CN114465779A - Reversible separable ciphertext domain information hiding method and system - Google Patents
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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
Technical Field
The invention relates to the technical field of information hiding, in particular to a reversible separable ciphertext domain information hiding method and system.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
With the rise of cloud computing and the wide application of cloud storage, a user stores own images in a third-party cloud service provider, but does not trust the other party, so that own data is encrypted firstly and then uploaded to a cloud service center. In order to facilitate management and authentication of data, cloud service providers need to mark all data for storage, and the marks are hidden secret information, and the processes do not need to know content information of images at all. Thus, the information hiding process is performed on the ciphertext domain of the image. For some application scenarios with high data authentication requirements, the extraction of information and the recovery of an image are required to be completely reversible, so a reversible information hiding technology for encrypting the image is developed.
However, with the changing demand, people have more requirements on reversible information hiding in a ciphertext domain, for example, when people want to transmit high-secret images, even if the images are encrypted, some high-secret images are not allowed to be transmitted in a public network, so the high-secret images need to be marked, and when the mark is detected to show high confidentiality, a network police automatically intercepts the images. This requires that the police only have the right to extract the tag information, cannot obtain the decrypted image, and after extracting the tag information, the image is not affected.
At present, reversible information hiding algorithms of a ciphertext domain are divided into two types: reserving space before encryption and vacating space after encryption. The pre-encryption space-reserving method obtains a bit-plane space that can be embedded together by using compression in most cases, resulting in high embedding capacity, but most algorithms cannot achieve separation of extracted information from image restoration. The method for vacating space after encryption has low redundancy of ciphertext images, has higher difficulty in vacating space to embed information, greatly limits the capacity of subsequent information embedding, improves the algorithm continuously, increases the correlation among ciphertext image pixels by utilizing various encryption rules, and can be used for people to embed information. But still has the problems of poor visual quality of the mark image after image decryption and the like.
From the above, the current ciphertext domain reversible information hiding algorithm has two disadvantages: (1) in pursuit of high embedding capacity, information extraction and image restoration cannot be separated. (2) The encrypted marker image is of poor image quality after decryption alone.
Disclosure of Invention
In order to solve the problems, the invention provides a reversible separable ciphertext domain information hiding method and a reversible separable ciphertext domain information hiding system, wherein only by simultaneously possessing an encryption key and an extraction key, secret information and a decrypted image can be obtained; on the premise of ensuring the embedding capacity, the information extraction and the image recovery can be separated, the visual quality of the decrypted marked image is relatively high, and the influence on the image content and the image quality is not large under the condition of only decrypting.
In some embodiments, the following technical scheme is adopted:
a reversible separable ciphertext domain information hiding method comprises the following steps:
acquiring 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 white pixels based on the predicted value 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 difference matrix D1 based on the encrypted white pixel image and the white pixel predicted image, and partitioning the difference matrix D1 to obtain a quadratic difference matrix diff _ D1; obtaining a marked white pixel image based on the quadratic difference matrix;
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;
encrypting the black pixel image and the black pixel predicted image respectively; obtaining a difference matrix D2 based on the encrypted black pixel image and the black pixel predicted image, and partitioning the difference matrix D2 to obtain a secondary difference matrix diff _ D2; 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.
In other embodiments, the following technical solutions are adopted:
a reversibly separable ciphertext domain information hiding system, comprising:
the image acquisition module is used for acquiring an original image and dividing the pixel interval of the original image into black and white pixels;
the first layer image encryption module is used for recombining the white pixels to form a white pixel image and combining the white pixels based on the predicted value of each white pixel to obtain a white pixel predicted image; respectively encrypting the white pixel image and the white pixel predicted image;
the first layer image marking module is used for obtaining a difference matrix D1 based on the encrypted white pixel image and the encrypted white pixel predicted image, and partitioning the difference matrix D1 to obtain a quadratic difference matrix diff _ D1; obtaining a marked white pixel image based on the quadratic difference matrix;
the second layer image encryption module is used for recombining the black pixels to form a black pixel image and combining the black pixel image based on the predicted value of each black pixel to obtain a black pixel predicted image; encrypting the black pixel image and the black pixel predicted image respectively;
the second layer image marking module is used for obtaining a difference matrix D2 based on the encrypted black pixel image and the black pixel predicted image, and partitioning the difference matrix D2 to obtain a secondary difference matrix diff _ D2; obtaining a marked black pixel image based on the quadratic difference matrix;
and the combined marking module is used for combining the marked white pixel image and the marked black pixel image to obtain an encrypted marked image of the original image, so that the ciphertext domain information of the original image is hidden.
In other embodiments, the following technical solutions are adopted:
a terminal device comprising a processor and a memory, the processor being arranged to implement instructions; the memory is configured to store a plurality of instructions adapted to be loaded by the processor and to perform the reversible separable ciphertext domain information hiding method described above.
In other embodiments, the following technical solutions are adopted:
a computer-readable storage medium, having stored therein a plurality of instructions adapted to be loaded by a processor of a terminal device and to execute the above-mentioned reversible separable ciphertext domain information hiding method.
Compared with the prior art, the invention has the beneficial effects that:
(1) the reversible separable ciphertext domain information hiding method increases redundancy among encrypted image pixels by utilizing the rule of an image encryption algorithm, keeps larger embedding capacity, and increases visual quality of a decrypted marked image.
(2) The receiving end receives the encrypted marked image and the encrypted key and the extracted key, the decrypted marked image can be obtained by using the encrypted key, the encrypted image can be obtained by using the extracted key, the two keys are independent from each other in use and can be exchanged in sequence, and only if the two keys are possessed at the same time, the secret information and the decrypted image can be obtained. The encryption and decryption and the information extraction are separated, and the receiving end can decrypt the received image or extract the information only when the receiving end has the right of encryption and decryption or information extraction.
(3) The method of the invention realizes that the decrypted image can not be obtained only by extracting the embedded information authority, namely, the specific content of the image can not be transmitted publicly, thereby ensuring the safety of information transmission; when only the decryption right exists, the authentication information or the copyright information embedded in the image cannot be modified, and the copyright of the image is protected. Furthermore, in the method, the visual quality of the decrypted image is superior to that of other methods, and the mark image is identical in appearance to the original image, and the embedded secret information is hardly noticeable to the naked eye.
Additional features and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
FIG. 1 is a flowchart of a reversible and separable ciphertext domain information hiding method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of image prediction stage hierarchy according to an embodiment of the present invention;
FIG. 3 is a diagram of a diamond predictor in accordance with an embodiment of the present invention;
FIG. 4 is a block diagram of an image during encryption and marking in an embodiment of the present invention;
FIG. 5 is a block diagram internal to the encryption and tagging process in an embodiment of the present invention;
FIG. 6 is a Lena image histogram in an embodiment of the present invention;
FIG. 7 is a Lena encrypted image histogram in an embodiment of the present invention;
FIG. 8 is a schematic diagram illustrating horizontal pixel correlation of a Lena image according to an embodiment of the present invention;
FIG. 9 is a histogram of quadratic difference values for a Lena encrypted image in an embodiment of the present invention;
FIG. 10 is a comparison graph of the Lena image PSNR of the BPP according to the different methods of the present invention;
FIG. 11 is a PSNR comparison diagram of Baboon images of different methods and BPP according to the present invention;
FIG. 12 is a PSNR comparison of a Plane image of BPP according to various methods provided by the present invention;
fig. 13 is a schematic diagram of the whole image processing process taking Lena image as an example in the embodiment of the present invention.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, 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 is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Example one
In one or more embodiments, a reversible separable ciphertext domain information hiding method is disclosed, which, with reference to fig. 1, specifically includes the following processes:
step S101: acquiring an original image, and dividing the pixel interval of the original image into black and white pixels;
in this embodiment, the original image I pixels with the size of 512 × 512 are divided into two black and white pixels at intervals, as shown in fig. 2, the white pixels are used as the first layer pixels, and the black pixels are used as the second layer pixels.
Step S102: calculating a predicted value of each white pixel by using the diamond predictor and the black pixel, recombining the white pixels into a white pixel image W, and combining the predicted values of each white pixel to obtain a white pixel predicted image W';
specifically, as shown in FIG. 3, the diamond predictor is calculated as follows:
wherein B (i, j-1) represents the pixel value of the black pixel at the point (i, j-1); the size of the first layer image W and its predicted image W' is reduced to 512 × 256.
B (i-1, j) represents a pixel value of the black pixel at a point (i-1, j), B (i, j +1) represents a pixel value of the black pixel at a point (i, j +1), B (i +1, j) represents a pixel value of the black pixel at a point (i +1, j), and W' (i, j) represents a pixel prediction value of the white pixel at a point (i, j).
Step S103: respectively encrypting the white pixel image and the white pixel predicted image; the specific encryption process is as follows:
a1: the Lorenz chaotic system is used for obtaining pseudo-random sequences S1 and S2, and the specific formula is as follows:
wherein, when a is 10, b is 8/3, c is 28 and-1.52 is less than or equal to r is less than or equal to-0.06, the system is in hyperchaotic state. Setting initial values of x, y, z and w in a formula as encryption keys, and generating pseudo-random sequences S1 and S2 by using a hyper-chaos Lorenz system, wherein the sequences are one-dimensional sequences and have the length of 512 x 256.
A2: the pseudo-random sequences S1 and S2 were converted into 512 × 256 two-dimensional sequences, and row permutation and column permutation were performed without repetition, and the permuted two-dimensional sequence Scrambling _ S1 was used as the encrypted sequence K.
A3: partitioning the Scrambling _ S1 into blocks according to a mode that the next element, the upper element, the lower element, the left element and the right element of the next element are reserved every 4 elements, the number of the blocks is Num, the previous Num elements are taken from a pseudorandom sequence S2 to form a new sequence S2_ Num, and the obtained sequence S2_ Num and the sequence Scrambling _ S1 are subjected to modular addition to obtain an encrypted sequence K'.
In this embodiment, the partitioning is performed as shown in fig. 4, and the number of completed blocks is calculated and recorded as Num. Taking the first Num elements from the pseudo-random sequence S2 to form a new sequence S2_ Num, and obtaining an encrypted sequence K' through modular addition, wherein the specific formula is as follows:
K'(i,j)＝S1(i,j)+S2_Num(count)i＝1,2,...M,j＝1,2,...N
where i, j are the rows and columns of the corresponding two-dimensional sequence, count is the serial number of each block corresponding, and M, N represents the size of the encrypted image, which in this embodiment is 512 x 256.
A4: the method comprises the following steps of respectively encrypting a first layer white pixel image W and a white pixel predicted image W 'by using encryption sequences K and K' in a mode of modulo addition, wherein a specific calculation formula is as follows:
here, EW (i, j), EW '(i, j) is an encrypted image corresponding to the first-layer white pixel image W and the white pixel predicted image W'.
Step S104: in three aspects of safety, relevance and randomness, the performance of the encrypted image is analyzed, and the specific steps are as follows:
b1: as shown in fig. 6, the histogram of Lena original image has non-uniform pixel distribution, and after being encrypted, as shown in fig. 7, the encrypted image has uniform pixel distribution, and the more uniform the pixel distribution, the higher the security of the encryption algorithm.
B2: 5000 pairs of adjacent pixels are randomly selected, the correlation between the original image and the encrypted image is respectively calculated in the horizontal direction, and the specific correlation coefficient calculation formula is as follows:
wherein X, Y represent two pixel values, RXYRepresenting the correlation between two horizontal adjacent pixels, cov (X, Y) representing the covariance of two pixels, d (X), d (Y) representing the variance of the pixel between the encrypted and unencrypted cases.
As shown in fig. 8, correlation between adjacent pixels of the Lena encrypted image is low, and randomness of the pixels is large.
B3: the information Entropy (Entropy) represents the randomness of the pixel, the information Entropy of an ideal encrypted image is close to 8, and the calculation formula of the information Entropy is as follows:
where H (p), H' (p) represents the entropy of information corresponding to the encrypted image, and p represents pixels in the range [0,255 ].
B4: the pixel change rate (NPCR) can reflect the sensitivity of the encryption method key, and the ideal encrypted image NPCR is close to 0.9960, and the specific calculation formula is as follows:
where NPCR represents the rate of change of the pixel at point (i, j).
Table1 shows the NPCR and information entropy tables for Lena, Babon and Plane, respectively
Information entropy and NPCR of Table1 test chart
As shown in table1, three test charts, named Lena, Baboon, and Plane, are selected for secret performance analysis, and it can be seen that the information entropy of Lena encrypted image is close to 8, the randomness is good, the pixel change rate is close to 0,9960, the encryption key has high flexibility and 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: obtaining a difference matrix D1 based on the encrypted white pixel image and the white pixel predicted image, and partitioning the difference matrix D1 to obtain a quadratic difference matrix diff _ D1; obtaining a marked white pixel image based on the quadratic difference matrix; the specific process is as follows:
c1: and (4) correspondingly subtracting the pixel values of the encrypted image EW and EW' and then performing modulo extraction to obtain a difference matrix D1.
The specific calculation formula is as follows: d1(i, j) ═ EW (i, j) -EW' (i, j)) mod256 i ═ 1,2
C2: partitioning the difference matrix D1 in a manner that the next element and the upper, lower, left and right elements thereof are reserved every 4 elements apart, and making the upper, lower, left and right elements and the middle element be differenced to obtain a quadratic difference matrix diff _ D1, wherein the detailed algorithm process is as follows:
according to the block division rule of the figure, the difference is made between the upper, lower, left and right elements and the middle element in each block, and the specific calculation formula is as follows:
where mod256 refers to taking the modulus of the contents of the preceding brackets. The remainder of the division by 256 is obtained.
C3: a histogram of the quadratic difference matrix diff _ D1 is obtained, and information is embedded by means of histogram shift, resulting in a marked white pixel encrypted image P1.
And taking the authentication information or the copyright information as secret information, representing the secret information as a binary sequence, generating a pseudo-random sequence by using a secret key, and performing exclusive-or operation with the secret information sequence, wherein the secret key is an extracted secret key which is used for subsequently extracting the information and decrypting the secret information to obtain correct authentication information or copyright information.
In order to more conveniently show the specific process of the method, the secret information is represented by using S epsilon (0,1) in the following.
The secret information is set to S e (0,1), and in the example of diff _ D1(i-1, j), the embedded secret information remains unchanged when it is 0.
When the embedded secret information is 1, it is equivalent to add 1 to the encrypted image EW (i-1, j) and take the modulus, and 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, a histogram bin of embedded information is called an expansion bin, and a histogram bin for generating a vacancy through movement is called a movement bin;
as can be seen from the above description, the expansion and shift of the quadratic difference histogram are actually performed by changing the position of the encrypted image EW, embedding the position of the encrypted image EW corresponding to the position of the expansion bin, and the pixel value of the labeled encrypted image P1 at a certain point is obtained according to the specific calculation formulas of the expansion bin and the shift bin.
The specific calculation formula of the extended bin is as follows:
the specific calculation formula of the position-corresponding pixel between the extended bin and the moving bin is as follows:
a matrix 0 having the same size as the original image is set as a marker map, pixels at positions corresponding to the moving bins are marked with 1 on the marker map, and other positions are marked with 0, the marker map and the pixels in the first row are subjected to LSB (least significant bit) replacement, and the replaced pixels are embedded into the image as auxiliary information together with secret information.
C4: selecting an expansion bin and a mobile bin according to the histogram characteristics;
as shown in the histogram of the quadratic difference matrix diff _ D1 of fig. 9, it was found that the histogram is high around 0 and 255, and the difference values are concentrated.
The four highest bins 0,1,255 and 254 are typically selected as expansion bins, and either the 0bin or the smallest number of bins is selected as the mobile bin.
Step S106: obtaining a predicted value of each black pixel by using the diamond predictor and the marked white pixel image, recombining the black pixels into a black pixel image, and combining the predicted values of each black pixel to obtain a black pixel predicted image;
step S107: encrypting the black pixel image and the black pixel predicted image;
specifically, referring to the encryption method for the white pixel image in step S103, a modulo addition method is used to encrypt the black pixel image B and the black pixel predicted image B 'using the encryption sequences 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
where EB (i, j) and EB' (i, j) represent the encrypted black pixel image and the black pixel predicted image, respectively.
Step S108: obtaining a difference matrix D2 based on the encrypted black pixel image and the black pixel predicted image, and partitioning the difference matrix D2 to obtain a secondary difference matrix diff _ D2; obtaining a marked black pixel image based on the quadratic difference matrix; the specific process is as follows:
d1: the encrypted black pixel image EB and the black pixel predicted image EB' are subtracted correspondingly to obtain a difference matrix D2, and 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: partitioning the difference matrix D2 in a manner that the next element and the upper, lower, left and right elements thereof are reserved every 4 elements apart, and making the upper, lower, left and right elements and the middle element be differenced to obtain a quadratic difference matrix diff _ D2, wherein the detailed algorithm process is as follows:
according to the partitioning rule of fig. 4 and 5, the difference between the upper, lower, left and right elements and the middle element in each block is calculated as follows:
d3: a histogram of the quadratic difference matrix diff _ D2 is obtained, and secret information, i.e. information such as identity authentication to be embedded, is embedded into the black pixel image B by means of histogram shift, so as to obtain a marked black pixel encrypted image P2.
When the embedded secret information is 1, it is equivalent to adding 1 to the encrypted image EW (i-1, j) and taking a modulo, and when the embedded secret information is 0, it remains unchanged.
The highest four histogram bins are selected to embed the information, typically 0,1,255, and 254. Select 0bin or the smallest number of bins as the mobile bin.
When the embedded expansion bin is smaller than the mobile bin, the mobile bin is added with 1, and when the embedded expansion bin is larger than the mobile bin, the mobile bin is subtracted with 1.
The pixel position corresponding to the moving bin is embedded in the image as auxiliary information together with the secret information using map flag 1 and other position flag 0.
Step S109: 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.
In this embodiment, the reversible separability and PSNR performance analysis thereof are verified, and the detailed steps are as follows:
e1, verifying the information extraction and image recovery reversibility of the encrypted markup image of the original image.
Extracting black pixels of the encrypted marked image, obtaining a predicted value of each black pixel by using the marked white pixel image according to the step S106, and combining the predicted values of each black pixel to obtain a black pixel predicted image; according to the step S108, a secondary difference histogram is obtained, and the extracted information is obtained and restored to an encrypted image by the following calculation formula:
the specific calculation formula of the extended bin is as follows:
the specific calculation formula of the position-corresponding pixel between the extended bin and the moving bin is as follows:
Pc kzis the pixel value before the extended bin is restored to no embedded information, P2 is the black pixel value after the encryption flag, S is the secret information, S belongs to (0,1), P belongs toc ydThe position-corresponding pixel between the extended bin and the moving bin is restored to the original pixel value.
And extracting white pixels of the encrypted marked image, repeating the steps to obtain the extracted information and restoring the extracted information into the encrypted image.
The LSB (least significant bit) of the first row of pixels is extracted, i.e., the marker map (which is used to record the position of the shifted Bin) is extracted, and the size is the same as that of the original image, i.e., 0 matrix. The pixel at the position corresponding to the moving bin is marked with 1 on the marker map, and the other positions are marked with 0, so that the value and position of the moving bin are obtained.
And finally, the auxiliary information in the extracted secret information is put back to the LSB of the first row of pixels to obtain a complete encrypted-only image.
The extracted information and the encrypted image with black pixels obtained by the operation are compared with the original encrypted image, and the corresponding pixels of the two images are the same, so that the reversibility is proved. The extracted secret information is compared with the original secret information, and the extracted information is correct.
E2 verification of the reversibility of encryption and decryption of black pixel encrypted images.
In this embodiment, the pseudo-random sequence is generated by using an encryption key, and an encrypted image is obtained by modulo addition, where 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)
and generating a pseudo-random sequence by encrypting the secret key, further obtaining two pseudo-random sequences K and K', and obtaining a decrypted image by the modular subtraction of the encrypted image and the pseudo-random sequence.
And comparing the black pixel image with the black pixel decryption image, and verifying the reversibility of encryption and decryption.
E3, verifying the reversible separability of the white pixel image.
The method of verifying the first layer image extraction information and the reversibility, the synchronization steps E1 and E2 being the same.
The above steps prove that the information hiding algorithm provided by the embodiment is reversible separability capable of realizing information extraction and image restoration.
E4: and (4) analyzing the performance of the PANR.
PSNR of an image decrypted only by EI and an original image I is calculated, and the specific formula is as follows:
wherein MSE represents the mean square error between the encrypted marker image and the original image, the size of the single-layer encrypted image is M x N, and the size of the image after being completely encrypted is M x 2N;
fig. 13 is a schematic diagram of the whole image processing process taking Lena image as an example. In conjunction with fig. 10-12, by comparing PSNR of the other three decryption-only images, it can be seen that:
the embodiment can realize separability of the encryption and decryption process and the information extraction process of the encrypted marked image, and has higher PSNR (peak signal to noise ratio) compared with other schemes of the original image and better image visual quality under the condition of only decryption.
In the embedding process, the method can realize the embedding of larger capacity compared with other methods, and in the embedding process, the capacity of the embedded secret information can be adjusted, so that the requirement of the actual situation on the embedding capacity can be met as far as possible.
Example two
In one or more embodiments, a reversibly separable ciphertext domain information hiding system is disclosed, comprising:
the image acquisition module is used for acquiring an original image and dividing the pixel interval of the original image into black and white pixels;
the first layer image encryption module is used for recombining the white pixels to form a white pixel image and combining the white pixels based on the predicted value of each white pixel to obtain a white pixel predicted image; respectively encrypting the white pixel image and the white pixel predicted image;
the first layer image marking module is used for obtaining a difference matrix D1 based on the encrypted white pixel image and the encrypted white pixel predicted image, and partitioning the difference matrix D1 to obtain a quadratic difference matrix diff _ D1; obtaining a marked white pixel image based on the quadratic difference matrix;
the second layer image encryption module is used for recombining the black pixels to form a black pixel image and combining the black pixel image based on the predicted value of each black pixel to obtain a black pixel predicted image; encrypting the black pixel image and the black pixel predicted image respectively;
the second layer image marking module is used for obtaining a difference matrix D2 based on the encrypted black pixel image and the black pixel predicted image, and partitioning the difference matrix D2 to obtain a secondary difference matrix diff _ D2; obtaining a marked black pixel image based on the quadratic difference matrix;
and the combined marking module is used for combining the marked white pixel image and the marked black pixel image to obtain an encrypted marked image of the original image, so that the ciphertext domain information of the original image is hidden.
It should be noted that, the specific implementation of each module described above has been described in the first embodiment, and is not described in detail.
EXAMPLE III
In one or more implementations, a terminal device is disclosed, which includes a server including a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the reversibly separable ciphertext domain information hiding method of the first embodiment when executing the program. For brevity, no further description is provided herein.
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 arrays FPGA or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, and so on. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory may include both read-only memory and random access memory, and may 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 implementation, the steps of the above method may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software.
Example four
In one or more implementations, a computer-readable storage medium is disclosed, in which a plurality of instructions are stored, the instructions being adapted to be loaded by a processor of a terminal device and to perform the reversible separable ciphertext domain information hiding method of the first embodiment.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (10)
1. A reversible separable ciphertext domain information hiding method is characterized by comprising the following steps:
acquiring 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 white pixels based on the predicted value 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 difference matrix D1 based on the encrypted white pixel image and the white pixel predicted image, and partitioning the difference matrix D1 to obtain a quadratic difference matrix diff _ D1; obtaining a marked white pixel image based on the quadratic difference matrix;
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;
encrypting the black pixel image and the black pixel predicted image respectively; obtaining a difference matrix D2 based on the encrypted black pixel image and the black pixel predicted image, and partitioning the difference matrix D2 to obtain a secondary difference matrix diff _ D2; 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.
2. The method of claim 1, wherein the obtaining of the predicted image of the white pixel based on the combination of the predicted values of each white pixel comprises:
obtaining a predicted value of each white pixel by using a diamond predictor and the black pixels; and combining the predicted values of each white pixel to obtain a white pixel predicted image.
3. The method for concealing information in a reversibly separable ciphertext domain according to claim 1, wherein encrypting the white pixel image and the white pixel predicted image respectively comprises:
obtaining pseudo-random sequences S1 and S2 by using a Lorenz chaotic system;
performing non-repeated row replacement and column replacement on the pseudo-random sequences S1 and S2, and taking a replaced sequence S1 as an encryption sequence K;
taking a set number of elements from the pseudo-random sequence S2 to form a new sequence, and carrying out modular addition on the new sequence and the replaced sequence S1 to obtain an encrypted sequence K';
the white pixel image is encrypted using an encryption sequence K and the white pixel predicted image is encrypted using an encryption sequence K'.
4. The reversibly separable ciphertext domain information hiding method of claim 1, wherein based on the encrypted white pixel image and the white pixel predicted image, obtaining a difference matrix D1, partitioning the difference matrix D1 to obtain a quadratic difference matrix diff _ D1; the method specifically comprises the following steps:
correspondingly subtracting the pixel values of the encrypted white pixel image and the white pixel predicted image, and then performing modular extraction to obtain a difference matrix D1;
the difference matrix D1 is partitioned in such a manner that the next element and its upper, lower, left, and right elements are retained at every interval setting element, and the upper, lower, left, and right elements are differentiated from the middle element to obtain a quadratic difference matrix diff _ D1.
5. The method of claim 1, wherein obtaining the marked white pixel image based on the quadratic difference matrix specifically comprises:
and acquiring a histogram of the quadratic difference matrix diff _ D1, and embedding information in a histogram shifting mode to obtain a marked white pixel image.
6. The reversibly separable ciphertext domain information hiding method of claim 1, wherein the diamond predictor and the marked white pixel image are used to obtain the predicted value of each black pixel, and the predicted values of each black pixel are combined to obtain a black pixel predicted image.
7. The reversibly separable ciphertext domain information hiding method of claim 1, further comprising:
the process of verifying the information extraction and the image recovery reversibility of the encrypted marked image of the original image;
a process of verifying the encryption and decryption reversibility of the marked white pixel image;
and (3) verifying the encryption and decryption reversibility of the marked black pixel image.
8. A reversibly separable ciphertext domain information hiding system, comprising:
the image acquisition module is used for acquiring an original image and dividing the pixel interval of the original image into black and white pixels;
the first layer image encryption module is used for recombining the white pixels to form a white pixel image and combining the white pixels based on the predicted value of each white pixel to obtain a white pixel predicted image; respectively encrypting the white pixel image and the white pixel predicted image;
the first layer image marking module is used for obtaining a difference matrix D1 based on the encrypted white pixel image and the encrypted white pixel predicted image, and partitioning the difference matrix D1 to obtain a quadratic difference matrix diff _ D1; obtaining a marked white pixel image based on the quadratic difference matrix;
the second layer image encryption module is used for recombining the black pixels to form a black pixel image and combining the black pixel image based on the predicted value of each black pixel to obtain a black pixel predicted image; encrypting the black pixel image and the black pixel predicted image respectively;
the second layer image marking module is used for obtaining a difference matrix D2 based on the encrypted black pixel image and the black pixel predicted image, and partitioning the difference matrix D2 to obtain a secondary difference matrix diff _ D2; obtaining a marked black pixel image based on the quadratic difference matrix;
and the combined marking module is used for combining the marked white pixel image and the marked black pixel image to obtain an encrypted marked image of the original image, so that the ciphertext domain information of the original image is hidden.
9. A terminal device comprising a processor and a memory, the processor being arranged to implement instructions; the memory for storing a plurality of instructions adapted to be loaded by the processor and to perform the invertible separable ciphertext domain information hiding method of any of claims 1-7.
10. A computer-readable storage medium having stored thereon a plurality of instructions adapted to be loaded by a processor of a terminal device and to perform the reversibly separable ciphertext domain information hiding method of any one of claims 1-7.
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| CN117676032B (en) * | 2023-11-24 | 2024-06-04 | 广东技术师范大学 | Multi-party reversible information hiding method and device for ciphertext binary image |
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