Double-factor encryption method based on HNN-like hyperchaotic mapping and geographic grid

Abstract

The present invention relates to the field of image encryption technology, and in particular to a dual-factor encryption method based on a HNN-like hyperchaotic map and a geographic grid, including constructing a two-dimensional HNN-like hyperchaotic map, setting a fixed point of the two-dimensional HNN-like hyperchaotic map, iterating the two-dimensional HNN-like hyperchaotic map several times using the initial value of the two-dimensional HNN-like hyperchaotic map, and obtaining a hyperchaotic sequence of several iterations; using a hexagonal grid for spatial partitioning, dividing geographic information into several regional indexes, and constructing a geographic grid system; and encrypting a plaintext file using an initial value offset factor and a corresponding grid index. The present invention solves the problems that the existing single-factor key cannot guarantee the geographic security of data, and has defects such as insensitivity to data geographic location, device anti-theft, and ciphertext data security.

Description

Technical Field

[0001] The present invention relates to the technical field of image encryption, and in particular to a double-factor encryption method based on HNN-like hyperchaotic mapping and geographic grid. Background Art

[0002] Chaos has a series of characteristics such as good pseudo-randomness, orbital unpredictability, sensitivity to initial state and control parameters, etc. These characteristics are consistent with the requirements of cryptography. It has broad application prospects in engineering applications in the fields of information security and confidential transmission, and has received great attention from the scientific community and even the national government.

[0003] In the paper Discrete Memristor Hyperchaotic Maps, some discrete chaotic maps are used to design pseudo-random number generators (PRNGs); in the paper Two-Dimensional Memristive Hyperchaotic Maps and Application in Secure Communication, memristive hyperchaotic maps are applied to secure communication applications, and experiments show that memristive maps perform better than some existing discrete maps.

[0004] Hardware encryption is a data security protection measure that uses dedicated equipment to perform encryption and decryption processes, providing a higher level of reliability and security than software encryption. In modern cryptographic systems, stateless hardware encryption can be used as an effective security measure to ensure the security of keys and algorithms through physical devices. In the literature, Spectral sensitivitynear exceptional points as a resource for hardware encryption, there is no need to store or transmit keys through secure channels, nor to save encryption and decryption states, which greatly ensures the security of keys and encryption algorithms.

[0005] However, traditional hardware encryption often ignores the security of geographical areas. In the literature Initial-offset-boosted coexisting hyperchaos in a 2D memristive Chialvo neuron map and its application in image encryption, only the initial value of the chaotic map is used as the security key, and the geographical factor is not considered. For geographically sensitive information data, the existing single-factor key cannot guarantee the geographical security of the data, and has defects such as data geographical location insensitivity, device anti-theft, and ciphertext data security. When data is encrypted in a secure area and does not want to be decrypted outside the secure area, hardware encryption based on geographical location becomes particularly important. Summary of the invention

[0006] In view of the shortcomings of the existing methods, the present invention combines geographic location with chaotic system encryption, uses geographic information as a unique identifier, and acts simultaneously with the hardware key to construct a dual-factor driven chaotic hardware encryption method, which makes it impossible to decrypt the encrypted data outside the effective security area, enhances the geographic location sensitivity of the data, and effectively protects the data from unauthorized access.

[0007] The technical solution adopted by the present invention is: a dual-factor encryption method based on HNN-like hyperchaotic mapping and geographic grid includes the following steps:

[0008] Step 1: construct a two-dimensional HNN-like hyperchaotic map, set a fixed point of the two-dimensional HNN-like hyperchaotic map, and iterate the two-dimensional HNN-like hyperchaotic map several times using the initial value of the two-dimensional HNN-like hyperchaotic map to obtain a hyperchaotic sequence of several iterations;

[0009] As a preferred implementation of the present invention, the formula of the hyperchaotic sequence of the several iterations is:

[0010]

[0011] Among them, (p, q) is the initial value offset factor; x, y represent the direction; x′, y′ are the hyperchaotic sequences in the x and y directions respectively.

[0012] Step 2: Use hexagonal grids to perform spatial partitioning, divide geographic information into several regional indexes, and construct a geographic grid system;

[0013] As a preferred embodiment of the present invention, the construction of the geographic grid system includes:

[0014] Step 21: World map and longitude and latitude coordinates obtained using Mercator projection and satellite positioning;

[0015] Step 22: Divide the world map into a hexagonal grid in a honeycomb arrangement;

[0016] Step 23, using a certain coordinate as the starting segmentation point to determine the grid size;

[0017] Step 24: Using the upper left corner of the world map as the starting point, index and number the grids with positive integers;

[0018] Step 25: Convert the located longitude and latitude coordinates into the grid index corresponding to the initial offset factor.

[0019] Step 3: Encrypt the plaintext file using the initial value offset factor and the corresponding grid index;

[0020] As a preferred embodiment of the present invention, step three specifically includes:

[0021] Step 31, processing the plaintext file into a one-dimensional binary sequence S;

[0022] Step 32, using the initial value offset factor (p, q) as the intrinsic encryption key and the encryption key (s1, s2) built into the microcontroller as the internal device credential, calculate the initial value of the two-dimensional HNN-like hyperchaotic map;

[0023] As a preferred implementation of the present invention, the formula for calculating the initial value of the two-dimensional HNN-like hyperchaotic map is:

[0024] (x0=s1+2pπ,y0=s2+2qπ) (8)

[0025] Among them, (s1, s2) is the encryption key, (p, q) is the initial value offset factor, and (x0, y0) is the initial value of the hyperchaotic map.

[0026] Step 33, iterating the two-dimensional HNN-like hyperchaotic mapping several times, and using the obtained hyperchaotic state value (x, y) as a pseudo-random number (X, Y);

[0027] Step 34: Use the one-dimensional binary sequence S to permute the order of the pseudo-random numbers X and Y respectively;

[0028] Step 35: Use diffusion method to obtain sequence C F , Sequence C B ;

[0029]

[0030] Among them, M() is the operation function, P is the value after substitution, and C is the value after diffusion;

[0031] As a preferred embodiment of the present invention, the formula of the operating function is:

[0032]

[0033] in, It represents rounding up operation, k is the amplification factor, and b is the bias factor.

[0034] Step 36: Repeat steps 34 and 35 several times to obtain the password data sequence.

[0035] As a preferred embodiment of the present invention, a dual-factor encryption device based on HNN hyperchaotic mapping and geographic grid includes: a single-chip microcomputer, a dynamic random access memory, a positioning module, a digital-to-analog conversion module and a USB bus conversion module; wherein,

[0036] The USB bus conversion module is used for data communication between the host and the microcontroller;

[0037] The digital-to-analog conversion module converts the encrypted ciphertext digital signal into an analog signal;

[0038] The positioning module is used to obtain the longitude and latitude coordinates in the world map;

[0039] Dynamic random access memory is used to store pseudo-random numbers and cryptographic data sequences;

[0040] The single chip microcomputer is used to receive the plain text from the host and encrypt the plain text to obtain the encrypted ciphertext digital signal.

[0041] As a preferred embodiment of the present invention, a two-factor encryption system based on HNN hyperchaotic mapping and geographic grid includes: a memory for storing instructions executable by a processor; a processor for executing instructions to implement a two-factor encryption method based on HNN-like hyperchaotic mapping and geographic grid.

[0042] As a preferred embodiment of the present invention, a computer readable medium stores a computer program code, and when the computer program code is executed by a processor, a two-factor encryption method based on a HNN-like hyperchaotic map and a geographic grid is implemented.

[0043] Beneficial effects of the present invention:

[0044] 1. For the first time, geographic location is combined with chaotic hardware encryption. Geographic information is used as a unique identifier and acts simultaneously with the hardware key to construct a dual-factor driven chaotic hardware encryption method, which makes it impossible to decrypt encrypted data outside the effective security area, enhances the geographic location sensitivity of the data, and effectively protects the data from unauthorized access;

[0045] 2. Solved the problem of data location insensitivity of single-factor hardware encryption;

[0046] 3. Solved the problem of anti-theft of encryption devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a flow chart of the dual-factor encryption method based on HNN-like hyperchaotic mapping and geographic grid of the present invention;

[0048] Figure 2 It is the grid homogeneous coexistence attractor of the two-dimensional HNN-like hyperchaotic mapping of the present invention.

[0049] Figure 3 It is a hyperchaotic sequence of the two-dimensional HNN-like hyperchaotic mapping of the present invention.

[0050] Figure 4 It is a schematic diagram of the geographic grid system of the present invention;

[0051] Figure 5 It is a structural schematic diagram of a dual-factor chaotic hardware encryption device based on a geographic grid according to the present invention;

[0052] Figure 6 A flowchart of grid key generation based on geographic location of the present invention;

[0053] Figure 7 This is a schematic diagram of the encryption and decryption process of the present invention;

[0054] Figure 8 This is a physical picture of a two-factor chaotic hardware encryption device based on a geographic grid. DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with the accompanying drawings and embodiments. This figure is a simplified schematic diagram, which only illustrates the basic structure of the present invention in a schematic manner, and therefore it only shows the components related to the present invention.

[0056] like Figure 1 As shown, the dual-factor encryption method based on HNN-like hyperchaotic mapping and geographic grid includes the following steps:

[0057] Step 1: Construct a two-dimensional HNN-like hyperchaotic map;

[0058] The mathematical model formula of two-dimensional HNN-like hyperchaotic mapping is:

[0059]

[0060] Where n is a natural number, x n and n are two discrete time variables at the nth iteration, x and y represent the electrical activities of the first and second neurons respectively; for neurons at the edge of internal decay, parameter g 11 , g 12 , g 21, g 22 is the connection weight, and the nonlinear function sin() is the activation function.

[0061] The fixed point of the two-dimensional HNN-like hyperchaotic mapping is set to S′=(X′,Y′), and by calculating X′=X′+g 11 sinX′+g 12 sinY′ and Y′=Y′+g 21 sinX′+g 22 sinY′, the fixed point can be obtained as:

[0062] S'=(X',Y')=(mπ,lπ) (2)

[0063] Here, m and l are two integers.

[0064] Therefore, the mapping has an infinite number of grid fixed points and can present a grid distribution on the X′-Y′ plane, such as Figure 2 As shown, this leads to the emergence of grid homogeneous coexistence attractors.

[0065] The initial value of the two-dimensional HNN-like hyperchaotic map is (x0, y0), and its value is within (-π, π). If x0 is offset by 2pπ and y0 is offset by 2qπ, that is, the new initial value (x′0, y′0) = (x0+2pπ, y0+2qπ), then the two-dimensional HNN-like hyperchaotic map generates a new set of sequences, represented by variables (x′, y′). For (x′0, y′0), the new sequence after the first iteration is:

[0066]

[0067] The new sequence after the second iteration is:

[0068]

[0069] The new sequence after the third iteration is:

[0070]

[0071] By analogy, the new sequence after (n+1) iterations can be expressed as:

[0072]

[0073] Therefore, when x0 and y0 are offset by 2pπ and 2qπ respectively, the solution of equation (1) is that the sequence of new variables x' and y' is offset by 2pπ in the x direction and 2qπ in the y direction, that is, the linear transformation between the original sequence and the new sequence is expressed as:

[0074]

[0075] It shows that when x0 moves 2pπ, the new sequence x′ moves 2pπ in the x direction; when y0 moves 2qπ, the new sequence y′ moves 2qπ in the y direction, resulting in the dynamic behavior of grid homogeneity coexistence.

[0076] The two integers p and q in formula (7) are the core parameters for determining the initial value of the grid. Therefore, (p, q) is defined as the initial value offset factor. The initial value offset factor is an important factor for using two-dimensional HNN-like hyperchaotic mapping in the subsequent dual-factor chaotic hardware encryption based on geographic grids.

[0077] The two-dimensional HNN-like hyperchaotic mapping generates eight hyperchaotic sequences, such as Figure 3 As shown, the numerical results show that the dynamic amplitude of the hyperchaotic sequence can be controlled by switching the initial value offset factor in two directions. The figure only shows 8 examples of hyperchaotic sequences, and the number of hyperchaotic sequences is determined by the integers p and q.

[0078] The two-dimensional HNN-like mapping can generate hyperchaotic sequences with excellent performance, which is very suitable for chaotic encryption applications. Its grid homogeneity coexistence characteristics are very consistent with geographic grid indexing;

[0079] Step 2: Construct a geographic grid system based on the grid homogeneity characteristics of the two-dimensional HNN-like hyperchaotic mapping;

[0080] In order to realize the dual-factor chaotic encryption based on geographic grid, the Beidou satellite system is used for positioning, the H3 geographic spatial index developed by Uber is used, and the hexagonal grid is used for spatial partitioning. The geographic information is divided into several regional indexes. Different indexes correspond to different geographic keys to ensure regional security. Since the geographic spatial index system is independent of the current positioning information, there is no need to save the positioning status information during encryption. It is a stateless encryption, which effectively ensures the stability and security of the system. Before encryption, a geographic grid system is designed, as shown in the schematic diagram. Figure 4 As shown, it includes Mercator projection, hexagonal tiles, geographic index, and conversion from geography to index.

[0081] Step 21. Mercator projection is one of the most commonly used cylindrical projections. It projects the earth's surface onto a cylinder and then unfolds it into a rectangle, thereby maintaining the accuracy of the map in terms of angles and shapes. Use the Mercator projection map and the longitude and latitude coordinates (x, y) obtained by satellite positioning to draw the map on Figure 4 (a) Medium;

[0082] Step 22. Subsequently, the world map may be divided into a hexagonal grid in a honeycomb arrangement, such as Figure 4(b) As shown; the hexagon is the polygon that is most similar to a circle. Due to its lower area-to-perimeter ratio, it can reduce the deviation caused by the boundary effect of the mesh shape, so that it can be divided into a uniform mesh. In addition, compared with square meshes and triangular meshes, the hexagonal mesh is easier to locate because the distance between its center and all adjacent centers is the same, making it the best choice for filling the plane.

[0083] Step 23: After determining the map projection and grid segmentation, a certain coordinate is used as the starting segmentation point, and the grid size is determined, that is, the radius is set, and the construction of the geographic grid system can be completed;

[0084] Step 24. Using the upper left corner of the world map as the starting point, use positive integers to index and number the grids. Each grid corresponds to a unique plane index, as shown in the schematic diagram. Figure 4 (c)

[0085] Step 25: The coordinates (x, y) obtained by satellite positioning fall within a certain grid. This positioning is converted into the grid index (p, q) corresponding to the initial value offset factor, such as Figure 4 As shown in (d); different coordinates falling on the same hexagonal grid will eventually be converted to the same index, which means that this hexagon is the valid range of this index and these coordinates are in the same safe zone.

[0086] The geographical location is associated with the initial value offset factor to obtain the chaotic encryption sensitive to the geographical location, thus realizing the chaotic encryption method based on the geographical grid;

[0087] The dual-factor encryption device based on HNN hyperchaotic mapping and geographic grid adopts a single-chip microcomputer (STM32H743IIT6), a dynamic random access memory SDRAM (W9825G6KH), a positioning module (ATK-1218 chip), a digital-to-analog conversion module (DAC856), and a USB bus conversion module (CH340G); wherein the single-chip microcomputer is electrically connected to the host through the USB bus conversion module, the dynamic random access memory is electrically connected to the single-chip microcomputer, and the digital-to-analog conversion module is electrically connected to the single-chip microcomputer and the oscilloscope respectively; the positioning module is electrically connected to the single-chip microcomputer; the USB bus conversion module is used for data communication between the host and the single-chip microcomputer; the digital-to-analog conversion module converts the encrypted ciphertext digital signal into an analog signal; the positioning module is used to obtain the longitude and latitude coordinates in the world map; the single-chip microcomputer is used to receive the plaintext in the host and encrypt the plaintext to obtain the encrypted ciphertext digital signal; the dynamic random access memory is used to store pseudo-random numbers and password data sequences; the dual-factor chaotic hardware encryption device based on the geographic grid can encrypt data in any format.

[0088] Step 3: The host reads the entire plaintext file in binary mode and writes its plaintext into byte slice S dat, and then stream the byte slice to the MCU. In order to facilitate security analysis, the reading method of the image format file is specially optimized. By judging the file header information, the host can identify common image types, such as JPEG, PNG, BMP and other formats; for a single-channel grayscale image, the host decodes the image to obtain 8-bit pixels of size M×N, where M and N are the width and height of the image respectively; then, the host uses a flattening method to obtain a one-dimensional binary sequence S of the image img , the length is L = M × N; it is worth noting that although S dat and S img Both are one-dimensional binary sequences, but the former represents complete data information, while the latter only contains image pixel information. In order not to lose universality, the one-dimensional binary sequence S is defined as any data received by the microcontroller (i.e., S dat ), the specific implementation steps on hardware are as follows:

[0089] 1. Send S from the host to the microcontroller through the USB bus conversion module. Considering the limited resources and communication requirements of the hardware memory, the loss of data exchange between the microcontroller and the random access memory is reduced. The binary data obtained by STM32 will be transferred to SDRAM for temporary storage.

[0090] 2. Use the positioning module of the Beidou satellite navigation system to receive the latitude and longitude information of the Beidou satellite, and combine it with the geographic grid system to map the current geographical location to the center coordinates of a hexagon, with the coordinates (p, q) used as the initial value offset factor;

[0091] 3. In order to protect the security of keys and encryption, the initial value offset factor (p, q) is used as the intrinsic encryption key, and the encryption key (s1, s2) built into the microcontroller is used as the internal device credential. The initial value (x0, y0) of the two-dimensional HNN-like hyperchaotic mapping is calculated by formula (8):

[0092] (x0=s1+2pπ,y0=s2+2qπ) (8)

[0093] The initial value (x0, y0) is not only controlled by the device credentials, but also affected by the geographic location. When the geographic location changes within the regional range, the geographic coordinates will be mapped to the same hexagonal center coordinates within the valid regional range; when the geographic location exceeds the regional range, it will be mapped to different hexagonal center coordinates. The initial value can be changed by changing the values ​​of the initial value offset factors p and q.

[0094] 4. After generating the initial value, the single chip microcomputer performs L+L on the two-dimensional HNN-like hyperchaotic map H iterations, where L H =100 is the number of preheating times; discard the first L HIterate, use the retained hyper-chaotic state value (x, y) as a pseudo-random number (X, Y), and store the pseudo-random number in SDRAM;

[0095] 5. Permutate the sorting position of S to X to get P X ; Then, use the same method to convert P X Permutate the sort position of Y to obtain P, and finally store P in SDRAM;

[0096] 6. Propagate the rule that the previous element M(i) affects the next element M(i+1) to the entire sequence, and obtain the sequence C F , propagate once more, and get sequence C B , the diffusion method can be described as formula (9):

[0097]

[0098] Among them, P is the value after substitution and C is the value after diffusion.

[0099] M(x) is an operation function described as:

[0100]

[0101] in, Indicates rounding up operation, k = 10 13 is the amplification factor, b = 2π is the bias factor, (X i ,Y i ,P i ) can be retrieved from SDRAM as needed.

[0102] 7. Steps 5 and 6 are repeated 3 times to obtain the password data sequence C. Then, C is transmitted to the host through the USB bus conversion module. During this process, data is exchanged between the microcontroller and the SDRAM to ensure the security of the memory.

[0103] The three repetitions are to increase security and improve diffusion effect, while also resisting cryptanalysis and ensuring key usage efficiency. In addition, the algorithm is reversible; the number of repetitions is a custom parameter.

[0104] After waiting for the data to be received, the host uses the rearrangement method to restore the original dimensional data from sequence C. In this way, the ciphertext data is finally obtained.

[0105] The schematic diagram of the structure of the dual-factor chaotic hardware encryption device based on the geographic grid is as follows: Figure 5 As shown, in the encryption algorithm, Figure 6The process of obtaining the initial value of the system based on geographic positioning is demonstrated. The above encryption steps describe the encryption operation in detail. The decryption operations of permutation and diffusion are the inverse steps of the encryption operation.

[0106] It is worth noting that in formula (10), a double-precision floating point number is used, which occupies 8 bytes. In order to maintain the correctness of the operation, all constants and variables used in formula (10) are defined as 64-bit double-precision floating point numbers, avoiding the problem of data overflow or precision loss when 32-bit and 64-bit mixed operations are performed. In terms of data storage, the data type partition of SDRAM is defined, which is divided into a 64-bit double-precision floating point partition for storing hyperchaotic sequences, a 32-bit unsigned integer partition for storing permutation information, and an 8-bit unsigned integer partition for storing binary numbers. In serial transmission, a maximum cache of 500 bytes is configured using the internal RAM of STM32. The data sent by the host first enters the cache and is then assigned to the predefined 8-bit unsigned integer partition addresses in turn, and then the cache is cleared and the SDRAM address offset of the next transmission cycle is recorded.

[0107] In the experiment, a 512×512 pixel image was selected as an example for testing. After the STM32 was powered on, the KEY0 key was pressed to enter the encryption mode. The plaintext data was transmitted to the MCU through the host, and the positioning module obtained the geographic location through the antenna. Figure 4 The geographic grid system in the image is used to transform the geographic coordinates into grid factors (p, q), and then the encryption process is completed through the iterative operation of two-dimensional HNN-like mapping and a series of permutation diffusion operations. The result is then transmitted to the host through CH340G to complete the chaotic encryption combined with geographical factors. Similarly, press KEY1 to enter the decryption mode. The decryption process is the same as the encryption process, and decryption can be performed according to the geographic coordinates at the time of decryption.

[0108] Figure 7 In the figure, the geographic coordinates during encryption are displayed below. The upper left corner is the original image, and the upper right corner is its corresponding binary sequence. The lower left corner is the binary data sent back from the hardware device, and the lower right corner is the corresponding encrypted image. The DAC8563 chip is used as a D / A converter to obtain the real-time sequence during the encryption and decryption process in the experiment. The plaintext data of the yellow sequence and the ciphertext data of the blue sequence are displayed by an oscilloscope. Figure 7 The hardware encryption and decryption process of the host is displayed, and the decryption results of different geographical locations are displayed. The encrypted images within the encrypted geographical location can be decrypted correctly, but the encrypted images beyond this location cannot be decrypted. The experimental results prove the feasibility of chaotic hardware encryption based on the geographical grid system. Figure 8 This is a schematic diagram of the hardware.

[0109] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A dual-factor encryption method based on HNN-like hyperchaotic mapping and geographic grid, characterized in that: The following steps are involved: Step 1: construct a two-dimensional HNN-like hyperchaotic map, set the fixed point of the two-dimensional HNN-like hyperchaotic map, use the initial value of the two-dimensional HNN-like hyperchaotic map to iterate the two-dimensional HNN-like hyperchaotic map several times, and obtain the hyperchaotic sequence of the severalth iteration. The formula is: Among them, (p, q) is the initial value offset factor; x, y represent the direction; x′, y′ are the hyperchaotic sequences in the x and y directions respectively; Step 2: Use hexagonal grids to perform spatial partitioning, divide geographic information into several regional indexes, and construct a geographic grid system; The construction of the geographic grid system includes: Step 21: World map and longitude and latitude coordinates obtained using Mercator projection and satellite positioning; Step 22: Divide the world map into a hexagonal grid in a honeycomb arrangement; Step 23, using a certain coordinate as the starting segmentation point to determine the grid size; Step 24: Using the upper left corner of the world map as the starting point, index and number the grids with positive integers; Step 25: convert the located longitude and latitude coordinates into the grid index corresponding to the initial value offset factor; Step 3: Encrypt the plaintext file using the initial value offset factor and the corresponding grid index; Step three specifically includes: Step 31, processing the plaintext file into a one-dimensional binary sequence S; Step 32: Using the initial value offset factor (p, q) as the intrinsic encryption key and the encryption key (s1, s2) as the internal device credential, the initial value of the two-dimensional HNN-like hyperchaotic map is calculated. The formula is: (x0=s1+2pπ,y0=s2+2qπ) (8) Among them, (s1, s2) is the encryption key, (p, q) is the initial value offset factor, and (x0, y0) is the initial value of the hyperchaotic map; Step 33, iterating the two-dimensional HNN-like hyperchaotic mapping several times, and using the obtained hyperchaotic state value (x, y) as a pseudo-random number (X, Y); Step 34: Use the one-dimensional binary sequence S to permute the order of the pseudo-random numbers X and Y respectively; Step 35: Use diffusion method to obtain sequence C F , Sequence C B ; Among them, M() is the operation function, P is the value after substitution, and C is the value after diffusion; The formula of the operation function is: in, Indicates rounding up operation, k is the amplification factor, and b is the bias factor; Step 36: Repeat steps 34 and 35 several times to obtain the password data sequence.

2. A device using the dual-factor encryption method based on HNN-like hyperchaotic mapping and geographic grid as claimed in claim 1, characterized in that: include: Single chip microcomputer, dynamic random access memory, positioning module, digital-to-analog conversion module and USB bus conversion module; wherein, The USB bus conversion module is used for data communication between the host and the microcontroller; The digital-to-analog conversion module converts the encrypted ciphertext digital signal into an analog signal; The positioning module is used to obtain the longitude and latitude coordinates in the world map; Dynamic random access memory is used to store pseudo-random numbers and cryptographic data sequences; The single chip microcomputer is used to receive the plain text from the host and encrypt the plain text to obtain the encrypted ciphertext digital signal.

3. A two-factor encryption system based on HNN hyperchaotic mapping and geographic grid, characterized in that: include: a memory for storing instructions executable by a processor; A processor, configured to execute instructions to implement the dual-factor encryption method based on HNN-like hyperchaotic mapping and geographic grid as claimed in claim 1.

4. A computer readable medium storing a computer program code, characterized in that: The computer program code implements the two-factor encryption method based on HNN-like hyperchaotic mapping and geographic grid as claimed in claim 1 when executed by a processor.

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