Privacy protection-oriented NCA-Arnold secure transmission method

Abstract

The invention discloses an NCA-Arnold secure transmission method for privacy protection, and the method comprises the steps: carrying out the position scrambling of image pixel positions, and obtaining an image after the pixel positions are changed; randomly selecting plaintext information and a user given key, generating a hash value by using an SHA-512 function, and determining a control parameter and an initial value of the NCA according to the hash value; generating a scrambling matrix according to the generated encryption key, determining a new scrambling matrix through the scrambling matrix, a position function pos () and a direction function dir (), and performing scrambling operation on image positions and pixel values by using a folding algorithm; and carrying out diffusion operation on the scrambled image by using a chaos diffusion formula to obtain a chaos vector, then carrying out XOR operation to obtain an encryption result, and after encryption is completed, carrying out data transmission for a receiving end to carry out decryption processing. According to the method, the complex dynamic characteristics of the NCA and the pixel scrambling capability of Arnold mapping are combined, so that efficient encryption and privacy protection of the digital image are realized.

Description

Technical Field

[0001] This invention relates to the field of artificial intelligence technology, and in particular to a privacy-preserving NCA-Arnold secure transmission method. Background Technology

[0002] With the rapid development of digital information technology and network communication technology, digital images, as an important information carrier, have been widely used in various fields such as medical diagnosis, military reconnaissance, online education, and social media. At the same time, image information involving personal privacy and sensitive data is at risk of being illegally stolen and tampered with during transmission and storage. Once image information is leaked, it not only causes serious violations of personal privacy but may also lead to significant losses to national security and commercial interests. Therefore, how to achieve efficient and secure privacy protection during image transmission has become an important research direction in the field of information security.

[0003] In existing technologies, traditional symmetric encryption algorithms (such as DES, 3DES, and AES) are used for digital image encryption. However, due to the characteristics of digital images, such as large data volume, strong correlation between adjacent pixels, and high redundancy, directly using these encryption algorithms often leads to low encryption efficiency and insufficient security to meet practical application requirements. To address this issue, researchers have proposed an image encryption method based on chaotic systems. Chaotic systems have advantages such as high sensitivity to initial conditions, complex trajectories, and strong ergodicity, which can improve the security of image encryption to a certain extent. However, existing chaotic encryption methods still have structural defects such as periodic windows, making them vulnerable to exploitation by attackers and thus weakening their overall resistance to attacks.

[0004] To further enhance the complexity and security of image encryption, nonlinear cellular automata (NCAs) have gained increasing attention in recent years. NCAs possess strong parallelism and simple evolutionary rules, yet can generate complex dynamic behaviors, making them suitable for generating high-quality pseudo-random sequences, thereby enhancing the confusion and diffusion of encryption algorithms. Meanwhile, in image scrambling, the Arnold map is widely used in image preprocessing due to its ability to effectively break the strong correlation between image pixels. However, a single Arnold map suffers from periodic recovery limitations; without further diffusion mechanisms, its security is difficult to guarantee. Summary of the Invention

[0005] The purpose of this invention is to provide a privacy-preserving NCA-Arnold secure transmission method. By combining the complex dynamic characteristics of NCA with the pixel scrambling capability of Arnold mapping, it achieves efficient encryption and privacy protection of digital images, thereby improving the security and robustness of images during network transmission.

[0006] To achieve the above objectives, the present invention provides a privacy-preserving NCA-Arnold secure transmission method, comprising the following steps:

[0007] S1. The positions of the image pixels are scrambled to obtain the image with changed pixel positions.

[0008] S2. Randomly select plaintext information and user-given key, use the SHA-512 function to generate hash value, and determine the control parameters and initial value of NCA based on the hash value;

[0009] S3. Generate a scrambling matrix based on the generated encryption key. Determine a new scrambling matrix using the scrambling matrix, the position function pos(), and the direction function dir(). Use the folding algorithm to scramble the image position and pixel values.

[0010] S4. Apply the chaotic diffusion formula to the scrambled image to obtain a chaotic vector, then perform an XOR operation to obtain the encryption result. After encryption, transmit the ciphertext image for the receiving end to decrypt.

[0011] Preferably, step S1 specifically includes:

[0012] S11. Input plaintext image P, randomly select pixel values, calculate the sum of these pixel values, and denot it as sumPixel;

[0013] S12. Use a sorting function to scramble the pixel positions, sort each row and column of image P in ascending order, and obtain the sorted result matrix and index matrix.

[0014] S13. Determine the index sequence index_row for each row and each column. i and index_col i As a key;

[0015] S14. Obtain the scrambled image P' i,j , where i = 1, 2, ..., M, j = 1, 2, ..., N.

[0016] Preferably, step S2 specifically includes:

[0017] S21. Using the SHA-512 hash function, calculate the 512-bit hash value by combining the plaintext information sumPixel obtained in step S11 with the user-given key.

[0018] S22. Convert the calculated hash value into a 128-bit hexadecimal array Hash, where Hash = [h1, h2, ..., h...]. 128 ];

[0019] S23. Use the Hash array obtained in S22 to calculate the initial value of the Logistic equation;

[0020] S24. Determine the control parameters and initial values ​​of the ACML system mapped from the NCA equations, using the following formula:

[0021]

[0022] In the formula, β and α represent the NCA equation parameters; mod represents the modulo operation; y(0) represents the initial value of Logistic.

[0023] Preferably, step S3 specifically includes:

[0024] S31. Using the encryption key generated in step S2 as the driving input to the NCA-based ACML system, and based on the control parameters and initial values, generate the initial scrambling matrix A after N iterations of selection following 2000+N iterations. i ;

[0025] S32. Use a hash function to determine the value of the dir() equation. The formula is:

[0026] dir = hex2doc(Hash(h 80 :h 84 ))mod3;

[0027] S33. Use a hash function to determine the value of the matrix selection function pos(). The formula is:

[0028] pos = hex2doc(Hash(h 100 :h 103 ))mod(MN);

[0029] S34. Use the determined initial scrambling matrix A i The position function pos() and the direction function dir() determine the scrambling matrix Q. i ;

[0030] S35, Based on the scrambling matrix Q i The image P' obtained in step S14 is processed using a folding algorithm. i,j Perform a scramble operation to obtain P. i '.

[0031] Preferably, in step S31:

[0032] The ACML system formula is:

[0033]

[0034] In the formula, function f is the NCA equation, and the formula is:

[0035] f(x) = y n+1 =(1-β) -4 )cot(α / (1+β))(1+1 / β) β tan(αy n (1-y) n ) β ;

[0036] In the formula, the values ​​of j and k are generated by the Arnold cat map, and the formula is as follows:

[0037]

[0038] In the formula, 1≤i,j,k≤L, L is the total number of grids, i,j,k are grid values, and p and q are system control parameters.

[0039] Preferably, step S4 specifically includes:

[0040] S41. Apply the chaotic diffusion formula to the obtained image P. i Perform a diffusion operation to obtain the chaotic vector, as shown in the formula:

[0041]

[0042] In the formula, X represents the diffusion sequence, P i P' and P1' represent the intermediate ciphertext for the i-th and j-th encryptions; M represents the number of image columns, N represents the number of image rows, and ε represents the coupling coefficient. This represents the XOR operation;

[0043] S42. Discard the first a chaotic sequences to obtain the chaotic vector, and perform an XOR operation to obtain the final key;

[0044] S43. After encryption is completed, the encrypted image is transmitted through a public channel or network for the receiving end to decrypt.

[0045] Preferably, the decryption process in step S43 includes:

[0046] D1. Obtain the initial key: By decomposing the final key, obtain the control parameters and initial value parameters required in each step;

[0047] D2. Perform reverse diffusion operation: Calculate the chaotic vector using the parameters in the key, and calculate the result of the reverse diffusion step.

[0048] D3. Confirm the direction function and position function: Obtain the direction function and position function through the key, use ACML to calculate the folding matrix in the encryption process, and then perform a bitwise XOR operation according to the direction function and position function to obtain the decryption result;

[0049] D4. Perform sorting using the `sort` function: utilize the `index_row` key. i and index_col i The text is rearranged to obtain the initial plaintext.

[0050] Preferably, the formula for calculating the reverse step result of diffusion in step D2 is:

[0051]

[0052] Therefore, the present invention employs the above-described privacy-preserving NCA-Arnold secure transmission method, which has the following beneficial effects:

[0053] (1) The pixel values ​​were changed by using the folding algorithm in different directions, thus achieving the purpose of scrambling the pixel values;

[0054] (2) The initial key and the final key are not the same because plaintext position information is added to the end of the key, which can improve the key's ability to resist brute-force attacks;

[0055] (3) By selecting a portion of plaintext information as part of the key, the SHA-512 algorithm is used to calculate the hash sequence of the key. Then, the generated hash sequence is used to generate the initial values ​​and system parameters of algorithms such as the chaotic system and the folding algorithm in the algorithm. Finally, the ACML system is improved by using NCA mapping, so that the proposed ACML can efficiently generate the diffusion sequence, achieve the purpose of one-time pad, and improve the performance of the image encryption method.

[0056] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0057] Figure 1 This is a flowchart of the encrypted transmission method according to an embodiment of the present invention;

[0058] Figure 2 This is a flowchart illustrating the decryption process according to an embodiment of the present invention;

[0059] Figure 3 This is a schematic diagram of the top-to-bottom folding method according to an embodiment of the present invention;

[0060] Figure 4 This is a schematic diagram of the left-to-right folding method according to an embodiment of the present invention;

[0061] Figure 5 This is a schematic diagram of the folding method from the lower left to the upper right according to an embodiment of the present invention;

[0062] Figure 6 This is a schematic diagram of the folding method from the top left to the bottom right according to an embodiment of the present invention. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. In the description of the present invention, it should be noted that the terms "upper," "lower," "inner," "outer," etc., indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product of the invention is in use. They are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0064] Example

[0065] like Figure 1 As shown, this invention provides a privacy-preserving NCA-Arnold secure transmission method, the steps of which include:

[0066] S1. Pixel Position Scrambling: This involves scrambling the positions of image pixels to obtain an image with altered pixel positions. Specifically, this includes:

[0067] S11. Input a plaintext image P of size M×N, where M represents the number of columns and N represents the number of rows. Randomly select pixel values, calculate the sum of these pixel values, and denot it as sumPixel.

[0068] S12. Use a sorting function to scramble the pixel positions, and sort each row and column of image P in ascending order to obtain the sorted result matrix and index matrix.

[0069] S13. Determine the index sequence index_row for each row and each column. i and index_col i As a key.

[0070] S14. Obtain the scrambled image P' i,j , where i = 1, 2, ..., M, j = 1, 2, ..., N.

[0071] S2. Encryption Key Generation: Randomly select plaintext information and a user-provided key, use the SHA-512 function to generate a hash value, and determine the control parameters and initial values ​​of NCA based on the hash value. Specifically, this includes:

[0072] S21. Using the SHA-512 hash function, calculate the 512-bit hash value by combining the plaintext information sumPixel obtained in step S11 with the user-given key.

[0073] S22. Convert the calculated hash value into a 128-bit hexadecimal array Hash, where Hash = [h1, h2, ..., h...]. 128 ];

[0074] S23. Using the Hash array obtained in S22, calculate the initial values ​​x0(1), x0(2), x0(3), x0(4) and control parameters μ1, μ2, μ3, μ4 of the Logistic equation. The specific calculation formula is as follows:

[0075]

[0076] In the formula, μ represents the parameters of the Logistic equation; hex2dec(·) represents the conversion from hexadecimal to decimal; and ε represents the coupling coefficient.

[0077] S24. Determine the control parameters and initial values ​​of the ACML system mapped from the NCA equations, using the following formula:

[0078]

[0079] In the formula, β and α represent the NCA equation parameters; mod represents the modulo operation; y(0) represents the initial value of Logistic.

[0080] S3, Pixel Value Folding and Diffusion: A scrambling matrix is ​​generated based on the generated encryption key. A new scrambling matrix is ​​determined using the scrambling matrix, the position function `pos()`, and the direction function `dir()`. A folding algorithm is then used to scramble the image positions and pixel values. Specifically, this includes:

[0081] S31. Using the encryption key generated in step S2 as the driving input to the NCA-based ACML system, and based on the control parameters and initial values, generate the initial scrambling matrix A after N iterations of selection following 2000+N iterations. i .

[0082] The ACML system formula is as follows:

[0083]

[0084] In the formula, function f is the NCA equation, and the formula is:

[0085] f(x) = y n+1 =(1-β) -4 )cot(α / (1+β))(1+1 / β) β tan(αy n (1-y) n ) β ;

[0086] In the formula, the values ​​of j and k are generated by the Arnold cat map, and the formula is as follows:

[0087]

[0088] In the formula, 1≤i,j,k≤L, L is the total number of grids, i,j,k are grid values, and p and q are system control parameters.

[0089] S32. Use a hash function to determine the value of the dir() equation. The formula is:

[0090] dir = hex2doc(Hash(h 80 :h 84 ))mod3;

[0091] S33. Use a hash function to determine the value of the matrix selection function pos(). The formula is:

[0092] pos = hex2doc(Hash(h 100 :h 103 ))mod(MN);

[0093] S34. Use the determined initial scrambling matrix A i The position function pos() and the direction function dir() determine the scrambling matrix Q. i ;

[0094] S35, Based on the scrambling matrix Q i The image P' obtained in step S14 is processed using folding algorithms in different directions. i,j Perform a scramble operation to obtain P. i Specifically:

[0095] Scrambling is performed using a top-to-bottom folding method, such as... Figure 3 As shown, (a) is the ciphertext image c, and (b) is the scrambling matrix Q1. The formula for the top-to-bottom folding method is:

[0096]

[0097] Scramble the system using a left-to-right folding method, such as... Figure 4As shown, (a) is the ciphertext image c, and (b) is the scrambling matrix Q2. The formula for the folding method from left to right is:

[0098]

[0099] Use the bottom-left to top-right folding method to perform scrambling operations, such as... Figure 5 As shown, (a) is the ciphertext image c, and (b) is the scrambling matrix Q3. The formula for the folding method from the bottom left to the top right is:

[0100]

[0101] Scramble the system using a folding method from top left to bottom right, such as... Figure 6 As shown, (a) is the ciphertext image c, and (b) is the scrambling matrix Q4. The formula for the folding method from the top left to the bottom right is:

[0102]

[0103] In the formula, Uh represents the upper half of the matrix; Dh represents the lower half of the matrix; Lh represents the left half of the matrix; Rh represents the right half of the matrix; Ld represents the lower left half of the matrix; Rup represents the upper right half of the matrix; Lup represents the upper left half of the matrix; Rd represents the lower right half of the matrix; bitxor represents bitwise XOR; and c represents the ciphertext image, i.e., P'.

[0104] S4. Diffusion Operation: The chaotic diffusion formula is used to perform a diffusion operation on the scrambled image to obtain a chaotic vector. Then, an XOR operation is performed to obtain the encryption result. After encryption, the ciphertext image is transmitted through a public channel or network for decryption at the receiving end.

[0105] Step S4 specifically includes:

[0106] S41. Apply the chaotic diffusion formula to the obtained image P. i Perform a diffusion operation to obtain the chaotic vector, as shown in the formula:

[0107]

[0108] In the formula, X represents the diffusion sequence, P i P', P1' represent the intermediate ciphertexts of the i-th and j-th encryptions; ε represents the coupling coefficient. This represents the XOR operation;

[0109] S42. Discard the first 500 chaotic sequences to obtain the chaotic vector, and perform an XOR operation to obtain the final key;

[0110] S43. After encryption is completed, the encrypted image is transmitted through a public channel or network for the receiving end to decrypt.

[0111] like Figure 2 As shown, the decryption process includes:

[0112] D1. Obtain the initial key: By decomposing the final key, obtain the control parameters and initial value parameters required in each step;

[0113] D2. Perform reverse diffusion operation: Calculate the chaotic vector using the parameters in the key, and calculate the result of the reverse diffusion step.

[0114] The formula for calculating the inverse step of diffusion is as follows:

[0115]

[0116] D3. Confirm the direction function and position function: Obtain the direction function and position function through the key, use ACML to calculate the folding matrix in the encryption process, and then perform a bitwise XOR operation according to the direction function and position function to obtain the decryption result;

[0117] D4. Perform sorting using the `sort` function: utilize the `index_row` key. i and index_col i The text is rearranged to obtain the initial plaintext.

[0118] Therefore, the present invention adopts the above-mentioned NCA-Arnold secure transmission method for privacy protection. By combining the complex dynamic characteristics of NCA with the pixel scrambling capability of Arnold mapping, it achieves efficient encryption and privacy protection of digital images, thereby improving the security and robustness of images during network transmission.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A privacy-oriented NCA-Arnold secure transmission method, characterized by the steps of The method comprises the following steps: S1, position scrambling is performed on image pixel positions, and an image with changed pixel positions is obtained after scrambling; S2, plaintext information and a user given key are randomly selected, a hash value is generated using an SHA-512 function, and control parameters and initial values of the NCA are determined according to the hash value; S3, a scrambling matrix is generated according to the generated encryption key, a new scrambling matrix is determined through the scrambling matrix, a position function pos() and a direction function dir(), and a folding algorithm is used to perform scrambling operations on image positions and pixel values; S4, a diffusion operation is performed on the scrambled image using a chaotic diffusion formula, a chaotic vector is obtained, then an exclusive OR operation is performed to obtain an encryption result, and after the encryption is completed, the ciphertext image is transmitted for decryption processing at a receiving end.

2. The privacy-oriented NCA-Arnold secure transmission method of claim 1, wherein, Step S1 specifically comprises: S11, inputting a plaintext image P, randomly selecting pixel values, calculating the sum of the pixel values, and recording the sum as sumPixel; S12, performing pixel position scrambling using a sorting function, performing ascending arrangement on each row and each column of the image P, and obtaining a sorted result matrix and an index matrix; S13, determine the index sequence index_row of each row and index_col of each column i and index_col i as the key; S14, get the scrambled image P' i,j where i = 1, 2,..., M, j = 1, 2,..., N.

3. The privacy-oriented NCA-Arnold secure transmission method of claim 2, wherein, Step S2 specifically comprises: S21, using an SHA-512 hash function to calculate a 512-bit hash value from the plaintext information sumPixel calculated in step S11 and a user given key; S22, convert the calculated hash value into a 128-bit hexadecimal array Hash, Hash = [h1, h2,......., h 128 ]; S23, calculating the initial value of the Logistic equation using the Hash array obtained in S22; S24, determining the control parameters and initial values of the ACML system of the NCA equation mapping, and the formula is: In the formula, β and α represent the parameters of the NCA equation, mod represents the modulo operation, and y(0) represents the initial value of the Logistic.

4. The privacy-oriented NCA-Arnold secure transmission method of claim 3, wherein, The step S3 specifically comprises: S31, using the encryption key generated in step S2 as a driving input into the NCA-based ACML system, according to the control parameters and the initial value, the initial scrambling matrix A is generated by selecting the last N iteration values after 2000+N iterations i ; S32, using Hash to determine the value of the dir() equation, and the formula is: dir = hex2doc(Hash(h 80 :h 84 )) mod 3; S33, using Hash to determine the value of the matrix selection function pos(), and the formula is: pos = hex2doc(Hash(h 100 :h 103 )) mod (MN); S34, using the determined initial permutation matrix A i , the position function pos() and the direction function dir(), determine the permutation matrix Q i ; S35, scrambling the matrix Q i , using the folding algorithm to the image P i ',j, and obtaining P i '.

5. The privacy-oriented NCA-Arnold secure transmission method of claim 4, wherein, In step S31: The formula of the ACML system is: In the formula, the f function is the NCA equation, and the formula is: f(x) = y n+1 = (1 - β -4 )cot(α / (1+β))(1+1 / β) β tan(αy n )(1-y n ) β ; In the formula, the values of j and k are generated by the Arnold cat map, and the formula is: In the formula, 1≤i,j,k≤L, L is the total number of lattices, i, j and k are all lattice values, and p and q represent system control parameters.

6. The privacy-oriented NCA-Arnold secure transmission method of claim 5, wherein, Step S4 specifically comprises: S41, using the chaotic diffusion formula on the obtained image P i diffusion operation is performed to obtain a chaotic vector, and the formula is: In the formula, X represents a diffusion sequence, P i P1' represents the i and j encrypted intermediate ciphertexts; M represents the number of image columns, N represents the number of image rows, and ε represents a coupling coefficient, represents an exclusive OR operation; S42, discarding the chaotic sequence for a times to obtain a chaotic vector, and performing an exclusive OR operation to obtain a final key; S43, transmitting the ciphertext image through a public channel or a network for decryption processing at a receiving end.

7. The privacy-oriented NCA-Arnold secure transmission method of claim 6, wherein: The decryption process in step S43 comprises: D1, obtaining an initial key: decomposing the final key to obtain control parameters and initial value parameters required in each step; D2, performing an inverse diffusion operation: calculating a chaotic vector through the parameters in the key, and calculating the inverse step result of the diffusion; D3, confirming a direction function and a position function: obtaining the direction function and the position function through the key, calculating the folding matrix in the encryption process using the ACML, and then performing a bitwise exclusive OR operation according to the direction function and the position function to obtain a decryption result; D4, perform sort function rearrangement: use index_row i and index_col i in the key to perform rearrangement to obtain the initial plaintext.

8. The privacy-oriented NCA-Arnold secure transmission method of claim 7, wherein, The formula for calculating the inverse step result of the diffusion in step D2 is:

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