CN114465779A - A reversible and separable ciphertext domain information hiding method and system - Google Patents

Abstract

The invention discloses a reversible separable ciphertext domain information hiding method and a system, comprising the following steps: acquiring an original image, and dividing the pixel interval of the original image into black and white pixels; combining the predicted values of each white pixel to obtain a white pixel predicted image; respectively encrypting the white pixel image and the white pixel predicted image; obtaining a marked white pixel image based on the quadratic difference matrix; obtaining a black pixel prediction image based on the prediction value combination of each black pixel; encrypting the black pixel image and the black pixel predicted image respectively; obtaining a marked black pixel image based on the quadratic difference matrix; and combining the marked white pixel image and the marked black pixel image to obtain an encrypted marked image of the original image, thereby realizing the hiding of the ciphertext domain information of the original image. The invention realizes information lossless extraction and image complete recovery, and the information extraction and the image recovery can be mutually independent and separated.

Description

A reversible and separable ciphertext domain information hiding method and system

technical field

The invention relates to the technical field of information hiding, in particular to a reversible and separable ciphertext domain information hiding method and system.

Background technique

The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

With the rise of cloud computing and the wide application of cloud storage, users store their images in a third-party cloud service provider, but do not trust the other party, so they encrypt their data first, and then upload it to the cloud service center. In order to facilitate data management and authentication, cloud service providers need to mark all data before storing. These marks are hidden secret information, and these processes do not need to know the content information of the image. Therefore, the information hiding process is carried out on the ciphertext domain of the image. For some application scenarios with high data authentication requirements, the extraction of information and the restoration of images are required to be completely reversible. Therefore, the reversible information hiding technology of encrypted images emerges as the times require.

However, with the continuous change of requirements, people have more requirements for reversible information hiding in the ciphertext domain. For example, people hope that when transmitting high-confidential images, even if they are encrypted images, some high-confidential images are not allowed in Therefore, these high-secret images need to be marked with "marks". When the mark is detected to show a high degree of confidentiality, the network police will automatically intercept them. This requires that the network police only have the authority to extract the marking information, and cannot obtain the decrypted image, and after the marking information is extracted, the image will not be affected.

At present, the reversible information hiding algorithms in the ciphertext domain are divided into two categories: reserving space before encryption and making space after encryption. The reserved space before encryption method, in most cases, obtains a co-embeddable bit-plane space by using compression, and obtains a high embedding capacity, but most algorithms cannot achieve separation of information extraction and image restoration. The ciphertext image of the method of freeing up space after encryption has low redundancy, and it is difficult to free up space to embed information, which greatly limits the capacity of subsequent information embedding. The algorithm is continuously improved, and the ciphertext is increased by using various encryption rules. The correlation between image pixels allows us to embed information. However, there are still problems such as poor visual quality of marked images after image decryption.

It can be seen from the above that the current reversible information hiding algorithms in the ciphertext domain have two shortcomings: (1) In pursuit of high embedding capacity, information extraction and image restoration cannot be separated. (2) After the encrypted marked image is only decrypted, the image quality is poor.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention proposes a reversible and separable ciphertext domain information hiding method and system. Only by possessing the encryption key and the extraction key at the same time, can the secret information and decryption image be obtained; In this case, the separation of information extraction and image restoration is realized, and the visual quality of the decrypted marked image is relatively high, and in the case of only decryption, the impact on the image content and image quality is small.

In some embodiments, the following technical solutions are adopted:

A reversible and separable ciphertext domain information hiding method, comprising:

Obtaining an original image, and dividing the pixel interval of the original image into black and white pixels;

Recombining the white pixels to form a white pixel image, and combining the predicted values of each white pixel to obtain a white pixel predicted image;

Encrypt the white pixel image and the white pixel prediction image respectively; obtain the difference matrix D1 based on the encrypted white pixel image and the white pixel prediction image, divide the difference matrix D1 into blocks, and obtain the quadratic difference matrix diff_D1; The quadratic difference value matrix obtains the marked white pixel image;

Recombining the black pixels to form a black pixel image, and combining the predicted values of each black pixel to obtain a black pixel predicted image;

Encrypt the black pixel image and the black pixel prediction image respectively; obtain the difference matrix D2 based on the encrypted black pixel image and the black pixel prediction image, and divide the difference matrix D2 into blocks to obtain a secondary difference matrix diff_D2 ; Obtain the marked black pixel image based on the quadratic difference matrix;

The marked white pixel image and the marked black pixel image are combined to obtain the encrypted marked image of the original image, thereby realizing the information hiding of the ciphertext domain of the original image.

In other embodiments, the following technical solutions are adopted:

A reversible and separable ciphertext domain information hiding system, including:

an image acquisition module for acquiring an original image, and dividing the pixel interval of the original image into black and white pixels;

The first layer of image encryption module is used to recombine the white pixels to form a white pixel image, and obtain a white pixel predicted image based on the predicted value combination of each white pixel; respectively encrypt the white pixel image and the white pixel predicted image;

The first layer image marking module is used to obtain the difference matrix D1 based on the encrypted white pixel image and the white pixel prediction image, and divide the difference matrix D1 into blocks to obtain a secondary difference matrix diff_D1; The difference matrix gets the marked white pixel image;

The second-layer image encryption module is used for recombining black pixels to form a black pixel image, and combining the predicted values of each black pixel to obtain a black pixel predicted image; respectively encrypt the black pixel image and the black pixel predicted image;

The second layer image marking module is used to obtain the difference matrix D2 based on the encrypted black pixel image and the black pixel prediction image, and divide the difference matrix D2 into blocks to obtain a secondary difference matrix diff_D2; The difference matrix gets the marked black pixel image;

The combined marking module is used to combine the marked white pixel image and the marked black pixel image to obtain the encrypted marked image of the original image, thereby realizing the information hiding of the ciphertext domain of the original image.

In other embodiments, the following technical solutions are adopted:

A terminal device, comprising a processor and a memory, the processor is used to implement each instruction; the memory is used to store a plurality of instructions, the instructions are suitable for being loaded by the processor and executing the above-mentioned reversible and separable ciphertext domain information hiding method .

In other embodiments, the following technical solutions are adopted:

A computer-readable storage medium stores a plurality of instructions, wherein the instructions are adapted to be loaded by a processor of a terminal device and execute the above-mentioned reversible and separable ciphertext domain information hiding method.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The reversible and separable ciphertext domain information hiding method of the present invention uses the rules of the image encryption algorithm to increase the redundancy between the pixels of the encrypted image, and while maintaining a large embedding capacity, the visual quality of the decrypted marked image is increased. , in the whole process, the present invention realizes the lossless extraction of information and the complete restoration of the image, and the information extraction and the image restoration can be independent and separated from each other.

(2) When the receiving end receives the encrypted marked image, it also receives the encrypted key and the extraction key. The decrypted marked image can be obtained by using the encrypted key, and the encrypted image can be obtained by using the extracted key. The use of keys is independent of each other, and the order can be exchanged with each other. Only by possessing two keys at the same time, can the secret information and decrypted image be obtained. Encryption and decryption are separated from extracting information. Only when the receiving end has the authority to encrypt and decrypt or extract information can it decrypt or extract information from the received image.

(3) The method of the present invention realizes that only the right to extract and embed information can be obtained, and the decrypted image cannot be obtained, that is, the specific content of the image will not be publicly transmitted, which ensures the security of information transmission; when there is only the right to decrypt, the authentication of image embedding cannot be performed. Information or copyright information is modified to protect the copyright of the image. Moreover, in this method, the visual quality of the decrypted image is superior to other methods, the marked image is consistent with the original image in appearance, and the embedded secret information is difficult to be detected by the naked eye.

Other features and advantages of additional aspects of the invention will be set forth in part from the description that follows, and in part will become apparent from the description below, or will be learned by practice of the present aspects.

Description of drawings

1 is a flowchart of a reversible and separable ciphertext domain information hiding method in an embodiment of the present invention;

FIG. 2 is a hierarchical schematic diagram of an image prediction stage in an embodiment of the present invention;

3 is a schematic diagram of a diamond predictor in an embodiment of the present invention;

4 is a schematic diagram of image segmentation in an encryption and marking process in an embodiment of the present invention;

Fig. 5 is the block diagram inside the encryption and marking process in the embodiment of the present invention;

6 is a Lena image histogram in an embodiment of the present invention;

Fig. 7 is the Lena encrypted image histogram in the embodiment of the present invention;

8 is a schematic diagram of pixel correlation in the horizontal direction of a Lena image in an embodiment of the present invention;

Fig. 9 is the quadratic difference value histogram of the Lena encrypted image in the embodiment of the present invention;

Fig. 10 is the Lena image PSNR comparison diagram of different methods provided by the present invention and BPP;

Fig. 11 is the Baboon image PSNR comparison diagram of different methods provided by the present invention and BPP;

Fig. 12 is the Plane image PSNR comparison diagram of different methods provided by the present invention and BPP;

FIG. 13 is a schematic diagram of the entire image processing process using a Lena image as an example in an embodiment of the present invention.

Detailed ways

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, devices, components and/or combinations thereof.

Example 1

In one or more embodiments, a reversible and separable ciphertext domain information hiding method is disclosed, which specifically includes the following process in conjunction with FIG. 1 :

Step S101: obtaining an original image, and dividing the pixel interval of the original image into two types of pixels, black and white;

In this embodiment, the original image with a size of 512*512 is divided into black and white pixels at intervals of 1 pixel. As shown in FIG. 2 , the white pixels are used as the first layer of pixels, and the black pixels are used as the second layer of pixels.

Step S102: use a diamond predictor and black pixels to calculate the predicted value of each white pixel, recombine the white pixel into a white pixel image W, and combine the predicted value of each white pixel to obtain a white pixel predicted image W';

Specifically, as shown in Figure 3, the calculation method of the diamond predictor is as follows:

Among them, B(i, j-1) represents the pixel value of the black pixel at point (i, j-1); at this time, the size of the first layer image W and its predicted image W' is reduced to 512*256.

B(i-1,j) represents the pixel value of the black pixel at point (i-1,j), B(i,j+1) represents the pixel value of the black pixel at point (i,j+1), B( i+1,j) represents the pixel value of the black pixel at point (i+1,j), and W'(i,j) represents the pixel predicted value of the white pixel at point (i,j).

Step S103: Encrypt the white pixel image and the white pixel prediction image respectively; the specific encryption process is as follows:

A1: Use Lorenz chaotic system to obtain pseudo-random sequences S1 and S2, the specific formula is as follows:

Among them, when a=10, b=8/3, c=28 and -1.52≤r≤-0.06, the system is in a hyperchaotic state. Set the initial values of x, y, z, and w in the formula as the encryption key, and use the hyper-chaotic Lorenz system to generate pseudo-random sequences S1 and S2. At this time, the sequence is a one-dimensional sequence with a length of 512*256.

A2: Convert the pseudo-random sequences S1 and S2 into a 512*256 two-dimensional sequence, perform row permutation and column permutation without repetition, and use the permuted two-dimensional sequence Scrambling_S1 as the encrypted sequence K.

A3: Divide Scrambling_S1 into blocks by keeping the next element and its upper, lower, left, and right elements every 4 elements. The number of blocks is Num, and the first Num elements are taken from the pseudo-random sequence S2 to form a new sequence S2_Num. The obtained sequence S2_Num and the sequence Scrambling_S1 are obtained by modulo addition to obtain the encrypted sequence K'.

In this embodiment, the blocks are divided as shown in FIG. 4 , and the number of complete blocks is calculated, which is denoted as Num. The first Num elements are taken from the pseudo-random sequence S2 to form a new sequence S2_Num, and the encrypted sequence K' is obtained by modulo addition. The specific formula is as follows:

K'(i,j)=S1(i,j)+S2_Num(count)i=1,2,...M,j=1,2,...N

Among them, i, j are the rows and columns of the corresponding two-dimensional sequence, count is the corresponding serial number of each block, M, N represent the size of the encrypted image, which is 512*256 in this embodiment.

A4: The first-layer white pixel image W and the white pixel prediction image W' are encrypted using the encryption sequence K and K' by modulo addition. The specific calculation formula is as follows:

Among them, EW(i,j), EW'(i,j) are the encrypted images corresponding to the first-layer white pixel image W and the white pixel prediction image W'.

Step S104: Analyze the performance of the encrypted image in terms of security, correlation and randomness, and the specific steps are as follows:

B1: As shown in Figure 6, the histogram of Lena's original image has uneven pixel distribution. After encryption, the encrypted image shown in Figure 7 has a uniform pixel distribution. The more uniform the pixel distribution, the higher the security of the encryption algorithm.

B2: Randomly select 5000 pairs of adjacent pixels, and calculate the correlation between the original image and the encrypted image in the horizontal direction. The specific correlation coefficient calculation formula is as follows:

Among them, X, Y represent two pixel values, R _XY represents the correlation between two adjacent pixels horizontally, cov(X, Y) represents the covariance of the two pixels, D(X), D(Y) represents The variance of the pixel between encrypted and unencrypted cases.

As shown in Figure 8, the correlation between adjacent pixels of the Lena encrypted image is low, and the randomness of the pixels is large.

B3: Information entropy (Entropy) represents the randomness of pixels. The information entropy of an ideal encrypted image is close to 8. The calculation formula of information entropy is as follows:

Among them, H(p), H'(p) represent the information entropy of the corresponding encrypted image, and p represents the pixels in the range [0, 255].

B4: The pixel change rate (NPCR) can reflect the sensitivity of the encryption method key. The ideal encrypted image NPCR is close to 0.9960. The specific calculation formula is as follows:

where NPCR represents the pixel change rate at point (i, j).

Table 1 gives the NPCR and information entropy tables of Lena, Baboon and Plane, respectively

Information entropy and NPCR of Table1 test graph

As shown in Table 1, three test images are selected and named as Lena, Baboon, and Plane for confidential performance analysis. It can be seen that the information entropy of Lena encrypted image is close to 8, the randomness is good, and the pixel change rate is close to 0 ,9960, the encryption key has high flexibility and high security.

From the above evaluation criteria, it can be proved that the encryption method has good performance in terms of security, correlation and randomness.

Step S105: Based on the encrypted white pixel image and the white pixel prediction image, obtain a difference matrix D1, divide the difference matrix D1 into blocks, and obtain a secondary difference matrix diff_D1; White pixel image; the specific process is as follows:

C1: Subtract the encrypted image EW and EW' pixel values correspondingly and then take the modulo to obtain the difference matrix D1.

The specific calculation formula is: D1(i,j)=(EW(i,j)-EW'(i,j))mod 256 i=1,2,...M,j=1,2,... N

C2: Divide the difference matrix D1 into blocks by keeping the next element and its upper, lower, left, and right elements every 4 elements, and make the difference between the upper, lower, left, and right elements and the middle element to obtain a quadratic difference matrix diff_D1. Details The algorithm process is as follows:

According to the block rules of the graph, in each block, the upper, lower, left and right elements are made to differ from the middle element. The specific calculation formula is as follows:

Among them, mod256 refers to modulo the contents of the preceding parentheses. Get the remainder after dividing by 256.

C3: Obtain the histogram of the quadratic difference matrix diff_D1, and perform information embedding by means of the histogram shift to obtain the marked white pixel encrypted image P1.

Take authentication information or copyright information as secret information, which is represented as a binary sequence, and use the secret key to generate a pseudo-random sequence, which is XORed with the secret information sequence. The secret key here is the extraction secret key, which is used for subsequent extraction of information and Decrypt the secret information to obtain correct authentication information or copyright information.

In order to show the specific process of this method more conveniently, the following uses S∈(0,1) to represent the secret information.

Set the secret information as S∈(0,1), take diff_D1(i-1,j) as an example, when the embedded secret information is 0, it remains unchanged.

When the embedded secret information is 1, it is equivalent to adding 1 to the encrypted image EW(i-1,j) and taking the modulo. The specific calculation formula is as follows:

(diff_D1(i-1,j)+1)mod256=((D1(i-1,j)-D1(i,j))mod256+1)mod256

=(D1(i-1,j)+1)mod256-D1(i,j)mod256

=((EW(i-1,j)+1)mod256-EW'(i-1,j))mod256-(EW(i,j)-EW'(i,j))mod256)mod256

The information embedding algorithm adopts histogram shift, the histogram bin of the embedded information is called extended bin, and the histogram bin used for shifting to generate vacancies is called moving bin;

From the above, it can be seen that the expansion and movement of the quadratic difference histogram is actually changed on the encrypted image EW, and the position of the encrypted image EW corresponding to the extended bin position is embedded, and the pixel value of the marked encrypted image P1 at a certain point is based on the expansion The specific calculation formulas of bin and moving bin are obtained.

The specific calculation formula of the extended bin is as follows:

The specific calculation formula of the pixel corresponding to the position between the extended bin and the mobile bin is as follows:

Set the 0 matrix with the same size as the original image as the marker map, move the pixels corresponding to the bin to mark 1 on the marker map, and mark 0 for other positions, and replace the marker map with the pixels in the first row LSB (least significant bit), replace The pixels are embedded into the image as auxiliary information along with the secret information.

C4: Select extended bins and mobile bins according to histogram features;

As shown in the histogram of the quadratic difference matrix diff_D1 as shown in Figure 9, it is found that the histogram is high near 0 and 255, and the difference is concentrated.

Generally, the four highest bins of 0, 1, 255 and 254 are selected as extended bins, and 0 bin or the smallest number of bins are selected as mobile bins.

Step S106: use the diamond predictor and the marked white pixel image to obtain the predicted value of each black pixel, recombine the black pixel into a black pixel image, and combine the predicted value of each black pixel to obtain a black pixel predicted image;

Step S107: encrypting the black pixel image and the black pixel prediction image;

Specifically, referring to the encryption method for the white pixel image in step S103, the method of modulo addition, the black pixel image B and the black pixel predicted image B' are encrypted using the encryption sequence K and K', and the specific calculation formula is as follows:

EB(i,j)=(B(i,j)+K(i,j))mod 256 i=1,2,...M,j=1,2,...N

EB'(i,j)=(B'(i,j)+K'(i,j))mod 256 i=1,2,...M,j=1,2,...N

Among them, EB(i,j), EB'(i,j) represent the encrypted black pixel image and the black pixel prediction image, respectively.

Step S108: Based on the encrypted black pixel image and the black pixel prediction image, a difference matrix D2 is obtained, and the difference matrix D2 is divided into blocks to obtain a secondary difference matrix diff_D2; Black pixel image; the specific process is as follows:

D1: The encrypted black pixel image EB and the black pixel prediction image EB' are correspondingly subtracted to obtain a difference matrix D2. The specific calculation formula is as follows:

D2(i,j)=(EB(i,j)-EB'(i,j))mod 256 i=1,2,...M,j=1,2,...N

D2: Divide the difference matrix D2 into blocks in such a way that the next element and its upper, lower, left, and right elements are kept every 4 elements, and make the difference between the upper, lower, left, and right elements and the middle element to obtain a secondary difference matrix diff_D2. Details The algorithm process is as follows:

According to the block rules shown in Figure 4 and Figure 5, in each block, the upper, lower, left, and right elements are made to differ from the middle element. The specific calculation formula is as follows:

D3: Obtain the histogram of the quadratic difference matrix diff_D2, and embed the secret information, that is, the identity authentication and other information that needs to be embedded, into the black pixel image B by means of the histogram shift to obtain the marked black pixel encrypted image P2.

When the embedded secret information is 1, it is equivalent to adding 1 and taking the modulo at the encrypted image EW(i-1,j), and when the embedded secret information is 0, it remains unchanged.

Select the highest four histogram bins to embed information, generally choose 0, 1, 255, and 254. Select 0 bin or the smallest number of bins as moving bins.

When the embedded expansion bin is smaller than the mobile bin, the mobile bin is increased by 1, and when the embedded expansion bin is greater than the mobile bin, the mobile bin is decreased by 1.

The pixel position corresponding to the moving bin is marked with map 1, and other positions are marked with 0, and the map is embedded into the image as auxiliary information and secret information.

Step S109 : combining the marked white pixel image and the marked black pixel image to obtain an encrypted marked image of the original image, thereby realizing information hiding of the ciphertext domain of the original image.

In the present embodiment, to verify its reversible separability and PSNR performance analysis, the detailed steps are as follows:

E1: Verification of the information extraction and image restoration reversibility of the encrypted labeled image of the original image.

Extract the black pixel of the encrypted marked image, use the marked white pixel image to obtain the predicted value of each black pixel according to step S106, and combine the predicted value of each black pixel to obtain the predicted image of black pixel; According to the above-mentioned step S108, obtain the secondary difference value The histogram is obtained by the following calculation formula to extract the information and restore it to become an encrypted image:

The specific calculation formula of the extended bin is as follows:

The specific calculation formula of the pixel corresponding to the position between the extended bin and the mobile bin is as follows:

P ^c _kz is the pixel value before the extended bin is restored to no embedded information, P2 is the black pixel value after encrypted marking, S is the secret information, S∈(0,1), P ^c _yd is the difference between the extended bin and the mobile bin The position of the corresponding pixel is restored to the original pixel value.

Extract the white pixels of the encrypted marked image, and repeat the above steps to obtain the extracted information and restore the encrypted image.

Extract the LSB (least significant bit) of the first row of pixels, that is, extract the marker map (the marker map is used to record the position of the moving Bin), a 0 matrix with the same size as the original image. The pixel at the corresponding position of the moving bin is marked with 1 on the marked map, and the other positions are marked with 0, and the value and position of the moving bin are obtained.

Finally, the auxiliary information in the extracted secret information is put back into the LSB of the first row of pixels to obtain a complete encrypted-only image.

The extracted information and black pixels are only encrypted images obtained through the above operations. Compared with the original encrypted images, the corresponding pixels of the two images are the same, which proves their reversibility. The extracted secret information is compared with the original secret information, and the extracted information is correct.

E2: Verify the encryption and decryption reversibility of the black pixel encrypted image.

In this embodiment, an encryption key is used to generate a pseudo-random sequence, and an encrypted image is obtained by modulo addition. The decryption method is as follows:

B(i,j)=mod(EB(i,j)-K(i,j),256)

B'(i,j)=mod(EB'(i,j)-K'(i,j),256)

The pseudo-random sequence is generated by encrypting the secret key, and then two pseudo-random sequences K and K' are obtained, and the decrypted image is obtained by modulo subtraction of the encrypted image and the pseudo-random sequence.

Compare the black pixel image with the black pixel decryption image to verify the reversibility of encryption and decryption.

E3: Verification of reversible separability of white pixel images.

The method of verifying the extraction information and reversibility of the first layer image is the same as steps E1 and E2.

The above steps prove that the information hiding algorithm proposed in this embodiment can realize the reversible separability of information extraction and image restoration.

E4: PANR performance analysis.

Calculate EI only the PSNR of the decrypted image and the original image I, the specific formula is as follows:

Among them, MSE represents the mean square error between the encrypted marked image and the original image, the size of the single-layer encrypted image is M*N, and the size of the fully encrypted image is M*2N;

Figure 13 shows a schematic diagram of the entire image processing process taking the Lena image as an example. Combined with Figure 10-12, by comparing the PSNR of the other three only decrypted images, we can see that:

This embodiment can realize the separability of the encryption and decryption process and the information extraction process of the encrypted marked image, and in the case of only decryption, the PSNR of the original image is higher than that of other solutions, and the image visual quality is better.

In the embedding process, the method of the present application can achieve larger capacity embedding than other methods, and in the embedding process, the capacity of the embedded secret information can be adjusted, which can meet the needs of the embedding capacity in reality as much as possible.

Embodiment 2

In one or more embodiments, a reversible and separable ciphertext domain information hiding system is disclosed, including:

an image acquisition module for acquiring an original image, and dividing the pixel interval of the original image into black and white pixels;

The first layer of image encryption module is used to recombine the white pixels to form a white pixel image, and obtain a white pixel predicted image based on the predicted value combination of each white pixel; respectively encrypt the white pixel image and the white pixel predicted image;

The first layer image marking module is used to obtain the difference matrix D1 based on the encrypted white pixel image and the white pixel prediction image, and divide the difference matrix D1 into blocks to obtain a secondary difference matrix diff_D1; The difference matrix gets the marked white pixel image;

The second-layer image encryption module is used for recombining black pixels to form a black pixel image, and combining the predicted values of each black pixel to obtain a black pixel predicted image; respectively encrypt the black pixel image and the black pixel predicted image;

The second layer image marking module is used to obtain the difference matrix D2 based on the encrypted black pixel image and the black pixel prediction image, and divide the difference matrix D2 into blocks to obtain a secondary difference matrix diff_D2; The difference matrix gets the marked black pixel image;

The combined marking module is used to combine the marked white pixel image and the marked black pixel image to obtain the encrypted marked image of the original image, thereby realizing the information hiding of the ciphertext domain of the original image.

It should be noted that the specific implementation manners of the above modules have been described in the first embodiment, and will not be described in detail.

Embodiment 3

In one or more embodiments, a terminal device is disclosed, including a server, the server including a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor executing the The program implements the reversible and separable ciphertext domain information hiding method in the first embodiment. For brevity, details are not repeated here.

It should be understood that, in this embodiment, the processor may be a central processing unit CPU, and the processor may also be other general-purpose processors, digital signal processors DSP, application-specific integrated circuits ASIC, off-the-shelf programmable gate array FPGA or other programmable logic devices , discrete gate or transistor logic devices, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The memory may include read-only memory and random access memory and provide instructions and data to the processor, and a portion of the memory may also include non-volatile random access memory. For example, the memory may also store device type information.

In the implementation process, each step of the above-mentioned method can be completed by a hardware integrated logic circuit in a processor or an instruction in the form of software.

Embodiment 4

In one or more embodiments, a computer-readable storage medium is disclosed, wherein a plurality of instructions are stored, and the instructions are adapted to be loaded by a processor of a terminal device and execute the reversibly separable described in the first embodiment. ciphertext domain information hiding method.

Although the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, they do not limit the scope of protection of the present invention. Those skilled in the art should understand that on the basis of the technical solutions of the present invention, those skilled in the art do not need to pay creative work. Various modifications or deformations that can be made are still within the protection scope of the present invention.

Claims (10)

1. a reversible and separable ciphertext domain information hiding method, is characterized in that, comprises: Obtaining an original image, and dividing the pixel interval of the original image into black and white pixels; Recombining the white pixels to form a white pixel image, and combining the predicted values of each white pixel to obtain a white pixel predicted image; Encrypt the white pixel image and the white pixel prediction image respectively; obtain the difference matrix D1 based on the encrypted white pixel image and the white pixel prediction image, divide the difference matrix D1 into blocks, and obtain the quadratic difference matrix diff_D1; The quadratic difference value matrix obtains the marked white pixel image; Recombining the black pixels to form a black pixel image, and combining the predicted values of each black pixel to obtain a black pixel predicted image; Encrypt the black pixel image and the black pixel prediction image respectively; obtain the difference matrix D2 based on the encrypted black pixel image and the black pixel prediction image, and divide the difference matrix D2 into blocks to obtain a secondary difference matrix diff_D2 ; Obtain the marked black pixel image based on the quadratic difference matrix; The marked white pixel image and the marked black pixel image are combined to obtain the encrypted marked image of the original image, thereby realizing the information hiding of the ciphertext domain of the original image. 2. a kind of reversible and separable ciphertext domain information hiding method as claimed in claim 1, is characterized in that, based on the predicted value combination of each white pixel, obtains the white pixel prediction image, specifically comprises: Using the diamond predictor and black pixels, the predicted value of each white pixel is obtained; the predicted value of each white pixel is combined to obtain the white pixel predicted image. 3. a kind of reversible and separable ciphertext domain information hiding method as claimed in claim 1 is characterized in that, the white pixel image and the white pixel prediction image are encrypted respectively, and specifically comprises: Use Lorenz chaotic system to get pseudo-random sequences S1 and S2; Perform non-repetitive row permutation and column permutation on the pseudorandom sequences S1 and S2, and the permuted sequence S1 is used as the encrypted sequence K; A set number of elements are taken in the pseudo-random sequence S2 to form a new sequence, and the new sequence and the replaced sequence S1 are obtained by modulo addition to obtain the encrypted sequence K'; The white pixel image is encrypted using the encryption sequence K, and the white pixel prediction image is encrypted using the encryption sequence K'. 4. a kind of reversible and separable ciphertext domain information hiding method as claimed in claim 1, is characterized in that, based on the white pixel image after encryption and white pixel prediction image, obtain difference value matrix D1, to difference value matrix D1 Divide into blocks to obtain a quadratic difference matrix diff_D1; specifically, it includes: The pixel values of the encrypted white pixel image and the white pixel prediction image are correspondingly subtracted and then modulo are obtained to obtain a difference matrix D1; The difference matrix D1 is divided into blocks according to the method of retaining the next element and its upper, lower, left, and right elements at each interval, and the upper, lower, left, and right elements are made difference with the middle element to obtain a quadratic difference matrix diff_D1. 5. a reversible and separable ciphertext domain information hiding method as claimed in claim 1, is characterized in that, obtains the marked white pixel image based on described quadratic difference value matrix, specifically comprises: Obtain the histogram of the quadratic difference matrix diff_D1, and perform information embedding by means of the histogram shift to obtain the marked white pixel image. 6. a kind of reversible and separable ciphertext domain information hiding method as claimed in claim 1, is characterized in that, obtains the predicted value of each black pixel using diamond shape predictor and the marked white pixel image, and each black pixel's predicted value is obtained. The predicted values are combined to obtain a predicted image of black pixels. 7. A kind of reversible and separable ciphertext domain information hiding method as claimed in claim 1, is characterized in that, also comprises: The process of verifying the information extraction and image restoration reversibility of the encrypted label image of the original image; The process of verifying the reversibility of encryption and decryption of the marked white pixel image; The process of verifying the reversibility of encryption and decryption of marked black pixel images. 8. A reversible and separable ciphertext domain information hiding system, characterized in that, comprising: an image acquisition module for acquiring an original image, and dividing the pixel interval of the original image into black and white pixels; The first layer of image encryption module is used to recombine the white pixels to form a white pixel image, and obtain a white pixel predicted image based on the predicted value combination of each white pixel; respectively encrypt the white pixel image and the white pixel predicted image; The first layer image marking module is used to obtain the difference matrix D1 based on the encrypted white pixel image and the white pixel prediction image, and divide the difference matrix D1 into blocks to obtain a secondary difference matrix diff_D1; The difference matrix gets the marked white pixel image; The second-layer image encryption module is used for recombining black pixels to form a black pixel image, and combining the predicted values of each black pixel to obtain a black pixel predicted image; respectively encrypt the black pixel image and the black pixel predicted image; The second layer image marking module is used to obtain the difference matrix D2 based on the encrypted black pixel image and the black pixel prediction image, and divide the difference matrix D2 into blocks to obtain a secondary difference matrix diff_D2; The difference matrix gets the marked black pixel image; The combined marking module is used to combine the marked white pixel image and the marked black pixel image to obtain the encrypted marked image of the original image, thereby realizing the information hiding of the ciphertext domain of the original image. 9. A terminal device, comprising a processor and a memory, the processor is used to implement each instruction; the memory is used to store a plurality of instructions, wherein the instructions are adapted to be loaded by the processor and execute any of claims 1-7. A reversible and separable ciphertext domain information hiding method. 10. A computer-readable storage medium, wherein a plurality of instructions are stored, wherein the instructions are adapted to be loaded by a processor of a terminal device and execute the reversibly detachable reversible detachable device according to any one of claims 1-7. Ciphertext domain information hiding method.

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