A method and system for steganography of encrypted domain images based on Huffman coding

Abstract

The present invention relates to a method and system for encrypted domain image steganography based on Huffman coding. The method comprises: obtaining the pixel value of each pixel block in the original image and encoding it based on Huffman coding to obtain an initial code table; encrypting the secret information based on an encryption algorithm to obtain encrypted data; embedding the encrypted data based on a least significant bit algorithm to obtain an embedded pixel value for each pixel block; and updating the initial code table based on the embedded pixel value to obtain an embedded code table. The present invention reduces the total number of bits of transmitted data and increases capacity, thereby increasing the amount of information embedded without affecting image distortion and providing high security.

Description

Technical Field

[0001] The present invention relates to the technical field of image steganography, and in particular to an encrypted domain image steganography method and system based on Huffman coding. Background Art

[0002] With the development of the internet and mobile applications, digital image media has become the mainstream medium for information communication. Images are not only a crucial carrier of information in personal communications and business, but also in military, political, and medical fields, where privacy and integrity are paramount. Existing image steganography technologies cannot effectively balance information embedding efficiency with image distortion, and they also have certain security limitations. Summary of the Invention

[0003] In view of this, the present invention provides an encrypted domain image steganography method and system based on Huffman coding to reduce the total number of data bits and increase capacity, thereby increasing the amount of information embedded without affecting the distortion of the image and having high security.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A Huffman coding-based encrypted domain image steganography method, comprising:

[0006] Obtain the pixel value of each pixel block in the original image and encode it based on Huffman coding to obtain an initial code table;

[0007] Encrypting the secret information based on the encryption algorithm to obtain encrypted data;

[0008] Embedding the encrypted data based on a least significant bit algorithm to obtain an embedded pixel value for each pixel block;

[0009] The initial code table is updated based on the embedded pixel value to obtain an embedded code table.

[0010] Preferably, the step of obtaining the pixel value of each pixel block in the original image and encoding it based on Huffman coding to obtain an initial code table includes:

[0011] Get the true pixel value of each pixel block in the original image;

[0012] Perform pixel prediction on the true pixel value of each pixel block based on the median predictor to obtain the predicted pixel value of each pixel block;

[0013] Convert the actual pixel value and predicted pixel value of each pixel block into 8-bit binary form;

[0014] Compare the (i, j)th pixel block bit by bit starting from the most significant bit. The number of consecutive identical bits is the label value of the (i, j)th pixel block; i∈I, j∈J, I×J are the pixels of the original image; let i and / or j take different values ​​and repeat this process to obtain the label values ​​of all pixel blocks;

[0015] Huffman coding is performed according to the distribution probability of the label value of each pixel block to obtain an initial code table; the initial code table includes the correspondence between code words and real pixel values ​​and the code word sequence; the pixel value of each pixel block in the original image is replaced by the corresponding code word.

[0016] Preferably, the method further comprises:

[0017] The embedded code table is decrypted based on an encryption algorithm to obtain the secret information.

[0018] Preferably, embedding the encrypted data based on a least significant bit algorithm to obtain an embedded pixel value of each pixel block includes:

[0019] For the (i, j)th pixel block, the 8-bit binary form of its true pixel value is defined as S8, S7, S6, S5, S4, S3, S2 and S1; any two of the lower four bits are combined to obtain the initial test table, and the 8-bit binary form of the encrypted data is defined as X8, X7, X6, X5, X4, X3, X2 and X1. Based on X8X7, the initial test table is traversed. If there is a SmSn match X8X7, then m, n and the corresponding test value in the initial test table are added to the embedded test table. If there is no SmSn match X8X7, then m=2, n=1, and the test value is 0 and added to the embedded test table;

[0020] Convert the test value into a 2-bit binary sequence and perform XOR encryption with S4S3 to obtain L1 and L2. Replace and update S1 based on L1, and replace and update S2 based on L2 to obtain the embedded pixel value of the (i, j)th pixel block;

[0021] Starting from the (i, j)th pixel block, the 8-bit binary form of the encrypted data is repeated in order from high bit to low bit from left to right and from top to bottom until all the encrypted data are embedded to obtain the embedded pixel value of each pixel block.

[0022] Preferably, decrypting the embedded code table based on an encryption algorithm to obtain the secret information includes:

[0023] For the embedded pixel value of the (i, j)th pixel block, perform an XOR operation on S2 and S4 to obtain F1, and perform an XOR operation on S1 and S3 to obtain F2;

[0024] Get the test value based on F2F1, and traverse the embedded test table to get the corresponding m and n, and then get Sm and Sn of the (i, j)th pixel block, and further get X8 and X7 of the encrypted data;

[0025] Starting from the (i, j)th pixel block, the above process is performed in order from left to right and from top to bottom until the 8-bit binary form of the encrypted data is obtained;

[0026] The 8-bit binary form of the encrypted data is decrypted based on the encryption algorithm to obtain the secret information.

[0027] The present invention also provides an encrypted domain image steganography system based on Huffman coding, comprising:

[0028] Huffman coding module, used to obtain the pixel value of each pixel block in the original image and encode it based on Huffman coding to obtain an initial code table;

[0029] An encryption module, used to encrypt secret information based on an encryption algorithm to obtain encrypted data;

[0030] an embedding module, configured to embed the encrypted data based on a least significant bit algorithm to obtain an embedded pixel value of each pixel block;

[0031] A data updating module is configured to update the initial code table based on the embedded pixel value to obtain an embedded code table.

[0032] Preferably, the Huffman encoding module includes:

[0033] A data acquisition unit, used to obtain the real pixel value of each pixel block in the original image;

[0034] A pixel prediction unit, configured to perform pixel prediction on the true pixel value of each pixel block based on a median predictor to obtain a predicted pixel value of each pixel block;

[0035] A data conversion unit, configured to convert both the actual pixel value and the predicted pixel value of each pixel block into 8-bit binary form;

[0036] The tag value unit is used to compare the (i, j)th pixel block bit by bit starting from the most significant bit. The number of consecutive identical bits is the tag value of the (i, j)th pixel block; i∈I, j∈J, I×J are the pixels of the original image; let i and / or j take different values ​​and repeat this process to obtain the tag values ​​of all pixel blocks;

[0037] The Huffman coding unit is used to perform Huffman coding according to the distribution probability of the label value of each pixel block to obtain an initial code table; the initial code table includes the correspondence between code words and real pixel values ​​and the code word sequence; the pixel value of each pixel block in the original image is replaced by the corresponding code word.

[0038] Preferably, the system further comprises:

[0039] The decryption module is used to decrypt the embedded code table based on an encryption algorithm to obtain the secret information.

[0040] Preferably, the embedded module includes:

[0041] In the test table unit, for the (i, j)th pixel block, the 8-bit binary form of its true pixel value is defined as S8, S7, S6, S5, S4, S3, S2, and S1; any two of the lower four bits are combined to obtain the initial test table, and the 8-bit binary form of the encrypted data is defined as X8, X7, X6, X5, X4, X3, X2, and X1. Based on X8X7, the initial test table is traversed. If there is a match between SmSn and X8X7, then m, n, and the corresponding test value in the initial test table are added to the embedded test table. If there is no match between SmSn and X8X7, then m=2, n=1, and the test value is 0 and added to the embedded test table;

[0042] The embedding unit is used to convert the test value into a 2-bit binary sequence and perform XOR encryption with S4S3 to obtain L1 and L2, replace and update S1 based on L1, and replace and update S2 based on L2 to obtain the embedded pixel value of the (i, j)-th pixel block; starting from the (i, j)-th pixel block, in order from left to right and from top to bottom, the 8-bit binary form of the encrypted data is in order from high bit to low bit, and the above process is repeated until the encrypted data is fully embedded to obtain the embedded pixel value of each pixel block.

[0043] Preferably, the decryption module includes:

[0044] XOR unit, for the embedded pixel value of the (i, j)th pixel block, performs XOR operation on S2 and S4 to obtain F1, and performs XOR operation on S1 and S3 to obtain F2;

[0045] The parsing unit is used to obtain the test value based on F2F1, and traverse the embedded test table to obtain the corresponding m and n, and then obtain Sm and Sn of the (i, j)-th pixel block, and further obtain X8 and X7 of the encrypted data; starting from the (i, j)-th pixel block, the above process is performed in sequence from left to right and from top to bottom until the 8-bit binary form of the encrypted data is obtained;

[0046] The decryption unit is used to decrypt the 8-bit binary form of the encrypted data based on the encryption algorithm to obtain the secret information.

[0047] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0048] The present invention relates to a method and system for encrypted domain image steganography based on Huffman coding. The method comprises: obtaining the pixel value of each pixel block in the original image and encoding it based on Huffman coding to obtain an initial code table; encrypting the secret information based on an encryption algorithm to obtain encrypted data; embedding the encrypted data based on a least significant bit algorithm to obtain an embedded pixel value for each pixel block; and updating the initial code table based on the embedded pixel value to obtain an embedded code table. The present invention reduces the total number of bits of transmitted data and increases capacity, thereby increasing the amount of information embedded without affecting image distortion and providing high security. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0050] Figure 1 This is a flow chart of the encrypted domain image steganography method based on Huffman coding of the present invention;

[0051] Figure 2 This is a structural diagram of the encrypted domain image steganography system based on Huffman coding of the present invention.

[0052] Explanation of symbols: 1-Huffman coding module, 2-encryption module, 3-embedding module, 4-data update module, 5-decryption module. DETAILED DESCRIPTION

[0053] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0054] The purpose of the present invention is to provide an encrypted domain image steganography method and system based on Huffman coding to reduce the total number of data bits and increase capacity, thereby increasing the amount of information embedded without affecting the distortion of the image and having high security.

[0055] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] Figure 1 The flowchart of the encrypted domain image steganography method based on Huffman coding of the present invention is shown in the figure. As shown in the figure, the present invention provides an encrypted domain image steganography method based on Huffman coding, comprising:

[0057] S1, obtain the pixel value of each pixel block in the original image, and encode it based on Huffman coding to obtain an initial code table. Specifically, S1 includes:

[0058] S11, obtaining the true pixel value of each pixel block in the original image.

[0059] S11, based on the median predictor, the real pixel value of each pixel block is predicted to obtain the predicted pixel value of each pixel block. The specific calculation formula is as follows:

[0060]

[0061] Where: c is the real pixel value of the adjacent pixel block on the left side of the current pixel block, b is the real pixel value of the adjacent pixel block above the current pixel block, and a is the real pixel value of the pixel block above the left side of the current pixel block.

[0062] S11, convert the actual pixel value and predicted pixel value of each pixel block into 8-bit binary form. The specific calculation formula is as follows:

[0063]

[0064] Where: i∈I, j∈J, I×J are the pixels of the original image, x(i, j) is the true pixel value of the (i, j)th pixel block, and k is the bit.

[0065] S12, compare the (i, j)th pixel block bit by bit starting from the most significant bit, and the number of consecutive identical bits is the label value of the (i, j)th pixel block; let i and / or j take different values, and repeat this process to obtain the label values ​​of all pixel blocks.

[0066] S13, performing Huffman coding according to the distribution probability of the label value of each pixel block to obtain an initial code table; the initial code table includes the correspondence between code words and real pixel values ​​and the code word sequence; the real pixel value of each pixel block in the original image is replaced by the corresponding code word.

[0067] S2, encrypting the secret information based on an encryption algorithm to obtain encrypted data. The encryption algorithm in this embodiment adopts the Paillier homomorphic encryption algorithm.

[0068] S3, embedding the encrypted data based on the least significant bit algorithm to obtain the embedded pixel value of each pixel block. Preferably, S3 includes:

[0069] S31, for the (i, j)th pixel block, the 8-bit binary representation of its true pixel value is defined as S8, S7, S6, S5, S4, S3, S2, and S1; any two of the lower four bits are combined to form the initial test table, as shown in Table 1. The 8-bit binary representation of the encrypted data is defined as X8, X7, X6, X5, X4, X3, X2, and X1. Based on X8X7, the initial test table is traversed. If SmSn matches X8X7, m, n, and the corresponding test value in the initial test table are added to the embedded test table. If SmSn does not match X8X7, m=2, n=1, and the test value is set to 0 and added to the embedded test table.

[0070] Table 1 Initial test table

[0071]

[0072]

[0073] S32 converts the test value into a 2-bit binary sequence and performs XOR encryption with S4S3 to obtain L1 and L2. S1 is replaced and updated based on L1, and S2 is replaced and updated based on L2 to obtain the embedded pixel value of the (i, j)th pixel block.

[0074] S33, starting from the (i, j)th pixel block, in the order from left to right and from top to bottom, the 8-bit binary form of the encrypted data is in the order from high bit to low bit, and the above process is repeated until the encrypted data is completely embedded to obtain the embedded pixel value of each pixel block.

[0075] S4, updating the initial code table based on the embedded pixel value to obtain an embedded code table, specifically, replacing and updating the real pixel values ​​in the initial code table based on the embedded pixel value to obtain the embedded code table.

[0076] S5, decrypting the embedded code table based on an encryption algorithm to obtain the secret information. Specifically, S5 includes:

[0077] S51, for the embedded pixel value of the (i, j)th pixel block, perform an XOR operation on S2 and S4 to obtain F1, and perform an XOR operation on S1 and S3 to obtain F2.

[0078] S52: Based on F2F1, the test value is obtained and traversed in the embedded test table to obtain the corresponding m and n. This is followed by Sm and Sn for the (i, j)th pixel block, and further by X8 and X7 for the encrypted data. S53: Starting from the (i, j)th pixel block, the above process is repeated from left to right and from top to bottom until the 8-bit binary form of the encrypted data is obtained.

[0079] S54, decrypting the 8-bit binary form of the encrypted data based on the encryption algorithm to obtain the secret information.

[0080] Figure 2 The structure diagram of the encrypted domain image steganography system based on Huffman coding of the present invention is shown in the figure. As shown in the figure, the present invention provides an encrypted domain image steganography system based on Huffman coding, which includes: a Huffman coding module 1, an encryption module 2, an embedding module 3, a data update module 4 and a decryption module 5.

[0081] The Huffman coding module 1 is used to obtain the pixel value of each pixel block in the original image, and encode it based on Huffman coding to obtain an initial code table.

[0082] As an optional implementation, the Huffman coding module 1 of the present invention includes: a data acquisition unit, a pixel prediction unit, a data conversion unit, a tag value unit and a Huffman coding unit.

[0083] The data acquisition unit is used to acquire the real pixel value of each pixel block in the original image.

[0084] The pixel prediction unit is used to perform pixel prediction on the real pixel value of each pixel block based on the median predictor to obtain the predicted pixel value of each pixel block.

[0085] The data conversion unit is used to convert the actual pixel value and the predicted pixel value of each pixel block into 8-bit binary form.

[0086] The marking value unit is used to compare the (i, j)th pixel block bit by bit starting from the most significant bit, and the number of consecutive identical bits is the marking value of the (i, j)th pixel block; i∈I, j∈J, I×J are pixels of the original image; let i and / or j take different values, and repeat this process to obtain the marking values ​​of all pixel blocks.

[0087] The Huffman coding unit is used to perform Huffman coding according to the distribution probability of the label value of each pixel block to obtain an initial code table; the initial code table includes the correspondence between code words and real pixel values ​​and the code word sequence; the pixel value of each pixel block in the original image is replaced by the corresponding code word.

[0088] The encryption module 2 is used to encrypt secret information based on an encryption algorithm to obtain encrypted data.

[0089] The embedding module 3 is used to embed the encrypted data based on the least significant bit algorithm to obtain the embedded pixel value of each pixel block.

[0090] As an optional implementation, the embedding module 3 of the present invention includes: a test table unit and an embedding unit.

[0091] The test table unit is used for the (i, j)th pixel block, and the 8-bit binary form of its true pixel value is defined as S8, S7, S6, S5, S4, S3, S2 and S1; any two of the lower four bits are combined to obtain the initial test table, and the 8-bit binary form of the encrypted data is defined as X8, X7, X6, X5, X4, X3, X2 and X1. Based on X8X7, traverse the initial test table. If there is SmSn matching X8X7, then m, n and the corresponding test value in the initial test table are added to the embedded test table. If there is no SmSn matching X8X7, then m=2, n=1, and the test value is 0 and added to the embedded test table.

[0092] The embedding unit is used to convert the test value into a 2-bit binary sequence and perform XOR encryption with S4S3 to obtain L1 and L2, replace and update S1 based on L1, and replace and update S2 based on L2 to obtain the embedded pixel value of the (i, j)th pixel block; starting from the (i, j)th pixel block, in order from left to right and from top to bottom, the 8-bit binary form of the encrypted data is in order from high bit to low bit, and the above process is repeated until the encrypted data is fully embedded to obtain the embedded pixel value of each pixel block.

[0093] The data updating module 4 is configured to update the initial code table based on the embedded pixel value to obtain an embedded code table.

[0094] The decryption module 5 is used to decrypt the embedded code table based on an encryption algorithm to obtain the secret information.

[0095] As an optional implementation, the decryption module 5 of the present invention includes: an XOR unit, a parsing unit and a decryption unit.

[0096] The XOR unit is used to perform an XOR operation on the embedded pixel value of the (i, j)th pixel block, S2 and S4 to obtain F1, and perform an XOR operation on S1 and S3 to obtain F2;

[0097] The parsing unit is used to obtain the test value based on F2F1, and traverse the embedded test table to obtain the corresponding m and n, and then obtain Sm and Sn of the (i, j)-th pixel block, and further obtain X8 and X7 of the encrypted data; starting from the (i, j)-th pixel block, the above process is performed in sequence from left to right and from top to bottom until the 8-bit binary form of the encrypted data is obtained;

[0098] The decryption unit is used to decrypt the 8-bit binary form of the encrypted data based on the encryption algorithm to obtain the secret information.

[0099] The beneficial effects of the present invention are as follows:

[0100] 1) The Huffman coding method is used to reduce the total number of bits of the message and increase the capacity, thereby improving the efficiency of transmission on the network.

[0101] 2) The least significant bit algorithm is slightly improved to increase the amount of information embedded without affecting the distortion of the image, which has high security.

[0102] 3) Under the premise of ensuring security, it has higher embedding efficiency.

[0103] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0104] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for steganography of encrypted domain images based on Huffman coding, characterized in that: include: Obtain the pixel value of each pixel block in the original image and encode it based on Huffman coding to obtain an initial code table; Encrypting the secret information based on the encryption algorithm to obtain encrypted data; Embedding the encrypted data based on a least significant bit algorithm to obtain an embedded pixel value for each pixel block includes: For the (i, j)th pixel block, the 8-bit binary form of its true pixel value is defined as S8, S7, S6, S5, S4, S3, S2 and S1; any two of the lower four bits are combined to obtain the initial test table, and the 8-bit binary form of the encrypted data is defined as X8, X7, X6, X5, X4, X3, X2 and X1. Based on X8X7, the initial test table is traversed. If there is a SmSn match X8X7, then m, n and the corresponding test value in the initial test table are added to the embedded test table. If there is no SmSn match X8X7, then m=2, n=1, and the test value is 0 and added to the embedded test table; Convert the test value into a 2-bit binary sequence and perform XOR encryption with S4S3 to obtain L1 and L2. Replace and update S1 based on L1, and replace and update S2 based on L2 to obtain the embedded pixel value of the (i, j)th pixel block; Starting from the (i, j)th pixel block, the 8-bit binary form of the encrypted data is repeated in order from high to low bits from left to right and from top to bottom until all the encrypted data is embedded, obtaining the embedded pixel value of each pixel block; The initial code table is updated based on the embedded pixel value to obtain an embedded code table.

2. The encrypted domain image steganography method based on Huffman coding according to claim 1 is characterized in that: The pixel value of each pixel block in the original image is obtained and encoded based on Huffman coding to obtain an initial code table, including: Get the true pixel value of each pixel block in the original image; Perform pixel prediction on the true pixel value of each pixel block based on the median predictor to obtain the predicted pixel value of each pixel block; Convert the actual pixel value and predicted pixel value of each pixel block into 8-bit binary form; Compare the (i, j)th pixel block bit by bit starting from the most significant bit. The number of consecutive identical bits is the label value of the (i, j)th pixel block; i∈I, j∈J, I×J are the pixels of the original image; let i and / or j take different values ​​and repeat this process to obtain the label values ​​of all pixel blocks; Huffman coding is performed according to the distribution probability of the label value of each pixel block to obtain an initial code table; the initial code table includes the correspondence between code words and real pixel values ​​and the code word sequence; the pixel value of each pixel block in the original image is replaced by the corresponding code word.

3. The encrypted domain image steganography method based on Huffman coding according to claim 1 is characterized in that: The method further comprises: The embedded code table is decrypted based on an encryption algorithm to obtain the secret information.

4. The encrypted domain image steganography method based on Huffman coding according to claim 1 is characterized in that: Decrypting the embedded code table based on an encryption algorithm to obtain the secret information includes: For the embedded pixel value of the (i, j)th pixel block, perform an XOR operation on S2 and S4 to obtain F1, and perform an XOR operation on S1 and S3 to obtain F2; Get the test value based on F2F1, and traverse the embedded test table to get the corresponding m and n, and then get Sm and Sn of the (i, j)th pixel block, and further get X8 and X7 of the encrypted data; Starting from the (i, j)th pixel block, the above process is performed in order from left to right and from top to bottom until the 8-bit binary form of the encrypted data is obtained; The 8-bit binary form of the encrypted data is decrypted based on the encryption algorithm to obtain the secret information.

5. An encrypted domain image steganography system based on Huffman coding, characterized in that: include: Huffman coding module, used to obtain the pixel value of each pixel block in the original image and encode it based on Huffman coding to obtain an initial code table; An encryption module, used to encrypt secret information based on an encryption algorithm to obtain encrypted data; An embedding module is used to embed the encrypted data based on a least significant bit algorithm to obtain an embedded pixel value of each pixel block, and the embedding module includes: In the test table unit, for the (i, j)th pixel block, the 8-bit binary form of its true pixel value is defined as S8, S7, S6, S5, S4, S3, S2, and S1; any two of the lower four bits are combined to obtain the initial test table, and the 8-bit binary form of the encrypted data is defined as X8, X7, X6, X5, X4, X3, X2, and X1. Based on X8X7, the initial test table is traversed. If there is a match between SmSn and X8X7, then m, n, and the corresponding test value in the initial test table are added to the embedded test table. If there is no match between SmSn and X8X7, then m=2, n=1, and the test value is 0 and added to the embedded test table; An embedding unit is configured to convert the test value into a 2-bit binary sequence and perform XOR encryption with S4S3 to obtain L1 and L2, replace and update S1 based on L1, and replace and update S2 based on L2 to obtain the embedded pixel value of the (i, j)th pixel block; starting from the (i, j)th pixel block, in order from left to right and from top to bottom, the 8-bit binary form of the encrypted data is repeated in order from high to low bits until all the encrypted data is embedded, thereby obtaining the embedded pixel value of each pixel block; A data updating module is configured to update the initial code table based on the embedded pixel value to obtain an embedded code table.

6. The encrypted domain image steganography system based on Huffman coding according to claim 5 is characterized in that: The Huffman coding module includes: A data acquisition unit, used to obtain the real pixel value of each pixel block in the original image; A pixel prediction unit, configured to perform pixel prediction on the true pixel value of each pixel block based on a median predictor to obtain a predicted pixel value of each pixel block; A data conversion unit, configured to convert both the actual pixel value and the predicted pixel value of each pixel block into 8-bit binary form; The tag value unit is used to compare the (i, j)th pixel block bit by bit starting from the most significant bit. The number of consecutive identical bits is the tag value of the (i, j)th pixel block; i∈I, j∈J, I×J are the pixels of the original image; let i and / or j take different values ​​and repeat this process to obtain the tag values ​​of all pixel blocks; The Huffman coding unit is used to perform Huffman coding according to the distribution probability of the label value of each pixel block to obtain an initial code table; the initial code table includes the correspondence between code words and real pixel values ​​and the code word sequence; the pixel value of each pixel block in the original image is replaced by the corresponding code word.

7. The encrypted domain image steganography system based on Huffman coding according to claim 5 is characterized in that: The system further comprises: The decryption module is used to decrypt the embedded code table based on an encryption algorithm to obtain the secret information.

8. The encrypted domain image steganography system based on Huffman coding according to claim 7 is characterized in that: The decryption module includes: XOR unit, for the embedded pixel value of the (i, j)th pixel block, performs XOR operation on S2 and S4 to obtain F1, and performs XOR operation on S1 and S3 to obtain F2; The parsing unit is used to obtain the test value based on F2F1, and traverse the embedded test table to obtain the corresponding m and n, and then obtain Sm and Sn of the (i, j)-th pixel block, and further obtain X8 and X7 of the encrypted data; starting from the (i, j)-th pixel block, the above process is performed in sequence from left to right and from top to bottom until the 8-bit binary form of the encrypted data is obtained; The decryption unit is used to decrypt the 8-bit binary form of the encrypted data based on the encryption algorithm to obtain the secret information.

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