Document steganography system and method based on confidential service

Abstract

The invention discloses a document steganography system and method based on confidential business, and relates to the technical field of document confidentiality, the document steganography system is in communication connection with a document preprocessing module, a steganography algorithm selection module, an information embedding module, an embedding strength adjustment module, a document generation verification module and an information extraction module, the modules are in electric signal connection; the document preprocessing module is used for preprocessing an original document and to-be-hidden information. By designing a steganography algorithm and setting parameters, the secret information is embedded into the document in a highly hidden mode, the risk that the information is intercepted and analyzed in the transmission process is effectively avoided, the integrity and authenticity of the information are ensured, meanwhile, the system further has high robustness, and the system is suitable for popularization and application. Various common attack means such as cutting, compression and noise addition can be resisted, and the information security is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of document confidentiality, and particularly relates to a document steganography system and method based on confidentiality services. Background Art

[0002] With the advent of the digital age, the importance of data has become increasingly prominent, and the risk of data leakage has also increased accordingly. Whether it is government agencies, large enterprises or individual users, they are all faced with the risk of illegal acquisition, tampering or abuse of data. Steganography technology hides secret information in other carriers, making the information less noticeable. Even if the carrier is intercepted, the existence of the secret information will not be immediately exposed, thus improving the confidentiality of the information. Moreover, the information embedded through steganography technology can only be read by those who master the correct extraction method, which further enhances the security of the information. With the rapid development of digital technology and artificial intelligence, steganography technology is also constantly innovating and improving.

[0003] In the prior art, when a steganography system embeds information into a document, it is necessary to ensure that the hidden information is neither easily noticeable nor can be accurately extracted when needed. However, in actual operation, due to the influence of various factors such as document format, content complexity, and image quality, the accuracy of information hiding and extraction will decrease. Therefore, how to determine and reduce the influence of external factors and improve the accuracy of information hiding and extraction is the problem we need to solve. Now, a document steganography system and method based on confidentiality services are proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a document steganography system and method based on confidentiality services to solve the problems raised in the above background art.

[0005] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0006] In the first aspect, a document steganography system based on confidentiality services, the document steganography system is communicatively connected to a document preprocessing module, a steganography algorithm selection module, an information embedding module, an embedding strength adjustment module, a document generation verification module, and an information extraction module, wherein, the modules are electrically connected to each other;

[0007] The document preprocessing module is used to preprocess the original document and the information to be hidden, including format conversion, content analysis, and quality optimization, to ensure that the document is suitable for information hiding, so as to improve the concealment and security of the information, and reduce the difficulty of information hiding caused by document format and content complexity;

[0008] The steganography algorithm selection module automatically selects a steganography algorithm according to the image characteristics, information type, and steganography requirements of the document, to ensure that the hidden information can achieve good concealment and robustness in different types of documents;

[0009] The information embedding module is used to analyze the texture and edge features of the document image, determine the optimal information embedding position, and embed the information to be hidden into the structural features of the document, so as to reduce the impact on the image quality, and while ensuring the concealment of the information, maximize the retention of the original quality of the document image;

[0010] The embedding strength adjustment module, based on the complexity of the document content and the image quality, simulates document processing operations, adjusts the embedding strength of the steganography algorithm, to ensure the accurate extraction of information, balance the concealment of information and the accuracy of extraction, and reduce the extraction error caused by external factors;

[0011] The document generation and verification module is used to convert the image after embedding information into a standard document format and perform verification, to ensure the correctness and integrity of the document, improve the usability of the document and the integrity of the information, and reduce the information loss caused by errors in the format conversion or transmission process;

[0012] The information extraction module, according to the steganography algorithm and document features used during embedding, identifies the information embedding position, locates and extracts the hidden information from the document, to ensure the complete extraction of the information, and performs post-processing operations on the document after embedding information, restores the original information, and ensures the usability and concealment of the document.

[0013] A further improvement of the technical solution of the present invention lies in: in the document preprocessing module, the process of preprocessing the original document and the information to be hidden is as follows:

[0014] The system receives the original document and the information to be hidden uploaded by the user, where the original document includes PDF, images, texts, etc., and the information to be hidden includes texts, images, binary data, etc.;

[0015] Perform preprocessing operation steps of format conversion, content analysis and quality optimization on the original document and the information to be hidden, where the format of the original document is detected, and the document is converted into a unified format suitable for steganography, and the unified format suitable for steganography is an image format;

[0016] Generate the preprocessed document, including an image file or an optimized text file, and output document feature information, and the document feature information is specifically the area mark suitable for steganography and the complexity analysis result.

[0017] A further improvement of the technical solution of the present invention lies in: in the steganography algorithm selection module, the process of automatically selecting a steganography algorithm is as follows:

[0018] Receive the document feature information output by the preprocessing module, analyze the image features, information types, and steganography requirements of the document. Among them, the image features of the document include texture, color distribution, and edge features, the information types include text, image, and binary data, and the steganography requirements include concealment, robustness, and embedding capacity;

[0019] According to the input document feature information and steganography requirements, match in the built-in steganography algorithm library of the system, and screen out the required steganography algorithm. Among them, the steganography algorithm library contains a variety of steganography algorithms, and each algorithm is optimized for different document features and information types. The steganography algorithms include LSB (Least Significant Bit), DCT domain transformation, texture synthesis, and spatial domain steganography;

[0020] Based on factors such as the concealment, robustness, embedding capacity, and computational complexity of the algorithm, evaluate the screened steganography algorithm, calculate the comprehensive score of the steganography algorithm, and analyze the overall performance of each steganography algorithm on the given document;

[0021] According to the evaluation results, select the steganography algorithm with the best performance as the final choice, and then output the selected steganography algorithm to the information embedding module for subsequent information hiding operations.

[0022] A further improvement of the technical solution of the present invention is that the expression of the comprehensive score of the steganography algorithm is:

[0023]

[0024] In the formula, S is the comprehensive score of the steganography algorithm, i is the number of steganography algorithms considered, i is the index of the steganography algorithm, representing the i-th steganography algorithm, ω i is the weight of the i-th steganography algorithm, H i is the concealment score of the i-th steganography algorithm, with a value range between 0 and 1. The larger the value, the better the concealment. R i is the robustness score of the i-th steganography algorithm, with a value range between 0 and 1. The larger the value, the better the robustness. C i is the embedding capacity score of the i-th steganography algorithm, with a value range between 0 and 1. The larger the value, the more information that can be embedded. E i is the computational complexity score of the i-th steganography algorithm, with a value range between 0 and 1. The smaller the value, the lower the computational complexity. α is an adjustment parameter used to balance the relationship between the embedding capacity and the computational complexity, and its value is a positive number. The value range of S is between 0 and 1. The larger the value, the better the comprehensive performance of the algorithm.

[0025] A further improvement of the technical solution of the present invention is that in the information embedding module, the process of determining the best information embedding position is:

[0026] Receive the selected steganography algorithm, the information to be hidden, and the preprocessed document image from the steganography algorithm selection module, and use image processing techniques to perform texture analysis on the document image, identify the smooth areas, texture complex areas, and existing redundant areas in the image, apply edge detection algorithms to detect the edge features in the image, identify the edge positions and distributions in the image, including the positions, directions, and intensities of the edges, mark the edge-dense areas, and exclude them from the potential information embedding areas;

[0027] According to the analysis results of the texture and edge features, select smooth and texture-redundant areas and determine them as the most suitable areas for embedding information to reduce the visual impact on the image quality and avoid embedding information near the edge areas or important structural information in the image;

[0028] According to the selected steganography algorithm and the type of information to be hidden, formulate a specific embedding strategy, determine the density and distribution of the embedded information to ensure the concealment and robustness of the information;

[0029] According to the formulated embedding strategy, embed the information to be hidden into the structural features of the document image, and after completing the information embedding, generate the embedded document image, and then recombine the document image embedded with the hidden information into a complete document format.

[0030] A further improvement of the technical solution of the present invention is that in the embedding strength adjustment module, the process of adjusting the embedding strength of the steganography algorithm is as follows:

[0031] Receive the embedded document image, steganography algorithm parameters, document content complexity evaluation index, and image quality evaluation index from the information embedding module, and perform simulated document processing operations on the embedded document image, including compression, scaling, rotation, and print-scanning, etc., record the image quality changes and the integrity of the embedded information after each simulated processing, where the document content complexity evaluation index includes text density and image details, and the image quality evaluation index includes peak signal-to-noise ratio and structural similarity index;

[0032] Set the initial embedding strength, and evaluate whether the current embedding strength is appropriate according to the image quality and information integrity after the simulated processing. If the information can still be accurately extracted after multiple processes and the image quality remains good, the current embedding strength is appropriate. If there are errors in information extraction or the image quality drops significantly, the embedding strength needs to be adjusted;

[0033] According to the document content complexity evaluation index and the image quality evaluation index, start from the initial embedding strength, gradually increase or decrease the embedding strength, dynamically adjust the embedding strength, and re-evaluate the image quality and simulate the processing operations after each adjustment;

[0034] For the document image after adjusting the embedding strength, record the image quality and information extraction accuracy at each embedding strength, generate an embedding adaptation score for each embedding strength value, and select the optimal embedding strength value according to the embedding adaptation score. Among them, the optimal embedding strength value should maximize the information extraction accuracy and minimize the image quality loss on the premise of ensuring sufficient concealment;

[0035] Transfer the determined optimal embedding strength value and its related parameters to the information embedding module for use in the actual embedding process, and record the process and final results of the embedding strength adjustment for subsequent analysis and optimization.

[0036] A further improvement of the technical solution of the present invention lies in that the expression of the embedding adaptation score is:

[0037]

[0038] In the formula, QS is the embedding adaptation score, m is the number of simulation processing operations, j is the index of the simulation processing operation, indicating the jth simulation processing operation, ω Y 、ω Z 、ω Q are the weight coefficients of concealment, extraction accuracy, and image quality loss respectively, and ω Y +ω Z +ω Q =1, Y j is the concealment score after the jth simulation processing, and its value is usually between 0 and 1. The larger the value, the better the concealment. Z j is the information extraction accuracy score after the jth simulation processing, and its value is usually between 0 and 1. The larger the value, the higher the extraction accuracy. Q j is the image quality loss score after the jth simulation processing, and its value range is between 0 and 1. The smaller the value, the smaller the image quality loss. The value range of QS is between 0 and 1. The larger the value, the better the comprehensive performance.

[0039] A further improvement of the technical solution of the present invention lies in that the document generation and verification module specifically includes:

[0040] Receive the image file with embedded information from the information embedding module, and preliminarily check whether the integrity and format of the image file meet the requirements;

[0041] Select the corresponding standard document format according to the requirements, embed the image with embedded information as the content or background of the document, and adjust the position, size, and rotation angle of the image in the document to meet the document design requirements;

[0042] Extract the embedded information from the converted document, verify its integrity and accuracy, check the display effect of the embedded images in the document to ensure there is no distortion or blurring, verify whether the document meets the requirements of the selected standard format, and then open the document in different versions of office software or readers for compatibility testing to ensure compatibility, and check whether the page order of the document is correct;

[0043] Record any errors or non - compliant situations detected during the conversion and verification processes, and generate a detailed error report, including the error type, location, reason, and recommended repair measures. Then, after confirming the correctness and integrity of the document, output the finally generated document in the standard format, save the generated document to the specified location, and distribute or further process it according to user requirements.

[0044] A further improvement of the technical solution of the present invention lies in that: in the information extraction module, the process of extracting hidden information is as follows:

[0045] Receive the document with hidden information already embedded from the document generation verification module, and receive the steganography algorithm parameters, including the steganography algorithm used during embedding and its specific parameter settings, clarify the working principle of the steganography algorithm and the characteristics of the embedded information, and then read and load the target document from which the hidden information is to be extracted;

[0046] According to the characteristics of the steganography algorithm and the analysis of the document content, identify the specific location where the information is embedded, and according to the identified embedding location, use the corresponding decoding technology to decode and restore, and extract the hidden information from the identified embedding location;

[0047] Compare the extracted information with the original information to be hidden, and verify by calculating the hash value to ensure the integrity and accuracy of the information, ensure that the extracted information is consistent with the original embedded information, without loss or tampering;

[0048] If any modifications (such as resizing the image, rotating the angle, etc.) are made to the document during the embedding process, corresponding post - processing operations need to be performed. Use image processing tools to restore the image to its original size and orientation to restore the original state of the document, and check the overall structure and content of the document to ensure that it remains complete and usable after extracting the hidden information, confirm that all texts, images, and other elements are correct, and ensure that the page order and directory structure have not changed;

[0049] Output the extracted hidden information in the format specified by the user, and generate an extraction report, recording the key steps and results during the extraction process, including the content of the extracted hidden information, the verification result, and the document post - processing situation.

[0050] Second aspect, a document steganography method based on confidentiality services, which is implemented based on the above-mentioned document steganography system based on confidentiality services, includes the following steps:

[0051] S1. Define the purpose of steganography and the type of document to be steganographed, and select a steganography algorithm according to the document type and steganography requirements;

[0052] S2. Preprocess the information to be hidden, and determine the embedding position and embedding strength of the information according to the steganography algorithm and document characteristics;

[0053] S3. According to the selected steganography algorithm and embedding strength, embed the information to be hidden into the structural features of the document, and convert the document after embedding the information into a standard document format;

[0054] S4. Save the document in the standard document format to generate a final document, and perform document integrity verification synchronously;

[0055] S5. According to the steganography algorithm and its parameter settings used during embedding, identify the specific position where the information is embedded, and use the corresponding decoding technology to decode and restore, and extract the hidden information from the embedding position.

[0056] Due to the adoption of the above technical solution, the technical progress achieved by the present invention compared with the prior art is:

[0057] 1. The present invention provides a document steganography system and method based on confidentiality services. By designing a steganography algorithm and setting parameters, the secret information is embedded into the document in a highly concealed manner, which not only effectively avoids the risk of the information being intercepted and analyzed during transmission, but also ensures the integrity and authenticity of the information. At the same time, the system also has strong robustness and can resist various common attack means such as cropping, compression, and noise addition, further enhancing the security of the information.

[0058] 2. The present invention provides a document steganography system and method based on confidentiality services, which can flexibly adjust the steganography algorithm and parameters according to actual needs to adapt to different application scenarios, greatly improving the flexibility and efficiency of information transmission, and enabling the secret information to be transmitted safely and quickly in various complex network environments. Description of the Drawings

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0060] Figure 1 It is a block diagram of the system composition of the present invention;

[0061] Figure 2 This is the working flowchart of the steganography algorithm selection module of the present invention;

[0062] Figure 3 This is the working flowchart of the embedding strength adjustment module of the present invention;

[0063] Figure 4 This is the method flowchart of the present invention. Specific implementation manners

[0064] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0065] Embodiment 1, as Figure 1 、 Figure 2 shown, the present invention provides a document steganography system based on confidential services. The document steganography system is communicatively connected to a document preprocessing module, a steganography algorithm selection module, an information embedding module, an embedding strength adjustment module, a document generation and verification module, and an information extraction module. Among them, the modules are electrically connected to each other;

[0066] Document preprocessing module, which is used to preprocess the original document and the information to be hidden, including format conversion, content analysis, and quality optimization, to ensure that the document is suitable for information hiding, so as to improve the concealment and security of information, and reduce the difficulty of information hiding caused by the document format and content complexity. The system receives the original document and the information to be hidden uploaded by the user. Among them, the original document includes PDF, images, texts, etc., and the information to be hidden includes texts, images, binary data, etc. The preprocessing operation steps of format conversion, content analysis, and quality optimization are performed on the original document and the information to be hidden. Among them, the format of the original document is detected, and the document is converted into a unified format suitable for steganography. The unified format suitable for steganography is the image format. If the document is a PDF, it is split into single pages and converted into the image format. If the document is a text, it is converted into an image or the information is directly embedded in the text; the content complexity of the document is analyzed to determine the area suitable for steganography. For image documents: analyze the texture, edges, color distribution and other characteristics of the image, and find redundant areas including smooth areas or low-complexity areas. For text documents: analyze the blank characters, line spacing, fonts and other characteristics of the text, find the positions suitable for embedding information, and mark the areas suitable for steganography in the document, avoiding embedding information in high-contrast areas or important text areas; perform noise reduction processing on the image document to remove the noise in the image, enhance the resolution or adjust the size of the image to ensure that the image quality is suitable for information embedding, and perform format optimization on the text document to ensure the clarity and consistency of the text, generate the preprocessed document, including the image file or the optimized text file, and output the document feature information. The document feature information is specifically the area mark suitable for steganography and the complexity analysis result;

[0067] The steganography algorithm selection module automatically selects a steganography algorithm based on the image features, information type, and steganography requirements of the document to ensure that the hidden information can achieve good concealment and robustness in different types of documents. It receives the document feature information output by the preprocessing module, analyzes the image features, information type, and steganography requirements of the document. Among them, the image features of the document include texture, color distribution, and edge features; the information type includes text, image, and binary data; the steganography requirements include concealment, robustness, and embedding capacity. According to the input document feature information and steganography requirements, it matches in the built-in steganography algorithm library of the system, filters out the required steganography algorithm. Among them, the steganography algorithm library contains a variety of steganography algorithms, and each algorithm is optimized for different document features and information types. The steganography algorithms include LSB (Least Significant Bit), DCT domain transformation, texture synthesis, and spatial domain steganography. LSB (Least Significant Bit) is applicable to most types of documents, but has low concealment. DCT domain transformation is applicable to JPEG format images and has high concealment and robustness. Texture synthesis is applicable to images with complex textures, and embeds information by synthesizing similar texture regions. Spatial domain steganography is applicable to grayscale images or images with simple backgrounds, and embeds information by using the change of pixel values. Based on factors such as the concealment, robustness, embedding capacity, and computational complexity of the algorithm, it evaluates the selected steganography algorithms, calculates the comprehensive score of the steganography algorithm, analyzes the overall performance of each steganography algorithm on the given document. According to the evaluation results, it selects the steganography algorithm with the optimal performance as the final choice, and then outputs the selected steganography algorithm to the information embedding module for subsequent information hiding operations;

[0068] Among them, the expression of the comprehensive score of the steganography algorithm is:

[0069]

[0070] In the formula, S is the comprehensive score of the steganography algorithm, indicating the overall performance of a certain steganography algorithm on the given document. i is the number of steganography algorithms considered. i is the index of the steganography algorithm, indicating the i-th steganography algorithm. ω i is the weight of the i-th steganography algorithm. H i is the concealment score of the i-th steganography algorithm, and the value range is between 0 and 1. The larger the value, the better the concealment. R i is the robustness score of the i-th steganography algorithm, and the value range is between 0 and 1. The larger the value, the better the robustness. C i is the embedding capacity score of the i-th steganography algorithm, and the value range is between 0 and 1. The larger the value, the more information that can be embedded. E i$C_i$ is the computational complexity score of the $i$-th steganography algorithm, with a value range between 0 and 1. The smaller the value, the lower the computational complexity. $\alpha$ is an adjustment parameter used to balance the relationship between the embedding capacity and the computational complexity, and it takes a positive value. The value range of $S$ is between 0 and 1. The larger the value, the better the comprehensive performance of the algorithm;

[0071] An information embedding module, which is used to analyze the texture and edge features of the document image, determine the best information embedding position, and embed the information to be hidden into the structural features of the document, so as to reduce the impact on the image quality, and while ensuring the concealment of the information, maximize the retention of the original quality of the document image;

[0072] An embedding strength adjustment module, based on the complexity of the document content and the image quality, simulates document processing operations, adjusts the embedding strength of the steganography algorithm, to ensure the accurate extraction of information, balance the concealment of information and the accuracy of extraction, and reduce the extraction error caused by external factors;

[0073] A document generation and verification module, which is used to convert the image after embedding information into a standard document format and perform verification, to ensure the correctness and integrity of the document, improve the usability of the document and the integrity of the information, and reduce the information loss caused by errors in the format conversion or transmission process;

[0074] An information extraction module, according to the steganography algorithm and document features used during embedding, identifies the information embedding position, locates and extracts the hidden information from the document, to ensure the complete extraction of the information, and performs post-processing operations on the document after embedding the information, restores the original information, and ensures the usability and concealment of the document.

[0075] Embodiment 2, as Figure 3 shown, based on Embodiment 1, the present invention provides a technical solution: Preferably, in the information embedding module, the process of determining the best information embedding position is:

[0076] Receive the selected steganographic algorithm, the information to be hidden, and the preprocessed document image from the steganographic algorithm selection module. Using image processing techniques, perform texture analysis on the document image to identify smooth regions, regions with complex textures, and redundant regions in the image. Apply an edge detection algorithm to detect edge features in the image, identify the positions and distributions of the edges in the image, including the positions, directions, and intensities of the edges, mark the edge-dense regions, and exclude them from potential information embedding regions. According to the analysis results of the texture and edge features, select smooth and texture-redundant regions and determine them as the most suitable regions for embedding information to reduce the visual impact on the image quality and avoid embedding information near the edge regions or important structural information in the image. According to the selected steganographic algorithm and the type of information to be hidden, formulate a specific embedding strategy to determine the density and distribution of the embedded information to ensure the concealment and robustness of the information. According to the formulated embedding strategy, embed the information to be hidden into the structural features of the document image. Among them, for the LSB algorithm, directly modify the least significant bit of the image to embed information. For the DCT domain transformation algorithm, modify the DCT coefficients of the image. For the texture synthesis algorithm, synthesize regions similar to the image texture to embed information. For the spatial domain steganographic algorithm, adjust the pixel values of the image to embed information. After completing the information embedding, generate the embedded document image, and then recombine the document image embedded with the hidden information into a complete document format;

[0077] In the embedding intensity adjustment module, the process of adjusting the embedding intensity of the steganographic algorithm is as follows:

[0078] Receive the embedded document image, steganography algorithm parameters, document content complexity evaluation metrics, and image quality evaluation metrics from the information embedding module, and perform simulated document processing operations on the embedded document image, including compression, scaling, rotation, and print-scan, etc. Record the image quality changes and the integrity of the embedded information after each simulated processing. Among them, the document content complexity evaluation metrics include text density and image details, and the image quality evaluation metrics include peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM). Text density measures the quantity and distribution of text in the document, and image details evaluate the degree of details in the image. Peak signal-to-noise ratio (PSNR) is a standard for measuring the quality of image reconstruction, and a higher value indicates better image quality. Structural similarity index (SSIM) evaluates the similarity between images, especially the structural similarity. Set the initial embedding strength. According to the image quality and information integrity after simulated processing, evaluate whether the current embedding strength is appropriate. If the information can still be accurately extracted after multiple processes and the image quality remains good, then the current embedding strength is appropriate. If there are errors in information extraction or the image quality significantly deteriorates, then the embedding strength needs to be adjusted. Starting from the initial embedding strength, gradually increase or decrease the embedding strength according to the document content complexity evaluation metrics and image quality evaluation metrics, dynamically adjust the embedding strength, and re-perform image quality evaluation and processing operation simulation after each adjustment. For the document image after adjusting the embedding strength, record the image quality and information extraction accuracy under each embedding strength, and generate an embedding adaptation score for each embedding strength value. Select the optimal embedding strength value according to the embedding adaptation score. Among them, the optimal embedding strength value should maximize the accuracy of information extraction and minimize the image quality loss on the premise of ensuring sufficient concealment. Transmit the determined optimal embedding strength value and its related parameters to the information embedding module for use in the actual embedding process, and record the process and final result of the embedding strength adjustment for subsequent analysis and optimization;

[0079] Among them, the expression of the embedding adaptation score is:

[0080]

[0081] In the formula, QS is the embedding adaptation score, representing the overall performance under a certain embedding strength. m is the number of simulated processing operations, j is the index of the simulated processing operation, indicating the jth simulated processing operation, ω Y 、ω Z 、ω Q are the weight coefficients of concealment, extraction accuracy, and image quality loss respectively, and ω Y +ω Z +ω Q =1, Y j is the concealment score after the jth simulated processing, and its value usually ranges from 0 to 1. The larger the value, the better the concealment. Z jis the information extraction accuracy score after the j-th simulation process, usually taking values between 0 and 1. The larger the value, the higher the extraction accuracy, Q j is the image quality loss score after the j-th simulation process, with a value range between 0 and 1. The smaller the value, the smaller the image quality loss. The value range of QS is between 0 and 1. The larger the value, the better the comprehensive performance;

[0082] The document generation and verification module specifically includes:

[0083] Receive the image file with embedded information from the information embedding module, and initially check whether the integrity and format of the image file meet the requirements. Select the corresponding standard document format according to the needs, embed the image with embedded information as the content or background of the document, adjust the position, size, and rotation angle of the image in the document to meet the document design requirements, extract the embedded information from the converted document, verify whether it is complete and accurate, check the display effect of the embedded image in the document to ensure there is no distortion or blur, verify whether the document meets the requirements of the selected standard format, and then open the document in different versions of office software or readers for compatibility testing to ensure compatibility, and check whether the page order of the document is correct. Record any errors or non-compliant situations detected during the conversion and verification process, and generate a detailed error report, including the error type, location, cause, and recommended repair measures. Then, after confirming the correctness and integrity of the document, output the finally generated document in the standard format, save the generated document to the specified location, and distribute or further process it according to the user's needs;

[0084] In the information extraction module, the process of extracting hidden information is as follows:

[0085] The document generation verification module receives the document with the hidden information already embedded, and receives the steganography algorithm parameters, including the steganography algorithm used during embedding and its specific parameter settings, clarifies the working principle of the steganography algorithm and the characteristics of the embedded information, and then reads and loads the target document from which the hidden information is to be extracted. According to the characteristics of the steganography algorithm and the analysis of the document content, the specific position of information embedding is identified, and according to the identified embedding position, the corresponding decoding technology is used for decoding and restoration. The hidden information is extracted from the identified embedding position. Among them, for the LSB algorithm, the least significant bit is read pixel by pixel and combined into the complete hidden information. For the DCT domain transformation algorithm, the corresponding coefficient is found in the frequency domain and inverse transformed to restore the hidden information. For the texture synthesis algorithm, the synthesis area is identified and the hidden information in it is extracted. For the spatial domain steganography algorithm, the pixel values are adjusted to extract the hidden information. The extracted information is compared with the original information to be hidden, and verified by calculating the hash value to ensure the integrity and accuracy of the information, ensuring that the extracted information is consistent with the original embedded information without loss or tampering. If any modifications (such as resizing the image, rotating the angle, etc.) are made to the document during the embedding process, corresponding post-processing operations need to be performed. Use image processing tools to restore the image to its original size and orientation to restore the original state of the document, and check the overall structure and content of the document to ensure that it remains complete and usable after extracting the hidden information. Confirm that all texts, images, and other elements are correct, and ensure that the page order and directory structure have not changed. The extracted hidden information is output in the format specified by the user, and an extraction report is generated, recording the key steps and results during the extraction process, including the content of the extracted hidden information, the verification result, and the document post-processing situation.

[0086] Example 3, as Figure 4 shown, on the basis of Examples 1-2, the present invention also provides a document steganography method based on a confidentiality service, which is implemented based on a document steganography system for confidentiality services, and includes the following steps:

[0087] S1. Clarify the purpose of steganography and the type of document to be steganographed, and select a steganography algorithm according to the document type and steganography requirements;

[0088] S2. Preprocess the information to be hidden, and determine the embedding position and embedding strength of the information according to the steganography algorithm and document characteristics;

[0089] S3. According to the selected steganography algorithm and embedding strength, embed the information to be hidden into the structural features of the document, and convert the document after embedding the information into a standard document format;

[0090] S4. Save the document in the standard document format, generate the final document, and synchronously perform document integrity verification;

[0091] S5. Identify the specific location of information embedding according to the steganography algorithm and its parameter settings used during embedding, and use the corresponding decoding technology for decoding and restoration to extract the hidden information from the embedding location.

[0092] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A document steganography system based on confidential services, characterized in that: The described document steganography system is communicatively connected to a document preprocessing module, a steganography algorithm selection module, an information embedding module, an embedding strength adjustment module, a document generation and verification module, and an information extraction module. Among them, the modules are electrically connected to each other; The described document preprocessing module is used to preprocess the original document and the information to be hidden; The described steganography algorithm selection module automatically selects a steganography algorithm according to the image features, information type, and steganography requirements of the document; The described information embedding module is used to analyze the texture and edge features of the document image, determine the best information embedding position, and embed the information to be hidden into the structural features of the document; The described embedding strength adjustment module simulates document processing operations based on the complexity of the document content and the image quality, and adjusts the embedding strength of the steganography algorithm; The described document generation and verification module is used to convert the image after embedding information into a standard document format and perform verification; The described information extraction module identifies the position where the information is embedded according to the steganography algorithm and document features used during embedding, and locates and extracts the hidden information from the document.

2. The document steganography system based on a confidentiality service according to claim 1, wherein: In the described document preprocessing module, the process of preprocessing the original document and the information to be hidden is as follows: The system receives the original document and the information to be hidden uploaded by the user. Among them, the original document includes PDF, images, and text, and the information to be hidden includes text, images, and binary data; Perform preprocessing operation steps of format conversion, content analysis, and quality optimization on the original document and the information to be hidden. Among them, detect the format of the original document, and convert the document into a unified format suitable for steganography. The unified format suitable for steganography is the image format; Generate the preprocessed document, including an image file or an optimized text file, and output document feature information. The document feature information is specifically the area marker suitable for steganography and the complexity analysis result.

3. The document steganography system based on a confidentiality service according to claim 2, wherein: In the described steganography algorithm selection module, the process of automatically selecting a steganography algorithm is as follows: Receive the document feature information output by the preprocessing module, and analyze the image features, information type, and steganography requirements of the document. Among them, the image features of the document include texture, color distribution, and edge features, the information type includes text, images, and binary data, and the steganography requirements include concealment, robustness, and embedding capacity; Match according to the input document feature information and steganography requirements in the built-in steganography algorithm library of the system, and screen out the required steganography algorithm. Among them, the steganography algorithms include LSB, DCT domain transformation, texture synthesis, and spatial domain steganography; Based on factors such as the concealment, robustness, embedding capacity, and computational complexity of the algorithm, evaluate the screened steganography algorithms, calculate the comprehensive score of the steganography algorithms, and analyze the overall performance of each steganography algorithm on the given document; According to the evaluation results, select the steganography algorithm with the optimal performance as the final choice, and then output the selected steganography algorithm to the information embedding module for subsequent information hiding operations.

4. The document steganography system based on a confidentiality service according to claim 3, characterized in that: The expression of the comprehensive score of the steganography algorithm is: Where S is the comprehensive score of the steganography algorithm, i is the number of steganography algorithms considered, i is the index of the steganography algorithm, representing the i-th steganography algorithm, ω i is the weight of the i-th steganography algorithm, H i is the concealment score of the i-th steganography algorithm, R i is the robustness score of the i-th steganography algorithm, C i is the embedding capacity score of the i-th steganography algorithm, E i is the computational complexity score of the i-th steganography algorithm, α is an adjustment parameter used to balance the relationship between the embedding capacity and the computational complexity, taking positive values, the value range of S is between 0 and 1, and the larger the value, the better the comprehensive performance of the algorithm.

5. The document steganography system based on a confidentiality service according to claim 4, characterized in that: In the described information embedding module, the process of determining the best information embedding position is: Receive the selected steganographic algorithm, the information to be hidden, and the preprocessed document image from the steganographic algorithm selection module, and use image processing techniques to perform texture analysis on the document image, identify the smooth areas, texture complex areas, and existing redundant areas in the image, apply an edge detection algorithm to detect the edge features in the image, identify the edge positions and distributions in the image, including the positions, directions, and intensities of the edges, mark the edge-dense areas, and exclude them from the potential information embedding areas; According to the analysis results of the texture and edge features, select the smooth and texture-redundant areas and determine them as the areas most suitable for embedding information; According to the selected steganographic algorithm and the type of information to be hidden, formulate a specific embedding strategy to determine the density and distribution of the embedded information; According to the formulated embedding strategy, embed the information to be hidden into the structural features of the document image, and after completing the information embedding, generate the embedded document image, and then recombine the document image embedded with the hidden information into a complete document format.

6. The document steganography system based on a confidentiality service according to claim 5, characterized in that: In the embedding intensity adjustment module, the process of adjusting the embedding intensity of the steganographic algorithm is as follows: Receive the embedded document image, steganographic algorithm parameters, document content complexity evaluation index, and image quality evaluation index from the information embedding module, and perform simulated document processing operations on the embedded document image, including compression, scaling, rotation, and print-scanning, and record the image quality changes and the integrity of the embedded information after each simulated processing; Set the initial embedding intensity, and evaluate whether the current embedding intensity is appropriate according to the image quality and information integrity after the simulated processing. If the information can still be accurately extracted after multiple processes and the image quality remains good, the current embedding intensity is appropriate. If there is an error in information extraction or the image quality drops significantly, the embedding intensity needs to be adjusted; According to the document content complexity evaluation index and the image quality evaluation index, start from the initial embedding intensity, gradually increase or decrease the embedding intensity, dynamically adjust the embedding intensity, and re-perform the image quality evaluation and processing operation simulation after each adjustment; For the document image after adjusting the embedding intensity, record the image quality and information extraction accuracy at each embedding intensity, generate an embedding adaptation score for each embedding intensity value, and select the best embedding intensity value according to the embedding adaptation score; Transfer the determined best embedding intensity value and its related parameters to the information embedding module, and record the process and final result of the embedding intensity adjustment.

7. A document steganography system based on a confidentiality service according to claim 6, characterized in that: The expression of the embedding adaptation score is: Wherein, QS is the embedding adaptation score, m is the number of simulation processing operations, j is the index of the simulation processing operation, representing the j-th simulation processing operation, ω Y , ω Z , ω Q are the weight coefficients of concealment, extraction accuracy, and image quality loss respectively, and ω Y + ω Z + ω Q = 1, Y j is the concealment score after the j-th simulation processing, Z j is the information extraction accuracy score after the j-th simulation processing, Q j is the image quality loss score after the j-th simulation processing. The value range of QS is between 0 and 1, and the larger the value, the better the comprehensive performance.

8. A document steganography system based on a confidentiality service according to claim 7, characterized in that: The document generation verification module specifically includes: Receive the image file that has embedded information from the information embedding module, and preliminarily check the integrity of the image file and whether the format meets the requirements; Select the corresponding standard document format according to the requirements, embed the image with the embedded information as the content or background of the document, and adjust the position, size, and rotation angle of the image in the document to make it meet the document design requirements; Extract the embedded information from the converted document, verify its integrity and accuracy, check the display effect of the embedded images in the document to ensure there is no distortion or blur, verify whether the document meets the requirements of the selected standard format, and then open the document in different versions of office software or readers for compatibility testing to ensure compatibility, and check whether the page order of the document is correct; Record any errors or non - compliant situations detected during the conversion and verification process, and generate a detailed error report, including error type, location, reason, and recommended repair measures. Then, after confirming the correctness and integrity of the document, output the finally generated document in the standard format, save the generated document to the specified location, and distribute or further process it according to user requirements.

9. The document steganography system based on a confidentiality service according to claim 8, wherein: In the information extraction module, the process of extracting hidden information is as follows: Receive the document with hidden information already embedded from the document generation and verification module, and receive the steganography algorithm parameters, including the steganography algorithm used during embedding and its specific parameter settings, clarify the working principle of the steganography algorithm and the characteristics of the embedded information, and then read and load the target document from which the hidden information is to be extracted; Based on the characteristics of the steganography algorithm and the analysis of the document content, identify the specific location where the information is embedded, and according to the identified embedding location, use the corresponding decoding technology to decode and restore, and extract the hidden information from the identified embedding location; Compare the extracted information with the original information to be hidden, and verify the integrity and accuracy of the information by calculating the hash value; If any modifications are made to the document during the embedding process, corresponding post - processing operations are required. Use image processing tools to restore the image to its original size and orientation to restore the original state of the document, and check the overall structure and content of the document; Output the extracted hidden information in the format specified by the user, and generate an extraction report, recording the key steps and results during the extraction process, including the content of the extracted hidden information, verification results, and document post - processing situation.

10. A document steganography method based on a confidential service, implemented based on the document steganography system for confidential services according to any one of the above claims 1-9, characterized in that, It includes the following steps: S1. Clarify the purpose of steganography and the type of document to be steganographed, and select a steganography algorithm according to the document type and steganography requirements; S2. Pre - process the information to be hidden, and determine the embedding location and embedding strength of the information according to the steganography algorithm and document characteristics; S3. According to the selected steganography algorithm and embedding strength, embed the information to be hidden into the structural features of the document, and convert the document after embedding the information into the standard document format; S4. Save the document in the standard document format to generate the final document, and simultaneously perform document integrity verification; S5. According to the steganography algorithm used during embedding and its parameter settings, identify the specific location where the information is embedded, and use the corresponding decoding technology to decode and restore, and extract the hidden information from the embedding location.

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