability.

[0110] The first plaintext is the transmission data plaintext after error correction coding, which can be used express.

[0111] Step 114: The transmitting end determines the first ciphertext according to the first encryption key and the first plaintext.

[0112] In some embodiments, the transmitting end determines the first ciphertext according to the first encryption key and the first plaintext, which may include: the transmitting end obtains the first ciphertext according to an encryption formula.

[0113] The encryption formula is: ; represents the first ciphertext; Indicates the first plaintext; represents a first encryption key; Represents the exclusive OR operation.

[0114] In the embodiment of the present application, the transmitting end may use the first encryption key For the first plaintext Encryption is performed. Specifically, the encryption formula is used to obtain the first ciphertext .

[0115] Step 115: The transmitting end sends the first ciphertext to the receiving end.

[0116] The receiving end receives the first ciphertext sent by the transmitting end.

[0117] Optionally, the transmitting end sends the first ciphertext to the receiving end, which may include: the transmitting end transmits the first ciphertext via a channel in the OFDM-OAM communication system. Send the first ciphertext to the receiving end.

[0118] Optionally, the receiving end receives the first ciphertext sent by the transmitting end, which may include: the receiving end receives the first ciphertext sent by the transmitting end through a channel in the OFDM-OAM communication system. Receive the first ciphertext sent by the transmitter.

[0119] Step 116: The receiving end performs OFDM-OAM demodulation on the first ciphertext sent by the transmitting end to obtain a second ciphertext.

[0120] Step 117: The receiving end decrypts the second ciphertext according to the second encryption key to obtain a second plaintext.

[0121] In some embodiments, the receiving end decrypts the second ciphertext according to the second encryption key to obtain the second plaintext, which may include: the receiving end obtains the second plaintext according to a decryption formula.

[0122] The decryption formula is: ; Indicates the second plaintext; represents the second ciphertext; represents a second encryption key; Represents the exclusive OR operation.

[0123] In the embodiment of the present application, the receiving end may use the second encryption key For the second ciphertext above Encryption is performed. Specifically, the decryption formula is used to obtain the second plaintext .

[0124] Step 118: The receiving end decodes and corrects the second plaintext to obtain a third plaintext.

[0125] Among them, the third plaintext can be used express.

[0126] In the embodiment of the present application, due to the influence of channel equalization and noise during the communication transmission process, the second ciphertext With the first ciphertext There will be some differences, so when using the above decryption formula, we get the second plaintext Afterwards, the second plaintext Perform decoding and error correction to recover the third plaintext This non-negotiated key encoding method is to generate the second encryption key and the second ciphertext Error correction is performed by focusing on the error correction coding in the encrypted communication stage.

[0127] For example, in combination Figure 3 , for the encrypted communication phase, At this moment, Alice and Bob both use the first encryption key obtained in the encryption key generation phase and the second encryption key , used for encrypted communication. First, similar to the encryption key generation phase, Alice and Bob respectively detect and estimate the channel for subsequent channel equalization. Then, Alice detects and estimates the plaintext of the transmitted data. Perform error correction coding to obtain the first plaintext , and then use the first encryption key For the first plaintext Encrypt and get the first ciphertext Alice uses the OFDM-OAM communication system channel The first ciphertext Sent to Bob's end; the first ciphertext sent by Bob to the transmitter Perform OFDM-OAM demodulation to obtain the second ciphertext , and then use the second encryption key For the second ciphertext Decrypt and get the second plaintext , and then the second plaintext Perform decoding and error correction to obtain the third plaintext The entire process couples the encryption key generation phase with the encryption communication phase, saving the communication resources required for key information negotiation.

[0128] Optionally, the OFDM-OAM communication system may further include an eavesdropper, which may also be referred to as an eavesdropper. The eavesdropper includes a UCA antenna, and the number of antennas of the UCA antenna is available. express.

[0129] For example, in combination Figure 3 ,like Figure 5 As shown in FIG, it is a schematic diagram of the UCA antenna of the eavesdropping end provided in the embodiment of the present application. Assuming that the eavesdropping end is Eve end, Figure 5 middle, Indicates the center of Alice's UCA antenna Center of the UCA antenna at Bob's end the distance between them; Representation Center Center of the UCA antenna with Eve end the distance between them; Representation Center with the center The distance between them. The angle at which the UCA plane on Bob's end deviates from the vertical direction, which is also the above-mentioned rotation angle; express The angle between the UCA plane and the Eve side; Eve represents the angle from the horizontal direction. represents the channel between Alice and Bob, i.e. the first channel mentioned above; represents the channel between Bob's end and Alice's end, i.e., the second channel mentioned above; Represents the channel between Alice and Eve; Indicates the channel between Bob and Eve.

[0130] The first UCA antenna on Alice's side The transmitting array element and the UCA antenna at Bob's end The transmission distance between the receiving elements Available transmission distance Considering the symmetry of the UCA antenna, the embodiment of the present application sets the Eve end near the Bob end. In order to facilitate the analysis of the coordinates of the Bob end, it can be set , that is, Eve is always facing Alice. At this time, the second coordinate conversion formula can be used to determine the first coordinate of Eve's UCA antenna. The array elements in the three-dimensional coordinate system The coordinates below.

[0131] Among them, the above second coordinate transformation formula is: .

[0132] Indicates the The array elements are in the above three-dimensional coordinate system The coordinates below.

[0133] At this time, The transmitting element to the The transmission distance between array elements The expression is: .

[0134] It should be noted that the The receiving array element to the The transmission distance between array elements The calculation process is the same as the above transmission distance The calculation process of is similar and will not be described in detail here.

[0135] Based on this, the channel matrix of the UCA-MIMO system between Alice and Eve can be determined as The expression is: = ; The channel matrix of the UCA-MIMO system between Bob and Eve can be determined The expression is: = .

[0136] It should be noted that the wireless channel used in the encryption key generation phase is available Indicates that the wireless channel experienced during the encryption communication phase is available It is indicated that, therefore, it is difficult for the eavesdropper to estimate the channel fading in the encryption key generation stage based on the channel fading in the encryption communication stage, and thus obtain the encryption key, which can effectively enhance the confidentiality of the above-mentioned OFDM-OAM communication system.

[0137] Optionally, in order to analyze the confidentiality of the key encoding generation method, it is assumed that the eavesdropping capability of Eve is greater than a preset eavesdropping capability threshold, that is, Eve has a strong eavesdropping capability. At time t, Eve eavesdrops on the first pilot signal sent by Alice and the second pilot signal sent by Bob. Then, it determines the first distance between Eve and Alice, and the second distance between Eve and Bob. Then, based on the first distance and the second distance, it calculates the channel length from Alice to Eve. and the channel from Bob to Eve A channel is selected as the key source of Eve, and the key source is quantified to obtain the third encryption key of Eve in the communication phase. , and then use the third encryption key For the first ciphertext above To decipher.

[0138] Among them, the first distance is the above distance ; The second distance is the above distance .

[0139] Optionally, the channel corresponding to the larger distance between the first distance and the second distance is the key source of Eve.

[0140] It should be noted that a channel corresponding to a larger distance has richer channel information. In addition, the timing of determining the first distance and determining the second distance by the Eve end is not limited.

[0141] In order to more intuitively reflect the confidentiality capability of OFDM-OAM communication systems, other devices can use indicators such as Key Disagreement Rate (KDR), Bit Error Rate (BER) and confidentiality capacity. etc. to assist in better analyzing the above confidentiality capabilities.

[0142] Optionally, the other devices may be electronic devices independent of the OFDM-OAM communication system, or may be electronic devices other than the transmitting end, the receiving end, and the eavesdropping end included in the OFDM-OAM communication system, which is not specifically limited here.

[0143] KDR refers to the difference between the initial key sequences obtained by the transmitter and the receiver, which is the ratio of the number of mismatched bits to the total number of bits of the quantized output. Specifically, it refers to the first encryption key and the second encryption key The bit inconsistency rate between them.

[0144] BER is one of the important indicators for measuring the transmission quality of digital communication systems (i.e., OFDM-OAM communication systems). It refers to the probability of binary codewords being transmitted incorrectly in a digital communication system. It is approximately equal to the ratio of the number of transmitted erroneous binary codewords to the total number of transmitted codewords. It can reflect the reliability of the OFDM-OAM communication system during the encrypted communication stage.

[0145] Confidentiality Capacity It means that Alice and Bob use the detection channel to start from the first channel. and the second channel The maximum number of key bits that can be extracted.

[0146] The following uses other devices as the execution subject to determine the confidentiality capacity. The determination process is described in detail: Optionally, Alice sends the first ciphertext to Bob. , and in the process where Eve is present, the other device determines a first distance between Eve and Alice, and a second distance between Eve and Bob; the other device determines a first distance between Eve and Alice, and a second distance between Eve and Bob; the other device calculates the channel from Alice to Eve based on the first distance and the second distance. and the channel from Bob to Eve Select a channel between them as the key source of Eve; the other device selects a channel between Alice and Bob according to the key source, the first channel between Alice and Bob , and the second channel between Bob and Alice , determine the confidentiality capacity ; Among them, confidentiality capacity Less than the preset confidentiality capacity , preset confidentiality capacity According to the first channel and the second channel Sure.

[0147] It should be noted that the timing for other devices to determine the first distance and the second distance is not limited.

[0148] It should be noted that in the absence of an eavesdropping terminal, the preset confidentiality capacity It is the theoretical maximum confidentiality capacity in OFDM-OAM communication system.

[0149] Optionally, preset confidentiality capacity According to the first channel The autocovariance matrix of the second channel The autocovariance matrix of the first channel and the second channel The covariance matrix of .

[0150] Optionally, other devices can configure the channel from Alice to Eve based on the first distance and the second distance. and the channel from Bob to Eve Selecting a channel between the two as the key source of the Eve end may include: if the first distance is greater than the second distance, using the first channel as the key source; if the first distance is less than the second distance, using the second channel as the key source; if the first distance is equal to the second distance, using either the first channel or the second channel as the key source.

[0151] In an embodiment of the present application, after determining a first distance and a second distance, other devices may compare the first and second distances and use the channel corresponding to the larger of the first and second distances as the key source. Specifically, if the first distance is greater than the second distance, it indicates that the first distance is larger, in which case the first channel corresponding to the first distance is used as the key source. If the first distance is less than the second distance, it indicates that the second distance is larger, in which case the second channel corresponding to the second distance is used as the key source. Of course, there may be cases where the first and second distances are the same. In this case, a channel corresponding to either distance can be selected as the key source. This ensures that more abundant channel information can be used later.

[0152] Optionally, other devices may use the key source, the first channel between Alice and Bob, , and the second channel between Bob and Alice , determine the confidentiality capacity , which may include: other devices according to the key source and the first channel The covariance matrix, key source and second channel The covariance matrix, key source and first channel and second channel The covariance matrix of the key source and the autocovariance matrix of the key source determine the confidentiality capacity .

[0153] In the embodiment of the present application, other devices may first determine the key source and the first channel The covariance matrix, key source and second channel The covariance matrix, key source and first channel and second channel The covariance matrix of the key source and the auto-covariance matrix of the key source are the four covariance matrices, and then the four covariance matrices are calculated to obtain the confidentiality capacity .

[0154] It should be noted that the time sequence for other devices to determine the above four covariance matrices is not limited.

[0155] Optionally, other devices may use the key source and the first channel The covariance matrix, key source and second channel The covariance matrix, key source and first channel and second channel The covariance matrix of the key source and the autocovariance matrix of the key source determine the confidentiality capacity , which may include: other devices obtaining the confidentiality capacity according to the first confidentiality capacity formula .

[0156] Among them, the first confidentiality capacity formula is: ; Indicates confidentiality capacity; Indicates the first channel; Indicates the second channel; Indicates the key source, which is the channel and Channel A channel in Indicates the key source and the first channel The covariance matrix of Indicates the key source and the second channel The covariance matrix of Indicates the key source and the first channel and second channel The covariance matrix of represents the autocovariance matrix of the key source; Represents the determinant operation.

[0157] Optionally, preset confidentiality capacity It is calculated based on the second confidentiality capacity formula.

[0158] The second confidentiality capacity formula is: ; Indicates the preset confidentiality capacity; Indicates the first channel; Indicates the second channel; Indicates the first channel The autocovariance matrix of ; Indicates the second channel The autocovariance matrix of ; Indicates the first channel and the second channel The covariance matrix of Represents the determinant operation.

[0159] In addition, when the UCA antenna at Alice's end is in an ideal alignment with the UCA antenna at Bob's end, the transmission of each OAM mode will not cause interference, and the modes have good orthogonality. At this time, in the OFDM-OAM communication system transmission In the case of multiple OAM modes, the above confidentiality capacity is The linear superposition of the confidentiality capacity of , based on this, the expression of confidentiality capacity is: .

[0160] in, Indicates single OAM mode the corresponding first channel; Indicates single OAM mode a corresponding second channel; Indicates the first channel The autocovariance matrix of ; Indicates the second channel The autocovariance matrix of ; Indicates the first channel and the second channel The covariance matrix of .

[0161] In summary, the performance of the key code generation method provided by the embodiment of the present application is evaluated through simulation experiments. In this simulation experiment, the carrier frequency ;wavelength ; Number of elements of the UCA antenna at the transmitting end ,radius ; Number of elements of the UCA antenna at the receiving end ,radius ; The distance between Alice's end and Bob's end is ; The distance between Alice and Eve is ; The noise power at Alice, Bob, and Eve is the same.

[0162] For example, Figure 6 The figure is a schematic diagram showing the relationship between the confidentiality capacity and the signal-to-noise ratio (SNR) provided in the embodiment of the present application. Figure 6 The figure also shows a comparison of the confidentiality capacity of OFDM-OAM communication systems using different total numbers of modes and in the presence of an eavesdropping terminal (i.e., Eve terminal) with the confidentiality capacity of traditional OFDM-MIMO communication systems.

[0163] from Figure 6It can be seen from the figure that as the signal-to-noise ratio (SNR) increases, the confidentiality capacity increases accordingly, but the increasing trend of the confidentiality capacity in different situations is inconsistent.

[0164] First, when using single mode transmission (i.e. ), the confidentiality capacity of OFDM-MIMO system Significantly lower than multi-mode transmission (such as , It should be noted that when the UCA antenna at Alice's end and the UCA antenna at Bob's end are in an ideal alignment state, the total confidentiality capacity of the multi-mode system is equal to the linear superposition of the confidentiality capacities of each single mode. Therefore, as With the increase of , the confidentiality capacity of OFDM-OAM communication system increases exponentially.

[0165] Secondly, when there is an Eve end, the confidentiality capacity Compared to confidentiality capacity There is some loss, but as the offset angle Increased confidentiality capacity It is also increasing.

[0166] Finally, by comparison, it can be found that the confidentiality capacity of OFDM-MIMO communication system Confidentiality capacity when OFDM-OAM communication system uses one mode transmission This comparison shows that the modulation of a traditional OFDM communication system is essentially equivalent to the single-mode transmission in the modulation of an OFDM-OAM communication system. However, when the OFDM-OAM communication system provided in the embodiment of the present application adopts multi-mode transmission, the confidentiality capacity of the OFDM-OAM communication system can be increased by several times compared to the confidentiality capacity of the OFDM-MIMO system.

[0167] For example, Figure 7 As shown, the bit error rate BER and the offset angle provided by the embodiment of the present application are This example compares the BER and offset angle between Alice and Eve during the encrypted communication phase. The relationship is simulated.

[0168] from Figure 7 It can be seen that: with As the BER of Eve increases, it becomes higher and higher. On the one hand, this is because the UCA antennas at Alice and Eve are not aligned, and Eve cannot demodulate the received signal (i.e., the first pilot signal). OAM inter-mode crosstalk occurs, and channel equalization cannot compensate for the influence of the channel and cannot restore the original data. On the other hand, due to the The key source (such as channel ) with the first channel , second channel The correlation is getting lower and lower, Eve side from the channel The extracted third encryption key With the first encryption key , the second encryption key The key inconsistency rate is getting bigger and bigger, and Eve cannot use the third encryption key The information on Alice's side is cracked to obtain the third plaintext. Under the condition of high signal-to-noise ratio, Eve's signal reception and key generation are less affected by noise, and Eve's BER will decrease, but as As the SNR increases, the BER at different SNRs tends to 0.5, which is about When BER does not change At this time, BER stabilizes at around 0.5, indicating that Eve cannot eavesdrop on any information from the legitimate communicating parties (i.e., Alice and Bob).

[0169] Combine Figure 6 and Figure 7 , the simulation results show that as the offset angle of the UCA antenna at Eve As the security capacity of the OFDM-OAM communication system increases, the BER at the Eve end approaches 0.5. Furthermore, in the key code generation method provided in the embodiments of the present application, the security capacity of the OFDM-OAM communication system is increased exponentially, achieving an extremely high security capacity, effectively achieving high key capacity and high security.

[0170] The key code generation device provided in an embodiment of the present application is described below. The key code generation device described below and the key code generation method described above can be referenced to each other. The device is applied to an OFDM-OAM communication system in industrial equipment manufacturing, including a transmitting end. The OFDM-OAM communication system also includes a receiving end, which is connected to the transmitting end.

[0171] Figure 8 This is a schematic diagram of the structure of the key code generation device provided in the embodiment of the present application. Figure 8As shown, the device includes: a first processing module 801 and a first transceiver module 802.

[0172] A first processing module 801 is configured to generate a first pilot signal according to a first transmit signal, where the first pilot signal is used by the receiving end to determine a first modulation signal; A first transceiver module 802 is configured to send the first pilot signal to the receiving end; The first processing module 801 is further configured to estimate a channel between the transmitting end and the receiving end based on the first pilot signal and the first modulation signal sent by the receiving end to obtain a first channel; quantize and encode the first channel to generate a first encryption key of the transmitting end during the communication phase; and determine a second modulation signal based on a second pilot signal sent by the receiving end, where the second pilot signal is determined by the receiving end based on the second transmitting signal. The first transceiver module 802 is further configured to send the second mediation signal to the receiving end, where the second mediation signal is used by the receiving end to generate a second encryption key for the receiving end during the communication phase.

[0173] Optionally, the first processing module 801 is also used to perform error correction encoding on the plaintext of the transmitted data to obtain a first plaintext; determine a first ciphertext based on the first encryption key and the first plaintext; and send the first ciphertext to the receiving end, where the first ciphertext is used by the receiving end to decrypt the first ciphertext in combination with the second encryption key.

[0174] Optionally, the first transmission signal is × Dimensional data blocks, and are all integers greater than 1; the first processing module 801 is specifically configured to process the first transmit signal in the frequency domain The OFDM signal is obtained by performing a 2D IFFT operation on the line. Indicates the number of modulation points in the 2-D IFFT operation, is an integer greater than 1; the OFDM signal is transformed into Perform a 2-D IFFT operation on the columns to obtain the OFDM-OAM signal. Indicates the number of antennas of the uniform circular array (UCA) antenna at the transmitting end. The UCA antenna is a type of UCA antenna element. is an integer greater than 1; a cyclic prefix is inserted into the OFDM-OAM signal, and then up-converted at the RF end to obtain the first pilot signal; The first transceiver module 802 is specifically configured to send the first pilot signal to the receiving end via a wireless channel.

[0175] Optionally, the OFDM-OAM signal is expressed as: Among them, the Indicates the OFDM-OAM signal; represents the antenna power allocation matrix, Indicates the UCA antenna of the transmitter. The power of each antenna; express The discrete Fourier transform matrix of the point; express The inverse discrete Fourier transform matrix of the point; represents the first transmitted signal, express In the OAM mode OAM mode data; represents the OFDM modulation matrix; Represents the OFDM modulation matrix The inverse matrix of Represents the discrete Fourier transform matrix The conjugate transposed matrix of is an OAM modulation matrix; represents the OFDM modulation matrix The conjugate transposed matrix of .

[0176] Optionally, the OAM modulation matrix The expression is: ;in, , represents the complex exponential term; Indicated by The azimuth angle of the UCA antenna array element composed of antennas, ; Indicates the The number of OAM modes.

[0177] Optionally, the first pilot signal sent through the wireless channel is expressed as: ; represents the first pilot signal; Indicates the number of antennas of the uniform circular array (UCA) antenna at the transmitting end; Indicates the number of modulation points in the 2-D IFFT operation; represents the channel matrix of the wireless channel; represents the antenna power allocation matrix, Indicates the UCA antenna at the transmitter. The power of each antenna; express The discrete Fourier transform matrix of the point; Represents the discrete Fourier transform matrix The conjugate transposed matrix of is an OAM modulation matrix; represents the first transmitted signal, express In the OAM mode OAM mode data; represents the OFDM modulation matrix; represents the OFDM modulation matrix The conjugate transposed matrix of ; It means the mean is zero and the variance is The complex Gaussian white noise matrix satisfies , express The identity matrix of order.

[0178] Optionally, the first processing module 801 is specifically configured to obtain the first ciphertext according to an encryption formula; wherein the encryption formula is: ; represents the first ciphertext; represents the first plaintext; represents the first encryption key; Represents the exclusive OR operation.

[0179] The key code generation device provided in an embodiment of the present application is described below. The key code generation device described below and the key code generation method described above can be referenced to each other. The device is applied to an OFDM-OAM communication system in industrial equipment manufacturing, including a receiving end. The OFDM-OAM communication system also includes a transmitting end, which is connected to the receiving end.

[0180] Figure 9 This is a schematic diagram of the structure of the key code generation device provided in the embodiment of the present application. Figure 9 As shown, the device includes: a second processing module 901 and a second transceiver module 902.

[0181] A second processing module 901 is configured to determine a first modulation signal according to a first pilot signal sent by the transmitting end, where the first pilot signal is determined by the transmitting end according to the first transmit signal; A second transceiver module 902 is configured to send the first mediation signal to the transmitter, where the first mediation signal is used by the transmitter to generate a first encryption key for the transmitter during a communication phase; The second processing module 901 is further configured to generate a second pilot signal according to the second transmit signal; The second transceiver module 902 is further configured to send the second pilot signal to the transmitting end, where the second pilot signal is used by the transmitting end to determine a second modulation signal; The second processing module 901 is further used to estimate the channel between the receiving end and the transmitting end based on the second pilot signal and the second modulation signal sent by the transmitting end to obtain a second channel; quantize and encode the second channel to generate a second encryption key for the receiving end during the communication phase.

[0182] Optionally, the second processing module 901 is also used to perform OFDM-OAM demodulation on the first ciphertext sent by the transmitter to obtain a second ciphertext, where the first ciphertext is determined by the transmitter based on the first encryption key and the plaintext of the transmitted data; decrypt the second ciphertext based on the second encryption key to obtain a second plaintext; and decode and correct the second plaintext to obtain a third plaintext.

[0183] Optionally, the second processing module 901 is specifically used to receive the first pilot signal sent by the transmitting end through a wireless channel, where the first pilot signal is obtained by the transmitting end after performing a two-dimensional inverse fast Fourier transform 2-DIFFT operation on the first transmitting signal; the first pilot signal is first down-converted at the RF end, and then the cyclic prefix is removed at the baseband end to obtain the processed first pilot signal, and the processed first pilot signal is subjected to a two-dimensional fast Fourier transform 2-DFFT operation to obtain the first modulation signal.

[0184] Optionally, the first mediation signal is expressed as: ;in, represents the first modulation signal; express The first Individual modulation signals.

[0185] Optionally, the channel matrix of the wireless channel The expression is: = ;in, Indicates the The transmitting element to the The channel gain between the receiving array elements is The transmitting array element is the array element in the UCA antenna of the transmitting end. The receiving array elements are the array elements in the UCA antenna of the receiving end; represents a constant related to signal attenuation; Indicates the wavelength of the OAM signal; Indicates that the transmit array element to the The transmission distance between the receiving elements.

[0186] Optionally, the transmission distance The expression is: Among them, the The three-dimensional coordinate system of the transmitting array element at the transmitting end The coordinates below are , Indicates the radius of the UCA antenna array element at the transmitting end; Indicates that the The azimuth angle of the transmitting array element in the UCA antenna at the transmitting end; The receiving array elements in this three-dimensional coordinate system The coordinates below are , , Represents the three-dimensional coordinate system Parallel to the three-dimensional coordinate system of the receiving end Around The rotation angle of the axis, Indicates that the The azimuth angle of the receiving array element in the UCA antenna at the receiving end, Represents the three-dimensional coordinate system With this three-dimensional coordinate system The distance between the origins.

[0187] Optionally, the second processing module 901 is specifically configured to obtain the second plaintext according to a decryption formula; wherein the decryption formula is: ; represents the second plaintext; represents the second ciphertext; represents the second encryption key; Represents the exclusive OR operation.

[0188] Figure 10 Schematic diagram of the structure of the electronic device provided in the embodiment of the present application. Figure 10 As shown, the electronic device may include: a processor 1010, a communications interface 1020, a memory 1030, and a communication bus 1040, wherein the processor 1010, the communications interface 1020, and the memory 1030 communicate with each other via the communication bus 1040. The processor 1010 may call logic instructions in the memory 1030 to execute a key code generation method, which is applied to a transmitting end included in an OFDM-OAM communication system used in industrial equipment manufacturing, wherein the OFDM-OAM communication system also includes a receiving end, or the method is applied to a receiving end included in an OFDM-OAM communication system used in industrial equipment manufacturing.

[0189] In addition, the logical instructions in the above-mentioned memory 1030 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application, or the part that contributes to the existing technology, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program code, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0190] On the other hand, an embodiment of the present application also provides a computer program product, which includes a computer program, and the computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the key coding generation method provided by the above methods. The method is applied to the transmitting end included in the OFDM-OAM communication system in industrial equipment manufacturing, or the method is applied to the receiving end included in the OFDM-OAM communication system in industrial equipment manufacturing.

[0191] On the other hand, an embodiment of the present application also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it is implemented to execute the key coding generation method provided by the above-mentioned methods. The method is applied to the transmitting end included in the OFDM-OAM communication system in industrial equipment manufacturing, or the method is applied to the receiving end included in the OFDM-OAM communication system in industrial equipment manufacturing.

[0192] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0193] Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a necessary general-purpose hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (such as a personal computer, server, or network device) to execute the methods described in each embodiment or certain portions of the embodiments.

[0194] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A key code generation method, characterized in that: An Orthogonal Frequency Division Multiplexing (OFDM)-Orbital Angular Momentum (OAM) communication system used in industrial equipment manufacturing includes a transmitting end, the OFDM-OAM communication system also includes a receiving end connected to the transmitting end; and the method includes: generating a first pilot signal according to the first transmission signal; and sending the first pilot signal to the receiving end, wherein the first pilot signal is used by the receiving end to determine a first modulation signal; estimating a channel from the transmitting end to the receiving end based on the first pilot signal and the first modulation signal sent by the receiving end to obtain a first channel; quantize and encode the first channel to generate a first encryption key for the transmitting end during the communication phase; A second modulation signal is determined based on a second pilot signal sent by the receiving end, where the second pilot signal is determined by the receiving end based on a second transmission signal; and the second modulation signal is sent to the receiving end, where the second modulation signal is used by the receiving end to generate a second encryption key for the receiving end during the communication phase.

2. The key code generation method according to claim 1, characterized in that: The method further comprises: Performing error correction encoding on the plaintext of the transmitted data to obtain a first plaintext; Determine a first ciphertext based on the first encryption key and the first plaintext; and send the first ciphertext to the receiving end, where the first ciphertext is used by the receiving end to decrypt the first ciphertext in combination with the second encryption key.

3. The key code generation method according to claim 1, characterized in that: The first transmission signal is × Dimensional data blocks, and are all integers greater than 1; generating a first pilot signal according to the first transmit signal; and sending the first pilot signal to the receiving end, comprising: The first transmission signal is processed in the frequency domain The OFDM signal is obtained by performing a 2D IFFT operation on the line. represents the number of modulation points in the 2-D IFFT operation, is an integer greater than 1; The OFDM signal is processed in the spatial domain Perform a 2-D IFFT operation on the columns to obtain the OFDM-OAM signal. represents the number of antennas of the uniform circular array (UCA) antenna at the transmitting end, wherein the UCA antenna is a UCA antenna array element, is an integer greater than 1; A cyclic prefix is inserted into the OFDM-OAM signal, and then up-converted at the radio frequency end to obtain the first pilot signal; and the first pilot signal is sent to the receiving end through a wireless channel.

4. The key code generation method according to claim 3, characterized in that: The expression of the OFDM-OAM signal is: ; Among them, the represents the OFDM-OAM signal; represents the antenna power allocation matrix, Indicates the UCA antenna of the transmitting end The power of each antenna; express The discrete Fourier transform matrix of the point; express The inverse discrete Fourier transform matrix of the point; represents the first transmitted signal, express In the OAM mode OAM mode data; represents the OFDM modulation matrix; Represents the OFDM modulation matrix The inverse matrix of Denotes the discrete Fourier transform matrix The conjugate transposed matrix of is an OAM modulation matrix; represents the OFDM modulation matrix The conjugate transposed matrix of .

5. The key code generation method according to claim 3, characterized in that: The expression of the first pilot signal sent through the wireless channel is: ； represents the first pilot signal; represents the number of antennas of the uniform circular array (UCA) antenna at the transmitting end; represents the number of modulation points in the 2-D IFFT operation; A channel matrix representing the wireless channel; represents the antenna power allocation matrix, Indicates the UCA antenna at the transmitter. The power of each antenna; express The discrete Fourier transform matrix of the point; Denotes the discrete Fourier transform matrix The conjugate transposed matrix of is an OAM modulation matrix; represents the first transmitted signal, express In the OAM mode OAM mode data; represents the OFDM modulation matrix; represents the OFDM modulation matrix The conjugate transposed matrix of ; It means the mean is zero and the variance is The complex Gaussian white noise matrix satisfies , express The identity matrix of order.

6. A key code generation method, characterized in that: An Orthogonal Frequency Division Multiplexing (OFDM)-Orbital Angular Momentum (OAM) communication system used in industrial equipment manufacturing includes a receiving end, the OFDM-OAM communication system also includes a transmitting end, the transmitting end is connected to the receiving end; and the method includes: determining a first modulation signal based on a first pilot signal sent by the transmitting end, where the first pilot signal is determined by the transmitting end based on the first transmitting signal; and sending the first modulation signal to the transmitting end, where the first modulation signal is used by the transmitting end to generate a first encryption key of the transmitting end during a communication phase; generating a second pilot signal according to the second transmission signal; and sending the second pilot signal to the transmitting end, where the second pilot signal is used by the transmitting end to determine a second modulation signal; estimating a channel from the receiving end to the transmitting end based on the second pilot signal and the second modulation signal sent by the transmitting end to obtain a second channel; The second channel is quantized and encoded to generate a second encryption key for the receiving end during the communication phase.

7. The key code generation method according to claim 6, characterized in that: The method further comprises: Performing OFDM-OAM demodulation on a first ciphertext sent by the transmitting end to obtain a second ciphertext, where the first ciphertext is determined by the transmitting end according to the first encryption key and plaintext of the transmitted data; decrypting the second ciphertext according to the second encryption key to obtain a second plaintext; The second plaintext is decoded and error-corrected to obtain a third plaintext.

8. The key code generation method according to claim 6, characterized in that: The determining the first modulation signal according to the first pilot signal sent by the transmitting end includes: receiving, through a wireless channel, the first pilot signal sent by the transmitting end, where the first pilot signal is obtained by the transmitting end performing a two-dimensional inverse fast Fourier transform (2-D IFFT) operation on the first transmit signal; The first pilot signal is first down-converted at the radio frequency end and then the cyclic prefix is removed at the baseband end to obtain a processed first pilot signal. Perform a two-dimensional fast Fourier transform (2-D FFT) operation on the processed first pilot signal to obtain the first modulation signal.

9. The key code generation method according to claim 8, characterized in that: The expression of the first modulation signal is: ； in, represents the first modulation signal; express The first Individual modulation signals.

10. The key code generation method according to claim 9, characterized in that: The channel matrix of the wireless channel The expression is: = ； in, Indicates the The transmitting element to the The channel gain between the receiving array elements, the The transmitting array element is an array element in the UCA antenna of the transmitting end, and the The receiving array elements are array elements in the UCA antenna of the receiving end; represents a constant related to signal attenuation; Indicates the wavelength of the OAM signal; Indicates the transmit array element to the The transmission distance between the receiving elements.

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