A multi-way reversible information hiding method for encrypted binary images without data diffusion

Abstract

This invention relates to the field of information security technology, specifically to a method for multi-party reversible information hiding of encrypted binary images without data diffusion. The method includes: binary image encryption, where all parties use a random lattice visual cryptography to encrypt the original binary image into n encrypted binary images of the same size as the original image, and distribute them to n different information hiding parties; information embedding, where each information hiding party embeds secret information encrypted with an information hiding key into its held encrypted binary images through pattern block replacement, generating labeled encrypted binary images; and information extraction and binary image recovery, where the receiver obtains at least k labeled encrypted binary images, extracts the secret information using a random lattice visual cryptography decryption algorithm, and performs operations on the encrypted binary images to recover the original binary image. This invention solves the problems of severe data diffusion and reliance on codebooks in existing technologies, improves storage and transmission efficiency and fault tolerance, ensures the security of the original binary image, and is suitable for scenarios such as cloud storage and remote sensing communication.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of information security, and more particularly to a ciphertext binary image multi-party reversible information hiding method without data diffusion. BACKGROUND

[0002] Reversible information hiding technology is a technology that embeds information into a carrier and can restore the original carrier and extract the embedded information in the subsequent process. Among them, binary image reversible information hiding technology takes electronic documents, scanned texts and other binary images as carriers, and also realizes the lossless recovery of the carrier and the extraction of the embedded information. With the continuous growth of security needs, in some application scenarios, it is necessary to embed information in ciphertext binary images, thus giving rise to ciphertext binary image reversible information hiding technology. This technology combines encryption technology and information hiding technology, not only can protect the security of binary images, but also can be used for integrity authentication, and is widely used in cloud storage, remote sensing communication and other fields.

[0003] Compared with the ciphertext binary image reversible information hiding technology, the ciphertext binary image multi-party reversible information hiding technology further optimizes the information security protection mechanism. The operation process is as follows: first, the original binary image is encrypted to generate multiple ciphertext binary images, and then each ciphertext binary image is distributed to different information hiding parties, and each information hiding party embeds information in the ciphertext binary image it holds to form a marked ciphertext binary image. This technical mechanism can ensure that even if part of the information hiding parties are attacked, the receiver can still obtain a sufficient number of marked ciphertext binary images from the information hiding parties that have not been attacked, and then complete the information extraction and original binary image recovery operations, further improving the security of the original binary image.

[0004] In the existing ciphertext binary image multi-party reversible information hiding method, the operation process is as follows: first, all parties use classical visual cryptography to encrypt the original binary image to generate multiple ciphertext binary images with data diffusion phenomenon, and distribute these ciphertext binary images to multiple information hiding parties; then, each information hiding party embeds the information to be embedded into the ciphertext binary image it holds by means of an information hiding key to generate a marked ciphertext binary image; finally, the receiver uses the information hiding key to extract the embedded information from the authorized marked ciphertext binary images, and by selecting any two marked ciphertext binary images, the original binary image can be reconstructed losslessly.

[0005] Although the existing ciphertext binary image multi-party reversible information hiding method meets the information security needs to some extent, in actual application process, there are still the following two significant technical problems:

[0006] Data diffusion problem is serious. In the existing technical solution, in order to be able to embed information in the ciphertext binary image, it is necessary to create enough space for information embedding. For this purpose, the existing scheme adopts the method of encrypting the original binary image into a ciphertext binary image with a size several times larger than the original image to obtain the embedding space. This practice directly leads to the serious data diffusion phenomenon of the generated ciphertext binary image, which not only increases the pressure of data storage, but also occupies more bandwidth resources in the data transmission process, which is not conducive to application in the scene with limited storage resources and low transmission bandwidth.

[0007] Highly dependent on codebook design. The existing scheme adopts the classical visual cryptography technology when encrypting the original binary image, and the application of this technology must depend on the pre-designed codebook. At the same time, when different encryption strategies are needed for the original binary image, different codebooks need to be used correspondingly. This high dependence on codebook not only increases the complexity of the technical solution design, limits the flexibility and expandability of the scheme, but also seriously threatens the security of the entire encryption system once the codebook is leaked or damaged, thereby affecting the overall reliability of the ciphertext binary image multi-party reversible information hiding technology. SUMMARY

[0008] Therefore, the present application provides a ciphertext binary image multi-party reversible information hiding method without data diffusion, aiming to solve the technical problems of serious data diffusion and high dependence on codebook design in the existing ciphertext binary image multi-party reversible information hiding method, thereby improving the efficiency of ciphertext binary image in the storage and transmission process, reducing the complexity and security risk of technical solution design, and at the same time ensuring that the receiving party can still obtain a sufficient number of marked ciphertext binary images to realize information extraction and original binary image recovery in the case of part of the information hiding party being attacked, further improving the security of the original binary image and the practicality of the scheme, making it more suitable for the needs of cloud storage, remote sensing communication and other practical application scenarios.

[0009] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0010] A ciphertext binary image multi-party reversible information hiding method without data diffusion, comprising:

[0011] Binary image encryption stage: all parties use random lattice visual cryptography to encrypt the original binary image into n ciphertext binary images, where n is a positive integer greater than 2, and the size of each ciphertext binary image is consistent with the size of the original binary image, and then the n ciphertext binary images are distributed to n different information hiding parties respectively, and each information hiding party holds one ciphertext binary image;

[0012] Information embedding stage: Each information hiding party embeds the secret information into its own encrypted binary image using pattern block replacement to generate a marked encrypted binary image, where the secret information is encrypted from the information to be embedded according to the information hiding key;

[0013] Information extraction and binary image restoration stage: When the receiver obtains at least any k marked encrypted binary images, where k is a positive integer satisfying 2 ≤ k < n, the embedded secret information is extracted from the k marked encrypted binary images through the random lattice visual cryptography decryption algorithm, and the original binary image is restored.

[0014] In a specific implementable embodiment, in the binary image encryption stage, the specific process of performing encryption operations on each pixel in the original binary image to generate n encrypted binary images includes:

[0015] Randomly generate a bit , where takes a value of 0 or 1;

[0016] According to the pixel value of the current pixel in the original binary image, generate a bit , if the pixel value of the current pixel is 0, then is equal to [[ID=二十一]] [[ID=二十二]] is equal to 1 minus ;

[0017] Randomly generate a bit , where takes a value of 0 or 1;

[0018] According to the value of the bit , generate a bit , if takes a value of 0, then is equal to , if takes a value of 1, then is equal to 1 minus ;

[0019] Repeat the operations of randomly generating bits and generating the current bit according to the previous bit until k bits , , ……, are obtained in sequence, and the bit is equal to the bit ;

[0020] Generate n - k bits with a value of 0, denoted as , ​... ;

[0021] The obtained n bits to The bits are randomly arranged, and each bit after the arrangement is used as the pixel value at the corresponding position in n encrypted binary images, thus completing the encryption of the current pixel;

[0022] Perform the above encryption operation on all pixels of the original binary image to obtain n encrypted binary images.

[0023] In one specific implementation, the process by which the information hiding party uses pattern block substitution to embed secret information into the ciphertext binary image to generate a labeled ciphertext binary image during the information embedding stage includes:

[0024] Divide the encrypted binary image it holds into several non-overlapping pattern blocks of size 1×2, and count the frequency of occurrence of each pattern block;

[0025] Based on the frequency of pattern blocks obtained from statistics, the pattern block with the highest frequency is selected as BM, the pattern block with the lowest frequency is selected as BF, and the pattern block with the second lowest frequency is selected as BFR.

[0026] The pattern block BF and pattern block BFR in the encrypted binary image are queried according to the raster scanning order, and a position mapping is generated. When the pattern block BF is scanned, the pattern block BF is modified to the pattern block BFR, and bit 1 is recorded as the value of the position in the position mapping. When the pattern block BFR is scanned, the pattern block BFR is kept unchanged, and bit 0 is recorded as the value of the position in the position mapping.

[0027] The pattern block BM in the encrypted binary image is queried according to the raster scan order. Information is embedded according to the bits of the secret information and the generated position mapping. First, the bits of the secret information are embedded, and then the bits of the position mapping are embedded. When the current bit of the secret information is 0, the pattern block BM remains unchanged. When the current bit of the secret information is 1, the pattern block BM is modified to the pattern block BF. The information embedding operation is completed, and the labeled encrypted binary image is obtained.

[0028] In a specific implementation, the process by which the receiver extracts the embedded secret information from k labeled ciphertext binary images during the information extraction and binary image restoration stage includes:

[0029] The acquired k labeled ciphertext binary images are divided into several non-overlapping pattern blocks of size 1×2.

[0030] Query the pattern blocks BM and BF in each marked ciphertext binary image in raster scan order. When the queried pattern block is BM, extract bit 0. When the queried pattern block is BF, extract bit 1, and modify the queried pattern block BF to pattern block BM.

[0031] Combine all the bits extracted from the k marked ciphertext binary images to obtain a bit sequence containing the secret information and the position mapping.

[0032] Separate the bit part corresponding to the secret information and the bit part corresponding to the position mapping from the bit sequence, and decrypt the bit part corresponding to the secret information according to the information hiding key to obtain the original information to be embedded.

[0033] In a specific feasible implementation scheme, in the information extraction and binary image restoration stage, the specific process for the receiver to restore the original binary image includes:

[0034] Divide each of the k marked ciphertext binary images after the secret information extraction into several non-overlapping pattern blocks of size 1×2.

[0035] Query the pattern block BFR in each marked ciphertext binary image in raster scan order. Combine the bit part corresponding to the separated position mapping. When the bit value at the current position in the position mapping is 0, keep the pattern block BFR unchanged. When the bit value at the current position in the position mapping is 1, modify the pattern block BFR to pattern block BF.

[0036] Perform an exclusive OR operation on the L ciphertext binary images after the above pattern block adjustment, where , to achieve the reconstruction of the original binary image, where n is the total number of encrypted ciphertext binary images, k is the minimum number of images required for restoration and satisfies 2≤k<n, and L is the number of images actually obtained by the receiver and used for the restoration operation and satisfies .

[0037] In a specific feasible implementation scheme, when L = n, perform an exclusive OR operation on the ciphertext binary images after the pattern block adjustment to achieve the lossless reconstruction of the original binary image.

[0038] In a specific feasible implementation scheme, the size of the original binary image is h×w, where h is the height of the original binary image, w is the width of the original binary image, and both h and w are positive integers. The size of each encrypted ciphertext binary image is h×w.

[0039] In a specific feasible implementation scheme, in the binary image encryption stage, the original binary images input by all parties are at least one of the binary images corresponding to electronic documents and the binary images corresponding to scanned texts.

[0040] In a specific implementation scheme, before performing the information embedding operation, the information hiding party needs to perform an integrity check on the encrypted binary image it holds. After confirming that the encrypted binary image has not been tampered with, it then performs the subsequent pattern block division and information embedding operations.

[0041] In one specific implementation, when the receiver obtains the labeled encrypted binary image, it needs to authenticate the labeled encrypted binary image sent by each information hiding party. Only after confirming the legitimate identity of the information hiding party can the receiver receive the corresponding labeled encrypted binary image.

[0042] Compared with existing technologies, the present invention provides a multi-party reversible information hiding method for encrypted binary images without data diffusion. This method ensures the security of binary images while achieving covert embedding and lossless extraction of secret information, meeting the needs of cloud storage, remote sensing communication, and other fields for multi-party collaborative processing of encrypted binary images. It employs a random grid visual cryptography algorithm to encrypt the original binary image into multiple encrypted binary images without data diffusion and distributes them to different information hiding parties. Combined with the introduction of all-black pixels to increase image redundancy and achieve the ability to embed information in the encrypted binary images, and the design of information embedding logic based on pattern block replacement and a mechanism supporting information extraction and image recovery from any k labeled encrypted binary images, the invention achieves secure encryption of the original binary image, effective embedding and lossless extraction of secret information, and the ability to recover the original binary image from a sufficient number of labeled encrypted binary images even when some information hiding parties are attacked. This effectively improves the storage and transmission efficiency of encrypted binary images, reduces the dependence of the technical solution on the codebook, and enhances the flexibility and fault tolerance of the solution, offering the following beneficial effects:

[0043] 1. Achieving no data diffusion: This invention uses random grid visual cryptography to encrypt the original binary image into multiple ciphertext binary images. The size of each ciphertext binary image is consistent with that of the original binary image, avoiding the problem of a significant increase in the size of the ciphertext image in order to obtain the embedding space in the prior art. This significantly reduces the data storage pressure and transmission bandwidth occupation, and is more suitable for lightweight application scenarios.

[0044] 2. Unlike existing technologies that rely on pre-designed codebooks for encryption and require different codebooks for different encryption strategies, this invention achieves encryption by randomly generating pixels and introducing all-black pixels. It does not rely on any pre-designed codebook, which simplifies the design process of the technical solution, reduces the security risks caused by codebook leakage or damage, and improves the scalability of the solution, which can flexibly adapt to different encryption needs.

[0045] 3. Ensuring the reliability of information embedding and image restoration: By introducing all-black pixels (all-black pixels are a bit stream of all "0"s) to increase image redundancy, the feasibility of embedding information in ciphertext binary images is ensured. Furthermore, the receiver only needs to acquire any k labeled ciphertext binary images to complete the extraction of secret information and the restoration of the original binary image. In particular, when all n labeled ciphertext binary images are acquired, lossless reconstruction of the original binary image can be achieved. Even if some information hiding parties are attacked, the core operations can still be completed using the labeled ciphertext binary images of the unattacked parties, further ensuring the security of the original binary image and the practical value of the solution. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0047] Figure 1 The flowchart illustrates the framework of the multi-party reversible information hiding method for encrypted binary images without data diffusion, as provided in this embodiment of the invention. Detailed Implementation

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] like Figure 1 As shown, the present invention discloses a multi-party reversible information hiding method for encrypted binary images without data diffusion. This method is applied to multi-party reversible information hiding of encrypted binary images, aiming to solve the problem of multiple information hiding parties and enhanced image recoverability. It includes three stages: a binary image encryption stage, an information embedding stage, and an information extraction and binary image recovery stage. The method mainly includes the binary image encryption stage, the information embedding stage, and the information extraction and binary image recovery stage.

[0050] During the binary image encryption stage, all parties use a random lattice visual cipher to encrypt the binary image. A set of encrypted binary images are generated and distributed to... There are several different information hiding parties. In the information embedding phase, each party holds a ciphertext binary image and embeds the secret information into it to generate a labeled ciphertext binary image. In the information extraction and binary image reconstruction phase, when the receiver obtains at least any... When dealing with a binary image with ciphertext labeled with a random grid visual cryptography algorithm, the original binary image can be recovered and the embedded information extracted from it.

[0051] The Random Grid-based Visual Cryptography used in this invention is a well-known encryption technique. Unlike classic visual cryptography, which relies on a pre-set codebook, Random Grid-based Visual Cryptography directly encrypts the original binary image into multiple ciphertext images through random bit generation and logical deduction. Each ciphertext image does not carry any visual information of the original image, and the original image can be recovered by superimposing and recombining the multiple ciphertext images (such as through XOR operations).

[0052] 1. Binary Image Encryption Stage

[0053] Binary image encryption utilizes random lattice-based methods. Visual cryptography algorithms encrypt binary images into A binary image containing encrypted text. All inputs are a single image of size [size missing]. The original binary image , and If the integer is positive, such as 256×256, after encryption, the resulting binary image will be the same size as the original binary image. Binary image of ciphertext For binary images Each pixel in Perform the encryption operation as follows.

[0054] Step 1: Randomly generate a bit ,in .

[0055] Step 2: Generate bits according to the following formula ,Right now

[0056]

[0057] Step 3: Randomly generate a bit ,in .

[0058] Step 4: Generate bits according to the following formula ,Right now

[0059]

[0060] Step 5: Following this pattern, repeat steps 3 to 4 to obtain the following results. bits Among them, bits Exactly equal to bits ,Right now

[0061]

[0062] Step 6: Generate indivual Bit, i.e.

[0063]

[0064] Step 7: Take the above-obtained... Randomly arrange the bits and use them as... Pixels at corresponding positions in a binary image of encrypted text The random arrangement, or shuffling into a random order, aims to ensure that the encrypted ciphertext image is a noise-like image that does not reveal any information about the original image. What is needed is an irregular, random arrangement, that is, truly shuffling n bits randomly before arranging them.

[0065] Finally, the generated A ciphertext binary image is distributed to There are several different information hiding parties, each holding a ciphertext binary image.

[0066] 2. Information Embedding Stage

[0067] In the information embedding stage, the information hiding party uses pattern block substitution to embed secret information into the ciphertext binary image, generating a labeled ciphertext binary image. The secret information is generated by encrypting information using the information hiding key. The specific steps of information embedding are described below.

[0068] Step 1: Divide the ciphertext binary image into non-overlapping pattern blocks of size 1×2, and count the frequency of different pattern blocks.

[0069] Step 2: Based on the statistical results, select the pattern block with the highest frequency, the pattern block with the lowest frequency, and the pattern block with the second lowest frequency, and assign them the names BM, BF, and BFR, respectively.

[0070] Step 3: Query pattern blocks BF and BFR in the binary image according to the raster scan order, and generate corresponding position maps. The position map is a bitstream of "0" and "1" bits, embedded into the ciphertext image along with the secret information. During information embedding, the secret information is embedded first. After embedding, 8 "0" bits are added as an identifier, and then the position map information is embedded. When the receiver extracts the information, it first identifies the pattern blocks to extract the secret information. When the 8 "0" bits identifier are extracted, it means the secret information extraction is complete. Then, it continues to identify pattern blocks to extract the position map information. When pattern block BF is scanned, it is modified to pattern block BFR, and bit 1 is used as the position map value. When pattern block BFR is scanned, it remains unchanged, and bit 0 is used as the position map value.

[0071] Step 4: Query the pattern block BM in the binary image according to the raster scan order, and embed information based on the secret information and the position mapping, that is, embed the secret information first, and then embed the position mapping. When the information bit is 0, BM remains unchanged; when the information bit is 1, BM is modified to BF.

[0072] Through the above information embedding operation, the information hiding party can obtain a labeled ciphertext binary image.

[0073] 3. Information Extraction and Binary Image Restoration Stage

[0074] In this stage, the receiver performs information extraction and binary image restoration operations, that is, from any... Extract embedded information and recover the original binary image from a band-marked ciphertext binary image.

[0075] Regarding information extraction, the recipient will arbitrarily... The ciphertext binary image with bandmarks is divided into non-overlapping pattern blocks of size 1×2, and pattern blocks BM and BF are queried according to the raster scan order. If the queried pattern block is BM, bit 0 is extracted; if the queried pattern block is BF, bit 1 is extracted, and pattern block BF is modified to be pattern block BM. The extracted bits are then combined to generate secret information and a location map. The generated secret information is decrypted using the information hiding key to obtain the original information.

[0076] For binary image restoration, the receiver will also arbitrarily... The ciphertext binary image with bandmarks is divided into segments of size . The non-overlapping mode blocks are queried according to the raster scan order. When the pattern block is found When the position mapping value is 0, then the mode block... Remain unchanged; if the value of the position mapping is 1, then modify the pattern block to the pattern block . Finally, the receiver performs an exclusive OR operation on any encrypted binary images, and the reconstruction of the original binary image can be achieved; the parameter L needs to meet the condition . If the receiver performs an exclusive OR operation on encrypted binary images, the lossless reconstruction of the original binary image can be achieved; the exclusive OR operation is a point-by-point exclusive OR operation on the pixels at the corresponding positions in images. When encrypting the original bits, first k - 1 bits are randomly generated, and the kth bit is obtained through the exclusive OR operation of the k - 1 bits and the original bit. At the same time, n - k bits of "0" are introduced to obtain n bits; during decryption, when = n, performing an exclusive OR operation on these n bits can obtain the original bits, that is, lossless recovery; when , that is, performing an exclusive OR operation on these bits, at this time, the original image cannot be completely losslessly recovered, but partial information of the original image can be obtained, that is, the original image is recovered in a lossy manner.

[0077] In this embodiment, performing an exclusive OR operation on all L encrypted binary images obtained, the larger L is, the better the visual quality of the recovered image, and k is the lowest threshold; at least k encrypted binary images need to be exclusive ORed to recover the image; when L is equal to n, it is complete lossless recovery.

[0078] The way this embodiment solves the problem of "severe data diffusion" is: the ciphertext size is the same as the original image, and the storage / transmission efficiency is increased by m times (such as doubling the efficiency when

[0079] The way this embodiment solves the problem of "high dependence on the codebook" is: no codebook design, n and k can be flexibly adjusted to adapt to different scenario requirements (such as multiple hiding parties, high fault-tolerance scenarios). Specifically, the encryption logic of "random bit generation + logical derivation" is adopted (such as generating n ciphertext bits in steps 1 - 7), without any preset codebook, reducing the complexity and security risk of the scheme, and at the same time supporting the flexible adjustment of n and k (such as , ), and the scalability is significantly improved.

[0080] The way this embodiment optimizes the problem of "recovery flexibility and accuracy" is: support any k images (2 ≤ k < n) for recovery, and the fault tolerance is increased to (such as , When tolerating 2 damaged ones); =n ( ) lossless reconstruction is achieved through exclusive OR operation, and the recovery accuracy reaches 100%. Specifically, it supports the recovery of "any k images (2 ≤ k < n)". Even if some information hiding parties are attacked, as long as k valid images are obtained, operations can be performed; and =n( ) lossless reconstruction is achieved through "exclusive OR operation", and the recovery accuracy and system fault tolerance are greatly improved.

[0081] As described above, this is the core method process of the present invention. As a further optimized implementation scheme, the integrity verification and identity authentication functions mentioned in the present invention can be implemented through standard security technologies in the art, and the specific description is as follows:

[0082] Regarding integrity verification: Before the information hiding party performs information embedding operations, the integrity of the ciphertext binary image it holds can be verified. A typical implementation method is that when all parties distribute the ciphertext image, an authentication tag can be provided synchronously (for example, the hash value obtained by calculating the ciphertext binary image through a cryptographic hash function such as SHA-256). After receiving the ciphertext binary image, the information hiding party recalculates the image hash value using the same hash function and compares it with the received authentication tag. If the two are consistent, it is confirmed that the ciphertext binary image is complete and not tampered with, and then the mode block division and information embedding operations are performed.

[0083] Regarding identity authentication: When the receiving party obtains the marked ciphertext binary image, the identity of each information hiding party can be verified. A typical implementation method is to adopt an authentication mechanism based on digital certificates. When the information hiding party sends the marked ciphertext binary image, it can use its private key to digitally sign the hash value of the image and send the signature together with the image. The receiving party uses the pre-stored and trusted public key of the information hiding party to verify the validity of the signature. If the signature verification passes, it is confirmed that the identity of the information hiding party is legal, and the marked ciphertext binary image is received.

[0084] The specific implementation means described above (such as hash functions, digital signatures) are only examples. Those skilled in the art know that other cryptographic protocols or methods with the same functions (such as message authentication code MAC, authentication based on pre-shared keys, etc.) can also be used to achieve the same integrity verification and identity authentication purposes. The implementation of these additional security features is independent of the core encryption / decryption and information hiding processes of the present invention and can be selectively loaded according to the security requirements of specific application scenarios.

[0085] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A ciphertext binary image multi-party reversible information hiding method without data diffusion, characterized in that, The method comprises the following steps: A binary image encryption stage: all parties encrypt an original binary image into n pieces of ciphertext binary images by using a random lattice visual password, wherein n is a positive integer greater than 2, the size of each piece of ciphertext binary image is consistent with the size of the original binary image, and the n pieces of ciphertext binary images are respectively distributed to n different information hiding parties, and each information hiding party holds one piece of ciphertext binary image; An information embedding stage: each information hiding party embeds secret information into the ciphertext binary image held by the information hiding party by using a pattern block replacement, to generate a marked ciphertext binary image, wherein the secret information is generated by encrypting the information to be embedded according to an information hiding key; An information extraction and binary image recovery stage: when a receiving party obtains at least any k pieces of marked ciphertext binary images, wherein k is a positive integer satisfying 2<=k<n, the receiving party extracts the embedded secret information from the k pieces of marked ciphertext binary images by using a random lattice visual password decryption algorithm, and recovers the original binary image.

2. The method of claim 1, wherein, In the binary image encryption stage, the specific process of performing an encryption operation on each pixel in the original binary image to generate n pieces of ciphertext binary images comprises: randomly generating a bit wherein has a value of 0 or 1; generating a bit according to a pixel value of a current pixel in the original binary image , if the pixel value of the current pixel is 0, then equals , if the pixel value of the current pixel is 1, then equals 1 minus ; randomly generating a bit wherein has a value of 0 or 1; According to the value of the bit , the bit is generated, if the value of the bit is 0, the bit is equal to , if the value of the bit is 1, the bit is equal to 1 minus ; repeating the operations of randomly generating a bit and generating a current bit according to a previous bit until k bits are sequentially obtained , , , , is equal to bit . n-k bits with value 0 are generated, respectively denoted as , , ; The n bits obtained to Randomly arrange the n bits, and each bit after the arrangement is used as a pixel value of a corresponding position in the n ciphertext binary images, thereby completing the encryption of the current pixel. All pixels in the original binary image are subjected to the above encryption operation to obtain n pieces of ciphertext binary images.

3. The method of claim 1, wherein, In the information embedding stage, the specific process of embedding secret information into the ciphertext binary image by using a pattern block replacement to generate a marked ciphertext binary image comprises: The ciphertext binary image held by the information hiding party is divided into a plurality of non-overlapping pattern blocks with a size of 1x2, and the frequency of each pattern block is counted; According to the counted frequency of the pattern blocks, the pattern block with the highest frequency is selected as BM, the pattern block with the lowest frequency is selected as BF, and the pattern block with the second lowest frequency is selected as BFR; The pattern blocks BF and BFR in the ciphertext binary image are queried in the raster scan order, and a position mapping is generated, when the pattern block BF is scanned, the pattern block BF is modified to the pattern block BFR, and bit 1 is recorded as the value of the position in the position mapping, when the pattern block BFR is scanned, the pattern block BFR is kept unchanged, and bit 0 is recorded as the value of the position in the position mapping; The pattern block BM in the ciphertext binary image is queried in the raster scan order, the secret information is embedded according to the bits of the secret information and the generated position mapping, the bits of the secret information are embedded first, and then the bits of the position mapping are embedded, when the current bit of the secret information is 0, the pattern block BM is kept unchanged, when the current bit of the secret information is 1, the pattern block BM is modified to the pattern block BF, the information embedding operation is completed, and a marked ciphertext binary image is obtained.

4. The method of claim 1, wherein, In the information extraction and binary image recovery stage, the specific process of extracting the embedded secret information from the k pieces of marked ciphertext binary images by the receiving party comprises: The k pieces of marked ciphertext binary images obtained are respectively divided into a plurality of non-overlapping pattern blocks with a size of 1x2. According to the raster scan order, the mode block BM and the mode block BF in each marked ciphertext binary image are queried, when the queried mode block is BM, bit 0 is extracted, when the queried mode block is BF, bit 1 is extracted, and the queried mode block BF is modified as the mode block BM; All bits extracted from the k marked ciphertext binary images are combined to obtain a bit sequence containing secret information and a position mapping; The secret information corresponding bit part and the position mapping corresponding bit part are separated from the bit sequence, the secret information corresponding bit part is decrypted according to an information hiding key to obtain the original information to be embedded.

5. The method of claim 4, wherein, In the information extraction and binary image recovery stage, the specific process of recovering the original binary image by the receiver includes: The k marked ciphertext binary images after the secret information extraction are divided into a plurality of non-overlapping mode blocks with a size of 1*2 respectively; According to the raster scan order, the mode block BFR in each marked ciphertext binary image is queried, and when the bit value of the current position in the separated position mapping corresponding bit part is 0, the mode block BFR is kept unchanged, and when the bit value of the current position in the position mapping corresponding bit part is 1, the mode block BFR is modified as the mode block BF; An exclusive OR operation is performed on the L-enciphered binary image after the above-mentioned pattern block adjustment, wherein , reconstruction of the original binary image is achieved.

6. The method of claim 5, wherein, When L=n, the ciphertext binary image after the mode block adjustment is subjected to an exclusive or operation to realize the lossless reconstruction of the original binary image.

7. The method of claim 1, wherein, The size of the original binary image is h*w, wherein h is the height of the original binary image, w is the width of the original binary image, and h and w are both positive integers, and the size of each ciphertext binary image generated by encryption is h*w.

8. The method of claim 1, wherein, In the binary image encryption stage, the original binary image input by all parties is at least one of a binary image corresponding to an electronic document and a binary image corresponding to a scanned text.

9. The method of claim 1, wherein, Before performing the information embedding operation, the information hiding party needs to perform integrity verification on the ciphertext binary image held by itself, and after confirming that the ciphertext binary image is not tampered, the subsequent mode block division and information embedding operation are performed.

10. The method of claim 1, wherein, When the receiver obtains the marked ciphertext binary image, the identity of each information hiding party sending the marked ciphertext binary image needs to be verified, and after confirming that the identity of the information hiding party is legal, the corresponding marked ciphertext binary image is received.

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