Color image encryption method based on 1-LDCMS system and dynamic DNA coding

Abstract

The application provides a color image encryption method based on a 1-LDCMS system and dynamic DNA coding, and the technical scheme comprises the following steps: 1. channel decomposition of an image, 2. generation of a key related to plaintext, 3. generation of a chaotic sequence and a key sequence by a 1-LDCMS system and a Chebyshev chaotic system respectively, 4. dynamic DNA operation (DNA coding, DNA addition, DNA XOR, DNA subtraction and DNA complement) of a channel matrix, 5. index scrambling, 6. DNA decoding operation, 7. XOR diffusion and merging of channel matrices, and output of a cipher image. The application can effectively improve the security and randomness of the algorithm, greatly reduce the correlation of the generated cipher image, significantly improve the information entropy, and can realize encryption by only one round of operation, thereby guaranteeing the security and real-time performance of image transmission.

Description

TECHNICAL FIELD

[0001] The present application relates to a color image encryption method based on 1-LDCMS system and dynamic DNA coding, and belongs to the technical field of image encryption. BACKGROUND

[0002] The rapid development of the Internet era makes the text, image, audio, video and other media methods widely used. Among them, digital images are widely used in multimedia channels due to their intuitive and visual characteristics. Such information usually carries unique private information, and preventing information leakage is an important issue in the security field. Unlike traditional text information, digital images have the characteristics of large data volume and high redundancy. Therefore, the traditional encryption methods such as AES and DES have the disadvantage of low efficiency when encrypting digital images. Therefore, it is particularly important to seek a secure and efficient encryption algorithm to realize the transmission of image information.

[0003] Chaos has the characteristics of initial value sensitivity, pseudo-randomness, ergodicity, etc., which are very consistent with the key sensitivity and randomness of the password system. Therefore, researchers gradually apply chaos system to the field of cryptography. Among them, the common chaotic system in the encryption process is divided into two categories: low-dimensional chaotic system and high-dimensional chaotic system. Both types of chaotic systems have advantages and disadvantages. Low-dimensional chaotic system is usually simple and efficient, but has a small key space and obvious periodic window. High-dimensional chaotic system usually has high complexity and strong randomness, but has long running time and low efficiency. In order to solve the above problems, on the one hand, an improved low-dimensional chaotic system is introduced. This type of chaos not only has a simple structure, but also has strong randomness and higher efficiency. On the other hand, a single image encryption algorithm based on chaos can no longer fully meet the current encryption needs. Combining chaotic image encryption with DNA technology can make the encryption system have higher security and better development prospects.

[0004] The existing DNA coding-based chaotic image encryption algorithm is relatively less suitable for color image, most of the chaotic systems increase the calculation complexity of the algorithm, and there is no correlation between the plaintext and the key, and the key sensitivity is weak. In addition, the encryption algorithm adopts fixed encoding or single operation mode, which reduces the difficulty of decryption. In view of the existing problems, the present application provides a color image encryption method based on 1-LDCMS system and dynamic DNA coding. In the encryption scheme, the plaintext image is used to generate the key, which can effectively resist the selected plaintext and known plaintext attack. The improved one-dimensional chaotic system 1-LDCMS is combined with the Chebyshev chaotic system, which greatly enhances the randomness of the algorithm. The chaotic sequence dynamically controls 8 DNA encoding rules and various DNA operation rules, realizes the bit-level diffusion of the color image, and improves the security and the ability to resist common attacks of the algorithm. Compared with the algorithm which needs multiple rounds of operation to complete encryption, only one round of operation can effectively realize encryption, reduces the calculation complexity, and has strong real-time performance. SUMMARY

[0005] In combination with the above analysis, in view of the shortcomings of the existing image encryption algorithm combining DNA coding and chaos, the present application provides a color image encryption method based on 1-LDCMS system and dynamic DNA coding. The scheme can effectively solve the problem that the key has no correlation with the plaintext, enhance the key sensitivity, and increase the key space. In addition, by adopting the double chaotic system form combining the improved one-dimensional chaotic system and the classical one-dimensional chaotic system, the encryption efficiency is improved, and the difficulties of small key space and long time consumption of the chaotic system are overcome. In addition, the chaotic sequence dynamically selects the DNA coding and operation rule for each pixel value, greatly increases the coding difficulty and the decryption difficulty. Therefore, the present application can safely and efficiently realize the encryption of image information.

[0006] A color image encryption method based on 1-LDCMS system and dynamic DNA coding, comprising the following steps:

[0007] Step S1: Channel decomposition of the image, input the color plaintext image P(M,N,3), and decompose the color image into R, G and B channel matrices;

[0008] Step S2: generating a key related to the plaintext a, using the mean value of each channel matrix of the plaintext image to generate the required key in the algorithm:

[0009] a = 8 + floor(mean(P) x 10 -2 )

[0010] Where, floor() is the floor function, and mean() is the average value function.

[0011] Step S3: generating chaotic sequence and key sequence, the key is input into the chaotic system as initial value and control parameter, respectively, wherein the chaotic sequence is generated by the 1-LDCMS system after system iteration, the chaotic sequence is generated by the Chebyshev chaotic system after iteration, and the key sequence is generated after the chaotic sequence is subjected to cyclic shift operation:

[0012] (1) Process of generating chaotic sequence by 1-LDCMS system

[0013] The key a related to plaintext, the known key b and x(1) generated in step S2 are input into the 1-LDCMS system, in order to avoid transient effect and improve randomness, the chaotic system is first iterated for N times, wherein N is between 300 and 500, then the results of the first N iterations are discarded and the iteration is continued for MN times to generate the chaotic sequence Seq.

[0014] (2) Process of generating key sequence by Chebyshev chaotic system

[0015] The known key p and k(1) are input into the Chebyshev chaotic system, and the chaotic sequence is generated after iteration for MN times; then the chaotic sequence is converted into a decimal integer between 1 and 255, and then converted into binary; finally, the binary chaotic sequence is subjected to cyclic shift operation to obtain the key sequence K_Seq:

[0016] K_Seq=cirshift(K_Seq,1)

[0017] Wherein, cirshift() is a cyclic shift function.

[0018] Step S4: the channel matrix is subjected to dynamic DNA encoding, DNA addition, DNA XOR, DNA subtraction and DNA complementary operation, respectively, wherein the DNA encoding and various DNA operation control rules are generated by the chaotic sequence, and the generation process and various DNA operations are as follows:

[0019] Step S41: the 1-LDCMS system is iterated for 4MN times on the basis of step S3 to generate the chaotic sequence S, and the chaotic sequence is converted into a decimal integer between 1 and 255:

[0020] S=abs(round(S*255))

[0021] Wherein, abs() is an absolute value function, and round() is a rounding function.

[0022] Step S42: the DNA encoding and various DNA operation control rules are generated after S is subjected to numerical processing:

[0023] R1=mod(S(1:MN),8)+1

[0024] R2=mod(S(MN+1:2MN),8)+1

[0025] R3=mod(S(2MN+1:3MN),8)+1

[0026] R4=mod(S(3MN+1:4MN),8)+1

[0027] Among them, mod() is the modulo function.

[0028] Step S43: DNA encoding is performed under the control of R1, DNA addition is performed under the control of R2, DNA XOR is performed under the control of R3, and DNA subtraction is performed under the control of R4. Each pixel value has its own DNA operation rule. The DNA encoding rule table, DNA addition rule table, DNA XOR rule table, and DNA subtraction rule table are as follows:

[0029] Table 1 DNA coding rules

[0030] Rules Rule 1 Rule 2 Rule 3 Rule 4 Rule 5 Rule 6 Rule 7 Rule 8 00 A A C C G G T T 01 C G A T A T C G 10 G C T A T A G C 11 T T G G C C A A

[0031] Table 2 DNA addition rules

[0032] + A C G T A A C G T C C A T G G G T A C T T G C A

[0033] Table 3 DNA XOR rule table

[0034]

[0035] Table 4 DNA subtraction rules

[0036] - A C G T A C G T A C A C G T G T A C G T G T A C

[0037] Step S44: In addition to the above DNA operations, a DNA complementation operation is also required. The specific complementary rules are: A and T are complementary, and C and G are complementary.

[0038] Step S5: The obtained DNA matrix is ​​subjected to index scrambling under the control of the chaotic sequence to disrupt the positions of each base and achieve bit-level scrambling:

[0039] Step S51: Sort the chaotic sequence obtained in step S3 in ascending order to obtain a sorted sequence S and an index sequence Index:

[0040] [S,Index] = sort(Seq)

[0041] Among them, sort() is a sorting function, which defaults to ascending order.

[0042] Step S52: Taking the R channel matrix as an example, the DNA matrix is ​​scrambled using the index sequence to disrupt the position of each base:

[0043] t=R_DNA(i)

[0044] R_DNA(i)=R_DNA(Index(i))

[0045] R_DNA(Index(i))=t

[0046] i=1,2,...,size(R_DNA,1)

[0047] Step S6: In order to convert the DNA matrix into a decimal pixel matrix, the scrambled DNA matrix is ​​subjected to dynamic DNA decoding;

[0048] Step S7: The matrix after DNA decoding is subjected to bitwise XOR operation and channel matrix merging operation:

[0049] Step S71: Perform a bitwise XOR operation on the key sequence K_Seq, the chaotic sequence Seq, and the DNA matrix R_DDNA after DNA decoding generated in step S2. The process is as follows:

[0050] C=bitxor(bitxor(Seq,Key_Seq),R_DDNA)

[0051] Among them, bitxor() is a bitwise exclusive OR function.

[0052] Step S72: Merge the channel matrices and output the ciphertext image to complete the encryption.

[0053] Step S8: Image decryption process:

[0054] (1) Decompose the encrypted image C into channels first, and then perform an XOR operation on it;

[0055] (2) After DNA encoding, reverse index scrambling is continued;

[0056] (3) performing DNA complementation, DNA addition, DNA XOR, DNA subtraction, and DNA decoding operations in sequence;

[0057] (4) Merge the channel matrices to obtain the decrypted image.

[0058] The beneficial effects of the above technical solution are:

[0059] (1) This scheme adopts a diffusion-scrambling-diffusion structure. Compared with the classic scrambling-diffusion structure, it has an additional diffusion operation, which can effectively enhance the security of the algorithm.

[0060] (2) The chaotic mapping used in the present application is an improved one-dimensional chaotic mapping and a Chebyshev chaotic mapping, the improved chaotic mapping can overcome the shortcoming that the chaotic characteristics of a low-dimensional chaotic system are not obvious, and the double chaotic mapping can ensure the key space of the algorithm.

[0061] (3) The algorithm adopts the combination of an external key and a key related to plaintext, so that the key space is larger, the robustness is stronger, and the key of the algorithm is more sensitive.

[0062] (4) When the pixel value is DNA encoded, the encoding rule is randomly controlled by a chaotic sequence, so that the randomness of the algorithm is enhanced. In addition, a series of complex DNA operations not only greatly change the size of the pixel value, but also increase the difficulty of decryption. BRIEF DESCRIPTION OF DRAWINGS

[0063] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the present application will be described in detail below with reference to the drawings and detailed embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings. Among them:

[0064] Figure 1 Flow chart of color image encryption method based on 1-LDCMS system and dynamic DNA encoding;

[0065] Figure 2 Bifurcation diagram of 1-LDCMS system;

[0066] Figure 3 Bifurcation diagram of Chebyshev chaotic mapping;

[0067] Figure 4 Decryption simulation experiment result graph; wherein (a), (b), (c) are the original image, the encrypted image and the decrypted image of Lena respectively, (d), (e), (f) are the original image, the encrypted image and the decrypted image of Baboon respectively, (g), (h), (i) are the original image, the encrypted image and the decrypted image of Peppers respectively;

[0068] Figure 5 R, G, B channel histogram of plaintext image and ciphertext image; wherein (a), (b), (c) are the R, G, B channel histograms of the plaintext image respectively, (d), (e), (f) are the R, G, B channel histograms of the encrypted image respectively;

[0069] Figure 6The scatter plots of the correlation between adjacent pixels in the R channel of the plaintext image and the ciphertext image are shown in Figure 2. (a), (b), and (c) are the distributions of adjacent pixel points in the horizontal, vertical, and diagonal directions of the R channel of the plaintext image, respectively; (d), (e), and (f) are the distributions of adjacent pixel points in the horizontal, vertical, and diagonal directions of the R channel of the encrypted image, respectively.

[0070] Figure 7 The scatter plots of the correlation between adjacent pixels of the G channel of the plaintext image and the ciphertext image are shown in Figure 2. (a), (b), and (c) are the distributions of adjacent pixel points in the horizontal, vertical, and diagonal directions of the G channel of the plaintext image, respectively; (d), (e), and (f) are the distributions of adjacent pixel points in the horizontal, vertical, and diagonal directions of the G channel of the encrypted image, respectively.

[0071] Figure 8 The scatter plots are the correlation plots of adjacent pixels in the B channel of the plaintext image and the ciphertext image. (a), (b), and (c) are the distributions of adjacent pixel points in the horizontal, vertical, and diagonal directions of the B channel of the plaintext image, respectively; (d), (e), and (f) are the distributions of adjacent pixel points in the horizontal, vertical, and diagonal directions of the B channel of the encrypted image, respectively. DETAILED DESCRIPTION

[0072] The implementation of the present invention is carried out on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0073] The specific implementation process of the color image encryption method based on the 1-LDCMS system and dynamic DNA coding is as follows:

[0074] 1. Key Generation

[0075] Step 1: Generate a key related to the plaintext, and use the mean value of each channel matrix of the plaintext image to generate the key required in the algorithm:

[0076] a=8+floor(mean(P)×10 -2 )

[0077] Among them, floor() is the floor function, and mean() is the average function.

[0078] Step 2: Given a known key, where b=5, x(1)=0.7, p=3.628, k(1)=0.632.

[0079] 2. Generation of Chaotic Sequences and Key Sequences

[0080] (1) The process of generating chaotic sequences in 1-LDCMS system

[0081] The generated plaintext-related key a, known key b, x(1) are input into the 1-LDCMS system, the chaotic system is first iterated N times in order to avoid transient effects and improve randomness, wherein N is between 300-500, then the results of the first N iterations are discarded and the chaotic system is iterated MN times to generate a chaotic sequence Seq.

[0082] (2) Process of generating key sequence by Chebyshev chaotic system

[0083] The known key p, k(1) are input into the Chebyshev chaotic system and iterated MN times to generate a chaotic sequence; then the chaotic sequence is converted into a decimal integer between 1-255, the decimal is converted into binary, and finally the binary chaotic sequence is subjected to a cyclic shift operation to obtain a key sequence K_Seq:

[0084] K_Seq = cirshift(K_Seq, 1)

[0085] Wherein, cirshift() is a cyclic shift function.

[0086] III. Image encryption processing

[0087] (1) Dynamic DNA encoding and DNA operation process

[0088] Step 1: The 1-LDCMS system is iterated 4MN times to generate a chaotic sequence S, and the chaotic sequence is converted into a decimal integer between 1-255:

[0089] S = abs(round(S*255))

[0090] Wherein, abs() is an absolute value function, and round() is a rounding function.

[0091] Step 2: Continue to generate DNA encoding and control rules for various DNA operations after numerical processing of S:

[0092] R1 = mod(S(1:MN), 8) + 1

[0093] R2 = mod(S(MN+1:2MN), 8) + 1

[0094] R3 = mod(S(2MN+1:3MN), 8) + 1

[0095] R4 = mod(S(3MN+1:4MN), 8) + 1

[0096] Wherein, mod() is a modulus function.

[0097] Step 3: DNA encoding under the control of R1, DNA addition under the control of R2, DNA XOR under the control of R3, and DNA subtraction under the control of R4, each pixel value has its own DNA operation rule. Among them, the DNA encoding rule table, the DNA addition rule table, the DNA XOR rule table, and the DNA subtraction rule table are as follows:

[0098] Table 1 DNA encoding rule table

[0099] Rules Rule 1 Rule 2 Rule 3 Rule 4 Rule 5 Rule 6 Rule 7 Rule 8 00 A A C C G G T T 01 C G A T A T C G 10 G C T A T A G C 11 T T G G C C A A

[0100] Table 2 DNA addition rule table

[0101] + A C G T A A C G T C C A T G G G T A C T T G C A

[0102] Table 3 DNA XOR rule table

[0103]

[0104] Table 4 DNA subtraction rule table

[0105] - A C G T A C G T A C A C G T G T A C G T G T A C

[0106] Step 4: In addition to the above DNA operations, DNA complementary operations are also required. The specific complementary rules are: A is complementary to T, and C is complementary to G. After DNA encoding and various DNA operations are completed, the image realizes DNA-level diffusion.

[0107] (1) Index scrambling process

[0108] Step 1: Sort the chaotic sequence obtained from the 1-LDCMS system in ascending order to obtain the sorted sequence S and the index sequence Index:

[0109] [S, Index] = sort(Seq)

[0110] Where sort() is the sorting function, and the default is ascending sorting.

[0111] Step 2: Take the R channel matrix as an example, use the index sequence to scramble the DNA matrix, and disturb the positions of each base:

[0112] t = R_DNA(i)

[0113] R_DNA(i) = R_DNA(Index(i))

[0114] R_DNA(Index(i)) = t

[0115] i = 1, 2,..., size(R_DNA, 1)

[0116] (2) XOR operation process

[0117] The key sequence K_Seq, the chaotic sequence Seq and the DNA matrix R_DDNA after DNA decoding are subjected to bitwise XOR operation to obtain the encrypted image C. Although this method is simple and easy to implement, it can effectively change the size of the pixel value.

[0118] C=bitxor(bitxor(Seq,Key_Seq),R_DDNA)

[0119] Among them, bitxor() is a bitwise exclusive OR function.

[0120] 4. Image Decryption Processing

[0121] Step 1: Decompose the encrypted image C into channels first, and then perform XOR operation;

[0122] Step 2: After DNA encoding, proceed to reverse index scrambling;

[0123] Step 3: Perform DNA complementation, DNA addition, DNA XOR, DNA subtraction, and DNA decoding operations in sequence;

[0124] Step 4: Merge the channel matrices to obtain the decrypted image P'.

[0125] To further verify the effectiveness and safety of the present invention, Matlab R2020a was used as an experimental platform on a Windows 10 system to verify the present invention. The following analysis was performed in conjunction with the data in the accompanying drawings and tables:

[0126] Table 5 Comparison of the correlation coefficient of the Lena image of the present invention and existing literature

[0127]

[0128] Table 6 Comparison of the information entropy of the Lena image of the present invention with that of existing literature

[0129]

[0130] Table 7 Time performance of the present invention and comparison with existing literature

[0131] Algorithm Image Encryption time (s) Decryption time (s) The invention Baboon 0.61 0.65 The invention Peppers 0.58 0.60 The invention Lena 0.59 0.62 Wang[3] Lena 19.14 20.93 Wen[4] Lena 0.64 -

[0132] from Figure 4 It can be seen that the encrypted image is in the shape of snowflake noise, and no valid information of the original image can be identified at all. The decrypted image restores the valid information of the original image, indicating that the encryption and decryption effects of the present invention are good.

[0133] from Figure 5It can be seen that the statistical characteristics in the histogram of each channel of the plaintext image are obvious and are vulnerable to attacks. The pixel values of each channel of the encrypted image are uniformly distributed, and the encrypted image can effectively resist statistical attacks.

[0134] From Figure 6 , Figure 7 , Figure 8 It can be seen that the adjacent pixel points in different directions of each channel of the plaintext image are concentrated on the diagonal and are positively correlated, and the correlation degree is high. The adjacent pixel points in different directions of each channel of the encrypted image are uniformly distributed and are in a random distribution state, which indicates that the present application can effectively reduce the correlation of adjacent pixels and improve the security of image transmission. In addition, from Table 5, it can be seen that the correlation coefficients of the adjacent pixel points in different directions of each channel of the encrypted image are close to 0, and the correlation has been effectively reduced. It indicates that the present application can effectively reduce the correlation of adjacent pixels and improve the security of image transmission.

[0135] From Table 6, it can be seen that the information entropy of the R, G and B channels of the encrypted image is close to 8, which indicates that the gray scale distribution is not uniform, the statistical characteristics are well hidden, and the difficulty for an attacker to obtain the plaintext image by analyzing the information entropy value is increased.

[0136] From Table 7, it can be seen that the present application can effectively encrypt and decrypt the image within 0.65s, and the encryption and decryption process is fast and efficient. In addition, the present application also has certain advantages compared with the encryption and decryption time of existing literature.

[0137] The above is only to illustrate the present application, and it should be understood that the present application is not limited to the above embodiments, and various modifications in accordance with the present application should be within the scope of the present application.

Claims

1. A color image encryption method based on a 1-LDCMS system and dynamic DNA coding, characterized by: The following steps are involved: Step S1: channel decomposition of the image: input the color plaintext image P(M,N,3), and decompose the color image into R, G, and B channel matrices; Step S2: Generate a key related to the plaintext, and use the mean value of each channel matrix of the plaintext image to generate the key required in the algorithm: a=8+floor(mean(P)×10 -2 ) Among them, floor() is the function of rounding down, and mean() is the function of taking the average value; Two types of chaotic mapping are used: (1) The mathematical definition of the 1-LDCMS system is as follows: x n+1 =a 8 (1+8asin(πx n ) b )mod1 Among them, x n is the variable of 1-LDCMS system, a and b are the control parameters of 1-LDCMS system, x n+1 ∈[0,1], a∈[0.59,15]; (2) The mathematical definition of the Chebyshev chaotic system is as follows: k n+1 =cos(parccosk n ) Among them, k n is the variable of the Chebyshev chaotic system, p is the control parameter of the Chebyshev chaotic system, k n+1 ∈[0,1]; Step S3: The key is input into the chaotic system as the initial value and control parameter respectively. The 1-LDCMS system generates a chaotic sequence after system iteration, and the Chebyshev chaotic system generates a chaotic sequence after iteration. The chaotic sequence is then subjected to a cyclic shift operation to generate a key sequence. The steps for generating the chaotic sequence and key sequence are as follows: (1) The process of generating chaotic sequences in 1-LDCMS system The key a, known key b, and x(1) related to the plaintext generated in step S2 are input into the 1-LDCMS system. The chaotic system first iterates N times, where N is between 300 and 500, and then discards the results of the first N iterations and continues to iterate MN times to generate a chaotic sequence Seq. (2) The process of generating key sequence by Chebyshev chaotic system The known keys p and k (1) are input into the Chebyshev chaotic system and iterated MN times to generate a chaotic sequence. The chaotic sequence is then converted into a decimal integer between 1 and 255, and then the decimal is converted into binary. Finally, the binary chaotic sequence is subjected to a cyclic shift operation to obtain the key sequence Key_Seq: Key_Seq=cirshift(Key_Seq,1) Among them, cirshift() is the circular shift function; Step S4: The channel matrix is ​​subjected to dynamic DNA encoding, DNA addition, DNA XOR, DNA subtraction, and DNA complementation operations, wherein the DNA encoding and the above DNA operation rules are generated by the chaotic sequence; after the DNA operation and calculation, a new DNA matrix is ​​generated; Step S5: The obtained DNA matrix is ​​subjected to index scrambling under the control of the chaotic sequence to disrupt the positions of each base and achieve bit-level scrambling; Step S6: performing dynamic DNA decoding on the scrambled DNA matrix to convert the DNA matrix into a decimal pixel matrix; Step S7: Perform an XOR operation on the matrix after DNA decoding, the chaotic sequence, and the key sequence, and combine the channel matrix to output the ciphertext image, and the encryption is completed; Step S8: Decrypt the image.

2. The color image encryption method based on the 1-LDCMS system and dynamic DNA coding according to claim 1 is characterized in that: The generation of DNA encoding, DNA computing control rules, and DNA complementation operations in step S4 are as follows: Step S41: The 1-LDCMS system is iterated 4MN times based on step S3 to generate a chaotic sequence S, and the chaotic sequence is converted into a decimal integer between 1 and 255: S = abs(round(S*255)) Among them, abs() is the absolute value function, and round() is the rounding function; Step S42: Continue to perform numerical processing on S to generate DNA coding and DNA operation control rules: R1=mod(S(1:MN),8)+1 R2=mod(S(MN+1:2MN),8)+1 R3=mod(S(2MN+1:3MN),8)+1 R4=mod(S(3MN+1:4MN),8)+1 Among them, mod() is the modulo function; Step S43: DNA encoding is performed under the control of R1, DNA addition is performed under the control of R2, DNA XOR is performed under the control of R3, and DNA subtraction is performed under the control of R4. Each pixel value has its own DNA operation. The DNA encoding rules, DNA addition rules, DNA XOR rules, and DNA subtraction rules are as follows: DNA encoding rules: When the input is 00, the corresponding bases are A, A, C, C, G, G, T, T; When the input is 01, the corresponding bases are C, G, A, T, A, T, C, G; When the input is 10, the corresponding bases are G, C, T, A, T, A, G, C; When the input is 11, the corresponding bases are T, T, G, G, C, C, A, A; DNA addition rules: A+A=A, A+C=C, A+G=G, A+T=T; C+A=C, C+C=A, C+G=T, C+T=G; G+A=G, G+C=T, G+G=A, G+T=C; T+A=T, T+C=G, T+G=C, T+T=A; DNA XOR rule: If the two bases are the same, the result is A; if the two bases are different, the calculation is based on the following rules: A⊕C=C, A⊕G=G, A⊕T=T; C⊕G=T,C⊕T=G; G⊕T=C; DNA subtraction rules: AA = C, AC = G, AG = T, AT = A; CA=A, CC=C, CG=G, CT=T; GA=T, GC=A, GG=C, GT=G; TA=G, TC=T, TG=A, TT=C; Step S44: Perform DNA complementation operation again, the specific complementation rules are: A and T are complementary, and C and G are complementary.

3. The color image encryption method based on the 1-LDCMS system and dynamic DNA coding according to claim 1 is characterized in that: The index scrambling steps in step S5 are as follows: Step S51: Sort the chaotic sequence obtained in step S3 in ascending order to obtain a sorted sequence S and an index sequence Index: [S,Index] = sort(Seq) Among them, sort() is a sorting function, which defaults to ascending order; Step S52: Use the index sequence Index to perform row permutation on the DNA matrices of the R channel, G channel, and B channel to disrupt the positions of each base. The following is the calculation process of the R channel matrix: t=R_DNA(i) R_DNA(i)=R_DNA(Index(i)) R_DNA(Index(i))=t i=1,2,...,size(R_DNA,1).

4. The color image encryption method based on the 1-LDCMS system and dynamic DNA coding according to claim 1 is characterized in that: The XOR operation in step S7 is as follows: Perform bitwise XOR operation on the generated key sequence "Key_Sep", the chaotic sequence Seq and the DNA matrix R_DDNA after DNA decoding; C=bitxor(bitxor(Seq,Key_Seq),R_DDNA) Among them, bitxor() is a bitwise exclusive OR function.

5. The color image encryption method based on the 1-LDCMS system and dynamic DNA coding according to claim 1 is characterized in that: The image decryption process in step S8 is as follows: (1) Decompose the encrypted image C into channels first, and then perform an XOR operation on it; (2) After DNA encoding, reverse index scrambling is continued; (3) performing DNA complementation, DNA addition, DNA XOR, DNA subtraction, and DNA decoding operations in sequence; (4) Merge the channel matrices to obtain the decrypted image.

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