CN115103080B

CN115103080B - Image encryption method and system based on DNA triploid variation

Info

Publication number: CN115103080B
Application number: CN202210492133.XA
Authority: CN
Inventors: 谢巍; 余锦伟; 魏金湖; 杨启帆
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2022-05-07
Filing date: 2022-05-07
Publication date: 2023-04-21
Anticipated expiration: 2042-05-07
Also published as: CN115103080A

Abstract

The invention relates to the technical field of data security, in particular to an image encryption method and system based on DNA triploid variation. The method comprises the following steps: obtaining an image to be encrypted to generate a plaintext associated random key, generating an integer random sequence based on a double-chaotic system, performing DNA encoding on the plaintext image to be encrypted, performing DNA triploid variant encryption on the image encoding matrix, performing DNA decryption on the encoding matrix after variant encryption, and performing secondary encryption on the decoded image by using diffusion operation. According to the scheme, the security protection of the privacy information of the image is realized by carrying out DNA triploid encryption on the image, the security of the encryption method is improved, the risk of image data leakage is effectively reduced, and the encryption method can effectively resist plaintext attack.

Description

Image encryption method and system based on DNA triploid variation

Technical Field

The invention relates to the technical field of data security, in particular to an image encryption method and system based on DNA triploid variation.

Background

In recent years, with the continuous deep application of multimedia technology, privacy protection problems in image data are receiving more and more attention. The wide application of the multimedia data greatly facilitates the daily life of people. However, the widespread use of data such as audio, image and video on the internet brings with it a potential risk of information leakage.

Privacy protection of image information is particularly important in government, military, medical, and other special fields. In order to prevent an illegal third party from acquiring and accessing confidential information in an image, research into image encryption algorithms becomes imperative. However, conventional methods for text encryption such as DES and AES are not applicable to image data having high redundancy and large capacity.

In recent years, image encryption technology based on DNA encoding has received increasing attention because of its high parallelism and large storage characteristics. The image encryption technology based on DNA coding can effectively protect information in an image, however, three main defects exist in the existing DNA encryption method, and potential security threat is formed: (1) The security of the DNA encryption algorithm using the low-dimensional chaotic system is insufficient. The encryption algorithms have small key space and cannot resist violent attacks; (2) There are only a few simple types of manipulation of existing DNA sequences. The only DNA operations currently used in most DNA encryption schemes are DNA addition, DNA subtraction, DNA exclusive or, DNA complementation, and DNA circular shift. Applying a limited type of DNA sequence manipulation makes the encryption algorithm predictable and easily hacked; (3) relatively poor resistance to selective plaintext attacks. The encryption algorithm is designed independently of the input image and the keystream used when encrypting the different images is fixed. This results in the encryption algorithm being vulnerable to selective plaintext attacks, and the security of the encryption system is weaker.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides the image encryption method and the system based on the DNA triploid variation.

The first object of the present invention is to provide an image encryption method based on DNA triploid variation.

A second object of the present invention is to provide an image encryption system based on DNA triploid variation.

The first object of the present invention can be achieved by adopting the following technical scheme:

an image encryption method based on DNA triploid variation, the method comprising:

s1, combining a plaintext image to be encrypted with an SHA-256 hash algorithm, and generating a 256-bit hash value through the SHA-256 hash algorithm; setting an initial key of the chaotic system, decomposing the hash value into a plurality of bit blocks, and calculating the initial key through the bit blocks and the initial key to obtain an initial value of the chaotic system associated with a plaintext;

s2, substituting an initial value of the chaotic system into a two-dimensional Logistic adjustment sinusoidal mapping and four-dimensional secondary autonomous hyper-chaotic system to generate two groups of chaotic sequences, discarding a random number of a preset number in the first half part of the chaotic sequences, and preprocessing the two groups of chaotic sequences to obtain a plurality of integer random sequences;

s3, decomposing a plaintext image to be encrypted into three RGB channel planes, and dynamically encoding each pixel of the three channel planes by using an integer random sequence to obtain three DNA encoding matrixes;

s4, dynamically selecting a DNA triploid variation rule according to the integer random sequence, and performing triploid variation conversion on each DNA base in the three DNA coding matrixes to obtain three encrypted DNA coding matrixes;

s5, decoding the three encrypted DNA matrixes by using an integer random sequence, and converting the DNA base matrixes into decimal pixels between 0 and 255 to obtain three decoded images;

s6, performing secondary diffusion encryption on the decoded image by using the integer random sequence, and fusing three channel planes to obtain the color ciphertext image.

The second object of the invention can be achieved by adopting the following technical scheme:

an image encryption system based on DNA triploid variation, comprising:

the operation module is used for combining the plaintext image to be encrypted with the SHA-256 hash algorithm and generating a 256-bit hash value through the SHA-256 hash algorithm; setting an initial key of the chaotic system, decomposing the hash value into a plurality of bit blocks, and calculating the initial key through the bit blocks and the initial key to obtain an initial value of the chaotic system associated with a plaintext;

the generation module is used for substituting the initial value of the chaotic system into the two-dimensional Logistic adjustment sinusoidal mapping and the four-dimensional secondary autonomous hyper-chaotic system to generate two groups of chaotic sequences, discarding the random numbers of the preset number of the first half part of the chaotic sequences, and preprocessing the two groups of chaotic sequences to obtain a plurality of integer random sequences;

the coding module is used for decomposing a plaintext image to be encrypted into three RGB channel planes, and dynamically coding each pixel of the three channel planes by using an integer random sequence to obtain three DNA coding matrixes;

the encryption module is used for dynamically selecting a DNA triploid variation rule according to the integer random sequence, executing triploid variation conversion on each DNA base in the three DNA coding matrixes and obtaining three encrypted DNA coding matrixes;

the decoding module is used for decoding the three encrypted DNA matrixes by using the integer random sequence, converting the DNA base matrixes into decimal pixels between 0 and 255, and obtaining three decoded images;

and the secondary diffusion encryption module is used for carrying out secondary diffusion encryption on the decoded image by using the integer random sequence and fusing three channel planes to obtain a color ciphertext image.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. according to the invention, by combining with the SHA-256 hash algorithm, the key stream generated by the encryption algorithm is associated with the plaintext image, and when the plaintext image changes, the key stream changes greatly, so that the encryption algorithm can effectively resist plaintext attack;

2. according to the invention, through the image encryption algorithm based on DNA encoding, DNA triploid variation encryption is introduced, so that the operation types of the DNA encryption algorithm are enriched, the security of the encryption algorithm is improved, and the risk of image data leakage is effectively reduced;

3. the invention increases the key space of the encryption algorithm by combining the double-chaotic system, and under the calculation power of the existing computer, the violent attack cannot traverse all possible key cracking encryption algorithms.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a basic flow chart of an image encryption method in one embodiment of the invention;

FIG. 2 is an overall architecture diagram of an image encryption method in one embodiment of the invention;

FIG. 3 is a schematic diagram of a DNA triploid variation in one embodiment of the present invention;

FIG. 4 is a schematic diagram of the superposition of DNA coding strands of a DNA triploid variation in one embodiment of the invention;

FIG. 5 is a diagram showing encryption and decryption effects according to an embodiment of the present invention;

fig. 6 is a schematic diagram of histogram contrast of images before and after encryption and decryption in an embodiment of the present invention.

Detailed Description

The technical solution of the present invention will be described in further detail below with reference to the accompanying drawings and examples, it being apparent that the described examples are some, but not all, examples of the present invention, and embodiments of the present invention are not limited thereto. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1

As shown in fig. 1, the image encryption method based on DNA triploid variation according to the present invention comprises the following steps:

s1: setting an initial key, and generating a plaintext-associated chaotic system initial value by applying an SHA-256 hash algorithm. Combining a plaintext image to be encrypted with an SHA-256 algorithm, generating a 256-bit hash value through a hash algorithm, setting an initial key of the chaotic system, decomposing the hash value into a plurality of bit blocks, and calculating the initial key through the bit blocks to obtain an initial value of the chaotic system associated with the plaintext.

Preferably, the plaintext image is used as input to a SHA-256 hash algorithm to generate a 256-bit hash value K, and the 256-bit hash value K is decomposed into 32-bit blocks:

K＝K ₁ ,K ₂ ,K ₃ ,…,K _32；

after setting an initial key of the chaotic system, decomposing the hash value into a plurality of bit blocks, and calculating the initial key with the bit blocks to obtain an initial value of the chaotic system associated with the plaintext.

Each bit block K _i (i=1, 2, …, 32) consists of 8 bits and a plurality of intermediate variables are generated by blocks of bits corresponding to decimal numbers between 0 and 255. In this embodiment, these bit blocks are used to generate the following 6 intermediate variables related to plaintext:

wherein the method comprises the steps of

Representing bitwise exclusive-or operations, intermediate variable ε _i ∈[0,1](i＝1,2,…,6)。/>

Preferably, the intermediate variable generated by the bit block is used for updating the key to obtain the initial value of the chaotic system associated with the plaintext, so that the initial value of the chaotic system is completely different when the plaintext image to be encrypted changes each time.

Setting the initial key to u ₀ ,t ₀ ,x ₀ ,y ₀ ,z ₀ ,w ₀ By associating an initial key with K _i (i＝1,2,…32) are combined to update the key to obtain the initial value of the plaintext-associated chaotic system.

The initial value of the two-dimensional Logistic adjustment sine mapping is updated as follows:

the initial value of the four-dimensional secondary autonomous hyper-chaotic system is updated as follows:

s2: and iterating the two-dimensional Logistic adjusting sinusoidal mapping and the four-dimensional secondary autonomous hyper-chaotic system to generate a plurality of plaintext-associated integer random sequences. Substituting an initial value of the chaotic system into a two-dimensional Logistic adjustment sinusoidal mapping and a four-dimensional secondary autonomous hyper-chaotic system to generate two groups of chaotic sequences, and discarding a certain number of random numbers in the first half part of the chaotic sequences so as to reduce the problem of uneven random number distribution caused by transient effects of the chaotic system; and preprocessing the two sets of chaotic sequences, and converting the two sets of chaotic sequences into integer random sequences for encoding, decoding and encrypting.

Specifically, the generation of the chaotic sequence is divided into two parts, including a two-dimensional Logistic adjustment sine mapping generation chaotic sequence and a four-dimensional secondary autonomous hyper-chaotic system generation chaotic sequence. In the two-dimensional Logistic adjustment sine mapping, the output of the Logistic mapping is used as an additional item of sine mapping input; and a more complex motion track of the chaotic system is derived through the modulation of the two maps, and the complexity of chaotic behaviors is increased. The two-dimensional Logistic adjustment sine mapping is as follows:

wherein u and t are state variables that produce a chaotic sequence, and u, t e [0,1]; i=0, 1,2, 3; mu is a parameter of the system and mu.epsilon. 0.44,0.93.

The iteration equation of the four-dimensional secondary autonomous hyper-chaotic system is as follows:

wherein x, y, z, w is a state variable that produces a chaotic sequence; i=0, 1,2, 3; a. b, c, d, e is a constant parameter and a=10, b=28, c=8/3, d=1, e=16.

Preferably, the initial value of the chaotic system associated with the plaintext obtained in the first step is used as the initial value of the two-dimensional Logistic adjustment sine mapping and four-dimensional quadratic autonomous hyper-chaotic system, and the two chaotic systems are respectively iterated to generate 6 chaotic sequences with certain lengths.

In this embodiment, the u 'generated in the first step is first' ₀ And t ₀ 'adjusting the initial value of the sine mapping as two-dimensional Logistic, and taking x' ₀ ,y′ ₀ ,z′ ₀ ,w′ ₀ And (3) as an initial value of the four-dimensional secondary autonomous hyper-chaotic system, iterating the chaotic system. Assuming that the size of the plaintext image is MxN×3, the iteration number of the sine mapping is adjusted to MxN+1000 by two-dimensional Logistic, the iteration number of the four-dimensional secondary autonomous hyper-chaotic system is Mx4N+1000, and 6 random sequences U, T, X, Y, Z and W are generated.

Secondly, preferably discarding the first 1000 random numbers of the chaotic sequence, taking the random number from the 1001 st bit as the subsequently used chaotic sequence, so as to avoid the problem of uneven random number distribution caused by transient effect of the chaotic system; the first m×n elements are truncated from U, T, X, Z, W, and the first m×4n elements are truncated from Y, resulting in the following 6 chaotic sequences of specific length:

finally, preprocessing two groups of chaotic sequences, and converting the two groups of chaotic sequences into integer random sequences X, Y, Z, W, U and T:

where x (i), y (i), z (i), w (i), u (i), T (i) are the i-th elements of the integer random sequence X, Y, Z, W, U and T; round (a) represents an integer nearest to a by a rounding rule; mod (a, b) represents a modulo operation of a on b.

S3: and decomposing the plaintext image to be encrypted into three RGB channel planes, and dynamically encoding each pixel of the three channel planes by using an integer random sequence to obtain three DNA encoding matrixes. Each pixel is broken down into 8 bits, each two bits being encoded into one of the A, T, C, G forms of DNA bases by the DNA encoding rule, which is randomly determined by elements in an integer random sequence.

As shown in fig. 2, assuming that the size of each channel plane is mxn, DNA encoding is performed on all elements of RGB channel planes, respectively, each pixel is decomposed into 8 bit planes, each two bits are encoded into DNA bases by the DNA encoding rule, and 4 DNA bases, i.e., a base (adenine), C base (cytosine), G base (guanine) and T base (thymine), each base is represented by a 2-bit binary number of 00, 01, 10 or 11.

Dynamically selecting DNA coding rules by integer random sequence X to obtain three DNA coding matrixes R _b ,G _b ,B _b ：

Wherein i=1, 2,. -%, M; j=1, 2,. -%, N; DNA (deoxyribonucleic acid) _b (a, b) represents a mapping of 8-bit decimal pixel a into four DNA bases using coding rule b.

In fig. 2, a plaintext image to be encrypted is subjected to SHA-256 hash algorithm to obtain a 256-bit hash value, and the hash value is used for updating an initial key to generate a plaintext-associated initial value of the chaotic system. The two-dimensional Logistic adjustment sine mapping and the four-dimensional secondary autonomous hyper-chaotic system are iterated to generate chaotic random sequences X, Y, Z, W, U and T, and the chaotic random sequences are used for each step in image encryption. The encryption process of the image specifically comprises the steps of firstly decomposing a plaintext into RGB components, and carrying out DNA dynamic coding on the RGB components to obtain a DNA matrix. Determining DNA triploid variation and DNA dynamic decoding rules by random sequences, and primarily encrypting the image to obtain an intermediate encrypted image. And performing cross row and column scrambling and pixel scrambling on the image, and finally merging RGB components to obtain a final ciphertext image.

Specifically, according to Watson-Crick base-pairing rules, the DNA coding rules include 8 DNA coding rules, the DNA coding rules are shown in Table 1:

TABLE 1

Preferably, for each pixel in the image R, G, B channel plane, an integer random sequence is used to randomly select one of the 8 rules for encoding, converting a single pixel into 4 DNA bases in A, T, C, G form, resulting in a DNA encoding matrix.

S4: and dynamically selecting DNA triploid variation rules according to the integer random sequences, and performing triploid variation conversion on each DNA base in the three DNA coding matrixes to obtain three encrypted DNA coding matrixes. The mutation rule of the DNA triploid is dynamically selected by the random sequence of the integer, and the DNA base in the A, T, C, G form is randomly converted into one of four bases according to the mutation rule, so that the encryption of the triploid mutation of the DNA code is realized.

Preferably, for each pixel in the image R, G, B channel, a chaotic sequence is used to randomly select one of the 8 rules for encoding, converting a single pixel into 4 DNA bases in A, T, C, G form, resulting in a DNA encoding matrix.

In the fourth step, the DNA triploid variation replicates each base into three completely identical bases, and then the three bases are superimposed on each other to generate a new base.

Specifically, there are 8 rules (mutation patterns) of DNA triploid corresponding to 8 DNA coding rules. The complete DNA triploid variation rules are shown in table 2:

TABLE 2

Preferably, for each base in the DNA coding matrix, an integer random sequence is used to randomly select one from 8 rules for triploid variation conversion, and a single base is converted into any one of A, T, C, G, so as to obtain the encrypted DNA coding matrix.

Preferably, for each base in the DNA coding matrix, a chaotic sequence is used to randomly select one from 8 rules for triploid variation conversion, and a single base is converted into any one of A, T, C, G, so as to obtain the encrypted DNA coding matrix.

DNA coding matrix R _b ,G _b 、B _b And the integer sequence Y is of size M×4N for R _b 、G _b And B _b The encryption operation was performed by randomly selecting a DNA triploid variation rule from table 2 using Y. According to mutation rule, randomly converting A, T, C, G DNA base into one of four bases to obtain three DNA triploid encryption matrices R with size of Mx4N _s ,G _s And B _s 。

Wherein i=1, 2,. -%, M; j=1, 2,..4N; DNA (deoxyribonucleic acid) _s (a, b) means that the DNA triploid mutation operation is performed on a using the rule b.

As shown in fig. 3, which is a schematic diagram of DNA triploid variation, an image is encoded into one DNA coding strand, and then copied into three copies, and the copies are superimposed to generate an encrypted DNA coding strand. As shown in FIG. 4, the superimposed schematic diagram of the DNA coding strand is obtained by converting the DNA bases into binary form according to the DNA coding rule, summing the three binary codes to obtain a new code, and converting the new code into the encrypted DNA bases.

S5: the three encrypted DNA matrices were decoded using an integer random sequence to convert the DNA base matrix in A, T, C, G form to decimal pixels between 0 and 255 resulting in three decoded images. Every four bases are decoded into a decimal pixel, and the decoding rule is dynamically selected by an integer random sequence which is different from that in the third step.

The DNA matrix decoding scheme corresponds to the DNA encoding scheme in table 1, and there are 8 decoding rules in total.

Preferably, for each encrypted base, an integer random sequence is used to dynamically select a rule from 8 rule sets for decoding, four adjacent bases are sequentially decoded into an 8-bit binary number, and converted into decimal numbers between 0 and 255, resulting in a decoded image.

Dynamically selecting a rule pair R from 8 rules in Table 1 using elements in an integer random sequence Z _s ,G _s And B _s Decoding is carried out, every four adjacent bases are decoded into a decimal pixel, and a decoded image R of three channels with the size of MXN is obtained _j ,G _j And B _j ：

Wherein i=1, 2,. -%, M; j=1, 2,. -%, N; DNA (deoxyribonucleic acid) _j (a, b) is a decoding map.

S6: and carrying out secondary diffusion encryption on the decoded image by using an integer random sequence, and fusing three channel planes to obtain a final color ciphertext image.

Preferably, the decoded image is converted into a one-dimensional vector, and then the elements in the one-dimensional vector and the integer random sequence are subjected to exclusive-or operation in sequence, and are subjected to exclusive-or diffusion with the encrypted pixels at the previous position; after the diffusion operation is completed, the secondary encryption vector is converted into a two-dimensional image matrix, and a color ciphertext image is obtained.

In this embodiment, the three decoded images after decoding are first converted into three one-dimensional vectors R ₁ 、G ₁ And B ₁ And performs different diffusion operations on the three one-dimensional vectors using three different integer random sequences U, T and W in a left-to-right order; for each element, performing exclusive OR operation with the chaotic random number, and then diffusing the result with the element encrypted before to obtain an encrypted vector R _c1 、G _c1 And B _c1 ：

Where i=2, 3,..m. Then three vectors R _c1 ,G _c1 And B _c1 Two-dimensional image matrix R remodelled to MXN _c ,G _c And B _c . After the diffusion operation is completed, the three channel planes are fused to obtain a color ciphertext image with the size of MxNx3.

Fig. 5 shows an encryption/decryption effect diagram in this embodiment, where a plaintext image, a ciphertext image, and a decrypted image to be encrypted are shown.

Fig. 6 is a schematic diagram showing the comparison of histograms of images before and after encryption and decryption in this embodiment, where fig. 6 (a), (b), and (c) are histograms of R, G, B channel planes of a plaintext image graph, and fig. 6 (d), (e), and (f) are histograms of R, G, B channel planes of a ciphertext image graph, respectively.

Example 2:

an image encryption system based on DNA triploid variation comprises an operation module, a generation module, an encoding module, an encryption module, a decoding module and a secondary diffusion encryption module, wherein the specific functions of the modules are as follows:

Combining the plaintext image to be encrypted with a SHA-256 hash algorithm, generating a 256-bit hash value through the SHA-256 hash algorithm, and comprising: taking a plaintext image to be encrypted as input data of an SHA-256 hash algorithm, and generating a 256-bit hash value K through the SHA-256 hash algorithm;

the method for setting the initial key of the chaotic system, decomposing the hash value into a plurality of bit blocks, and obtaining the initial value of the chaotic system associated with the plaintext through the operation of the bit blocks and the initial key comprises the following steps: setting an initial key of the chaotic system, decomposing a hash value into 32 bit blocks, wherein each bit block consists of 8 bits, and generating 6 intermediate variables through the bit blocks, wherein the intermediate variables are used for updating and acquiring initial values of the chaotic system associated with a plaintext;

the dynamically encoding each pixel of the three channel planes using an integer random sequence includes: decomposing each pixel into 8 bits, wherein each two bits are encoded into a DNA base by a DNA encoding rule;

the DNA base comprises 4 forms, wherein the 4 forms of the DNA base are respectively an A base, a T base, a C base and a G base, and each DNA base is represented by a 2-bit binary number.

The DNA coding rules comprise 8 DNA coding rules, and for each pixel in a R, G, B channel plane of a plaintext image to be encrypted, an integer random sequence is used for randomly selecting one from the 8 DNA coding rules to code the pixel, and a single pixel is converted into 4 DNA bases in A, T, C, G form, so that a DNA coding matrix is obtained.

The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.

Claims

1. An image encryption method based on DNA triploid variation is characterized by comprising the following steps:

s6, performing secondary diffusion encryption on the decoded image by using an integer random sequence, and fusing three channel planes to obtain a color ciphertext image;

the DNA triploid mutation rule corresponds to a DNA coding rule, the DNA triploid mutation rule comprises 8 DNA triploid mutation rules, for each DNA base in the DNA coding matrix, one DNA base is randomly selected from the 8 DNA triploid mutation rules by using an integer random sequence to perform triploid mutation conversion, and a single DNA base is converted into any one of an A base, a T base, a C base and a G base to obtain an encrypted DNA coding matrix;

the performing triploid variant switching on each DNA base in the three DNA coding matrices comprises: each DNA base is replicated to three identical DNA bases, and the three identical DNA bases are superimposed on each other to create a new base.

2. The method for encrypting an image based on DNA triploid variation according to claim 1, wherein: the step S1 includes: taking a plaintext image to be encrypted as input data of an SHA-256 hash algorithm, and generating a 256-bit hash value K through the SHA-256 hash algorithm; an initial key of the chaotic system is set, the hash value is decomposed into 32 bit blocks, each bit block consists of 8 bits, 6 intermediate variables are generated through the bit blocks, and the intermediate variables are used for updating and acquiring initial values of the chaotic system associated with plaintext.

3. The method for encrypting an image based on DNA triploid variation according to claim 1, wherein: the two-dimensional Logistic-adjusted sinusoidal mapping is described as:

wherein u and t are state variables that produce a chaotic sequence, and u, t e [0,1]; i=0, 1,2, 3; mu is a parameter of the system and mu epsilon [0.44,0.93];

the iterative equation of the four-dimensional quadratic autonomous hyper-chaotic system is described as:

x, y, z, w is a state variable that produces a chaotic sequence; i=0, 1,2, 3; a. b, c, d, e is a constant parameter and a=10, b=28, c=8/3, d=1, e=16.

4. A method of encrypting an image based on DNA triploid variation as claimed in claim 3, wherein: the random numbers of the preset number of the first half part of the discarded chaotic sequence are specifically the first 1000 values of the discarded chaotic sequence, and the random numbers from the 1001 st bit are taken as the subsequently used chaotic sequence;

the chaotic sequence is preprocessed to obtain six integer random sequences, namely an integer random sequence X, Y, Z, W, U and T:

wherein x (i), y (i), z (i), w (i), u (i), T (i) are the i-th elements of the integer random sequences X, Y, Z, W, U and T, respectively; round (a) represents an integer nearest to a by a rounding rule; mod (a, b) represents a modulo operation of a on b.

5. The method for encrypting an image based on DNA triploid variation according to claim 1, wherein: the dynamically encoding each pixel of the three channel planes using an integer random sequence includes: decomposing each pixel into 8 bits, wherein each two bits are encoded into a DNA base by a DNA encoding rule;

the DNA base comprises 4 forms, wherein the 4 forms of the DNA base are respectively an A base, a T base, a C base and a G base, and each DNA base is represented by a 2-bit binary number;

the DNA coding rules comprise 8 DNA coding rules, and for each pixel in a R, G, B channel plane of a plaintext image to be encrypted, an integer random sequence is used for randomly selecting one from the 8 DNA coding rules to code the pixel, and a single pixel is converted into 4 DNA bases to obtain a DNA coding matrix.

6. The method for encrypting an image based on DNA triploid variation according to claim 5, wherein: the step S5 includes: and dynamically selecting a decoding rule corresponding to the rule of DNA coding by using an integer random sequence for decoding each encrypted DNA base, sequentially decoding four adjacent DNA bases into an 8-bit binary number, and converting the 8-bit binary number into decimal number pixels between 0 and 255 to obtain a decoded image.

7. The method for encrypting an image based on DNA triploid variation according to claim 1, wherein: the step S6 includes: converting the decoded image into a one-dimensional vector, performing exclusive-or operation on elements in the one-dimensional vector and the integer random sequence in sequence, and performing exclusive-or diffusion on the elements and the encrypted pixels in the previous position; after the diffusion operation is completed, the secondary encryption vector is converted into a two-dimensional image matrix, and three channel planes are combined to obtain a color ciphertext image.

8. An image encryption system based on DNA triploid variation, the system comprising:

the secondary diffusion encryption module is used for carrying out secondary diffusion encryption on the decoded image by using an integer random sequence and fusing three channel planes to obtain a color ciphertext image;

9. An image encryption system based on DNA triploid variation as set forth in claim 8, wherein,