CN109657483B - Image encryption method and system - Google Patents

Abstract

The invention discloses an image encryption method and system, comprising the following steps: s1, marking the size of the to-be-processed area of the to-be-processed image as M multiplied by N, and outputting a three-dimensional matrix E; s2, randomly generating a matrix RA, acquiring an index matrix RO, randomly generating a matrix PA, and acquiring an index matrix PO; s3, generating a matrix TA; s4, selecting the coordinate (RO) in the matrix E layer by layer and line by line_r,n,n,PO_n,p) As the parameter to be transformed; s5, the coordinates in the matrix TA are (RO) layer by layer and line by line_r,n,n,PO_n,p) The values of (a) are ordered to obtain a vector V, and the parameters to be transformed are processed based on the vector V to obtain a scrambling matrix D; s6, exclusive-or scrambling the matrix D to obtain the encrypted image. The system is used for executing the method. The encryption range is determined according to the data volume of the bit plane, the encryption processing is realized by the replacement of pixels, the encryption safety is increased by the exclusive OR of rows, columns and layers, and the processing can be performed aiming at key areas so as to obtain the ideal encryption effect aiming at the image with high bits.

Description

An image encryption method and system

technical field

The invention relates to the technical field of image encryption, in particular to an image encryption method and system.

Background technique

The vigorous development of multimedia has caused the rapid growth of multimedia data such as images, music, and videos in the Internet. Digital image is the most common form of multimedia data in the Internet, which has the characteristics of vivid, intuitive and rich information. Therefore, it is one of the main forms for people to transmit information. Among these massive digital images, many images are private images, such as some military and medical images. Therefore, how to ensure the security of these private images in the Internet becomes very important.

A popular image encryption scheme treats image data as binary data, and then encrypts the image using existing data encryption techniques. However, this scheme has many limitations. Although in terms of data storage format, both image information and text information are stored in the form of binary streams, and there is no substantial difference, but each pixel of the image usually uses 8 or more pixels. Multi-bit representation makes the amount of image data far more than text information. Encrypting images with traditional text encryption algorithms results in inefficiencies. In addition, images have many unique features at the level of color, texture, organization, etc., which make each data area have great correlation and redundancy, and traditional text encryption does not consider these features of images, which may result in to the desired encryption result.

SUMMARY OF THE INVENTION

The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, an object of the present invention is to provide an image encryption method and system.

The technical scheme adopted in the present invention is:

An image encryption method, comprising the steps of: S1, layering images to be processed according to bit planes, marking the size of the to-be-processed area of the to-be-processed image as M×N, and outputting a corresponding three-dimensional matrix E, where the size of E is M×N ×L, where L is the number of bit plane layers; S2, randomly generate an M×N matrix RA, obtain the corresponding index matrix RO, randomly generate an N×L matrix PA, and obtain the corresponding index matrix PO; S3, generate and The three-dimensional matrix E is a matrix TA with the same size, TA _i,j,k =|RA _i,j -PA _j,k |, where i, j, k are three-dimensional coordinates; S4, select the matrix E layer by layer and row by row The pixel whose median coordinate is (RO _r,n ,n,PO _n,p ) is used as the parameter to be transformed, where r∈1～M is the row index, p∈1～L is the bit plane layer index, n∈1～ N; S5. Sort the values with the coordinates (RO _r,n ,n,PO _n,p ) in the matrix TA layer by layer and row by row to obtain a vector V, and process the corresponding parameters to be transformed based on the vector V to Obtain a scrambled matrix D; S6, XOR the scrambled matrix D to obtain an encrypted image.

Preferably, the method further includes step S0, preprocessing the initial image, and step S0 includes: performing binary processing on the initial image to obtain an edge image, filtering out a first area that meets the threshold by using a connected area function, and performing morphological processing on the first area to obtain the image to be processed.

Preferably, step S6 specifically includes: XORing the scrambled matrix D according to the order of rows, columns and layers to obtain the encrypted image.

Preferably, step S2 specifically includes: generating an M×N matrix RA and an N×L matrix PA based on a chaotic system or a pseudo-random number generator, and then sorting each column of the PA to obtain an index matrix RO, and for each column of the PA One row is sorted to get the index matrix PO.

Preferably, performing morphological processing on the part that meets the threshold specifically includes: performing corrosion processing on the first area, removing isolated pixels, and thickening compensation to obtain the second area, the first area is divided into pixels and the second area, by calculating the convex hull The third region is obtained, and the properties of the third region are measured to obtain the image to be processed.

The technical scheme adopted in the present invention is:

An image encryption system, comprising: a marking module for layering images to be processed according to bit planes, marking the size of the to-be-processed area of the to-be-processed image as M×N, and outputting a corresponding three-dimensional matrix E, where the size of E is M ×N×L, where L is the number of bit plane layers; the index module is used to randomly generate an M×N matrix RA, obtain the corresponding index matrix RO, randomly generate an N×L matrix PA, and obtain the corresponding index matrix PO ; The reorganization module is used to generate a matrix TA that is consistent with the size of the three-dimensional matrix E, TA _i,j,k =|RA _i,j -PA _j,k |, wherein, i, j, k are three-dimensional coordinates; scrambling module , which is used to select the pixels whose coordinates are (RO _r,n ,n,PO _n,p ) in the matrix E layer by layer and row by row as the parameters to be transformed, where r∈1～M is the row index, p∈1 ～L is the bit plane layer index, n∈1～N; the scrambling module is also used to sort the values in the matrix TA whose coordinates are (RO _r,n ,n,PO _n,p ) layer by layer and row by row To obtain a vector V, the corresponding parameters to be transformed are processed based on the vector V to obtain a scrambled matrix D; an XOR module is used to XOR the scrambled matrix D to obtain an encrypted image.

Preferably, it also includes: a preprocessing module for performing binary processing on the initial image to obtain an edge image, filtering out a first region that meets the threshold by using a connected region function, and performing morphological processing on the first region to obtain an image to be processed.

Preferably, the XOR module is specifically configured to XOR the scrambled matrix D in the order of rows, columns and layers to obtain the encrypted image.

Preferably, the indexing module is used to generate an M×N matrix RA and an N×L matrix PA based on a chaotic system or a pseudo-random number generator, and then sort each column of the PA to obtain the index matrix RO, and the PA Sort each row of , to get the index matrix PO.

Preferably, the morphological processing of the part that meets the threshold by the preprocessing module specifically includes:

The first area is eroded, the isolated pixels are removed, the thickness compensation is increased to obtain the second area, the first area is divided into pixels and the second area, the third area is obtained by calculating the convex hull, and the properties of the third area are measured to obtain the desired area. Process images.

The beneficial effects of the present invention are:

The invention determines the encryption range according to the data amount of the bit plane, realizes the encryption processing by replacing the pixels, increases the encryption security by the exclusive OR of the rows, columns and layers, and can process the key areas to obtain Ideal for encryption of high-bit images.

Description of drawings

Fig. 1 is a kind of image encryption method of the present invention;

Fig. 2 is a matrix example of the present invention;

Fig. 3 is an image encryption system of the present invention.

Detailed ways

It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict.

Example 1

The purpose of this embodiment is to explain the shortcomings of the prior art and to illustrate the idea of the present invention.

Bit depth describes the level of detail that an image can achieve. Generally speaking, the deeper the bit depth, the higher the contrast of the image. Due to the limited recognition of color depth by the human eye, the general images in life are 8-bit depth. However, in some special fields, such as medical, military, etc., they have very strict requirements on details, and general 8-bit images cannot be To meet their work needs, high-precision images were born. For example, in the medical field, X-ray pictures are 16-bit depth. Compared with ordinary images, 16-bit depth images contain richer information, and each of its The amount of information contained in each bit plane is different. The information content of the highest bit plane accounts for half of the total information, while the information content of the ninth bit plane accounts for less than 1%. Therefore, for high-precision images , the security of the high bit plane (ie "bitplane") affects the overall security.

This embodiment provides an image encryption method as shown in FIG. 1 , including steps: S1. Layer the to-be-processed images according to the bit plane, mark the size of the to-be-processed area of the to-be-processed image as M×N, and output the corresponding three-dimensional The dimensions of the matrices E and E are M×N×L, where L is the number of plane layers; S2, randomly generate an M×N matrix RA, obtain the corresponding index matrix RO, randomly generate an N×L matrix PA, and obtain Corresponding index matrix PO; S3, generate a matrix TA with the same size as the three-dimensional matrix E, TA _i,j,k =|RA _i,j -PA _j,k |, where i,j,k are three-dimensional coordinates; S4 , layer by layer and row by row, select the pixels whose coordinates are (RO _r,n ,n,PO _n,p ) in the matrix E as the parameters to be transformed, where r∈1～M is the row index, p∈1～L is the bit plane layer index, n∈1～N; S5, layer by layer and row by row, sort the values in the matrix TA whose coordinates are (RO _r,n ,n,PO _n,p ) to obtain the vector V, layer by layer (bit plane layer), process the corresponding parameters to be transformed based on the vector V on a row-by-row (row of pixels) basis to obtain a scrambled matrix D; S6, XOR the scrambled matrix D to obtain an encrypted image. Among them, the specific steps include:

Step 1: Assume that the size of the encrypted part (that is, the area to be processed) of the plaintext image (that is, the image to be processed) that needs to be encrypted after preprocessing is M×N;

Step 2: Layer the plaintext image by bit planes, and obtain a three-dimensional matrix E according to the bit planes to be encrypted, with a size of M×N×L, where L is the number of encrypted bit planes; (that is, step S1 Including steps 1 to 2)

Step 3: Use a chaotic system or a pseudo-random number generator to generate two matrices with sizes M×N and N×L, denoted as RA and PA;

Step 4: Sort each column of PA to obtain an index matrix RO; sort each row of PA to obtain an index matrix PO; (that is, step S2 includes the third step to the fourth step)

Step 5: Generate a matrix TA of size M×N×L, where TA _i,j,k =|RA _i,j -PA _j,k |; (ie step S3), i, j, k are corresponding Specific values for three dimensions (M, N, L). (ie step S3)

Step 6: Set the row index to r=1;

Step 7: Set the bit plane index to p=1;

Step 8: Put {(RO _r,1 ,1,PO _1,p ),(RO _r,2 ,2,PO _2,p ),・・,(RO _r,N ,N,PO _{N, p} )} position pixels are selected as a group; (that is, step S4 includes the fifth step to the eighth step)

The ninth step: in TA to {(RO _r,1 ,1,PO _1,p ),(RO _r,2 ,2,PO _2,p ),・・,(RO _r,N ,N,PO _{N ,p} )} sort the values of these positions to get a vector v;

Step 10: Use the vector v to transform these pixels in E;

The eleventh step: perform the same operation on each bit plane, p=2～L iterates the eighth to tenth steps;

The twelfth step: perform the same operation on each row, r=2～M iterates the seventh to eleventh steps. (That is, step S5 includes the ninth step to the twelfth step)

Step 12: XOR the scrambled matrix D to obtain an encrypted image. (ie step S6)

Specific numerical example: Assuming that the size of the image after preprocessing is 2×4, and the number of bit planes to be encrypted is 3, a three-dimensional matrix E of size 2×4×3 can be obtained. Each position of E is either 0 or 0. 1, to scramble its position. First, use a chaotic system or a pseudo-random number generator to generate a matrix instance as shown in Figure 2, RA with a size of 2 × 4 and PA with a size of 4 × 3; sort the columns of RA to obtain the index matrix RO; Sort the rows to get the index matrix PO; use the scrambling algorithm to find different rows and different column positions, and expand it to three dimensions, the first row of RO is (2,2,2,1), and the first column of PO is (1, 2,1,1), combine them with the natural order to get the positions of different rows, columns and bit planes: (2,1,1),(2,2,2),(2,3, 1), (1,4,1), by analogy in E, 6 groups of different row, column and bit plane positions can be obtained;

_TA is _obtained by taking the absolute value of the difference between _RA and _PA . =|RA _2,2 -PA _2,2 |=|0.2125-0.1525|=0.0600,TA _2,3,1 =|RA _2,3 -PA _3,1 |=|0.4274-0.1612|=0.2662,TA _{1 ,4,1} =|RA _1,4 -PA _4,1 |=|0.4815-0.9408|=0.4593; and so on, sort the values in E corresponding to TA to get the vector v, for example, one of the vectors is ( 2,1,3,4), scrambling according to the vector: D _2,1,1 =E _2,2,2 ,D _2,2,2 =E _2,1,1 ,D _2,3,1 =E _2,3,1 , D _1,4,1 =E _1,4,2 , and so on for the remaining five groups, and finally a scrambled three-dimensional matrix D is obtained.

The XOR steps include:

The first step: the image matrix obtained by scrambling is D, and the size is M×N×L;

The second step: operate on the row, regard the elements belonging to the same row in the image as a whole, and apply the diffusion formula, where C _i , T _i represent the XOR result/XOR value of the plane where the i-th row is located, respectively, G=M;

The third step: operate on the bit plane, regard the elements belonging to the same bit plane in the image as a whole, and apply the diffusion formula, where C _i , T _i represent the XOR result of the i-th bit plane/is XORed The value of , G=L;

Step 4: Operate on the row, regard the elements (pixels) belonging to the same column in the image as a whole, and apply the diffusion formula, where C _i , T _i represent the XOR result of the plane where the i-th column is located / XORed value, G=N;

Diffusion formula:

Finally, the bit plane is integrated with the previously unencrypted bit plane, compressed into the pixel value of the image, and combined with the unpreprocessed part to obtain the ciphertext image.

The specific preprocessing steps include:

之间的部分AO(第一区域),S为图像的面积；(3)对AO进行形态学处理，先腐蚀，再移除孤立像素，最后加厚补偿得到MO(第二区域)；(4)AO按像素与MO，再求凸包得到CH(第三区域)；(5)最后度量CH的属性，得到目标区域(待处理图像)。(1) Use the Sobel operator to detect the edge of the image (initial image) to obtain the binary edge image BW (edge image); (2) Use the connected area function to filter out the connected area area in

The part between AO (first area), S is the area of the image; (3) Morphological processing is performed on AO, first etching, then removing isolated pixels, and finally thickening compensation to obtain MO (second area); (4) ) AO is based on pixels and MO, and then the convex hull is calculated to obtain CH (third region); (5) Finally, the attribute of CH is measured to obtain the target region (image to be processed).

Example 2

This embodiment provides an image encryption system, including: a marking module 1, configured to layer images to be processed according to bit planes, mark the size of the to-be-processed area of the to-be-processed image as M×N, and output a corresponding three-dimensional matrix E, The size of E is M×N×L, where L is the number of bit plane layers; the index module 2 is used to randomly generate an M×N matrix RA, obtain the corresponding index matrix RO, and randomly generate an N×L matrix PA, Obtain the corresponding index matrix PO; the reorganization module 3 is used to generate a matrix TA with the same size as the three-dimensional matrix E, TA _i,j,k =|RA _i,j -PA _j,k |, where i,j,k is the three-dimensional coordinate; scrambling module 4 is used to select the pixels whose coordinates are (RO _r,n ,n,PO _n,p ) in the matrix E layer by layer and row by row as the parameters to be transformed, where r∈1～ M is the row index, p∈1～L is the bit plane layer index, n∈1～N; the scrambling module is also used for layer-by-layer and row-by-row coordinates in the matrix TA as (RO _r,n ,n,PO _{n, p} ) values are sorted to obtain a vector V, and the corresponding parameters to be transformed are processed based on the vector V to obtain a scrambled matrix D; XOR module 5 is used to XOR the scrambled matrix D to obtain encrypted Image.

The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the described embodiments, and those skilled in the art can also make various equivalent deformations or substitutions on the premise of not violating the spirit of the present invention , these equivalent modifications or substitutions are all included within the scope defined by the claims of the present application.

Claims (10)

1. an image encryption method, is characterized in that, comprises the steps: S1. Layer the to-be-processed images according to the bit plane, mark the size of the to-be-processed area of the to-be-processed image as M×N, and output the corresponding three-dimensional matrix E, where the size of E is M×N×L, where L is the bit plane layers; S2. Randomly generate an M×N matrix RA, obtain a corresponding index matrix RO, randomly generate an N×L matrix PA, and obtain a corresponding index matrix PO; S3, generate a matrix TA with the same size as the three-dimensional matrix E, TA _i,j,k =|RA _i,j -PA _j,k |, wherein, i,j,k are three-dimensional coordinates; S4. Select the pixel whose coordinates are (RO _r,n ,n,PO _n,p ) in the matrix E layer by layer and row by row as the parameter to be transformed, where r∈1～M is the row index, p∈1～ L is the index of the plane layer, n∈1～N; S5. Sort the values with coordinates (RO _r,n ,n,PO _n,p ) in the matrix TA layer by layer and row by row to obtain a vector V, and process the corresponding parameters to be transformed based on the vector V to obtain the set chaotic matrix D; S6, XOR the scrambled matrix D to obtain an encrypted image. 2. An image encryption method according to claim 1, further comprising step S0, preprocessing the initial image, wherein step S0 comprises: Binary processing is performed on the initial image to obtain an edge image, a connected area function is used to filter out a first area that meets the threshold, and morphological processing is performed on the first area to obtain an image to be processed. 3. a kind of image encryption method according to claim 1, is characterized in that, step S6 specifically comprises: XOR the scrambled matrix D in row, column and layer order to obtain an encrypted image. 4. a kind of image encryption method according to claim 1, is characterized in that, step S2 specifically comprises: Generate an M×N matrix RA and an N×L matrix PA based on a chaotic system or a pseudo-random number generator, then sort each column of PA to get the index matrix RO, and sort each row of PA to get the index matrix PO . 5. A kind of image encryption method according to claim 2, is characterized in that, performing morphological processing to the part that meets the threshold value specifically comprises: The first area is eroded, the isolated pixels are removed, the thickness compensation is increased to obtain the second area, the first area is divided into pixels and the second area, the third area is obtained by calculating the convex hull, and the properties of the third area are measured to obtain the desired area. Process images. 6. an image encryption system, is characterized in that, comprises: The marking module is used for layering the to-be-processed images according to the bit plane, marking the size of the to-be-processed area of the to-be-processed image as M×N, and outputs the corresponding three-dimensional matrix E, where the size of E is M×N×L, where L is the number of plane layers; The index module is used to randomly generate an M×N matrix RA, obtain the corresponding index matrix RO, randomly generate an N×L matrix PA, and obtain the corresponding index matrix PO; The reorganization module is used to generate a matrix TA with the same size as the three-dimensional matrix E, TA _i,j,k =|RA _i,j -PA _j,k |, where i, j, k are three-dimensional coordinates; The scrambling module is used to select the pixels whose coordinates are (RO _r,n ,n,PO _n,p ) in the matrix E layer by layer and row by row as the parameters to be transformed, where r∈1～M is the row index, p∈1～L is the bit plane layer index, n∈1～N; The scrambling module is also used to sort the values whose coordinates are (RO _r,n ,n,PO _n,p ) in the matrix TA layer by layer and row by row to obtain a vector V, and process the corresponding pending Transform parameters to obtain scrambling matrix D; The XOR module is used to XOR the scrambled matrix D to obtain the encrypted image. 7. A kind of image encryption system according to claim 6, is characterized in that, also comprises: The preprocessing module is used to perform binary processing on the initial image to obtain an edge image, filter out the first region that meets the threshold by using the connected region function, and perform morphological processing on the first region to obtain the image to be processed. 8 . The image encryption system according to claim 6 , wherein the XOR module is specifically configured to XOR the scrambled matrix D according to the order of rows, columns and layers to obtain the encrypted image. 9 . . 9. A kind of image encryption system according to claim 6, is characterized in that, described index module is used for generating the matrix RA of M×N and the matrix PA of N×L based on chaotic system or pseudo-random number generator, Then sort each column of PA to get the index matrix RO, and sort each row of PA to get the index matrix PO. 10. An image encryption system according to claim 7, characterized in that, the morphological processing performed by the preprocessing module on the part that meets the threshold specifically comprises: The first area is eroded, the isolated pixels are removed, the thickness compensation is increased to obtain the second area, the first area is divided into pixels and the second area, the third area is obtained by calculating the convex hull, and the properties of the third area are measured to obtain the desired area. Process images.

Images