Editable image encryption storage method

Abstract

The invention discloses an editable image encryption storage method, and relates to the technical field of information security, and the method comprises the steps: 1, system initialization: a data owner generates an additive secret sharing public modulus sk, and recruits a first cloud server and a second cloud server; step 2, image encryption segmentation: carrying out encryption segmentation operation on pixel points by using an encryption function epsilon to obtain a first ciphertext cim1 and a second ciphertext cim2; and step 3, generating an image thumbnail: calculating according to a nearest neighbor interpolation method to obtain a thumbnail share cimgi, and sending the thumbnail share cimgi to a data owner for decryption to obtain a visual thumbnail. And step 4, encrypted image clipping: obtaining the left upper corner coordinates (xlt, ylt) and the right lower corner coordinates (xrb, yrb) of the encrypted image held by any server, and clipping the encrypted image to obtain a target encrypted image. And 5, adjusting the brightness of the encrypted image: calling a brightness adjustment factor B to carry out brightness editing on the share of the encrypted image to obtain the image share cimgi after brightness adjustment, and sending the image share cimgi to a data owner for decryption to obtain a visual brightness adjustment graph. And step 6, contrast adjustment of the encrypted image: calling a contrast adjustment factor alpha to carry out contrast editing on the share of the encrypted image to obtain an image share cimgi after contrast adjustment, and sending the image share cimgi to a data owner for decryption to obtain a visual contrast adjustment graph. The method has remarkable advantages, and particularly, the optimal balance between privacy protection and operation convenience is realized.

Description

Technical Field

[0001] The present invention relates to the field of information security technology, and in particular to an editable image encryption storage method. Background Art

[0002] The popularity of smartphones has led to a rapid increase in the number of photos taken by users in their daily lives, and traditional local storage methods can no longer meet the ever-expanding storage needs. As a modern solution, cloud photo storage not only provides larger storage capacity, but also provides users with convenient access methods, allowing them to easily upload photos to the cloud and manage them. By browsing thumbnails, users can view and manage their photos anytime, anywhere. Currently, almost all smartphone manufacturers provide similar cloud storage services, such as Apple's iCloud and Google's Google Photos, which significantly reduce the pressure on local storage and improve the availability and convenience of photos.

[0003] The development of cloud photo storage has brought many conveniences to users, but it has also created some thorny problems. Privacy protection issues highlight the shortcomings of cloud storage solutions. Frequent cloud storage service leaks, such as the theft of iCloud accounts that led to the leakage of a large number of celebrity private photos, have exposed the shortcomings of existing cloud photo storage solutions in terms of privacy protection. Users have expressed concerns about whether their private photos can be properly protected.

[0004] In addition, although traditional image encryption methods can effectively protect privacy, they usually change the structure of the image, increase storage overhead, and make it difficult for cloud storage providers to store encrypted images. This limits the applicability of traditional encryption technology in cloud photo storage.

[0005] In response to the above problems, the academic community has proposed a new solution - thumbnail-preserving encryption technology. This technology can ensure that the ciphertext obtained after encryption is still an image, and the ciphertext has the same thumbnail as the original image, which balances the privacy protection and availability of cloud photo storage to a certain extent. However, this technology also has some limitations: the generated ciphertext thumbnail may still leak part of the image content; at the same time, it can only generate image thumbnails, and cannot perform operations such as cropping, brightness adjustment, and contrast adjustment; in addition, it also increases the computation and upload burden of uploading encrypted images and thumbnails on the client. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides an editable image encryption storage method, which can improve the efficiency of image encryption processing, effectively protect the privacy of images stored in cloud photos, and realize the editing of images in an encrypted state.

[0007] The technical solution of the present invention is achieved in this way:

[0008] An editable image encryption storage method comprises the following steps:

[0009] Step 1, system initialization: the data holder generates a public modulus sk for additive secret sharing; the data holder invites two independent cloud servers, the first cloud server and the second cloud server;

[0010] Step 2: Image encryption: The data holder uses the encryption function ε to encrypt each pixel of the original image and obtains an encrypted pair (cimg 1 , cimg 2 ), respectively, the first ciphertext cimg 1 and the second ciphertext cimg 2 The original image is an RGB three-channel image with n and m pixels in height and width respectively. The encryption function is: ε(sk, cimg)→(cimg 1 , cimg 2 ), where c∈{R, G, B} represents RED, GREEN and BLUE channels respectively; represents the single channel pixel value of the pixel point, and cimg∈[0, 255];

[0011] Step 3: Encrypted image thumbnail generation: The first cloud server and the second cloud server respectively call the nearest neighbor interpolation method to calculate the encrypted thumbnail share cimg i , sending the two encrypted thumbnail shares to the data owner; the data owner decrypts the two encrypted thumbnail shares to obtain visible thumbnails;

[0012] Step 4: Encrypted image clipping: The first cloud server and the second cloud server respectively hold the encrypted image, and obtain the upper left corner coordinates (x lt ,y lt ) and the lower right corner coordinate (x rb ,y rb ), the cropping of the encrypted image includes a left cropping width w1, a right cropping width w2, an upper cropping height h1 and a lower cropping height h2, wherein h=y rb -y lt , w = x rb -y lt . Performing the cropping to obtain a target encrypted image;

[0013] Step 5: Encrypted image brightness adjustment: The first cloud server and the second cloud server respectively call the brightness adjustment factor cB iWhere B is a custom brightness constant, c∈{R, G, B}, cB i This means that the brightness adjustment operation is performed on different channels (RED, GREEN, BLUE). The encrypted image share is edited for brightness, and the image share after brightness adjustment is obtained. i , sending the two brightness-adjusted image shares to the data owner; the data owner decrypts the two brightness-adjusted image shares to obtain a visible brightness-adjusted image;

[0014] Step 6: Encrypted image contrast adjustment: The first cloud server and the second cloud server respectively call the contrast adjustment factor α to perform contrast editing on the encrypted image share to obtain the image share cimg after contrast adjustment i , sending the two contrast-adjusted image shares to the data owner; the data owner decrypts the two contrast-adjusted image shares to obtain a visible contrast-adjusted image;

[0015] The encryption function ε can be used to segment and encrypt the original image. The data uploaded to the first server and the second server are encrypted data, so that users can ensure the privacy and security of image data while making full use of cloud resources.

[0016] As a further optimization of the above scheme, the additive secret sharing public modulus is sk=2 8 .

[0017] As a further optimization of the above scheme, the encryption function ε1 based on additive secret sharing in the encryption function is expressed as:

[0018]

[0019] in, That means cimg 1 is from [0, 2 8 ) is a number randomly selected from .

[0020] As a further optimization of the above solution, a decryption function D1 is further included, which is used to restore the first ciphertext and the second ciphertext to pixels cimg, that is: cimg = D1 (sk, cimg 1 , cimg 2 )=cimg 1 +cimg 2 mod sk.

[0021] As a further optimization of the above scheme, the encryption function ε2 based on matrix transformation in the encryption function is expressed as:

[0022]

[0023] Where r∈[0, 255] is a randomly selected uniform value and K is a 2×2 reversible matrix key.

[0024] As a further optimization of the above solution, a decryption function D2 is further included, which is used to restore the first ciphertext and the second ciphertext to pixels cimg, that is:

[0025]

[0026] As a further optimization of the above solution, in step 2, the encryption satisfies the addition support of the brightness adjustment operation: Where B is the brightness adjustment factor.

[0027] As a further optimization of the above scheme, in step 2, the encryption satisfies the multiplication support of the contrast adjustment operation:

[0028] Among them, α is the contrast constant.

[0029] As a further optimization of the above solution, in step 2, in order to save the encrypted image matrix, cimg 1 and cimg 2 The value should satisfy cimg 1 , cimg 2 ∈[0,2 32 ].

[0030] As a further optimization of the above solution, in step 3, the image thumbnail generation process is:

[0031] Step 31, set the zoom ratio, calculate the height and width of the visual thumbnail as n' and m' respectively; the zoom ratio is an integer; n' and m' correspond to n and m respectively, both refer to the number of pixels;

[0032] Step 32: Set the scaling factor β < 1, and calculate the height and width of the encrypted thumbnail share to be n' and m' respectively, that is: The scaling ratio is an integer;

[0033] Step 33: scale the encrypted image in proportion to each encrypted segment, obtain the thumbnail image segment pixel position (y, x), and reversely map it to the nearest pixel position (t in the original image) by the scaling factor. x , t y ),Right now:

[0034] Step 34: assign the pixel value of the encrypted segmented image position (tx, ty) calculated to the position (x, y) in the thumbnail image share, that is, THM y,x，C =img ty,tx,C , among which THM y,x,C Represents a thumbnail;

[0035] Step 35: According to the ciphertext value THM y，x，C , using the decryption function D1 or D2 to calculate the pixel value of the specified coordinates;

[0036] The ciphertext value includes the first ciphertext and the second ciphertext. According to step 45, the pixel value can be calculated, such as: the first ciphertext cimg 1 and the second ciphertext cimg 2 Including Rimg 1 、Gimg 1 、Bimg 1 and Rimg 2 、Gimg 2 、Bimg 2 , and then decrypt the function D according to the decryption function to obtain the three-channel pixel value of the image at the specified point, and finally restore the entire original image. That is: Rimg=D(sk,Rimg 1 , Rimg 2 )=Rimg 1 +Rimg 2 mod sk, Gimg = D(sk, Gimg 1 ,Gimg 2 )=Gimg 1 +Gimg 2 mod skBimg=D(sk,Gimg 1 ,Gimg 2 )=Bimg 1 +Bimg 2 mod sk, and then get (Rimg, Gimg, Bimg).

[0037] Step 36, traverse each coordinate of the encrypted segmented share image, and repeat steps 32 to 35, and finally obtain the visual zoom image;

[0038] As a further optimization of the above solution, the encrypted image is also cropped; in step 4, the encrypted image includes the upper left corner coordinate (x lt ,y lt ) and the lower right corner coordinate (x rb ,y rb); The cropping of the encrypted image includes a left cropping width w1, a right cropping width w2, an upper cropping height h1 and a lower cropping height h2, and the cropped image is:

[0039]

[0040] Among them, (x lt′ ,y lt′ ) and (x rb′ ,y rb′ ) are the coordinates of the upper left corner and lower right corner of the cropped image.

[0041] The cropping result in the encrypted image is directly mapped to the original image, that is, the cropping operation has the same effect on the encrypted image and the original image.

[0042] As a further optimization of the above solution, step 5 also includes brightness adjustment of the encrypted image. The specific steps are as follows:

[0043] Step 51: Set the brightness adjustment factor cB i , and initialize the height m and width n of the encrypted image;

[0044] Step 52: For each pixel position (x, y) in the encrypted image, calculate the pixel value after brightness adjustment, that is: Iterate over all color channels, that is:

[0045] Step 53, traverse all pixel coordinates and repeat step 52, and finally obtain the encrypted image cimg after brightness adjustment i ;

[0046] As a further optimization of the above solution, step 6 also includes contrast adjustment of the encrypted image. The specific steps are as follows:

[0047] Step 61, set the contrast constant α and calculate the contrast-adjusted pixel value of the pixel position (x, y) in the encrypted segmented share image, that is:

[0048] Step 62: Encrypt the image after contrast adjustment Return to the data owner;

[0049] Step 63, traverse all pixel coordinates and repeat step 61, and finally obtain the encrypted segmented image cimg after contrast adjustment i ;

[0050] Compared with the prior art, the present invention achieves the following beneficial effects:

[0051] (1) The present invention designs two encryption schemes, an encryption function based on additive secret sharing and an encryption function based on matrix transformation, to encrypt an image into two encrypted images, thereby enhancing the security of the image and solving the problem of privacy protection in cloud photo storage.

[0052] (2) A unique image editing mechanism is proposed, which allows cloud storage providers to directly perform operations such as thumbnail generation, cropping, brightness adjustment, and contrast adjustment on encrypted images. This effectively overcomes the defect that traditional methods cannot edit images in an encrypted state, which not only improves the security of the system but also enriches its functionality.

[0053] (3) The parallel computing and distributed storage characteristics of the cloud computing platform are utilized to effectively improve the computing efficiency of privacy data. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a working principle diagram of an editable image encryption storage method provided by an embodiment of the present invention;

[0055] Figure 2 It is an interactive diagram of an editable image encryption storage method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] like Figure 1 , Figure 2 As shown, this embodiment provides an editable image encryption storage method, comprising the following steps:

[0058] Step 1, system initialization: the data holder generates a public modulus sk for additive secret sharing; the data holder recruits two cloud servers that do not collude with each other, the first cloud server and the second cloud server;

[0059] Step 2: The data holder uses the encryption function ε to encrypt each pixel of the original image and obtains an encrypted pair (cimg 1 , cimg 2 ), respectively, the first ciphertext cimg 1 and the second ciphertext cimg 2The original image is an RGB three-channel image with n and m pixels in height and width respectively. The encryption function is: ε(sk,cimg)→(cimg 1 , cimg 2 ), where c∈{R, G, B} represents RED, GREEN and BLUE channels respectively; represents the single channel pixel value of the pixel point, and cimg∈[0, 255];

[0060] In this embodiment, the encryption function ε is expressed as:

[0061] ε(sk,cimg)→(cimg 1 , cimg 2 );

[0062] Taking the BLUE channel of a 4*4 RGB three-channel image as an example, the corresponding pixels are:

[0063] [[79, 9, 57, 127], [56, 168, 174, 191], [156, 138, 89, 197], [149, 26, 172, 178];

[0064] The first ciphertext and the second ciphertext obtained after segmentation are:

[0065] cimg 1 (also known as Bimg 1 ) = [[50, 6, 36, 72], [32, 110, 170, 126], [156, 106, 28, 156], [106, 8, 140, 146]];

[0066] cimg 2 (also known as Bimg 2 ) = [[29, 3, 21, 55], [24, 58, 4, 65], [0, 32, 61, 41], [43, 18, 32, 32]];

[0067] It also includes a decryption function D for restoring the first ciphertext and the second ciphertext to a pixel value cimg, that is: cimg = D(sk, cimg 1 , cimg 2 )=cimg 1 +cimg 2 mod sk.

[0068] Step 3: Encrypted image thumbnail generation: The first cloud server and the second cloud server respectively call the nearest neighbor interpolation method to calculate the encrypted thumbnail share cimg i, sending the two encrypted thumbnail shares to the data owner; the data owner decrypts the two encrypted thumbnail shares to obtain visible thumbnails.

[0069] The specific process is:

[0070] Step 31, set the scaling factor β < 1, and calculate the height and width of the encrypted thumbnail share to be n' and m' respectively, that is: The scaling ratio is an integer;

[0071] Step 32: scale the encrypted image in proportion to each encrypted segment, obtain the thumbnail image segment pixel position (y, x), and reversely map it to the nearest pixel position (t in the original image) by the scaling factor. x , t y ),Right now:

[0072] Step 33: assign the pixel value of the encrypted segmented image position (tx, ty) calculated to the position (x, y) in the thumbnail image share, that is, THM y，x,C =img ty,tx,C , among which THM y，x，C Represents a thumbnail;

[0073] Step 34: According to the ciphertext value THM y,x，C , use the decryption function D to calculate the pixel value of the specified coordinate;

[0074] The ciphertext value includes the first ciphertext and the second ciphertext. According to step 44, the pixel value can be calculated, such as: the first ciphertext cimg 1 and the second ciphertext cimg 2 Including Rimg 1 、Gimg 1 、Bimg 1 and Rimg 2 、Gimg 2 、Bimg 2 , and then decrypt the function D according to the decryption function to obtain the three-channel pixel value of the image at the specified point, and finally restore the entire original image. That is: Rimg=D(sk,Rimg 1 , Rimg 2 )=Rimg 1 +Rimg 2 mod sk, Gimg = D(sk, Gimg 1 ,Gimg 2 )=Gimg 1 +Gimg 2 mod skBimg=D(sk,Gimg 1,Gimg 2 )=Bimg 1 +Bimg 2 mod sk, and then get (Rimg, Gimg, Bimg).

[0075] Therefore, the data owner obtains the ciphertext thumbnail from the first cloud server and the second cloud server Figure 1 and ciphertext abbreviation Figure 2 After that, the final visual thumbnail (single channel) can be synthesized.

[0076] Step 35, traverse each coordinate of the encrypted segmented share image, and repeat steps 32 to 34, and finally obtain the visual zoom image;

[0077] The encryption function ε can be used to segment and encrypt the original image. The data uploaded to the first server and the second server is encrypted data, so that users can ensure the privacy and security of image data while making full use of cloud resources. The Fenwick tree construction algorithm can accelerate the encryption segmentation operation, significantly improve the calculation speed of the encrypted image in the subsequent calculation process, and optimize the processing efficiency of the encrypted image.

[0078] Step 4: Cropping of the encrypted image: For the encrypted image, the upper left corner coordinates (x lt ,y lt ) and the lower right corner coordinate (x rb ,y rb ); The cropping of the encrypted image includes a left cropping width w1, a right cropping width w2, an upper cropping height h1 and a lower cropping height h2, and the cropped image is:

[0079]

[0080] Among them, (x lt′ ,y lt′ ) and (x rb′ ,y rb′ ) are the coordinates of the upper left corner and lower right corner of the cropped image.

[0081] The cropping result in the encrypted image is directly mapped to the original image, that is, the cropping operation has the same effect on the encrypted image and the original image.

[0082] Step 5: Brightness adjustment of the encrypted image. The specific steps are as follows:

[0083] Step 51: Set the brightness adjustment factor cB i , and initialize the height m and width n of the encrypted image;

[0084] Step 52: For each pixel position (x, y) in the encrypted image, calculate the pixel value after brightness adjustment, that is: Iterate over all color channels, that is:

[0085] Step 53, traverse all pixel coordinates and repeat step 52, and finally obtain the encrypted image cimg after brightness adjustment i ;

[0086] Step 6: Adjust the contrast of the encrypted image. The specific steps are as follows:

[0087] Step 61, set the contrast constant α and calculate the contrast-adjusted pixel value of the pixel position (x, y) in the encrypted segmented share image, that is:

[0088] Step 62: Encrypt the image after contrast adjustment Return to the data owner;

[0089] Step 63, traverse all pixel coordinates and repeat step 61, and finally obtain the encrypted segmented image cimg after contrast adjustment i ;

[0090] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. An editable image encryption storage method, characterized in that: The following steps are involved: Step 1, system initialization: the data holder generates a public modulus sk for additive secret sharing; the data holder recruits two cloud servers that are not colluding with each other, the first cloud server and the second cloud server; Step 2: Image encryption: The data holder uses the encryption function ε to encrypt each pixel of the original image and obtains an encrypted pair (cimg 1 , cimg 2 ), respectively, the first ciphertext cimg 1 and the second ciphertext cimg 2 The original image is an RGB three-channel image with n and m pixels in height and width respectively. The encryption function is: ε(sk, cimg)→(cimg 1 , cimg 2 ), where c∈{R, G, B} represents RED, GREEN and BLUE channels respectively; represents the single channel pixel value of the pixel point, and cimg∈[0, 255]; Step 3: Encrypted image thumbnail generation: The first cloud server and the second cloud server respectively call the nearest neighbor interpolation method to calculate the encrypted thumbnail share cimg i , sending the two encrypted thumbnail shares to the data owner; the data owner decrypts the two encrypted thumbnail shares to obtain visible thumbnails; Step 4: Encrypted image clipping: The first cloud server and the second cloud server respectively hold the encrypted image, and obtain the upper left corner coordinates (x lt ,y lt ) and the lower right corner coordinate (x rb ,y rb ), the cropping of the encrypted image includes a left cropping width w1, a right cropping width w2, an upper cropping height h1 and a lower cropping height h2, wherein h=y rb -y lt , w = x rb -y lt . Performing the cropping to obtain a target encrypted image; Step 5: Encrypted image brightness adjustment: The first cloud server and the second cloud server respectively call the brightness adjustment factor cB i Where B is a custom brightness constant, c∈{R, G, B}, cB i This means that the brightness adjustment operation is performed on different channels (RED, GREEN, BLUE). The encrypted image share is edited for brightness, and the image share after brightness adjustment is obtained. i , sending the two brightness-adjusted image shares to the data owner; the data owner decrypts the two brightness-adjusted image shares to obtain a visible brightness-adjusted image; Step 6: Encrypted image contrast adjustment: The first cloud server and the second cloud server respectively call the contrast adjustment factor α to perform contrast editing on the encrypted image share to obtain the image share cimg after contrast adjustment i , sending the two contrast-adjusted image shares to the data owner; the data owner decrypts the two contrast-adjusted image shares to obtain a visible contrast-adjusted image.

2. The editable image encryption storage method according to claim 1, characterized in that: The public modulus of the additive secret sharing is sk=2 8 .

3. The editable image encryption storage method according to claim 2, characterized in that: In step 2, the encryption function ε1 based on additive secret sharing is expressed as: in, That means cimg 1 is from [0, 2 8 ) is a number randomly selected from .

4. The editable image encryption storage method according to claim 3, characterized in that: It also includes a decryption function D1, which is used to restore the first ciphertext and the second ciphertext to a pixel value cimg, that is: cimg = D1 (sk, cimg 1 , cimg 2 )=cimg 1 +cimg 2 mod sk.

5. The editable image encryption storage method according to claim 1, characterized in that: In step 2, the encryption function ε2 based on matrix transformation is expressed as: Where r∈[0, 255] is a randomly selected uniform value and K is a 2×2 reversible matrix key.

6. The editable image encryption storage method according to claim 5, characterized in that: It also includes a decryption function D2, which is used to restore the first ciphertext and the second ciphertext to pixel values ​​cimg, that is:

7. The editable image encryption storage method according to claim 1, characterized in that: In step 2, encryption satisfies the addition support of the brightness adjustment operation: Where B is the brightness adjustment factor.

8. The editable image encryption storage method according to claim 1, characterized in that: In step 2, the multiplication support that satisfies the contrast adjustment operation is encrypted: Among them, α is the contrast constant.

9. The editable image encryption storage method according to claim 1, characterized in that: In step 2, in order to save the encrypted image matrix, cimg 1 and cimg 2 The value should satisfy cimg 1 , cimg 2 ∈[0,2 32 ].

10. The editable image encryption storage method according to claim 1, characterized in that: In step 3, the image thumbnail generation process is as follows: Step 31, set the scaling factor β<1, and calculate the height and width of the encrypted thumbnail share to be n′ and m′ respectively, that is: The scaling ratio is an integer; Step 32: scale the encrypted image in proportion to each encrypted segment, obtain the thumbnail image segment pixel position (y, x), and reversely map it to the nearest pixel position (t in the original image) by the scaling factor. x , t y ),Right now: Step 33: assign the pixel value of the encrypted segmented image position (tx, ty) calculated to the position (x, y) in the thumbnail image share, that is, THM y，x，C =img ty，tx，C , among which THM y,x,C Represents a thumbnail; Step 34: According to the ciphertext value THM y，x，C , using the decryption function D to calculate the pixel value of the specified coordinates; Step 35, traverse each coordinate of the encrypted segmented share image, and repeat steps 32 to 34, and finally obtain the visual zoom image.

11. The editable image encryption storage method according to claim 1, characterized in that: In step 4, the encrypted image cropping process is as follows: for the encrypted image cimg i , including the upper left corner coordinates (x lt ,y lt ) and the lower right corner coordinate (x rb ,y rb ); The cropping of the encrypted image includes a left cropping width w1, a right cropping width w2, an upper cropping height h1 and a lower cropping height h2, and the cropped image is: Among them, (x lt′ , t lt′ ) and (x rb′ ,y rb′ ) are the coordinates of the upper left corner and lower right corner of the cropped image respectively.

12. According to the requirement of the editable image encryption storage method according to claim 1, it is characterized in that: In step 5, the encrypted image brightness adjustment process is: Step 51: Set the brightness adjustment factor cB i , and initialize the height m and width n of the encrypted image; Step 52: For each pixel position (x, y) in the encrypted image, calculate the pixel value after brightness adjustment, that is: Iterate over all color channels, that is: Step 53, traverse all pixel coordinates and repeat step 52, and finally obtain the encrypted image cimg after brightness adjustment i .

13. According to the requirements of the editable image encryption storage method according to claim 1, it is characterized in that: In step 6, the encrypted image contrast adjustment process is: Step 61, set the contrast constant α and calculate the contrast-adjusted pixel value of the pixel position (x, y) in the encrypted segmented share image, that is: Step 62: Encrypt the image after contrast adjustment Return to the data owner; Step 63, traverse all pixel coordinates and repeat step 61, and finally obtain the encrypted segmented image cimg after contrast adjustment i .

Images