阅读说明：本技术 输电线路图像数据加密和解密方法 (Power transmission line image data encryption and decryption method ) 是由 张迪 于 2021-09-02 设计创作，主要内容包括：一种输电线路图像数据加密方法,包括以下步骤：一、对原图像进行预处理和像素置乱得到第一加密图像；二、利用原图像生成用于对图像加密的哈希值密钥；三、基于所述密钥得到四条混沌序列；四、基于所述密钥,利用得到加密数字矩阵；五、对加密矩阵和第一加密图像进行DNA编码得到第一加密矩阵和第二加密图像；六、将第一加密矩阵和第二加密图像进行DNA加密运算并对运算结果进行DNA解码得到第三加密图像。(A method for encrypting image data of a power transmission line comprises the following steps: firstly, preprocessing and pixel scrambling are carried out on an original image to obtain a first encrypted image; generating a hash value key for encrypting the image by using the original image; thirdly, four chaotic sequences are obtained based on the secret key; fourthly, based on the secret key, an encrypted digital matrix is obtained through utilization; fifthly, carrying out DNA coding on the encryption matrix and the first encrypted image to obtain a first encryption matrix and a second encrypted image; and sixthly, performing DNA encryption operation on the first encryption matrix and the second encryption image, and performing DNA decoding on an operation result to obtain a third encryption image.)

1. A method for encrypting image data of a power transmission line is characterized by comprising the following steps:

firstly, preprocessing and pixel scrambling are carried out on an original image to obtain a first encrypted image;

generating a hash value key for encrypting the image by using the original image;

thirdly, four chaotic sequences are obtained based on the secret key;

fourthly, based on the secret key, an encrypted digital matrix is obtained through utilization;

fifthly, carrying out DNA coding on the encryption matrix and the first encrypted image to obtain a first encryption matrix and a second encrypted image;

and sixthly, performing DNA encryption operation on the first encryption matrix and the second encryption image, and performing DNA decoding on an operation result to obtain a third encryption image.

2. The method according to claim 1, wherein the preprocessing and the pixel scrambling of the original image to obtain the first encrypted image comprises performing a gray processing on the original image and resizing the original image to 256 x 256; then, diagonal pixels of the original image are extracted and recombined to obtain the first encrypted image;

the generating of the hash value key for encrypting the image by using the original image includes performing hash value extraction on the original image by using an SHA-3 algorithm, and using the obtained hash value as the key of the image encryption algorithm.

3. The method for encrypting the image data of the power transmission line according to claim 1, wherein the obtaining of the four chaotic sequences comprises solving the Chen hyperchaotic system by using the Hash value key as an input initial value of the Chen hyperchaotic system and using a Runge-Kutta differential solving method to obtain the four chaotic sequences;

obtaining the encrypted number matrix comprises iterating the secret key by using the SHA-3 algorithm, obtaining eight binary sequences with the length of 256 after eight times, changing the sequences into decimal numbers to obtain eight number sequences with the length of 32, and then recombining the decimal number sequences to obtain a 16 x 16 encrypted matrix.

4. The method for encrypting the image data of the power transmission line according to any one of claims 1 to 3, wherein the step of performing DNA encoding on the encryption matrix and the first encrypted image to obtain the first encryption matrix and the second encrypted image comprises the steps of:

mapping a DNA coding rule by using a first chaotic sequence of the four chaotic sequences, and carrying out DNA coding on the first encrypted image to obtain a second encrypted image; and mapping a DNA coding rule by using a second chaotic sequence of the four chaotic sequences, and carrying out DNA coding on the encryption matrix to obtain the first encryption matrix.

5. The method for encrypting the image data of the power transmission line according to claim 4, wherein performing DNA encryption operation on the first encryption matrix and the second encryption image and performing DNA decoding on the operation result to obtain a third encryption image comprises performing DNA operation on the first encryption matrix and the second encryption image by mapping a DNA operation rule by using a third chaotic sequence of the four chaotic sequences to obtain an operation result; and mapping a DNA coding rule by using a fourth chaotic sequence of the four chaotic sequences, and carrying out DNA decoding on the operation result to obtain the third encrypted image.

6. The decryption method of the power transmission line image data encryption method according to claim 1, comprising the steps of:

obtaining the third encrypted image and an encryption key sequence related to the encrypted image;

secondly, obtaining an encryption matrix according to the encryption key sequence;

thirdly, four hyperchaotic sequences are obtained according to the encryption key sequence;

fourthly, performing DNA coding on the encryption matrix by using the four hyperchaotic sequences to obtain a first encryption matrix;

fifthly, performing DNA coding on the third encrypted image by using the four hyperchaotic sequences, and performing DNA inverse operation on the third encrypted image and the first encrypted matrix to obtain a second encrypted image;

sixthly, performing DNA inverse coding on the second encrypted image by using the four hyperchaotic sequences to obtain the first encrypted image;

and seventhly, restoring the first encrypted image pixel, and performing color processing to obtain the original image.

7. The decryption method according to claim 6, wherein the obtaining of the encryption matrix from the sequence of encryption keys comprises iterating the keys using the SHA-3 algorithm, eight times later obtaining eight binary sequences of length 256, taking the sequences into decimal form to obtain eight digit sequences of length 32, and then recombining the decimal sequences to obtain a 16 x 16 encryption matrix; the encryption of the key sequence to obtain four hyperchaotic sequences comprises the steps of utilizing the hash value key as an input initial value of the Chen hyperchaotic system, and utilizing a Runge-Kutta differential solving method to solve the Chen hyperchaotic system to obtain four hyperchaotic sequences.

8. The decryption method according to claim 6, wherein the four hyper-chaotic sequences perform DNA encoding on the encryption matrix to obtain the first encryption matrix, and the DNA encoding on the encryption matrix to obtain the first encryption matrix is performed by mapping a DNA encoding rule with a second chaotic sequence of the four chaotic sequences.

9. The decryption method according to claim 6, wherein the performing DNA encoding on the third encrypted image using the four hyper-chaotic sequences and then performing DNA inverse operation with the first encryption matrix to obtain the second encrypted image comprises performing DNA encoding on the third encrypted image by mapping a DNA encoding rule with a fourth chaotic sequence of the four hyper-chaotic sequences, and performing DNA inverse operation on the third encrypted image after the DNA encoding and the first encryption matrix by mapping a DNA encoding rule with a third chaotic sequence of the four hyper-chaotic sequences to obtain the second encryption matrix.

10. The decryption method according to claim 6, wherein the second encrypted image performs inverse DNA coding using the four hyper-chaotic sequences to obtain the first encrypted image comprises performing DNA decoding on the second encrypted image using a first chaotic sequence mapping DNA coding rule of the four hyper-chaotic sequences to obtain the first encrypted image;

and the first encrypted image is subjected to pixel reduction and color processing to obtain the original image, wherein the step of equally dividing the first encrypted image into 256 parts of sub-matrixes from left to right and from top to bottom is carried out, then the 256 parts of sub-matrixes are reduced into original diagonal pixels to obtain a gray original image, and the gray original image is subjected to color processing to obtain the original image.

Technical Field

The present invention relates to the field of information security, and more particularly to methods for encrypting and decrypting power line images.

Background

Digital images are a common form of multimedia, and image file formats typically include JPG, BMP, GIF, and the like. Images can be classified into color images, which can represent the color of ten pixels using three primary colors of red, green, and blue, and gray images, which have only one color for ten pixels, which are generally displayed in gray scales from darkest black to brightest white, according to whether color information is included. For example, each pixel typically uses 8 bits to represent the gray scale value of the pixel, and there may be 256 gray scale levels per pixel.

The power transmission and distribution network of the power system is an important national facility, and the safe and stable transmission of the related power inspection data is an important guarantee for the reliable operation of the power system. Along with the rapid development of the unmanned aerial vehicle inspection technology, the unmanned aerial vehicle inspection technology gradually replaces the traditional manual inspection to become the mainstream mode of power inspection. However, the amount of transmission engineering of massive picture data caused by unmanned aerial vehicle inspection is huge, and data needs to be transmitted in real time by means of an efficient 5G network. The increasingly huge power routing inspection data enables facility information of a power system to be more refined, and the power data is leaked and damaged due to the fact that threats such as illegal stealing and hacking exist in the data transmission process, so that the power safety problem cannot be ignored.

With the development of communication technology, images are frequently transmitted between different devices, and image security has become a focus, for example, in image sharing and video conferencing. In order to ensure the security of the image content, the image needs to be encrypted by adopting a computer encryption technology. Different from the traditional text encryption mode, the power transmission line image has the characteristics of large data content, complex structure and the like, so that the traditional text encryption method is not suitable for encrypting the power transmission line image. In addition, some existing image encryption methods have extremely low image encryption efficiency, take a lot of time, have insufficient encryption security, and are easy to attack or crack.

Disclosure of Invention

The invention aims to solve the technical problem of providing an image encryption and decryption method suitable for an unmanned aerial vehicle power inspection scene of a power transmission line. According to the invention, the transmission line image is encrypted by using a combination mode of the hyperchaotic system and the DNA coding, so that the image encryption efficiency can be improved, and the image encryption safety can be improved.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method for encrypting image data of a power transmission line comprises the following steps:

firstly, preprocessing and pixel scrambling are carried out on an original image to obtain a first encrypted image;

generating a hash value key for encrypting the image by using the original image;

thirdly, four chaotic sequences are obtained based on the secret key;

fourthly, based on the secret key, an encrypted digital matrix is obtained through utilization;

fifthly, carrying out DNA coding on the encryption matrix and the first encrypted image to obtain a first encryption matrix and a second encrypted image;

sixthly, performing DNA encryption operation on the first encryption matrix and the second encryption image, and performing DNA decoding on an operation result to obtain a third encryption image;

preferably, the preprocessing and the pixel scrambling of the original image to obtain the first encrypted image includes performing gray processing on the original image, and adjusting the size of the original image to 256 × 256; then, diagonal pixels of the original image are extracted and recombined to obtain the first encrypted image;

the generating of the hash value key for encrypting the image by using the original image includes performing hash value extraction on the original image by using an SHA-3 algorithm, and using the obtained hash value as the key of the image encryption algorithm.

Preferably, the obtaining of the four chaotic sequences comprises solving the Chen hyperchaotic system by using the Hash value key as an input initial value of the Chen hyperchaotic system and using a Runge-Kutta differential solving method to obtain the four chaotic sequences;

obtaining the encrypted number matrix comprises iterating the secret key by using the SHA-3 algorithm, obtaining eight binary sequences with the length of 256 after eight times, changing the sequences into decimal numbers to obtain eight number sequences with the length of 32, and then recombining the decimal number sequences to obtain a 16 x 16 encrypted matrix.

Preferably, the obtaining of the first encryption matrix and the second encryption image by performing DNA encoding on the encryption matrix and the first encryption image includes:

mapping a DNA coding rule by using a first chaotic sequence of the four chaotic sequences, and carrying out DNA coding on the first encrypted image to obtain a second encrypted image; and mapping a DNA coding rule by using a second chaotic sequence of the four chaotic sequences, and carrying out DNA coding on the encryption matrix to obtain the first encryption matrix.

Preferably, performing DNA encryption operation on the first encryption matrix and the second encryption image and performing DNA decoding on an operation result to obtain a third encryption image includes mapping a DNA operation rule with a third chaotic sequence of the four chaotic sequences, and performing DNA operation on the first encryption matrix and the second encryption image to obtain an operation result; and mapping a DNA coding rule by using a fourth chaotic sequence of the four chaotic sequences, and carrying out DNA decoding on the operation result to obtain the third encrypted image.

A decryption method of an image data encryption method of a power transmission line comprises the following steps:

obtaining the third encrypted image and an encryption key sequence related to the encrypted image;

secondly, obtaining an encryption matrix according to the encryption key sequence;

thirdly, four hyperchaotic sequences are obtained according to the encryption key sequence;

fourthly, performing DNA coding on the encryption matrix by using the four hyperchaotic sequences to obtain a first encryption matrix;

fifthly, performing DNA coding on the third encrypted image by using the four hyperchaotic sequences, and performing DNA inverse operation on the third encrypted image and the first encrypted matrix to obtain a second encrypted image;

sixthly, performing DNA inverse coding on the second encrypted image by using the four hyperchaotic sequences to obtain the first encrypted image;

and seventhly, restoring the first encrypted image pixel, and performing color processing to obtain the original image.

Preferably, the obtaining an encryption matrix according to the encryption key sequence includes iterating the key by using the SHA-3 algorithm, obtaining eight binary sequences with a length of 256 after eight times, changing the sequences into decimal sequences to obtain eight number sequences with a length of 32, and then recombining the decimal sequences to obtain a 16 × 16 encryption matrix; the encryption of the key sequence to obtain four hyperchaotic sequences comprises the steps of utilizing the hash value key as an input initial value of the Chen hyperchaotic system, and utilizing a Runge-Kutta differential solving method to solve the Chen hyperchaotic system to obtain four hyperchaotic sequences.

Preferably, the four hyper-chaotic sequences perform DNA coding on the encryption matrix to obtain the first encryption matrix, and the DNA coding is performed on the encryption matrix to obtain the first encryption matrix by mapping a DNA coding rule with a second chaotic sequence of the four chaotic sequences.

Preferably, the DNA coding of the third encrypted image by using the four hyper-chaotic sequences, and then performing DNA inverse operation with the first encrypted matrix to obtain the second encrypted image includes mapping DNA coding rules with the fourth hyper-chaotic sequences of the four hyper-chaotic sequences, performing DNA coding on the third encrypted image, and performing DNA inverse operation with the third chaotic sequences of the four hyper-chaotic sequences and the first encrypted matrix to obtain the second encrypted matrix.

Preferably, the second encrypted image performs DNA inverse coding by using the four hyper-chaotic sequences to obtain the first encrypted image, and the first encrypted image performs DNA decoding on the second encrypted image by using a first chaotic sequence mapping DNA coding rule of the four hyper-chaotic sequences to obtain the first encrypted image;

and the first encrypted image is subjected to pixel reduction and color processing to obtain the original image, wherein the step of equally dividing the first encrypted image into 256 parts of sub-matrixes from left to right and from top to bottom is carried out, then the 256 parts of sub-matrixes are reduced into original diagonal pixels to obtain a gray original image, and the gray original image is subjected to color processing to obtain the original image.

The invention provides a method for encrypting and decrypting image data of a power transmission line, which has the following beneficial effects:

1. the important power transmission line image data collected by the unmanned aerial vehicle can be encrypted, and data loss or damage caused by hacker attack or natural severe environment is avoided, so that benefit loss of state network companies is avoided.

2. The algorithm is small in size, high in operation speed and low in required equipment performance, can be combined with various unmanned aerial vehicle front-end equipment, achieves front-end encryption and rear-end decryption of data, guarantees real-time performance of data encryption, and further strengthens safety of the data.

3. The algorithm uses the SHA-3 algorithm to generate the image key, realizes one image key, reduces the storage difficulty of the data key on the premise of ensuring the data security, and improves the efficiency of data encryption and decryption.

Drawings

The invention is further illustrated by the following examples in conjunction with the accompanying drawings:

fig. 1 is a schematic diagram of an application scenario of the method for encrypting and decrypting the image of the power transmission line according to the present invention;

FIG. 2 is a flow chart of an image encryption method of the present invention;

FIG. 3 is a diagram illustrating an image encryption process according to another embodiment of the present invention;

FIG. 4 is a flow chart of an image decryption method of the present invention;

FIG. 5 is a diagram illustrating an image decryption process according to another embodiment of the present invention;

Detailed Description

As shown in fig. 1, the unmanned aerial vehicle power inspection data transmission process includes several parts, namely, data acquisition by the unmanned aerial vehicle microcomputer 120, image data encryption 130, image data return 140, image data reception 150, image data decryption 160, and manual line maintenance 170. Because the data backhaul part uses the open 5G network, the data backhaul part is attacked by hackers, and the risk of data leakage is relatively high. According to the embodiment of the disclosure, data encryption is added after data acquisition, each acquired electric power system picture is encrypted by using an airborne microcomputer of an unmanned aerial vehicle and then is transmitted back to a ground receiving station for image decryption and subsequent image processing, even if data leakage is caused by hacker attack in the data transmission back process, the hacker cannot obtain the original electric power system picture on the premise of not breaking the text encryption algorithm, and damage caused by electric power data safety accidents can be reduced to the minimum.

Fig. 2 is a flowchart 200 of an image encryption method of the present invention, which should be performed after the data acquisition by the drone microcomputer 120 is completed. Preprocessing an original image and laying out eggs on pixels to obtain a first encrypted image 210, performing gray processing on the original image, and adjusting the size to be 256 multiplied by 256; and then, diagonal pixel extraction is carried out on the original image and recombination is carried out to obtain the first encrypted image. A hash value key 220 for encrypting an image is generated from an original image, and the original image is subjected to hash value extraction using the SHA-3 algorithm, and the obtained hash value is used as a key of the image encryption algorithm. Four chaotic sequences 230 are obtained based on the key, the hash value key is used as an input initial value of the Chen hyperchaotic system, and the Longge-Kutta differential solving method is used for solving the Chen hyperchaotic system to obtain four chaotic sequences.

Based on the key, using the resulting encrypted number matrix 240, the key is iterated using the SHA-3 algorithm, eight times later, eight binary sequences of length 256 are obtained, the sequences are converted into decimal numbers to obtain eight number sequences of length 32, and then the decimal sequences are recombined to obtain a 16 × 16 encryption matrix. After the encryption matrix and the first encrypted image are subjected to DNA coding to obtain a first encryption matrix and a second encrypted image 250, the first chaos sequence of the four chaos sequences is used for mapping a DNA coding rule to perform DNA coding on the first encrypted image to obtain the second encrypted image; and mapping a DNA coding rule by using a second chaotic sequence of the four chaotic sequences, and carrying out DNA coding on the encryption matrix to obtain the first encryption matrix. Performing DNA encryption operation on the first encryption matrix and the second encryption image and performing DNA decoding on an operation result to obtain a third encryption image 260, and performing DNA operation on the first encryption matrix and the second encryption image by using a third chaotic sequence mapping DNA operation rule of the four chaotic sequences to obtain an operation result; and mapping a DNA coding rule by using a fourth chaotic sequence of the four chaotic sequences, and carrying out DNA decoding on the operation result to obtain the third encrypted image.

As shown in fig. 3, after the original color picture 315 is obtained, the gray processing and zero padding operations are performed on the original color picture 315, as shown in formulas (1) and (2). The gray processing method comprises three methods, namely a maximum value method, a pixel average method and a weighted average method, wherein the maximum value method is to take the maximum pixel value in the three pixel values of red, green and blue as a gray value; the pixel averaging method is that the value obtained by adding the red, green and blue pixel values and dividing by the total number three is used as the gray value; the weighted average method is to multiply the red, green and blue pixel values by a weight and add the values to obtain a gray value, wherein the three weights are 0.299, 0.578 and 0.114 respectively. Since the human eye has the highest sensitivity to green and the lowest sensitivity to blue, the weighted average method employed by another embodiment of the present disclosure can result in a more balanced grayscale image.

Since the image encryption method of another embodiment of the present disclosure requires that the size of the input image is 256 × 256, and the sizes of the images of the power transmission lines are not the same, it is necessary to perform pixel value filling, i.e., zero padding operation on the rectangular picture, and then scale the picture that is changed into a square after zero padding to obtain the required size.

Gray＝0.299×R+0.587×G+0.114×B (1)

In the formula: r, G, B are the red, green, and blue pixel values of the image, respectively; n is the length and height of the image,is composed ofAnd (6) rounding the upper part.

Next, the gray-scale image obtained in the step of gray-scale processing and zero padding operation 315 obtains a corresponding hash value by using the SHA-3 algorithm of the hash value key 330 generated in the step of SHA-3 algorithm, and uses the hash value as a key of the encryption algorithm, the random key matrix 345 generated in the step of using is iterated for 8 times and recombined into a matrix O with a size of 16 × 16, the gray-scale image is partitioned and recombined by using the diagonal extraction method in the step 320 to obtain 256 recombination matrices with a size of 16 × 16, and the recombination matrices are pieced together in sequence to obtain the first encrypted image R', as shown in (3) and (4).

In the formula: r is_NNThe pixel value representing the original image after the gradation processing is 1,2, …, 256.

Using the hash value obtained in step 330 as the key H₁₆In step 360, four initial values x of the Chen hyperchaotic matrix are obtained by formula (5)₁(0),x₂(0),x₃(0),x₄(0) Is prepared from H₁₆According to byte division, can be divided into k₁,k₂,k₃,…,k₃₂And four chaotic sequences { X with a length of 256 are obtained by using equation (6) in step 365₁}，{X₂}，{X₃}，{X₄}。

Wherein the content of the first and second substances,

k₁＝dec2bin(hex2dec('9e'))＝{'10011110'},……,……,……,k₂＝dec2bin(hex2dec('c4'))＝{'11000100'},……,……,……,……,k₃₁＝dec2bin(hex2dec('ee'))＝{'11101110'}，k₃₂＝dec2bin(hex2dec('c0'))＝{'11000000'}。

the solving mode of the formula (6) is a Runge-Kutta differential solving equation, and the formula is shown as (7).

In the formula: and K represents a chaotic sequence generated by solving the Chen hyperchaotic equation in a Runge-Kutta mode.

Wherein, a, b, c, d and e represent control parameters of the chaotic system, and the chaotic system is in a hyperchaotic state when a is 35, b is 7, c is 12, d is 3 and e is 0.58.

Generating four chaotic sequences 365 from the Chen hyperchaotic system in the step to obtain { X in the four sequences₁}，{X₂}，{X₄Processing the sequence into numbers in 1-8 by using formula (8), wherein each number corresponds to a DNA coding or decoding mode respectively; { X₃The sequence is processed into numbers in 0-3 by using the formula (9), and each number corresponds to a DNA operation mode. The sequence { X ] is expressed by equation (10)₁}，{X₂}，{X₃}，{X₄Processing into a number matrix X of 16 × 16 size₁,X₂,X₃,X₄。

X＝mod(round(X×10⁴),8)+1 (8)

X＝mod(round(X×10⁴),4) (9)

X＝reshape(X,16,16) (10)

In the formula: x represents the number sequence to be processed, and mod, round and reshape represent functions in the Matlab program.

Using X obtained in step 365₁The matrix pair diagonal line extraction block scrambling 320 step is performed to obtain a first encrypted image, and in the step of performing DNA encoding 325 on each subblock, DNA encryption is performed to obtain a second encrypted image R ″, specifically: numbering the 256 blocks of the first encrypted picture R' in sequence, wherein the number of each sub-matrix corresponds to X₁The element i, i ∈ (1,8) at a corresponding position of the matrix is DNA-encoded. The same applies to X in the DNA encoding 350 of the encryption matrix in step₂The matrix is used to encrypt the corresponding elements in the matrix O to obtain a first encryption matrix O'.

The DNA encryption algorithm is based on biologyFour basic groups A, T, G, C of the mathematical DNA and binary pixel values are replaced under a certain rule to achieve a pixel value scrambling effect, the scrambling effect is good, time consumption is low, and the method is suitable for image data encryption of massive data scenes, and the specific rule is shown in Table 1. The scrambled image matrix R' as shown in equation (4), assuming a sub-matrix R₁ ^dnElement r of (1)₁₁＝123，X₁、X₄The medium element value corresponds to the DNA coding rule as follows:

each element in the scrambled image matrix R' and the encryption matrix O is DNA encoded and decoded as above.

Table 1: rules of DNA coding

Using matrix X₄And performing DNA operation on a second encrypted image R 'obtained by performing DNA encoding 325 on each sub-block and a first encrypted matrix O' obtained by performing DNA encoding 350 on the encrypted matrix in step 370 to obtain a DNA encrypted matrix Q with the size of 256 multiplied by 256.

The matrix X is then utilized in step 380₄The encryption matrix Q is DNA decoded to obtain a third encrypted image 390.

In the encryption algorithm of another embodiment of the present disclosure, the addition and subtraction are reciprocal operations, so the encryption and decryption must be based on the same DNA encoding method, and the xor and the xnor are both self-operations, and the encryption and decryption can be based on different DNA encoding methods. Tables 2 and 3 show the addition, subtraction, exclusive-nor and exclusive-or operation rules of DNA corresponding to the first DNA encoding rule.

TABLE 2 addition and subtraction rules for DNA coding method 1

TABLE 3 rule of DNA coding method 1

Fig. 4 is a flow chart of an image decryption method 400 of the present invention. It should be understood that the image encryption method is performed at step image data decryption 160. Obtaining the third encrypted image and an encryption key sequence 410 related to the encrypted image, obtaining an encryption matrix 420 according to the encryption key sequence, obtaining four hyperchaotic sequences 430 according to the encryption key sequence, performing DNA encoding on the encryption matrix by using the four hyperchaotic sequences to obtain the first encryption matrix 440, performing DNA encoding on the third encrypted image by using the four hyperchaotic sequences, then performing DNA inverse operation on the third encrypted image and the first encryption matrix to obtain the second encrypted image 450, performing DNA inverse encoding on the second encrypted image by using the four hyperchaotic sequences to obtain the first encrypted image 460, and performing pixel reduction and color processing on the first encrypted image to obtain the original image 470.

Fig. 5 is a flowchart of an image decryption method 500 according to another embodiment of the invention.

The decryption method 500 is the reverse of the encryption method 300. After the third encrypted image 510 is obtained, first at step 535 the random encryption matrix is generated using key H₁₆Generating an encryption matrix O, and carrying out DNA encryption on the encryption matrix by DNA coding 540 to obtain a first encryption matrix O'; partitioning and DNA coding the third encrypted picture in the step of DNA coding 520 of each subblock, performing DNA inverse operation on each partition and O ' in the step of DNA inverse operation 560 to obtain a second encrypted picture R ', performing DNA decoding to obtain a first encrypted image R ' with diagonal lines extracted, and selecting coding operation rules consistent with the encryption process; finally, the elements of each block of the matrix R' are reduced to corresponding diagonal elements, and the zero padding is removed in the step zero padding 580 to obtain the original gray picture 590, and the decryption is completed.

The above-described embodiments are merely preferred embodiments of the present invention, and should not be construed as limiting the present invention, and the scope of the present invention is defined by the claims, and equivalents including technical features described in the claims. I.e., equivalent alterations and modifications within the scope hereof, are also intended to be within the scope of the invention.