Multi-image reversible information hiding method and device based on asymmetric direction combination

Abstract

The invention provides a multi-image reversible information hiding method and device based on asymmetric direction combination, and relates to the technical field of image processing and data security. The method comprises the steps of obtaining an original image and to-be-hidden secret information; based on each pixel of the original image, combining a set variation range and the number n of carrier images to generate n hidden pixels corresponding to the pixel, namely a hidden pixel combination; calculating a difference value set based on the hidden pixel combination, and constructing a direction combination structure table; and based on the direction combination structure table and the secret information, respectively storing the secret pixel combination corresponding to each pixel into n independent images to obtain n carrier images, and completing secret information hiding of the original image. According to the method, the embedding rate is improved through single-pixel embedding, the security of the system is enhanced through multi-carrier image collaboration, a structural table is prevented from being reversely cracked by using secret key scrambling, and meanwhile, complete reversible recovery of an original image is ensured.

Description

Technical Field

[0001] This invention relates to the fields of image processing and data security technology, and more specifically, to a method and apparatus for reversible information hiding of multiple images based on asymmetric directional combinations. Background Technology

[0002] With the rapid development of network communication technology, data transmission in open network environments is becoming increasingly frequent, but it also faces security risks such as eavesdropping, tampering, or destruction. While traditional encryption technologies can effectively protect data content, their encryption and decryption processes are computationally complex and time-consuming, and the encrypted ciphertext often appears as meaningless gibberish, easily attracting the attention of attackers and becoming a target for interference or damage. In contrast, information hiding technology embeds secret information into ordinary carriers (such as images, audio, and video), achieving covert communication while maintaining the carrier's appearance largely unchanged. This provides stronger resistance to detection and is particularly suitable for applications where the integrity of the carrier is critical.

[0003] In information hiding technology, reversible information hiding encryption has attracted much attention because it can losslessly restore the original carrier after extracting secret information. Existing technologies generate two hidden pixel pairs by mapping every two adjacent pixels in the original image to a two-dimensional space, embedding them into two carrier images respectively. The receiving end needs to acquire both carrier images simultaneously to reconstruct the original pixels and extract the secret information. This method ensures reversibility while possessing a certain embedding capacity and visual imperceptibility.

[0004] However, the aforementioned existing technologies still have several limitations. First, they use pixel pairs as processing units, and each pixel pair can only embed one base symbol, resulting in limited information embedding efficiency per pixel, making it difficult to meet the needs of high-capacity covert communication. Second, the system only generates two carrier images. Once an attacker obtains either one, although they cannot directly recover the original data, they may be able to deduce the hiding mechanism through statistical analysis, leaving room for improvement in the overall system security. More importantly, the lack of a dynamic change mechanism means that once reverse-engineered and reconstructed, the entire hiding scheme faces the risk of being cracked, making it unsuitable for high-security application scenarios.

[0005] In view of the above, this application is hereby submitted. Summary of the Invention

[0006] The present invention aims to provide a multi-image reversible information hiding method and apparatus based on asymmetric direction combination, so as to solve the technical defects of existing dual-image reversible information hiding methods, such as limited embedding capacity, insufficient system security and susceptibility to reverse engineering.

[0007] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: A multi-image reversible information hiding method based on asymmetric direction combination includes: S1, Obtain the original image and the secret information to be hidden; S2, based on each pixel of the original image, and combined with the set range of variation and the number of carrier images n, n hidden pixels corresponding to the pixel are generated, i.e., hidden pixel combination; S3, calculate the difference set based on the hidden pixel combination and construct the direction combination structure table; S4. Based on the direction combination structure table and the secret information, the hidden pixel combination corresponding to each pixel is stored in n independent images to obtain n carrier images, thus completing the hiding of the secret information of the original image.

[0008] Preferably, the process of generating the hidden pixel combination is as follows: Let each pixel of the original image be... The range of variation is t. , The resolution of the original image; Based on pixels , n hidden pixels are generated from the number of carrier images n. The combination of hidden pixels is represented as follows: ,and ; in, For pixels The j-th hidden pixel.

[0009] Preferably, the construction process of the direction combination structure table is as follows: Initialize the direction combination mechanism table , Indicates empty; Iterate through all possible combinations of hidden pixels. Calculate the corresponding set of differences: , , ; in, Let j be the j-th difference; then the set of differences is ; If the difference set is not in L, then the hidden pixel combination will be... With the corresponding set of differences Add to L; Otherwise, extract the existing hidden pixel combination corresponding to the difference combination in L. And calculate the distortion value corresponding to the two hidden pixel combinations respectively. , The formula for calculating the distortion value is: ; like Then replace L with the current better combination. ; The process continues until all possible combinations of hidden pixels have been traversed, resulting in the final direction combination structure table L.

[0010] Preferably, the method further includes: setting a key to scramble the direction combination structure table to improve data security; the scrambling rules are as follows: Assumption Let L be the set of all direction combinations, that is, all entries in the direction combination structure table L, where... number of elements ,Right now The number of elements in L is the same as the number of records N in L; , represents a set of indexed values; Establish a mapping function from direction combination to the original index. That is, for each combination of directions Each has a unique correspondence One of the elements, This indicates the corresponding raw index; Using keys Generate a set of index values bijective permutation function on ; based on For each direction combination Through mapping function get The original index, then used Replace with a new index, scramble the direction combination structure table, and obtain a new mapping function. The formula is: ; in, Indicates direction combination A new mapping function.

[0011] Preferably, based on the direction combination structure table and the secret information, the hidden pixel combination corresponding to each pixel is stored in n independent images, specifically: Convert the secret information into a standard binary stream; Based on the aforementioned direction combination structure table, the standard binary stream is converted into an N-ary embedded number set. Where N is the number of records in L; Furthermore, each set of differences in L uniquely corresponds to an embedded number in base N. That is, each Corresponding to the row direction combination in L, ; Based on the aforementioned direction combination structure table For each pixel Hide an embedded number and generate A hidden pixel marker, generated according to the following rules: ; in, For the j-th carrier image, the corresponding original pixel Hidden pixels in the location; For the direction combination structure table Corresponding numbers The hidden pixel value in that row.

[0012] Preferably, it also includes receiving a key during decryption. Then, generate the bijective permutation function. inverse permutation function ; Then through the formula Restore the original correspondence and recover the complete directional combination structure table.

[0013] Preferably, it further includes: during decryption, extracting secret information and restoring the original image by receiving n carrier images and a range of variation t, specifically: Based on the variation range t and n carrier images, construct the orientation combination structure table L; Extract hidden pixel combinations from the same location in n carrier images. ; The difference combination is calculated based on the hidden pixel combination; Match the difference combinations to the direction combination structure table L; the corresponding row is the embedded secret number. ; The original pixels can be recovered using the following formula: ; in, Original pixels; For the direction combination structure in table L, the corresponding The rows record the original pixel values.

[0014] Preferably, it further includes: if the original pixel If the boundary pixel is not embedded with secret information, the original pixel is copied to the corresponding pixel position in the n carrier images. Similarly, during the decryption process, the boundary pixels of the n carrier images are the original pixels.

[0015] The present invention also provides a multi-image reversible information hiding device based on asymmetric direction combination, comprising: The data acquisition unit is used to acquire the original image and the secret information to be hidden; The hidden pixel generation unit is used to generate n hidden pixels corresponding to each pixel of the original image, based on a set range of variation and the number of carrier images n, i.e., a hidden pixel combination; The orientation combination structure table construction unit is used to construct the orientation combination structure table based on the set of differences calculated by the hidden pixel combination. The information hiding unit is used to store the hidden pixel combination corresponding to each pixel into n independent images based on the direction combination structure table and the secret information, thereby obtaining n carrier images and completing the hiding of the secret information of the original image.

[0016] Preferably, it further includes: a decryption unit, used to construct a direction combination structure table by acquiring n carrier images and their variation ranges, extract secret information and restore the original image.

[0017] The present invention also provides a multi-image reversible information hiding device based on asymmetric direction combination, including a processor and a memory. The memory stores a computer program that can be executed by the processor to implement the multi-image reversible information hiding method based on asymmetric direction combination as described above.

[0018] The present invention also provides a computer-readable storage medium storing computer-readable instructions, which, when executed by a processor of the device on which the computer-readable storage medium is located, implement the multi-image reversible information hiding method based on asymmetric direction combination as described above.

[0019] In summary, compared with the prior art, the present invention has the following beneficial effects: First, this invention reduces the basic unit of information embedding to a single pixel by employing a single-pixel embedding mechanism, significantly improving the information carrying capacity of a single pixel. Second, by generating multiple carrier images, the extraction of secret information and the restoration of the original image depend on the collaborative participation of all carrier images; any missing image will result in incomplete information restoration, thereby raising the system's fault tolerance threshold and resistance to scatter attacks. Third, by introducing a key-driven dynamic scrambling mechanism for the directional combination structure table, this invention deeply integrates the information hiding process with the encryption process. Even if an attacker obtains all carrier images and reverse-engineers all offset vectors, they cannot establish a mapping relationship between offset vectors and secret information indices without the key, thus elevating security to the computational security level. Finally, through a boundary pixel-free processing strategy and a reversible design based on the uniqueness of directional offset vectors, this invention ensures that the original image can be 100% losslessly restored provided the legitimate recipient possesses all carrier images and the key, meeting the requirements of applications with strict requirements for carrier integrity, such as medical imaging, legal evidence, and military reconnaissance.

[0020] Furthermore, by adjusting the number and range of carrier images, this invention can flexibly balance embedding capacity, visual fidelity, and computational complexity, adapting to the performance requirements of different application scenarios. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a flowchart illustrating a multi-image reversible information hiding method based on asymmetric direction combination, as provided in Embodiment 1.

[0023] Figure 2 This is a schematic diagram of the framework of a multi-image reversible information hiding method based on asymmetric direction combination provided in Embodiment 1.

[0024] Figure 3 This is a schematic diagram of a multi-image reversible information hiding device based on asymmetric direction combination, provided in Embodiment 2.

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] Example 1 Embodiment 1 of the present invention provides a multi-image reversible information hiding method based on asymmetric direction combination, which can be implemented by a multi-image reversible information hiding device based on asymmetric direction combination (hereinafter referred to as reversible information hiding device), specifically, executed by one or more processors within the reversible information hiding device.

[0028] In this embodiment, the reversible information hiding device can be an electronic device equipped with a processor. The processor carries a computer program for the multi-image reversible information hiding method based on asymmetric direction combination, and the computer program can be executed. Examples include computers, smartphones, smart tablets, workstations, etc., which are not limited here.

[0029] like Figure 1 As shown, a multi-image reversible information hiding method based on asymmetric direction combination includes steps S1 to S4.

[0030] S1, Obtain the original image and the secret information to be hidden.

[0031] In this step, the secret information to be hidden can be text, images, files, etc., and there are no restrictions here.

[0032] S2, based on each pixel of the original image, and combined with the set range of variation and the number of carrier images n, n hidden pixels corresponding to the pixel are generated, i.e., hidden pixel combination.

[0033] Specifically, let each pixel of the original image be... The range of variation is t, and the number of carrier images is n. , The resolution of the original image, i.e., the height and width of the original image; Based on pixels , n hidden pixels are generated from the number of carrier images n. The combination of hidden pixels is represented as follows: ,and ; in, For pixels The j-th hidden pixel.

[0034] S3. Calculate the difference set based on the hidden pixel combination and construct the direction combination structure table.

[0035] Specifically, the direction combination mechanism table is initialized first. , Indicates empty; Then iterate through all possible combinations of hidden pixels. Calculate the corresponding set of differences: , , ; in, Let j be the j-th difference; then the set of differences is ;and The number of combinations is .

[0036] Considering there may be multiple different The value will make Therefore, this embodiment calculates and compares distortion values, retaining only those pixels identical to the original pixels. By comparing the hidden pixel combinations with the smallest distortion values ​​and discarding the others, an effective directional combination is found.

[0037] That is: if the set of differences is not in L, then the hidden pixel combination will be... With the corresponding set of differences Add to L; Otherwise, extract the existing hidden pixel combination corresponding to the difference combination in L. And calculate the distortion value corresponding to the two hidden pixel combinations respectively. , The formula for calculating the distortion value is: ; like Then replace L with the current better combination. ; The process continues until all possible combinations of hidden pixels have been traversed, resulting in the final direction combination structure table L.

[0038] The directional combination structure table L selects combinations based on the principle of "minimum distortion," ensuring that hidden pixels are as close as possible to the original pixels. This avoids the regular noise caused by fixed codebook quantization and reduces the probability of detection.

[0039] S4. Based on the direction combination structure table and the secret information, the hidden pixel combination corresponding to each pixel is stored in n independent images to obtain n carrier images, thus completing the hiding of the secret information of the original image.

[0040] Specifically, first, the secret information is converted into a standard binary stream.

[0041] If the secret information is text: convert each character to 8 bits (bytes) according to the character encoding (such as UTF-8, ASCII); if the secret information is binary data (such as encrypted ciphertext): use the original binary stream directly; if the secret information is a number: first convert it to decimal, then convert it to a binary stream.

[0042] Based on the aforementioned direction combination structure table, the standard binary stream is converted into an N-ary embedded number set. Where N is the number of records in L;

[0043] The binary stream is grouped and calculated according to the place value rules of N-ary numbers to obtain a set of integers from "0 to N-1". If the length of the binary stream is not divisible by the number of binary digits corresponding to each of the N base digits, pad the end of the binary stream with 0s (padding markers can be added later to ensure that invalid padding is removed during decryption). The resulting sequence of integers from 0 to N-1 is the embedded number set.

[0044] Furthermore, each set of differences in L uniquely corresponds to an embedded number in base N. That is, each Corresponding to the row direction combination in L, .

[0045] Based on the aforementioned direction combination structure table For each pixel Hide an embedded number and generate A hidden pixel marker, generated according to the following rules: ; in, For the j-th carrier image, the corresponding original pixel Hidden pixels in the location; For the direction combination structure table Corresponding numbers The hidden pixel value in that row.

[0046] During decryption, the secret information is extracted and the original image is restored by receiving n carrier images and a range of variation t, specifically as follows: Based on the variation range t and n carrier images, construct the orientation combination structure table L; Extract hidden pixel combinations from the same location in n carrier images. ; The difference combination is calculated based on the hidden pixel combination; Match the difference combinations to the direction combination structure table L; the corresponding row is the embedded secret number. ; The original pixels can be recovered using the following formula: ; in, Original pixels; For the direction combination structure in table L, the corresponding The rows record the original pixel values.

[0047] In a preferred embodiment, if the original pixel If the boundary pixel is a single pixel, then no secret information needs to be embedded; the pixel can be copied to the corresponding pixel positions in n carrier images. Similarly, during the decryption process, when this... When the hidden pixels at the same position in n carrier images are all boundary pixels and are equal to each other, no secret information will be extracted. The boundary pixels of n carrier images are the original pixels.

[0048] In another preferred embodiment, to further enhance system security, the present invention utilizes a key. The records in the direction combination structure table are scrambled.

[0049] Specifically, such as Figure 2 As shown, set a key. The directional combination structure table is scrambled to improve data security; the scrambling rules are as follows: Assumption Let L be the set of all direction combinations, that is, all entries in the direction combination structure table L, where... number of elements ,Right now The number of elements in L is the same as the number of records N in L; This yields the set of index values. .

[0050] Then, a mapping function is established from the direction combination to the original index. That is, for a set Each element in the array, i.e., each directional combination Each has a unique correspondence One of the elements, and Every element in the text is overwritten; This indicates the original index it corresponds to.

[0051] Using keys As a seed, a cryptographically secure pseudo-random number generator is used to generate a set of index values. bijective permutation function on Construct a scrambled direction combination structure table.

[0052] A permutation function is a bijective function that "rearranges" the elements of a set. Its core characteristic is that each element uniquely maps to another element, with no repetition or omission. It is often used to shuffle the order of information to achieve encryption or scrambling.

[0053] based on For each direction combination Through mapping function get The original index, then used Replace with a new index, scramble the direction combination structure table, and obtain a new mapping function. The formula is: ; in, Indicates direction combination A new mapping function; It means any.

[0054] Next, the secret information to be embedded is converted into a set of N-ary embedding numbers. Each pixel position in the original image is traversed, and the scrambled direction combination structure table is consulted according to the numbers to be embedded to obtain the corresponding n hidden pixels, which are then written into the n carrier images respectively.

[0055] During decryption, the key It will be shared with the recipient, allowing them to reconstruct the complete directional combination structure table.

[0056] Specifically, receiving the key Then, generate the bijective permutation function. inverse permutation function ; Then through the formula Restore the original correspondence and recover the complete directional combination structure table.

[0057] Iterate through the pixel positions of each carrier image, read pixel values ​​from n carrier images, calculate the differences, and search for a unique matching row in the scrambled direction combination structure table. This allows us to obtain the original secret information index and thus deduce the original pixel.

[0058] This invention employs a permutation function generated based on key k. By disrupting the correspondence between direction combinations and indices, unauthorized individuals cannot decipher information by statistically analyzing the distribution patterns of difference combinations, thus further enhancing resistance to detection.

[0059] In a preferred embodiment, with varying range Number of carrier images key Taking an example, the method of the present invention will be described in detail.

[0060] First, according to , and keys It is possible to construct a directional combination structure table. .

[0061] when (The range of changes in the original pixels is) ), When generating 3 hidden pixels: Hidden Pixels The range of values ​​is That is, each hidden pixel can only take , Three values.

[0062] The difference corresponding to the direction combination is , There are a total of n-1=2 differences.

[0063] Each difference The range of values ​​for is {-2,-1,0,1,2}.

[0064] Then, based on the principle of minimizing distortion, valid direction combinations are selected, resulting in 19 final valid and unique difference combinations, i.e., the number of records in the direction combination structure table L is N=19. As shown in Table 1, these combinations are not processed by the key. The scrambled direction combination structure table, as shown in Table 2, is processed by the key. Disordered direction combination structure table.

[0065] Table 1. =1, Directional combination structure table when =3

[0066] Table 2. Passed through the key Scrambled direction combination structure table

[0067] because The number of records N is 19, therefore, each original pixel can be used to hide one base-19 secret number. Suppose two original pixels {14, 240} are to be used to hide two base-19 secret numbers. The details are as follows: (1) Put the numbers It is hidden within the original pixel 14. (Based on the numbers...) In the corresponding row of data in Table 2, we modified the original pixel 14 to three hidden pixels, that is... , and Hidden Pixels , and The images are stored on different carrier images, so the pixels in the three carrier images are {15}, {13} and {15}, respectively.

[0068] (2) Put the numbers It is hidden within the original pixel 240. Similarly, based on the numbers... In the corresponding row of data in Table 2, we modified the original pixel 240 to... , and Hidden Pixels , and The pixels were added to different carrier images and saved separately. Therefore, the final pixel counts in the three carrier images are {15,239}, {13,240}, and {15,240}.

[0069] During the decryption and extraction phase, the receiver obtains three carrier images with pixel values ​​of {15,239}, {13,240}, and {15,240} respectively. The receiver needs to... , and keys First construct the same Then, pixels at the same location in the three carrier images are processed sequentially to extract secret information and restore the original image, as follows: (1) Extract the three hidden pixels 15, 13, and 15 from the three carrier images. Calculate the difference using the formula. .because The values ​​are located in Table 2 The line corresponds to the hidden secret number 2. Simultaneously, the original pixel can be recovered as... In other words, the hidden secret information is... The original pixel value is {14}.

[0070] (2) Extract the three hidden pixels 239, 240, and 240 from the three carrier images. Calculate the difference using the same formula. .Will Mapping the values ​​to Table 2, we can obtain the hidden secret number as 15. Simultaneously, the original pixels can be recovered as... In other words, the hidden secret information is... The original pixel count is {240}. Ultimately, the hidden secret information is... The original pixel values ​​are {14, 240}.

[0071] The hidden capacity of this invention is determined by the number of records N in the directional combination structure table and the number of carrier images n: the larger N is (which can be flexibly adjusted by the t and n parameters), the larger the amount of N-ary digital information that can be embedded in a single pixel; the more n there are (the number of hidden pixels), the stronger the parallel embedding capability of multiple carriers, which can support the hidden transmission of large-capacity information (such as long text, encrypted files, and short videos) without having to split the information into multiple segments for separate transmission, thus achieving higher efficiency.

[0072] Existing single-carrier steganography techniques centrally modify the pixel values ​​of a single image, causing significant changes in the image's statistical properties (such as histogram and correlation), making it easily detectable by steganalysis tools (such as RS detection and SPA detection); fixed-codebook quantization steganography produces significant quantization noise. This invention distributes the modification of a single original pixel across n carrier images. The difference between the hidden pixels and the original pixels in each carrier image is minimal, and the visual distortion and changes in statistical properties of a single image are negligible, making them difficult for both the human eye and detection tools to detect.

[0073] This invention is applicable to scenarios with high requirements for image integrity (such as medical images, military images, and copyright-protected images), preserving the original image's usability even after information is hidden. This invention is particularly suitable for medical image transmission scenarios: hospitals use patient CT images as the original carrier, embedding a diagnostic report summary, generating three carrier images that are sent through different channels; only authorized doctors who simultaneously receive all three images and input the key can recover the original CT image (for subsequent diagnosis) and report content, ensuring data integrity and confidentiality.

[0074] In summary, compared with the prior art, the present invention has the following beneficial effects: First, this invention reduces the basic unit of information embedding to a single pixel by employing a single-pixel embedding mechanism, significantly improving the information carrying capacity of a single pixel. Second, by generating multiple carrier images, the extraction of secret information and the restoration of the original image depend on the collaborative participation of all carrier images; any missing image will result in incomplete information restoration, thereby raising the system's fault tolerance threshold and resistance to scatter attacks. Third, by introducing a key-driven dynamic scrambling mechanism for the directional combination structure table, this invention deeply integrates the information hiding process with the encryption process. Even if an attacker obtains all carrier images and reverse-engineers all offset vectors, they cannot establish a mapping relationship between offset vectors and secret information indices without the key, thus elevating security to the computational security level. Finally, through a boundary pixel-free processing strategy and a reversible design based on the uniqueness of directional offset vectors, this invention ensures that the original image can be 100% losslessly restored provided the legitimate recipient possesses all carrier images and the key, meeting the requirements of applications with strict requirements for carrier integrity, such as medical imaging, legal evidence, and military reconnaissance.

[0075] Furthermore, by adjusting the number and range of carrier images, this invention can flexibly balance embedding capacity, visual fidelity, and computational complexity, adapting to the performance requirements of different application scenarios.

[0076] Example 2 like Figure 3 As shown, the second embodiment of the present invention also provides a multi-image reversible information hiding device based on asymmetric direction combination, comprising: The data acquisition unit is used to acquire the original image and the secret information to be hidden; The hidden pixel generation unit is used to generate n hidden pixels corresponding to each pixel of the original image, based on a set range of variation and the number of carrier images n, i.e., a hidden pixel combination; The orientation combination structure table construction unit is used to construct the orientation combination structure table based on the set of differences calculated by the hidden pixel combination. The information hiding unit is used to store the hidden pixel combination corresponding to each pixel into n independent images based on the direction combination structure table and the secret information, thereby obtaining n carrier images and completing the hiding of the secret information of the original image.

[0077] Example 3 The third embodiment of the present invention also provides a multi-image reversible information hiding device based on asymmetric direction combination, which includes a memory and a processor. The memory stores a computer program, which can be executed by the processor to implement the multi-image reversible information hiding method based on asymmetric direction combination as described above.

[0078] Example 4 The fourth embodiment of the present invention also provides a computer-readable storage medium storing computer-readable instructions. When the computer-readable instructions are executed by the processor of the device where the computer-readable storage medium is located, they implement the multi-image reversible information hiding method based on asymmetric direction combination as described above.

[0079] In the several embodiments provided in this invention, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus and method embodiments described above are merely illustrative. For example, the flowcharts in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of the invention. In this regard, each block in the flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and combinations of blocks in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0080] In addition, the functional modules in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0081] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, electronic device, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks. It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. In the absence of further restrictions, an element defined by the phrase "comprising a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0082] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0083] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0084] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0085] The use of "first" and "second" in the embodiments is merely to distinguish similar objects and does not represent a specific ordering of objects. It is understood that "first" and "second" can be interchanged in a specific order or sequence where permitted. It should be understood that the objects distinguished by "first" and "second" can be interchanged where appropriate so that the embodiments described herein can be implemented in an order other than those illustrated or described herein.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-image reversible information hiding method based on asymmetric direction combination, characterized in that, include: Obtain the original image and the secret information to be hidden; Based on each pixel of the original image, n hidden pixels corresponding to the pixel are generated by combining the set range of variation and the number of carrier images n, i.e., hidden pixel combination; Based on the hidden pixel combination, calculate the difference set and construct the direction combination structure table; Based on the directional combination structure table and the secret information, the hidden pixel combination corresponding to each pixel is stored in n independent images to obtain n carrier images, thus completing the hiding of the secret information of the original image.

2. The multi-image reversible information hiding method based on asymmetric direction combination according to claim 1, characterized in that... The process of generating the hidden pixel combination is as follows: Let each pixel of the original image be... The range of variation is t. , The resolution of the original image; Based on pixels , n hidden pixels are generated from the number of carrier images n. The combination of hidden pixels is represented as follows: ,and ; in, For pixels The j-th hidden pixel.

3. The multi-image reversible information hiding method based on asymmetric direction combination according to claim 2, characterized in that... The construction process of the direction combination structure table is as follows: Initialize the direction combination mechanism table , Indicates empty; Iterate through all possible combinations of hidden pixels. Calculate the corresponding set of differences: ， ， ； in, Let j be the j-th difference; then the set of differences is ; If the difference set is not in L, then the hidden pixel combination will be... With the corresponding set of differences Add to L; Otherwise, extract the existing hidden pixel combination corresponding to the difference combination in L. And calculate the distortion value corresponding to the two hidden pixel combinations respectively. , The formula for calculating the distortion value is: ； like Then replace L with the current better combination. ; The process continues until all possible combinations of hidden pixels have been traversed, resulting in the final direction combination structure table L.

4. The multi-image reversible information hiding method based on asymmetric direction combination according to claim 3, characterized in that... It also includes: setting a key to scramble the direction combination structure table to improve data security; the scrambling rules are as follows: Assumption Let L be the set of all direction combinations, that is, all entries in the direction combination structure table L, where... number of elements ,Right now The number of elements in L is the same as the number of records N in L; This yields the set of index values. ; Then, a mapping function is established from the direction combination to the original index. That is, for each combination of directions Each has a unique correspondence One of the elements, This indicates the corresponding raw index; Using keys Generate a set of index values bijective permutation function on ; based on For each direction combination Through mapping function get The original index, then used Replace with a new index, scramble the direction combination structure table, and obtain a new mapping function. The formula is: ； in, Indicates direction combination A new mapping function; It means any.

5. A multi-image reversible information hiding method based on asymmetric direction combination according to claim 4, characterized in that... Based on the direction combination structure table and the secret information, the hidden pixel combination corresponding to each pixel is stored in n independent images, specifically: Convert the secret information into a standard binary stream; Based on the aforementioned direction combination structure table, the standard binary stream is converted into an N-ary embedded number set. Where N is the number of records in L; Furthermore, each set of differences in L uniquely corresponds to an embedded number in base N. That is, each Corresponding to the row direction combination in L, ; Based on the aforementioned direction combination structure table For each pixel Hide an embedded number and generate A hidden pixel marker, generated according to the following rules: ； in, For the j-th carrier image, the corresponding original pixel Hidden pixels in the location; For the direction combination structure table Corresponding numbers The hidden pixel value in that row.

6. The multi-image reversible information hiding method based on asymmetric direction combination according to claim 4, characterized in that... It also includes receiving the key during decryption. Then, generate the bijective permutation function. inverse permutation function ; Then through the formula Restore the original correspondence and recover the complete directional combination structure table.

7. A multi-image reversible information hiding method based on asymmetric direction combination according to claim 5, characterized in that... It also includes: during decryption, by receiving n carrier images and a range of variation t, extracting the secret information and restoring the original image, specifically: Based on the variation range t and n carrier images, construct the orientation combination structure table L; Extract hidden pixel combinations from the same location in n carrier images. ; The difference combination is calculated based on the hidden pixel combination; Match the difference combinations to the direction combination structure table L; the corresponding row is the embedded secret number. ; The original pixels can be recovered using the following formula: ； in, Original pixels; For the direction combination structure in table L, the corresponding The rows record the original pixel values.

8. A multi-image reversible information hiding method based on asymmetric direction combination according to claim 7, characterized in that... It also includes: if the original pixel If the boundary pixel is not embedded with secret information, the original pixel is copied to the corresponding pixel position in the n carrier images. Similarly, during the decryption process, the boundary pixels of the n carrier images are the original pixels.

9. A multi-image reversible information hiding device based on asymmetric direction combination, characterized in that, include: The data acquisition unit is used to acquire the original image and the secret information to be hidden; The hidden pixel generation unit is used to generate n hidden pixels corresponding to each pixel of the original image, based on a set range of variation and the number of carrier images n, i.e., a hidden pixel combination; The orientation combination structure table construction unit is used to construct the orientation combination structure table based on the set of differences calculated by the hidden pixel combination. The information hiding unit is used to store the hidden pixel combination corresponding to each pixel into n independent images based on the direction combination structure table and the secret information, thereby obtaining n carrier images and completing the hiding of the secret information of the original image.

10. A multi-image reversible information hiding device based on asymmetric direction combination according to claim 9, characterized in that... It also includes: The decryption unit is used to construct a direction combination structure table by acquiring n carrier images and their variation ranges, extract secret information, and restore the original image.

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