Security transmission method and system based on low-power LoRa system

Abstract

The application relates to a secure transmission method and system based on a low-power LoRa system. The method comprises the following steps: generating a key by using a Lorenz chaotic system, obtaining a corresponding chaotic sequence, further generating a scrambling matrix by using the chaotic sequence, and using the scrambling matrix for signal scrambling before chirp signal modulation. The scrambled signal is subjected to chirp spread spectrum modulation, and finally sent to a wireless channel. The receiver first demodulates, then uses the same scrambling matrix for inverse scrambling, and finally decodes and recovers the signal. In the method, an encryption method is designed to securely encrypt the LoRa system, the decryption difficulty of an eavesdropper is increased on the basis of ensuring the reliability of the system, and the security of the system is ensured.

Description

Technical Field

[0001] This application relates to the field of network security transmission technology, and in particular to a secure transmission method and system based on the low-power LoRa architecture. Background Technology

[0002] The development of the Internet of Things (IoT) is currently attracting considerable attention. Various functional sensors, cameras, positioning tools, and other terminal nodes aggregate information to users through networks with specific architectures, enabling interconnectivity between things. These networks can be the Internet, broadcast networks, wireless mobile networks, and various private networks, integrating and connecting information to provide services to users. The development of IoT is a very challenging topic, and discussions about IoT are interested in all layers of the protocol stack, from physical transmission to data representation and service composition. However, the entire construction of IoT relies on long-range wireless communication technologies for providing data access to terminal devices. For many years, multi-hop, short-range transmission technologies such as ZigBee and Bluetooth have been considered viable pathways to realizing IoT services. These standards offer very low power consumption, a fundamental requirement for many IoT devices (such as smart sensors), but their limited coverage constitutes a major obstacle, especially when application scenarios involve services requiring urban coverage, such as typical smart city applications. LoRa transmission technology, with its outstanding long-range, low-power transmission characteristics and excellent coverage capabilities, is considered a viable solution for realizing IoT.

[0003] "LoRa" is short for Long Range, a long-range wireless transmission technology that can be used to build Low Power Wide Area Networks (LPWANs). LoRa technology mainly includes two aspects: first, LoRa modulation technology based on physical layer spread spectrum; and second, the LoRaWAN protocol proposed by the LoRa Alliance. In general wireless communication, increasing the communication distance requires increasing the transmission power, but this inevitably leads to higher energy consumption. In practical applications, many battery-powered devices, such as various devices on drones, sensors in remote areas, and household water meters, generally use low-power wireless communication. This limits the communication distance of these devices. LoRa technology effectively solves this problem. Unlike previous "long-range, high-power" transmission methods, LoRa technology provides an easily implemented long-range, low-power transmission solution, thus enabling its widespread application in building low-power sensor networks. LoRa operates in the unlicensed spectrum (ISM) band, meaning that the use of LoRa technology does not require additional network costs.

[0004] As a member of the Internet of Things (IoT) technology family, LoRa faces the challenge of information security. Currently, the LoRa system employs a two-layer security technology: one for the network layer and the other for the application layer. Network layer security ensures the authentication of nodes within the network, while application layer security ensures that network operators have no right to access end-user applications. In terms of key management, both the LoRa network and application layers use the same root key and random number generation, meaning the two layers are not isolated. Furthermore, the encryption / integrity protection key is derived using AES-128 encryption, resulting in insufficient security level and encryption strength. Therefore, there is a risk of key leakage leading to data privacy breaches and data tampering. The security methods currently employed by the LoRa system pose significant challenges and threats to the protection of core and private data for governments, enterprises, and individuals in the IoT. While there is considerable research on physical layer security technologies for wireless communication systems, not all existing physical layer security technologies are suitable for LoRa IoT. This is because LoRa devices have some unique characteristics compared to smartphones and tablets currently using 3G and 4G broadband networks. LoRa devices have low data rate requirements, periodic data traffic arrivals, limited hardware and signal processing capabilities, limited storage memory, compact form factor, and significant power limitations. Summary of the Invention

[0005] Therefore, it is necessary to provide a secure transmission method and system based on the low-power LoRa architecture that can increase the difficulty of decryption for eavesdroppers, in order to address the aforementioned technical problems.

[0006] A secure transmission method based on the low-power LoRa architecture, the method being implemented between the transmitter and receiver in the LoRa architecture, the method comprising:

[0007] Both the transmitting end and the receiving end are configured with a scrambling matrix, which is constructed based on a chaotic sequence generated by the Lorenz chaotic system.

[0008] The sending end encodes the sequence information to be sent, and scrambles and encrypts the encoded sequence information according to the scrambling matrix to generate ciphertext. The ciphertext is then modulated using CSS to generate a transmission file, and finally the transmission file is sent to the receiving end.

[0009] The receiving end performs CSS demodulation on the transmitted file to obtain the ciphertext, decrypts the ciphertext according to the scrambling matrix, and then performs corresponding decoding to obtain the sequence information.

[0010] In one embodiment, the scrambling matrix is ​​constructed based on a chaotic sequence generated from a Lorenz chaotic system, comprising:

[0011] Randomly select from the chaotic sequence element Where N represents the total number of medians in the sequence information;

[0012] According to the element h i Solve for y i The formula used is: y i =10 6 h i -floor(10 6 h i ),in,

[0013] For y i Sort the elements from largest to smallest, and then number them according to their positions to obtain a result. Randomly distributed column vectors

[0014] Construct a length of The column vector of all 1s is shifted to the right element by element, with the number of shifts taken as 1. The corresponding element values ​​yield the scrambling matrix.

[0015] In one embodiment, the mathematical expression of the Lorenz chaotic system is:

[0016]

[0017] In the above formula, a, b, and r are the parameters of the Lorenz chaotic system.

[0018] In one embodiment, the transmitting end uses error-correcting coding when encoding the sequence information to be transmitted.

[0019] In one embodiment, the transmission file is transmitted between the receiving end and the sending end in LoRa data frame format.

[0020] A secure transmission system based on the low-power LoRa architecture, the system comprising a transmitter and a receiver in the LoRa architecture;

[0021] Both the transmitting end and the receiving end are configured with a scrambling matrix, which is constructed based on a chaotic sequence generated by the Lorenz chaotic system.

[0022] The sending end encodes the sequence information to be sent, and scrambles and encrypts the encoded sequence information according to the scrambling matrix to generate ciphertext. The ciphertext is then modulated using CSS to generate a transmission file, and finally the transmission file is sent to the receiving end.

[0023] The receiving end performs CSS demodulation on the transmitted file to obtain the ciphertext, decrypts the ciphertext according to the scrambling matrix, and then performs corresponding decoding to obtain the sequence information.

[0024] The aforementioned secure transmission method and system based on the low-power LoRa architecture utilizes the Lorenz chaotic system to generate a key, obtaining a corresponding chaotic sequence. This chaotic sequence is then used to generate a scrambling matrix for signal scrambling before chirp signal modulation. The scrambled signal is then subjected to chirp spread spectrum modulation and finally transmitted to the wireless channel. The receiver first demodulates the signal, then uses the same scrambling matrix for descrambling and final decoding to recover the signal. In this method, an encryption method is designed to securely encrypt the LoRa architecture, increasing the difficulty of decryption for eavesdroppers while ensuring system reliability, thus guaranteeing system security. Attached Figure Description

[0025] Figure 1 This is a flowchart of a secure transmission method based on the low-power LoRa architecture in one embodiment;

[0026] Figure 2 This is a schematic diagram of the phase space of the Lorenz chaotic system in one embodiment;

[0027] Figure 3 This is a schematic diagram of the structure of a LoRa remote modem in one embodiment;

[0028] Figure 4 This is a schematic diagram of the instantaneous frequency and phase, in-phase and quadrature components of an unmodulated linear frequency modulated signal c0(t) in one embodiment;

[0029] Figure 5 This is a schematic diagram of the instantaneous frequency of a modulated linear frequency modulation signal in one embodiment;

[0030] Figure 6 In one embodiment, the instantaneous frequency and phase, in-phase and quadrature components of the modulated linear frequency modulated signal c1(t) are given.

[0031] Figure 7 This is a schematic diagram of the LoRa data frame structure in one embodiment;

[0032] Figure 8 This is a schematic diagram illustrating the peak value generated after performing an FFT on the product signal in one embodiment.

[0033] Figure 9 This is a schematic diagram of LoRa demodulation in one embodiment;

[0034] Figure 10 This is a schematic diagram comparing the bit error rate of the LoRa system before and after encryption using this method in one embodiment;

[0035] Figure 11 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0037] like Figure 1 As shown, a secure transmission method based on the low-power LoRa system is provided, implemented between the transmitter (Alice) and receiver (Bob) in the LoRa system. The method includes: both the transmitter and receiver are configured with a scrambling matrix, which is composed of a chaotic sequence generated based on the Lorenz chaotic system.

[0038] The sending end encodes the sequence information to be sent, and scrambles and encrypts the encoded sequence information according to the scrambling matrix to generate ciphertext. The ciphertext is then modulated by CSS to generate a transmission file, and finally the transmission file is sent to the receiving end.

[0039] The receiving end demodulates the transmitted file using CSS to obtain the ciphertext, decrypts the ciphertext according to the scrambling matrix, and then performs corresponding decoding to obtain the sequence information.

[0040] In this method, a scrambling matrix is ​​constructed by using a chaotic sequence generated by the Lorenz chaotic system when transmitting data in the LoRa system. The scrambling matrix is ​​then used to encrypt the data to ensure the reliability of the system and increase the difficulty of decryption for eavesdroppers, thereby ensuring the security of the system.

[0041] In this embodiment, the sequence information to be transmitted is first encoded using an encoder at the receiving end to correct errors. The encoder output depends on the chosen code rate (CR) value, which defines the amount of forward error correction (FEC) in a LoRa frame. For LoRa IoT, CR can be 1, 2, 3, or 4. LoRa IoT uses code rates of 4 / 5, 2 / 3, 4 / 7, and 1 / 2 (code rate = 4 / (CR+4)). This means that if the code rate is expressed as k / n, where k represents useful information and the encoder generates n output bits, then nk are redundant bits. Error correction coding reduces the bit error rate in the presence of brief bursts of interference.

[0042] Next, the encoded sequence information is encrypted. The key used for encryption needs to have good randomness and a large key space to resist brute-force attacks by eavesdroppers. All mapping encryption involves a trade-off between security and computational complexity. From a security perspective and to minimize computational complexity, this method chooses the Lorenz chaotic system for key generation.

[0043] The mathematical expression for the Lorenz chaotic system is:

[0044]

[0045] In formula (1), a, b, and r are the parameters of the Lorenz chaotic system. Different values ​​for the parameter r can yield different solutions to the Lorenz equations. When r∈(1,∞), the system has three equilibrium points O(0,0,0). and Furthermore, the equilibrium point O(0,0,0) is unstable. Setting the parameter r = 28, calculations show that the system's solution first revolves around the singularity A1, then jumps to another singularity A. -1 The motion moves around the surface, circling it, then jumping back, repeating this cycle until it approaches a bifurcated surface S, where all subsequent motion is confined to this surface. Surface S is the Lorenz strange attractor, as... Figure 2 As shown. During the motion, the number of revolutions around the two singularities in each round is also unequal. That is, the trajectory jumps randomly around the two fixed points, forming a spiral shape, like the two wings of a butterfly. Thus, the chaotic sequence can be obtained by solving formula (1).

[0046] In this embodiment, generating a scrambling matrix based on a chaotic sequence includes: randomly selecting from the chaotic sequence. element Where N represents the total number of medians in the sequence information. Then, based on element h... i Solve for y i The formula used is: y i =10 6 h i -floor(10 6 h i ),in, For y i Sort the elements from largest to smallest, and then number them according to their positions to obtain a result. Randomly distributed column vectors Next, construct a length of The column vector of all 1s is shifted to the right element by element, with the number of shifts taken as 1. The corresponding element values ​​yield the scrambling matrix.

[0047] Specifically, the algorithm for generating the scrambling matrix is ​​shown in Table 1:

[0048]

[0049] In this embodiment, after encrypting the sequence information according to the scrambling matrix, the CSS modulation method is then used for modulation.

[0050] Specifically, in LoRa modulation mode, the most important parameters are bandwidth (BW), spreading factor (SF), and coding rate (CR). Each LoRa symbol consists of 2... SF Each symbol consists of 12 chirps and occupies the entire bandwidth BW. The value of SF ranges from 7 to 12, and each symbol can encode SF bits of information. In LoRa modulation, the chirp rate is numerically equal to the bandwidth BW (i.e., each chirp per second per hertz). Whenever SF increases by 1, the frequency band occupied by each chirp in a symbol decreases by half, and the duration doubles, but this does not halve the bit rate because each symbol transmits one more bit of information. For a given SF, the symbol rate is proportional to the bit rate and the bandwidth BW, and the above relationship can be expressed as:

[0051]

[0052] In formula (2), Ts is the symbol period, Rs is the symbol rate, and Rc is the chirp rate.

[0053] LoRa modulation also combines spread spectrum technology with error correction coding technology, adding forward error correction codes to the symbols. Assuming the transmitted information codeword consists of 4 information bits, followed by n redundant bits (n can be 0, 1, 2, 3, or 4), the coding rate is: The effective bit rate Rb can also be derived as: R b =R s ·log22 SF ·CR.

[0054] Furthermore, the structure of the LoRa remote modem is as follows: Figure 3 As shown. This modulator is used to generate a linear frequency modulated (LFM) signal, which is decomposed into an in-phase signal (I) and a quadrature-phase signal (Q). This LFM signal can be used to expand the spectrum of the transmitted information signal, which is then up-converted to the carrier frequency by a mixer, amplified by a power amplifier, and transmitted through the antenna.

[0055] The demodulation section, after receiving the signal, decomposes it into I and Q channels for transmission, then down-converts the signal and sends it to the demodulator for demodulation.

[0056] like Figure 3As shown, the modulator can generate linear frequency modulated (LFM) signals. Each LFM signal exists between an initial time and a final time. These signals have an initial instantaneous frequency and an initial phase at the initial time, and a final instantaneous frequency and a final phase at the final time. The phase of these signals is essentially continuous. These signals can be divided into two categories: unmodulated LFM signals c0(t) and modulated LFM signals c1(t), both of which have a duration equal to the symbol period Ts. The following section details the spread spectrum of Chirp signals.

[0057] The basic Chirp waveform at intermediate frequencies can be expressed as:

[0058]

[0059] In formula (2), φ(t) is the chirp phase; therefore, the instantaneous frequency of the chirp is:

[0060]

[0061] For a linear chirp, f(t) is defined as:

[0062]

[0063] In formula (3), fc is the carrier center frequency; "μ=1" corresponds to up-chirp, "μ=-1" corresponds to down-chirp; BW represents the bandwidth and the difference between the maximum and minimum instantaneous frequencies of chirp.

[0064] For ease of discussion, both the unmodulated linear frequency modulated signal c0(t) and the modulated linear frequency modulated signal c1(t) are considered as baseband signals (fc omitted), with continuous phase correction at the beginning and end. The time-domain expression of c0(t) is:

[0065]

[0066] The instantaneous frequency function f0(t) of c0(t) is:

[0067]

[0068] The instantaneous frequency and phase of c0(t) are as follows: Figure 4 As shown.

[0069] The instantaneous frequency f1(t) of the modulated linear frequency modulated signal is obtained by cyclically shifting the instantaneous frequency function of the unmodulated linear frequency modulated signal. The instantaneous frequency of the resulting signal is as follows: Figure 5 As shown.

[0070] Therefore, the instantaneous frequency function f1(t) of the modulated linear frequency hopping signal can be obtained:

[0071]

[0072] In formula (5), a is the cyclic shift variable. One symbol contains SF bits of information, so one symbol period Ts can be divided into 2 equal parts. SF For each time slot segment, the value of 'a' corresponds to a specific time slot segment. Different values ​​of 'a' correspond to different modulation values. The modulation value of the generated modulated linear frequency modulated signal is obtained from the specific encoding method.

[0073] The modulated linear frequency modulated signal c1(t) is:

[0074]

[0075] The instantaneous frequency and phase of c1(t) are as follows: Figure 6 As shown.

[0076] In this embodiment, the file is transmitted between the receiving end and the sending end in LoRa data frame format.

[0077] Furthermore, the LoRa data frame mainly consists of three parts: (1) preamble; (2) optional header; and (3) payload, the specific structure of which is as follows: Figure 7 As shown. The preamble is used to keep the receiver synchronized with the input data, and its length is variable. For example, in receiver-intensive applications, the preamble length can be shortened to reduce the synchronization time between the transmitted data and the receiver; the minimum preamble length must meet all communication requirements. Optional headers are divided into explicit headers and implicit headers. Explicit headers include payload-related information, including: (1) payload length in bytes; (2) forward error correction code rate; (3) whether to use an optional 16-bit payload CRC. The header is sent with the maximum error correction code (4 / 8) and contains its own CRC for receiver verification. When the payload-related information is fixed and known, an implicit header can be used to shorten transmission time. The payload length is variable and includes CRC.

[0078] When demodulating the transmitted file at the receiving end, after synchronization calibration using the preamble in the LoRa data frame, the header content is read to obtain relevant payload information, and then demodulation of the payload information begins. As mentioned above, the data information contained in the payload is represented by modulated linear frequency modulated (LFM) signals. The instantaneous frequency functions of these LFM signals are cyclically shifted by different values ​​'a' to correspond to different modulation values. The receiver needs to obtain the value 'a', then use an index to find the corresponding modulation value, and demodulate the specific information. The principle is as follows:

[0079] The instantaneous frequency of the received modulated signal is f1(t). Multiplying the received signal by the receiver's locally generated conjugate unmodulated linear frequency modulated signal (c0(t))* yields a product signal with an instantaneous frequency of f2(t). Performing an FFT on the product signal allows detection of a peak at the point of abrupt change in instantaneous frequency value, such as... Figure 8 As shown, different shift values ​​a1 and a2 result in different peak positions. The cyclic shift value indicates modulation in the time domain, while the peak position represents modulation in the frequency domain. After obtaining different a values, the receiver demodulates the modulation value corresponding to the corresponding a value by looking up the index in a table.

[0080] The instantaneous frequency expression of the modulated signal is:

[0081]

[0082] In formula (8), a is the number of chirps shifted. If we consider... Figure 4 (a) in the text is for reference only. Figure 6 (a) in the middle is cyclically shifted by a chirp.

[0083] At the receiving end, multiplying the received signal by a down-chirp with a carrier frequency of fd (assuming perfect synchronization) yields the instantaneous frequency as follows:

[0084]

[0085] The generated signal can be divided into two segments, each with a constant frequency, such as... Figure 9 As shown in (a), 'a' determines the switching position. Sampling at the chip rate (i.e., BW Hz) makes the instantaneous frequency continuous across the entire chirp. Subtracting "fc + fd" results in a frequency proportional to 'a'. Performing a Fast Fourier Transform (FFT) on the sampled signal produces a flat response with a peak at 'a'. To ensure this result, the phase of the transmitted signal must be continuous, especially at frequency transitions. Furthermore, the instantaneous phase of a symbol must be consistent from beginning to end, ensuring the usability of the FFT result. This characteristic is controlled by the transmitter.

[0086] After demodulating the transmitted file at the receiving end, a scrambling matrix is ​​used for decryption. After decryption, the sequence information sent by the sending end can be obtained.

[0087] like Figure 10As shown in the figure, the bit error rate performance before and after scrambling encryption is also presented in this paper. The selected channel is a multipath Rayleigh channel. It can be seen that encryption does not affect the bit error rate of LoRa transmission. Since eavesdroppers cannot recover the original signal without knowing the scrambling matrix, the bit error rate is basically kept at around 0.5, thus ensuring the security of the LoRa system.

[0088] The aforementioned secure transmission method based on the low-power LoRa system generates a key using the Lorenz chaotic system, resulting in a corresponding chaotic sequence. This chaotic sequence is then used to generate a scrambling matrix for signal scrambling before chirp modulation. The scrambled signal is then subjected to chirp spread spectrum modulation and finally transmitted to the wireless channel. The receiver first demodulates the signal, then uses the same scrambling matrix to descramble it and ultimately decode and recover the signal. In this method, an encryption method is designed to securely encrypt the LoRa system, increasing the difficulty of decryption for eavesdroppers while ensuring system reliability, thus guaranteeing system security.

[0089] This application also provides a secure transmission system based on the low-power LoRa architecture, which includes a transmitter and a receiver in the LoRa architecture;

[0090] Both the transmitting and receiving ends are equipped with scrambling matrices, which are constructed based on chaotic sequences generated by the Lorenz chaotic system.

[0091] The sending end encodes the sequence information to be sent, and scrambles and encrypts the encoded sequence information according to the scrambling matrix to generate ciphertext. The ciphertext is then modulated by CSS to generate a transmission file, and finally the transmission file is sent to the receiving end.

[0092] The receiving end performs CSS demodulation on the transmitted file to obtain the ciphertext, decrypts the ciphertext according to the scrambling matrix, and then performs corresponding decoding to obtain the sequence information.

[0093] For specific limitations on secure transmission systems based on the low-power LoRa architecture, please refer to the limitations on secure transmission methods based on the low-power LoRa architecture mentioned above, which will not be repeated here.

[0094] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 11As shown, the computer device includes a processor, memory, network interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The network interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a secure transmission method based on the low-power LoRa architecture. The display screen can be an LCD screen or an e-ink display screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the computer device casing, or an external keyboard, touchpad, or mouse.

[0095] Those skilled in the art will understand that Figure 11 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0096] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0097] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A secure transmission method based on the low-power LoRa architecture, characterized in that, The method is implemented between the transmitter and receiver in a LoRa system, and the method includes: Both the transmitting and receiving ends are configured with scrambling matrices, which are constructed based on chaotic sequences generated by the Lorenz chaotic system. Specifically, the scrambling matrices include: randomly selecting from the chaotic sequences... element ,in, The total number of medians in the sequence information is represented by the element. Solve The formula used is: ,in, ,right Sort the elements from largest to smallest, and then number them according to their positions to obtain a result. Randomly distributed column vectors Construct a length of The column vector of all 1s is shifted to the right element by element, with the number of shifts taken as 1. The corresponding element values ​​yield the scrambling matrix; The sending end encodes the sequence information to be sent, and scrambles and encrypts the encoded sequence information according to the scrambling matrix to generate ciphertext. The ciphertext is then modulated using CSS to generate a transmission file, and finally the transmission file is sent to the receiving end. The sending end uses error correction coding when encoding the sequence information to be sent. The receiving end performs CSS demodulation on the transmitted file to obtain the ciphertext, decrypts the ciphertext according to the scrambling matrix, and then performs corresponding decoding to obtain the sequence information.

2. The secure transmission method according to claim 1, characterized in that, The mathematical expression for the Lorenz chaotic system is: In the above formula, , as well as represents the parameters of the Lorenz chaotic system.

3. The secure transmission method according to claim 1 or 2, characterized in that, The transmission file is transmitted between the receiving end and the sending end in LoRa data frame format.

4. A secure transmission system based on the low-power LoRa architecture, characterized in that, The system includes a transmitter and a receiver in the LoRa architecture; Both the transmitting and receiving ends are configured with scrambling matrices, which are constructed based on chaotic sequences generated by the Lorenz chaotic system. Specifically, the scrambling matrices include: randomly selecting from the chaotic sequences... element ,in, The total number of medians in the sequence information is represented by the element. Solve The formula used is: ,in, ,right Sort the elements from largest to smallest, and then number them according to their positions to obtain a result. Randomly distributed column vectors Construct a length of The column vector of all 1s is shifted to the right element by element, with the number of shifts taken as 1. The corresponding element values ​​yield the scrambling matrix; The sending end encodes the sequence information to be sent, and scrambles and encrypts the encoded sequence information according to the scrambling matrix to generate ciphertext. The ciphertext is then modulated using CSS to generate a transmission file, and finally the transmission file is sent to the receiving end. The sending end uses error correction coding when encoding the sequence information to be sent. The receiving end performs CSS demodulation on the transmitted file to obtain the ciphertext, decrypts the ciphertext according to the scrambling matrix, and then performs corresponding decoding to obtain the sequence information.

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