Dual-image confidential sharing steganography method and system based on jigsaw reference matrix

Abstract

The invention discloses a double-image confidential sharing steganography method and system based on a jigsaw reference matrix. According to the method, the original image is processed to generate two coverage images, confidential information is embedded into the coverage images by adopting a jigsaw reference matrix technology, and finally two disguise images are output. The difference between each disguise image and the original image is difficult to distinguish independently, and the original image and confidential information can be completely recovered only through cooperation of two disguise images. Besides, according to the method, the embedding capacity is remarkably improved, the security of embedded information is ensured, and high execution efficiency is realized while good visual quality is ensured. Experimental results show that compared with the most advanced scheme, the method has obvious advantages.

Description

Technical Field

[0001] The present invention belongs to the field of secret sharing steganography, and in particular relates to a double-image secret sharing steganography method and system based on a jigsaw reference matrix. Background Art

[0002] With the rapid growth of information security needs, more and more application scenarios need to achieve efficient data transmission and storage while ensuring data privacy. Image steganography is an effective solution. However, although traditional image steganography technology can embed confidential information, its embedding capacity is small and it is difficult to meet the growing needs of users.

[0003] Secret Image Sharing is a cryptographic scheme, also known as visual cryptography. The scheme generates several disguised images by embedding confidential information into the original image and distributes them to different sharing participants. When the number of participants reaches the specified condition, the confidential information can be extracted and the original image can be reconstructed. Dual-image steganography is a unique branch of this field. It uses two disguised images for reversible steganography and allows the two images to collaborate to extract confidential information and reconstruct the original image. This type of method has higher flexibility and security, and has been widely used in fields such as digital copyright protection, identity authentication, confidential communications, and medical imaging. Summary of the invention

[0004] The purpose of the present invention is to propose a new dual-image secret sharing steganography method based on a reference matrix, which is named the "jigsaw" reference matrix. In our method, the original image is processed to generate two cover images, and the confidential information is embedded in them using the "jigsaw" reference matrix technology, and finally two camouflage images are output. Each camouflage image is difficult to distinguish from the original image individually. Only through the collaboration of the two camouflage images can the original image and the confidential information be fully restored. In addition, this method significantly improves the embedding capacity, ensures the security of the embedded information, and achieves fast execution efficiency while ensuring good visual quality. Experimental results show that the present invention has obvious advantages compared with the most advanced schemes.

[0005] The technical solution steps of the present invention are as follows:

[0006] In a first aspect, the present invention provides a dual-image secret sharing steganography method based on a jigsaw reference matrix, and the specific steps are as follows:

[0007] S1: Generate a puzzle reference matrix consisting of puzzle pieces arranged in the same structure;

[0008] S2: For the original image to be embedded with confidential information, two overlay images with the same pixel domain as the original image are copied and generated; the pixel domain is divided into a series of non-overlapping pixel pairs with unique index values ​​in the same way, and a pixel pair is composed of two adjacent pixels in the image; the confidential information to be embedded is encrypted and segmented using a key, and each encrypted confidential information segment is traversed in turn, and the value of the pixel pair is regarded as the position coordinate of the matrix element, and according to the preset secret information embedding rule, the corresponding position of the pixel pair in the puzzle reference matrix and the position coordinate of the quaternary matrix element value and the binary confidential information value in the puzzle block structure of the extended position are determined, and the position coordinates are recorded in the two overlay images;

[0009] S3: Generate two camouflaged images of the same size as the original images, and map the pixel values ​​of each pixel pair in the two covered images to the two camouflaged images according to the preset pixel assignment rule, with the pixel pair as the smallest unit, and finally generate two camouflaged images for distribution to the two sharing participants for safekeeping respectively.

[0010] Preferably, in S1, the method for generating the jigsaw reference matrix is ​​as follows:

[0011] S11: Generate a puzzle reference matrix of size 256×256, where the horizontal and vertical coordinates of the puzzle reference matrix are both 0 to 255;

[0012] S12: Divide the puzzle reference matrix into a series of non-overlapping image blocks of size 4×4, each image block consists of 4 puzzle pieces, each puzzle piece consists of 4 matrix elements in a convex structure, and the values ​​of the 4 elements are filled with 4 non-repeating numbers 0, 1, 2, and 3, respectively, representing a total of 2 bits.

[0013] Preferably, in the jigsaw reference matrix, all jigsaw pieces have the same convex-shaped structure, and all 4×4 image blocks composed of 4 jigsaw pieces in the jigsaw reference matrix are also exactly the same.

[0014] Preferably, the specific method of S2 is as follows:

[0015] S21: copy the original image to generate two overlay images, and the pixel domains of the three images are exactly the same;

[0016] S22: Split the pixel domain into non-overlapping pixel pairs, each pixel pair consists of the values ​​of two adjacent pixels and is represented by (x k ,y k ), where m and n represent the size of the original image, and k represents the index of the pixel pair;

[0017] S23: Use the key to encrypt the current confidential information to be embedded, obtain the binary confidential information S encrypted by the key, and divide the confidential information S into The segment length is 6 bits. Each 6-bit segment is further divided into three 2-bit sub-segments and represented in sequence as s 1,k 、s 2,k and 3,k ,s 1,k 、s 2,k and 3,k The corresponding quaternary values ​​are (s 1,k )4、(s 2,k )4 and (s 3,k )4; for each segment of 6-bit confidential information (s 1,k ,s 2,k ,s 3,k ), execute the secret information embedding operation composed of S24 and S25, embed the confidential information into the two cover images CI1 and CI2 segment by segment, where the kth segment of 6-bit confidential information (s 1,k ,s 2,k ,s 3,k ) corresponds to the pixel pair (x) with index k in the two overlay images. k ,y k )middle:

[0018] S24: The pixel pair (x k ,y k ) is considered as the matrix element coordinates. In the puzzle reference matrix PM, find the coordinates (x k ,y k ) of the reference matrix element PM(x k ,y k ), and determine the reference matrix element PM(x k ,y k ) in the first puzzle piece, replace s 1,k Convert to quaternary value (s 1,k )4, find the quaternary value (s) in the first puzzle piece 1,k )4 corresponds to the reference matrix element PM(x 1,k ,y 1,k ), read the coordinates of this reference matrix element (x 1,k ,y 1,k ), and the pixel pairs (x k ,y k ) is replaced by (x 1,k ,y 1,k )The pixel pair of the first overlay image is (,);

[0019] S25: Determine the relative direction of the first puzzle piece in the 4×4 image block to which it belongs, the relative direction being one of the upper right corner, the upper left corner, the lower left corner, and the lower right corner; then expand the 4×4 image block in the same relative direction so that the expanded area covers a 16×16 image block. If the expansion process exceeds the boundary of the reference matrix, it is necessary to translate it to be just within the puzzle reference matrix; in each 16×16 image block, the 4×4 image blocks located in the upper right corner, the upper left corner, the lower left corner, and the lower right corner are marked with 0, 1, 2, and 3, respectively, and the puzzle blocks located in the upper right corner, the upper left corner, the lower left corner, and the lower right corner in each 4×4 image block are marked with 0, 1, 2, and 3, respectively; in the 16×16 image block, find the index PM(x k ,y k ) in a 4×4 image block with index (s 2,k )4 puzzle piece has a matrix element value of (s 3,k )4 matrix element PM(x 2,k ,y 2,k ), read the coordinates of this matrix element (x 2,k ,y 2,k ), and the pixel pairs (x k ,y k ) is replaced by (x 2,k ,y 2,k ).

[0020] Preferably, the specific method of S3 is as follows:

[0021] S31: traverse each pixel pair (x k ,y k ), according to each pixel pair index k, the pixel pairs in the two cover images are covered to the mapping positions of the two camouflage images according to the parity mapping rule; in the parity mapping rule, if the pixel pair index k is an even number, the pixel pair (x k ,y k ) in the first overlay image CI1. 1,k ,y 1,k ) replaces the pixel pair at the corresponding position of the first disguised image SI1, and uses the pixel pair (x k ,y k ) in the second overlay image CI2. 2,k ,y 2,k ) replaces the pixel pair at the corresponding position of the second disguised image SI2; if the pixel pair index k is an odd number, the pixel pair (x k ,y k ) in the second overlay image CI2. 2,k ,y 2,k) replaces the pixel pair at the corresponding position of the first disguised image SI1, and uses the pixel pair (x k ,y k ) in the first overlay image CI1. 1,k ,y 1,k ) replace the pixel pairs at corresponding positions of the second disguised image SI2;

[0022] S32: After all pixel pairs are replaced, two camouflage images are generated and allocated to two sharing participants for safekeeping.

[0023] In a second aspect, the present invention provides a dual-image confidential information decryption system based on a jigsaw reference matrix. After receiving two camouflaged images generated by the sender according to the dual-image confidential sharing steganography method as described in any one of the first aspects above, the decryption system uses the jigsaw reference matrix and the key to re-extract the confidential information and reconstruct the original image.

[0024] Preferably, the specific method for the decryption party to extract confidential information and reconstruct the original image is as follows:

[0025] S41: After receiving the two disguised images, the decryption system sequentially traverses each pixel pair (x k ,y k ), according to each pixel pair index k, two cover images CI1 and cover image CI2 are restored based on the two disguised images;

[0026] S42: According to the inverse operation of the secret information embedding operation, the 6-bit confidential information (s) embedded in all pixel pairs in the pixel domain is extracted from the two overlay images. 1,k ,s 2,k ,s 3,k ), and determine the reference matrix element PM(x) corresponding to each pixel pair in the puzzle reference matrix k ,y k );

[0027] S43: sequentially merging the 6-bit confidential information corresponding to all pixel pairs to obtain the confidential information S encrypted by the key, and extracting the embedded confidential information after decryption using the key;

[0028] S44: Using the reference matrix elements PM(x k ,y k )’s position coordinates (x k ,y k ) and reconstruct the original image.

[0029] In a third aspect, the present invention provides a computer program product, comprising a computer program / instruction, which, when executed by a processor, can implement the dual-image secret sharing steganography method based on the puzzle reference matrix as described in any one of the first aspects above.

[0030] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the dual-image secret sharing steganography method based on the puzzle reference matrix as described in any one of the above-mentioned first aspects can be implemented.

[0031] In a fifth aspect, the present invention provides a computer electronic device comprising a memory and a processor;

[0032] The memory is used to store computer programs;

[0033] The processor is used to implement the dual-image secret sharing steganography method based on the jigsaw reference matrix as described in any one of the first aspects above when executing the computer program.

[0034] Equivalent to the prior art, the advantages and beneficial effects of the present invention are:

[0035] The present invention combines secret sharing with steganography to achieve reversible information hiding with high embedding capacity. The dual-image secret sharing scheme ensures the security of embedded information while achieving high embedding capacity and fast execution efficiency while ensuring good visual quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a flow chart of the method of the present invention;

[0037] Figure 2 Refer to the matrix effect diagram for the puzzle;

[0038] Figure 3 The camouflage image effect diagram is constructed;

[0039] Figure 4 An example diagram of the secret sharing steganography phase;

[0040] Figure 5 This is an example diagram of the shared decryption phase. DETAILED DESCRIPTION

[0041] In order to facilitate those skilled in the art to understand and implement the present invention, the following embodiments are further described in conjunction with the accompanying drawings. It should be clear that the embodiment is only one possibility, which is illustrative and explanatory and does not constitute a limitation of the present invention.

[0042] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings:

[0043] In a preferred embodiment of the present invention, a dual-image secret sharing steganography method based on a puzzle reference matrix is ​​provided. Figure 1 As shown, the original image is first copied into two cover images, and the two cover images are shared and steganographically encrypted with the key through the puzzle reference matrix to generate two camouflage images. In the shared decryption process, the key can be used to extract the confidential information and reconstruct the original image through the collaboration of the two camouflage images. The specific steps of this method are as follows:

[0044] S1: Generate a 256×256 puzzle reference matrix, which consists of a puzzle piece structure.

[0045] In step S1 of this embodiment, the method for generating the “puzzle” reference matrix is ​​as follows:

[0046] S11: Generate a puzzle reference matrix of size 256×256, where the horizontal and vertical coordinates of the puzzle reference matrix are both 0 to 255;

[0047] S12: Divide the puzzle reference matrix into a series of non-overlapping image blocks of size 4×4, each image block consists of 4 puzzle pieces, each puzzle piece consists of 4 matrix elements in a convex structure, and the values ​​of the 4 elements are filled with 4 non-repeating numbers 0, 1, 2, and 3, respectively, representing a total of 2 bits.

[0048] In the jigsaw puzzle reference matrix of the present invention, all jigsaw puzzle pieces have the same structure, which is a convex structure. The structure and internal value distribution of all 4×4 image blocks finally formed are also exactly the same. The "jigsaw puzzle" reference matrix generated in this embodiment is as follows: Figure 2 shown.

[0049] S2: For the original image to be embedded with confidential information, copy and generate two overlay images with the same pixel domain as the original image; divide the pixel domain into a series of non-overlapping pixel pairs with unique index values ​​in the same way, and a pixel pair is composed of two adjacent pixels in the image; use the key to encrypt and segment the confidential information to be embedded, traverse each encrypted confidential information segment in turn, regard the value of the pixel pair as the position coordinate of the matrix element, and determine the position coordinates of the corresponding position of the pixel pair in the puzzle reference matrix and the position of its extended position in the puzzle block structure (the position coordinates of the pixel pair in the puzzle block structure of the corresponding position of the pixel pair in the puzzle reference matrix) according to the preset secret information embedding rules, which are equivalent to the binary confidential information value (the position coordinates of the pixel pair in the puzzle block structure of the corresponding position of the pixel pair in the puzzle reference matrix), and record the position coordinates in the two overlay images.

[0050] It should be noted that the position coordinates recorded in the two overlay images, i.e., the position coordinates corresponding to the pixel pairs in the two types of puzzle blocks, are the position coordinates where the quaternary matrix element value is equivalent to the binary confidential information value (i.e., the values ​​are equal) in the puzzle block structure to which the pixel pair corresponds in the puzzle reference matrix, and the position coordinates where the quaternary matrix element value is equivalent to the binary confidential information value (i.e., the values ​​are equal) in the puzzle block structure to which the extended position of the pixel pair corresponds in the puzzle reference matrix. Since the binary confidential information is segmented and hidden, the binary confidential information segment used to determine the first position coordinate is different from the binary confidential information segment used to determine the second position coordinate.

[0051] The specific implementation method of step S2 in this embodiment is as follows:

[0052] S21: Copy the original image to generate two overlay images. It should be noted that, since the overlay images are copied from the original images, the pixel domains of the three images are exactly the same, and the pixel domains of the three images can be regarded as the same pixel domain, and a pixel pair in the pixel domain can correspond to a fixed position in each of the three images.

[0053] S22: Split the pixel domain into non-overlapping pixel pairs, each pixel pair consists of the values ​​of two adjacent pixels and is represented by (x k ,y k ), where m and n represent the size of the original image and k represents the index of the pixel pair.

[0054] S23: Use the key to encrypt the current confidential information to be embedded, obtain the binary confidential information S encrypted by the key, and divide the confidential information S into The segment length is 6 bits. Each 6-bit segment is further divided into three 2-bit sub-segments and represented in sequence as s 1,k 、s 2,k and 3,k ,s 1,k 、s 2,k and 3,k The corresponding quaternary values ​​are (s 1,k )4、(s 2,k )4 and (s 3,k )4; for each segment of 6-bit confidential information (s 1,k ,s 2,k ,s 3,k ), execute the secret information embedding operation composed of S24 and S25, embed the confidential information into the two cover images CI1 and CI2 segment by segment, where the kth segment of 6-bit confidential information (s 1,k ,s2,k ,s 3,k ) corresponds to the pixel pair (x) with index k in the two overlay images. k ,y k )middle.

[0055] S24: The pixel pair (x k ,y k ) is considered as the matrix element coordinates. In the puzzle reference matrix PM, find the coordinates (x k ,y k ) of the reference matrix element PM(x k ,y k ), and determine the reference matrix element PM(x k ,y k ) in the first puzzle piece, replace s 1,k Convert to quaternary value (s 1,k )4, find the quaternary value (s) in the first puzzle piece 1,k )4 corresponds to the reference matrix element PM(x 1,k ,y 1,k ), read the coordinates of this reference matrix element (x 1,k ,y 1,k ), and the pixel pairs (x k ,y k ) is replaced by (x 1,k ,y 1,k )The pixel pair of the first overlay image is (,).

[0056] S25: Determine the relative direction of the first puzzle piece in the 4×4 image block to which it belongs, the relative direction being one of the upper right corner, the upper left corner, the lower left corner, and the lower right corner; then expand the 4×4 image block in the same relative direction so that the expanded area covers a 16×16 image block. If the expansion process exceeds the boundary of the reference matrix, it is necessary to translate it to be just within the puzzle reference matrix; in each 16×16 image block, the 4×4 image blocks located in the upper right corner, the upper left corner, the lower left corner, and the lower right corner are marked with 0, 1, 2, and 3, respectively, and the puzzle blocks located in the upper right corner, the upper left corner, the lower left corner, and the lower right corner of each 4×4 image block are marked with 0, 1, 2, and 3, respectively, and the four elements of each puzzle block are also represented by 0 to 3; in the 16×16 image block, find the index PM(x k ,y k ) in a 4×4 image block with index (s 2,k )4 puzzle piece has a matrix element value of (s 3,k )4 matrix element PM(x 2,k ,y 2,k ), read the coordinates of this matrix element (x 2,k,y 2,k ), and the pixel pairs (x k ,y k ) is replaced by (x 2,k ,y 2,k ). It can be seen that the above index positioning process is actually using PM(x k ,y k ), s 2,k The converted quaternary value and s 3,k The converted quaternary values ​​are used as three indexes to find a 4×4 block in the 16×16 block, a puzzle piece in the 4×4 block, and the position PM (x 2,k ,y 2,k ), and use its coordinates to cover and replace the pixel pairs of the second cover image CI2. This process can be used for reverse decryption later.

[0057] S3: Generate two camouflaged images of the same size as the original images, and map the pixel values ​​of each pixel pair in the two covered images to the two camouflaged images according to the preset pixel assignment rules, with pixel pairs as the smallest unit. Finally, two camouflaged images are generated for distribution to the two sharing participants for safekeeping to ensure information security.

[0058] In step S3 of this embodiment, the specific method is as follows:

[0059] S31: traverse each pixel pair (x k ,y k ), according to each pixel pair index k, the pixel pairs in the two cover images are covered to the mapping positions of the two camouflage images according to the parity mapping rule; in the parity mapping rule, if the pixel pair index k is an even number, the pixel pair (x k ,y k ) in the first overlay image CI1. 1,k ,y 1,k ) replaces the pixel pair at the corresponding position of the first disguised image SI1, and uses the pixel pair (x k ,y k ) in the second overlay image CI2. 2,k ,y 2,k ) replaces the pixel pair at the corresponding position of the second disguised image SI2; if the pixel pair index k is an odd number, the pixel pair (x k ,y k ) in the second overlay image CI2. 2,k ,y 2,k ) replaces the pixel pair at the corresponding position of the first disguised image SI1, and uses the pixel pair (xk ,y k ) in the first overlay image CI1. 1,k ,y 1,k ) replace the pixel pairs at corresponding positions of the second disguised image SI2;

[0060] S32: After all pixel pairs are replaced, two camouflage images are generated and allocated to two sharing participants for safekeeping.

[0061] The above steps S1 to S3 describe the process of generating two disguised images using a dual-image secret sharing steganography method. In this embodiment, the two disguised images constructed are as follows: Figure 3 shown.

[0062] In an embodiment of the present invention, a dual-image confidential information decryption system based on a jigsaw reference matrix can be further provided. After receiving two disguised images generated by the sender according to the dual-image confidential sharing steganography method described in steps 1 to S3 above, the decryption system can use the jigsaw reference matrix and the key to re-extract confidential information and reconstruct the original image.

[0063] In step S4 of this embodiment, the specific method for the decryption party to extract confidential information and reconstruct the original image is as follows:

[0064] S41: After receiving the two disguised images, the decryption system sequentially traverses each pixel pair (x k ,y k ), according to each pixel pair index k, two cover images CI1 and cover image CI2 are restored based on the two disguised images.

[0065] It should be noted that the inverse mapping relationship of the above-mentioned parity mapping rule can be reversed according to the parity mapping rule described in the above S31. Specifically, after receiving the two disguised images, the decryption system restores the two cover images according to the pixel pair index k according to the following rules: if k is an even number, the pixel pair of the disguised image SI1 is used as the pixel pair corresponding to the cover image CI1, and the pixel pair of the disguised image SI2 is used as the pixel pair corresponding to the cover image CI2; if k is an odd number, the pixel pair of the disguised image SI2 is used as the pixel pair corresponding to the cover image CI1, and the pixel pair of the disguised image SI1 is used as the pixel pair corresponding to the cover image CI2.

[0066] S42: According to the inverse operation of the secret information embedding operation, the 6-bit confidential information (s) embedded in all pixel pairs in the pixel domain is extracted from the two cover images. 1,k ,s 2,k ,s 3,k), and determine the reference matrix element PM(x) corresponding to each pixel pair in the puzzle reference matrix k ,y k ).

[0067] It should be noted that the inverse operation of the above-mentioned secret information embedding operation can be inferred from the secret information embedding operation described in the above-mentioned S24 and S25. Specifically, the inverse operation process of the secret information embedding operation is as follows:

[0068] 1) Split each overlay image into non-overlapping pixel pairs, represented by (x 1,k ,y 1,k ) and (x 2,k ,y 2,k );

[0069] 2) According to the reference matrix element PM(x 1,k ,y 1,k ) position corresponding to the value converted to binary to extract s 1,k ;

[0070] 3) Observe PM(x 1,k ,y 1,k ) to determine its position and direction in the 4×4 block to which it belongs. Then, expand the 4×4 block in the same direction to a 16×16 block. If the expansion process exceeds the boundary of the reference matrix, it needs to be translated into the matrix. Each 16×16 block contains 4 4×4 blocks, represented by 0 to 3, and each 4×4 block contains 4 "puzzle pieces", represented by 0 to 3. Each "puzzle piece" contains 4 elements, also represented by 0 to 3. Therefore, using PM(x 2,k ,y 2,k ), we can determine the position of a 4×4 block in the 16×16 block, a “puzzle piece” in the 4×4 block, and the position of an element in the puzzle piece. The three indexes in the above process are PM(x k ,y k ), s 2,k The converted quaternary value and s 3,k The converted quaternary value. 2,k and 3,k The corresponding quaternary value can be converted to binary to extract s 2,k and 3,k ;

[0071] S43: sequentially merging the 6-bit confidential information corresponding to all pixel pairs to obtain the confidential information S encrypted by the key, and extracting the embedded confidential information after decryption using the key;

[0072] S44: Using the reference matrix elements PM(xk ,y k )’s position coordinates (x k ,y k ), reconstruct the original image. The specific reconstruction method can also be reversed according to the encryption process, that is, first find the reference matrix element PM (x 1,k ,y 1,k ), get the "puzzle piece" where it is located, and find PM(x k ,y k ) corresponding to the value of the element PM(x k ,y k ), and use its coordinates as the pixel pairs of the reconstructed image. After processing all pixel pairs, the original image can be reconstructed.

[0073] To further illustrate the details of the embodiment of the present invention, in this embodiment, the pixel pair in the secret sharing steganography stage is exemplified as follows: Figure 4 As shown. It is known that the index of the pixel pair being processed is an odd number, the pixel pair is (4,6), and the segmented confidential information s1, s2 and s3 are (10)2, (10)2, (00)2 respectively. Figure 4 As shown in (a), first find the corresponding position of the pixel pair in the "puzzle" reference matrix (PM) (i.e. Figure 4 (3) marked by the purple box in (a) is located in the yellow puzzle piece. Since s1 is converted to quaternary (2)4, find the position with the value (2)4 in the puzzle piece (i.e. Figure 4 2) marked by the red box in (b), and the coordinates of this position are used as the pixel pair covering image 1. Figure 4 As shown in (c), because the yellow puzzle piece is located in the upper left corner of the 4×4 block marked by the red frame, it expands to the upper left to become the 16×16 block marked by the purple frame. The 16×16 block contains four 4×4 blocks numbered 0 to 3. Figure 4 As shown in (d), since PM(4,6)=3, s2:(10)2=(2)4, s3:(00)2=(0)4, the blue "puzzle block" represented by 2 is selected in the 4×4 block numbered 3, and the element with a value of 0 is found in it. The coordinates of this position are used as the pixel pair of overlay image 2. Finally, since the pixel pair index is an odd number, the pixel pair of disguised image 1 is represented by the pixel pair of overlay image 2, and the pixel pair of disguised image 2 is represented by the pixel pair of overlay image 1.

[0074] In this embodiment, the pixel pair is exemplified in the shared decryption phase as follows: Figure 5As shown. It is known that the pixel pairs of disguised image 1 and disguised image 2 are (5,4) and (4,7) respectively, and the index of the pixel pair being processed is an odd number, so the pixel pairs of cover image 1 are represented by the pixel pairs of disguised image 2, and the pixel pairs of cover image 2 are represented by the pixel pairs of disguised image 1. By mapping the pixel pairs of cover image 1 to the "puzzle" reference matrix, the value corresponding to s1 can be directly determined, as follows: Figure 5 The red circle in (a) is converted to binary and s1 is (10)2. Figure 5 As shown in (b), the position corresponding to the overlay image 1 is located in the yellow "puzzle piece" at the upper left corner of the 4×4 block marked by the red frame, so it is expanded to the upper left direction to become the 16×16 block marked by the purple frame. The 16×16 block contains four 4×4 blocks numbered 0 to 3. Figure 5 As shown in (c), the position corresponding to the overlay image 2 is in the 4×4 block marked by the light blue box numbered 3. The 2 in this block represents the element with a value of 0 in the blue "puzzle block". Therefore, the value of the corresponding position of the reconstructed image pixel pair and the corresponding values ​​of s2 and s3 can be obtained. After conversion to binary, s2 and s3 are (10)2 and (00)2 respectively. Figure 5 As shown in (d), the value of the position corresponding to the pixel pair of the reconstructed image is 3, and within the yellow "puzzle piece" corresponding to the pixel pair of the overlay image 1 marked by the red circle, the two can be combined to find the position corresponding to the pixel pair of the reconstructed image marked by the purple circle, and its coordinates are the pixel pair of the reconstructed image.

[0075] The method proposed in the present invention embeds confidential information into two constructed camouflage images through secret sharing steganography, and achieves high embedding rate and fast execution efficiency while ensuring the visual quality of the camouflage images. It should be noted that the method steps S1 to S2 in the above embodiment can essentially be implemented in the form of a computer program.

[0076] Similarly, based on the same inventive concept, the present invention also provides a computer electronic device corresponding to the double-image secret sharing steganography method based on the jigsaw reference matrix provided in the above embodiment, which includes a memory and a processor;

[0077] The memory is used to store computer programs;

[0078] The processor is used to implement the double-image secret sharing steganography method based on the jigsaw reference matrix as described above when executing the computer program;

[0079] In addition, the logic instructions in the above-mentioned memory can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention.

[0080] Therefore, based on the same inventive concept, the present invention provides a computer-readable storage medium corresponding to a dual-image secret sharing steganography method based on a jigsaw reference matrix, and a computer program is stored on the storage medium. When the computer program is executed by a processor, it can implement the dual-image secret sharing steganography method based on the jigsaw reference matrix as described above.

[0081] Therefore, based on the same inventive concept, the present invention provides a computer program product, including a computer program / instruction, which, when executed by a processor, can implement the dual-image secret sharing steganography method based on the puzzle reference matrix as described above.

[0082] Specifically, in the computer-readable storage medium of the above three embodiments, the stored computer program is executed by the processor to perform the above steps S1 to S2.

[0083] However, it should be noted that the above-mentioned programs of S1 and S2 may be stored and executed by different computer devices.

[0084] It is also understandable that the above storage medium may include a random access memory (RAM) or a non-volatile memory (NVM), such as at least one disk storage. The storage medium may also be a U disk, a mobile hard disk, a magnetic disk or an optical disk, etc., which may store program codes.

[0085] It can also be understood that the above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0086] It should also be noted that those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the system described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. In the various embodiments provided in this application, the division of steps or modules in the system and method is only a logical function division, and there may be other division methods in actual implementation, such as multiple modules or steps can be combined or integrated together, and a module or step can also be split.

[0087] To further illustrate the technical effect of the present invention, the experimental results of the proposed method are specifically demonstrated by using specific data sets. As shown in Table 1, this embodiment mainly evaluates the embedding capacity, bits per pixel (bpp) and peak signal-to-noise ratio (PSNR). The experimental results show that both the scheme of Liu et al. [5] and the present invention achieve an embedding capacity of up to 786,432 bits, i.e., 1.5bpp. Other dual-image secret sharing steganography schemes [1-4] provide an embedding capacity of 1bpp, while the scheme of Kim et al. [6] achieves 1.1bpp. These results highlight the advantages of the present invention in embedding capacity. The PSNR value of the present invention is approximately 39 decibels. When the PSNR value exceeds 30 decibels, the human eye can hardly feel the distortion, which meets the visual quality standard.

[0088] Table 1 Performance comparison of the present invention and other dual-image secret sharing steganography schemes.

[0089]

[0090]

[0091] As shown in Table 2, this example compares the present invention with the scheme of Liu et al. [5], and both methods can achieve 1.5bpp. The difference between disguised image 1 and disguised image 2 in the two schemes is negligible, which shows that the visual quality is balanced and helps to improve security. The PSNR value of Liu et al.'s scheme is about 36 dB, while the PSNR value of the present invention is about 39 dB. The structural similarity (SSIM) of Liu et al.'s scheme ranges from 0.8915 to 0.9645, while the SSIM value of the present invention ranges from 0.9468 to 0.9839. These results show that the present invention provides better visual quality at the same 1.5bpp embedding capacity.

[0092] Table 2 Comparison of visual quality between the present invention and the scheme of Liu et al. [5].

[0093]

[0094] As shown in Table 3, this embodiment compares the execution time of the present invention and the scheme of Liu et al. [5] at different stages. The execution time of the scheme of Liu et al. in the secret sharing steganography stage is 0.5242 seconds, while the execution time of the present invention is 0.0804 seconds, achieving an improvement of 84.66%. In the shared decryption stage, the scheme of Liu et al. takes 0.9158 seconds, while the present invention only takes 0.1236 seconds, achieving an improvement of 86.50%. These results show that the present invention has a significant efficiency advantage in terms of execution time.

[0095] Table 3 Comparison of execution time between the present invention and the solution of Liu et al. [5].

[0096]

[0097] The specific methods of related work in the prior art are shown in the following documents:

[0098] 1.Chang,CC,Kieu,TDand Chou,YC,2007,October.Reversible datahiding scheme using two steganographic images.In TENCON 2007-2007 IEEE Region10 Conference(pp.1-4).IEEE.

[0099] 2.Lu,T.C.,Tseng,C.Y.and Wu,J.H.,2015.Dual imaging-based reversiblehiding technique using LSB matching.Signal Processing,108,pp.77-89.

[0100] 3.Sahu,A.K.and Swain,G.,2019.Dual stego-imaging based reversible datahiding using improved LSB matching.International Journal of IntelligentEngineering and Systems,12(5),pp.63-73.

[0101] 4.Tseng,H.W.and Leng,H.S.,2022.Areversible modified least significantbit(LSB)matching revisited method.Signal Processing:Image Communication,101,p.116556.

[0102] 5.Liu,J.C.,Chang,C.C.,Lin,Y.,Chang,C.C.and Horng,J.H.,2023.AMatrixCoding-Oriented Reversible Data Hiding Scheme Using Dual DigitalImages.Mathematics,12(1),p.86.

[0103] 6.Kim,C.,Cavazos Quero,L.,Jung,K.H.and Leng,L.,2024.Advanced DualReversible Data Hiding:A Focus on Modification Direction and Enhanced LeastSignificant Bit(LSB)Approaches.Applied Sciences,14(6),p.2437.

[0104] The above-described embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention. A person skilled in the art may make various changes, substitutions or improvements without departing from the spirit of the present invention and the scope of the claims. Therefore, any technical solution obtained by equivalent substitution or equivalent transformation shall be deemed to fall within the protection scope of the present invention.

Claims

1. A dual-image secret sharing steganography method based on a puzzle reference matrix, characterized in that: The specific steps are as follows: S1: Generate a puzzle reference matrix consisting of puzzle pieces arranged in the same structure; S2: For the original image to be embedded with confidential information, two overlay images with the same pixel domain as the original image are copied and generated; the pixel domain is divided into a series of non-overlapping pixel pairs with unique index values ​​in the same way, and a pixel pair is composed of two adjacent pixels in the image; the confidential information to be embedded is encrypted and segmented using a key, and each encrypted confidential information segment is traversed in turn, and the value of the pixel pair is regarded as the position coordinate of the matrix element, and according to the preset secret information embedding rule, the corresponding position of the pixel pair in the puzzle reference matrix and the position coordinate of the quaternary matrix element value and the binary confidential information value in the puzzle block structure of the extended position are determined, and the position coordinates are recorded in the two overlay images; S3: Generate two camouflaged images of the same size as the original images, and map the pixel values ​​of each pixel pair in the two covered images to the two camouflaged images according to the preset pixel assignment rule, with the pixel pair as the smallest unit, and finally generate two camouflaged images for distribution to the two sharing participants for safekeeping respectively.

2. The dual-image secret sharing steganography method based on the jigsaw reference matrix according to claim 1 is characterized in that: In S1, the method for generating the jigsaw reference matrix is ​​as follows: S11: Generate a puzzle reference matrix of size 256×256, where the horizontal and vertical coordinates of the puzzle reference matrix are both 0 to 255; S12: Divide the puzzle reference matrix into a series of non-overlapping image blocks of size 4×4, each image block consists of 4 puzzle pieces, each puzzle piece consists of 4 matrix elements in a convex structure, and the values ​​of the 4 elements are filled with 4 non-repeating numbers 0, 1, 2, and 3, respectively, representing a total of 2 bits.

3. The dual-image secret sharing steganography method based on the jigsaw reference matrix according to claim 2 is characterized in that: In the jigsaw reference matrix, all jigsaw pieces have the same convex-shaped structure, and all 4×4 image blocks composed of 4 jigsaw pieces in the jigsaw reference matrix are also exactly the same.

4. The dual-image secret sharing steganography method based on the jigsaw reference matrix according to claim 2 is characterized in that: The specific method of S2 is as follows: S21: copy the original image to generate two overlay images, and the pixel domains of the three images are exactly the same; S22: Split the pixel domain into non-overlapping pixel pairs, each pixel pair consists of the values ​​of two adjacent pixels and is represented by (x k ,y k ), where m and n represent the size of the original image, and k represents the index of the pixel pair; S23: Use the key to encrypt the current confidential information to be embedded, obtain the binary confidential information S encrypted by the key, and divide the confidential information S into The segment length is 6 bits. Each 6-bit segment is further divided into three 2-bit sub-segments and represented in sequence as s 1,k 、s 2,k and 3,k ,s 1,k 、s 2,k and 3,k The corresponding quaternary values ​​are (s 1,k )4、(s 2,k )4 and (s 3,k )4; for each segment of 6-bit confidential information (s 1,k ,s 2,k ,s 3,k ), execute the secret information embedding operation composed of S24 and S25, embed the confidential information into the two cover images CI1 and CI2 segment by segment, where the kth segment of 6-bit confidential information (s 1,k ,s 2,k ,s 3,k ) corresponds to the pixel pair (x) with index k in the two overlay images. k ,y k )middle: S24: The pixel pair (x k ,y k ) is considered as the matrix element coordinates. In the puzzle reference matrix PM, find the coordinates (x k ,y k ) of the reference matrix element PM(x k ,y k ), and determine the reference matrix element PM(x k ,y k ) in the first puzzle piece, replace s 1,k Convert to quaternary value (s 1,k )4, find the quaternary value (s) in the first puzzle piece 1,k )4 corresponds to the reference matrix element PM(x 1,k ,y 1,k ), read the coordinates of this reference matrix element (x 1,k ,y 1,k ), and the pixel pairs (x k ,y k ) is replaced by (x 1,k ,y 1,k )The pixel pair of the first overlay image is (,); S25: Determine the relative direction of the first puzzle piece in the 4×4 image block to which it belongs, the relative direction being one of the upper right corner, the upper left corner, the lower left corner, and the lower right corner; then expand the 4×4 image block in the same relative direction so that the expanded area covers a 16×16 image block. If the expansion process exceeds the boundary of the reference matrix, it is necessary to translate it to be just within the puzzle reference matrix; in each 16×16 image block, the 4×4 image blocks located in the upper right corner, the upper left corner, the lower left corner, and the lower right corner are marked with 0, 1, 2, and 3, respectively, and the puzzle blocks located in the upper right corner, the upper left corner, the lower left corner, and the lower right corner in each 4×4 image block are marked with 0, 1, 2, and 3, respectively; in the 16×16 image block, find the index PM(x k ,y k ) in a 4×4 image block with index (s 2,k )4 puzzle piece has a matrix element value of (s 3,k )4 matrix element PM(x 2,k ,y 2,k ), read the coordinates of this matrix element (x 2,k ,y 2,k ), and the pixel pairs (x k ,y k ) is replaced by (x 2,k ,y 2,k ).

5. The dual-image secret sharing steganography method based on the jigsaw reference matrix according to claim 4 is characterized in that: The specific method of S3 is as follows: S31: traverse each pixel pair (x k ,y k ), according to each pixel pair index k, the pixel pairs in the two cover images are covered to the mapping positions of the two camouflage images according to the parity mapping rule; in the parity mapping rule, if the pixel pair index k is an even number, the pixel pair (x k ,y k ) in the first overlay image CI1. 1,k ,y 1,k ) replaces the pixel pair at the corresponding position of the first disguised image SI1, and uses the pixel pair (x k ,y k ) in the second overlay image CI2. 2,k ,y 2,k ) replaces the pixel pair at the corresponding position of the second disguised image SI2; if the pixel pair index k is an odd number, the pixel pair (x k ,y k ) in the second overlay image CI2. 2,k ,y 2,k ) replaces the pixel pair at the corresponding position of the first disguised image SI1, and uses the pixel pair (x k ,y k ) in the first overlay image CI1. 1,k ,y 1,k ) replace the pixel pairs at corresponding positions of the second disguised image SI2; S32: After all pixel pairs are replaced, two camouflage images are generated and allocated to two sharing participants for safekeeping.

6. A dual-image confidential information decryption system based on a puzzle reference matrix, characterized in that: After receiving the two disguised images generated by the sender according to the dual-image secret sharing steganography method as described in any one of claims 1 to 5, the decryption system uses the puzzle reference matrix and the key to re-extract the confidential information and reconstruct the original image.

7. The double-image confidential information decryption system based on the jigsaw reference matrix according to claim 6, characterized in that: The specific method for the decryption party to extract confidential information and reconstruct the original image is as follows: S41: After receiving the two disguised images, the decryption system sequentially traverses each pixel pair (x k ,y k ), according to each pixel pair index k, two cover images CI1 and cover image CI2 are restored based on the two disguised images; S42: According to the inverse operation of the secret information embedding operation, the 6-bit confidential information (s) embedded in all pixel pairs in the pixel domain is extracted from the two cover images. 1,k ,s 2,k ,s 3,k ), and determine the reference matrix element PM(x) corresponding to each pixel pair in the puzzle reference matrix k ,y k ); S43: sequentially merging the 6-bit confidential information corresponding to all pixel pairs to obtain the confidential information S encrypted by the key, and extracting the embedded confidential information after decryption using the key; S44: Using the reference matrix elements PM(x k ,y k )’s position coordinates (x k ,y k ) and reconstruct the original image.

8. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, it can implement the dual-image secret sharing steganography method based on the jigsaw reference matrix as described in any one of claims 1 to 5.

9. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by a processor, the dual-image secret sharing steganography method based on a jigsaw reference matrix as described in any one of claims 1 to 5 can be implemented.

10. A computer electronic device, characterized in that: including memory and processor; The memory is used to store computer programs; The processor is used to implement the dual-image secret sharing steganography method based on the jigsaw reference matrix as described in any one of claims 1 to 5 when executing the computer program.

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