A method for information hiding and intelligence transmission based on lattice cipher signature fields

Abstract

This invention discloses a method for information hiding and intelligence transmission based on lattice cipher signature fields. This method allows both communicating parties to simultaneously extract secret information upon correct signature verification, thereby achieving information hiding and communication within the lattice cipher protocol's signature field. This invention records all operations of both communicating parties, ensuring traceable operational traceability. Furthermore, this invention constructs a client and a server, with the server managing the client's information and operations. The client can communicate as both an intelligence sender and receiver. Based on the fault tolerance of lattice ciphers, this invention achieves lossless extraction of secret information and recovery of the carrier without requiring any external information. It also improves upon the classic differential extended steganography scheme, ensuring a high information embedding bit rate even with a small number of carriers.

Description

Technical Field

[0001] This invention relates to the field of information hiding technology, and specifically to an information hiding intelligence transmission method based on lattice cryptographic signature fields. Background Technology

[0002] When discussing the innovative directions of current information hiding and intelligence transmission technologies, traditional methods often focus on two core areas of image processing: the spatial domain and the frequency domain. Classic spatial domain techniques, such as Least Significant Bit (LSB) embedding, while simple and easy to implement, are susceptible to detection by statistical methods like chi-square analysis due to their direct modification of the least significant bit of the image pixel value, thus exposing the presence of steganography. On the other hand, frequency domain techniques, such as Discrete Cosine Transform (DCT) and Discrete Fourier Transform (DFT) domain information hiding, while achieving information embedding with low distortion, are highly dependent on carriers with complex variable correlations, such as images, limiting their versatility and flexibility. Crucially, these techniques fail to fundamentally solve the problem of unavoidable permanent distortion of the original carrier after information embedding, a deficiency that significantly increases the risk of detection by third parties during information transmission.

[0003] Furthermore, with the rapid development of quantum computing technology, traditional intelligence transmission systems based on modern cryptography are facing unprecedented security challenges. The rise of quantum cryptography indicates the vulnerability of traditional encryption methods in a quantum computing environment, forcing us to seek more secure and reliable intelligence protection strategies. Summary of the Invention

[0004] The purpose of this invention is to overcome the aforementioned deficiencies in the prior art and provide an information-hidden intelligence transmission method based on lattice cryptography signature fields. This method integrates information hiding technology into an advanced lattice cryptographic framework, utilizing the unique mathematical complexity and security of lattice cryptography to achieve the covert embedding and efficient transmission of secret information.

[0005] The objective of this invention can be achieved by adopting the following technical solutions:

[0006] A method for information-hidden intelligence transmission based on lattice cipher signature fields, the method comprising the following steps:

[0007] S1. The intelligence sender uses the system establishment algorithm Setup(Info) to establish the system. Info is the input, which is the identity information of the intelligence sender. After the identity information is successfully verified, the system is established and run. The intelligence sender is both the sender of intelligence and the producer of public and private keys and the sender of public keys.

[0008] S2. The intelligence receiver uses the system establishment algorithm Setup(Info) to establish the system. Info is the input, which is the identity information of the intelligence receiver. After the identity information is successfully verified, the system is established and run. The intelligence receiver is both the receiver of intelligence and the receiver of public key.

[0009] S3. The intelligence sender uses the SendPKE function to generate a public key Pk and a private key Sk, keeps the private key Sk private, and sends the public key Pk to the intelligence receiver.

[0010] S4. The intelligence sender selects the desired transmission method for intelligence transmission. There are two transmission methods: a signature method without secret information and a signature method with secret information. If the intelligence sender selects the signature method without secret information, the sender uses its self-generated private key Sk as the signing key and calls the function NoSecretSign(Message, Sk) to sign the plaintext Message, generating a signature S. The system then sends the plaintext and the generated signature to the intelligence receiver. The input to the function NoSecretSign(Message, Sk) is the plaintext Message and the private key Sk, and the output is the signature S. The signature S belongs to the signature field and is in matrix form. Each element in the matrix stores the corresponding data element, and each data element is stored in decimal in the matrix. If the intelligence sender selects the signature method with secret information, the function Embed is called. The Sign(Message,Sk,Secret,LenSecret) function generates a signature S, and then uses the differential extended steganography function DE_HS_n_H(Carrier,Secret) to hide information on the signature, generating a signature S′. The plaintext and the new signature S′ are then sent to the intelligence receiver. The input of the EmbedSign(Message,Sk,Secret,LenSecret) function is the plaintext Message, the private key Sk, the secret information Secret, and the length of the secret information LenSecret. The output is the signature S. The input of the differential extended steganography function DE_HS_n_H(Carrier,Secret) is the carrier Carrier and the secret information Secret. The carrier Carrier corresponds to the signature S and the secret information Secret corresponds to the information to be hidden. The output is the new signature S′.

[0011] S5. After receiving the plaintext and signature, the intelligence receiver selects the desired processing method to verify the information. There are two verification methods: direct verification and verification after extracting secret information. If direct verification is selected, the direct verification function Verrify(S, Message, Pk) is called to directly verify and obtain the verification result. The input of the function Verrify(S, Message, Pk) is the signature S, the plaintext Message, and the public key Pk, and the output is the verification result. If verification after extracting secret information is selected, the differential extension extraction function DE_HS_n_E(S) is first called to extract the secret information. The input of the function DE_HS_n_E(S) is the signature S, and the output is the secret information. Then, the function Verrify(S, Message, Pk) is called to obtain the verification result.

[0012] Furthermore, in the system establishment algorithm Setup(Info), the intelligence receiver or sender inputs personal identity information Info by connecting to the backend database. The personal identity information Info is then verified against the information in the backend database. The success of the system establishment is determined based on the verification result. If verification is successful, the intelligence receiver or sender's system is established, generating an intelligence receiver database and an intelligence sender database, and system functions are invoked. The intelligence receiver database includes a public key data table and a plaintext and signature table, while the intelligence sender database includes a private key data table. If verification fails, the system cannot be established, and the information-hidden intelligence transmission method cannot be initiated.

[0013] Furthermore, in the implementation of the SendPKE function, the system generates random public-private key pairs. Both the public and private keys are in matrix form, and the elements in the matrix are all decimal numbers. The generated public key is transmitted to the public key data table of the intelligence receiver by connecting to the backend database, while the private key is stored in the private key data table of the intelligence sender. The public key data table stores all public keys received by the intelligence receiver, and the private key data table stores all private keys saved by the intelligence sender.

[0014] Furthermore, in the process of sending NoSecretSign(Message, Sk) without secret information signature by the intelligence sender, the system connects to the backend database, selects the private key used for signing from the private key data table, inputs the message to be signed (Message), and then the system signs the message to generate a signature (S). The message (Message), signature (S), and other descriptive information are encapsulated and sent to the plaintext and signature tables in the intelligence receiver's database. The other descriptive information includes the length of the secret information (LenSecret), where the length of the secret information in the signature information without secret information is 0.

[0015] Furthermore, in the direct verification function Verify(S, Message, Pk), by connecting to the backend database, the intelligence receiver selects the message Message to be verified and the signature S from the plaintext and signature information table, selects the public key corresponding to the signature from the public key data table, and the system uses the signature S to verify the message Message, obtains the verification result, and outputs it.

[0016] Furthermore, in the implementation of the differential extended steganography function DE_HS_n_H(Carrier, Secret), the input carrier Carrier is the signature S, and the Secret is the information to be hidden. The matrices S1 and S2 of the signature S = {S1, S2} are concatenated end-to-end to form an N-dimensional square matrix. First, each element is preprocessed by adding a constant Num, where Num = 128 or 256. Then, adjacent elements in each row of the preprocessed matrix are grouped pairwise. Each row has... There are 1 group, with a total of 1 group. There are 1 group, where N is the dimension of the square matrix formed by concatenating matrices S1 and S2 end to end. Calculate the difference h and mean i for each group, construct matrix H and mean matrix I, and draw a histogram of the difference distribution. Then, the hidden information `Secret` is converted into binary information according to ASCII code format. The length of the binary information, `LenSecret`, is calculated. Following the raster scan order, groups with smaller absolute differences and the ability to expand into M bits of all-1 secret information are selected from the difference histogram. M is a constant with a limited range of values ​​(M = 1, 2, 4, or 8). The maximum absolute value of the selected difference, `Delta`, is determined, and the histogram is shifted accordingly. The two least significant bits (LSBs) of the four corner elements of the shifted matrix are retained and sequentially added to the end of the hidden information `Secret` to generate `Secret'`. `Delta` is converted into an 8-bit binary number and sequentially embedded into the two least significant LSBs of the four corner elements. Then, `Secret'` is split into groups of M bits, where M is a constant with a limited range of values ​​(M = 1, 2, 4, or 8). Following the raster scan order, a secret information group is embedded into each selected difference group. The generated signature after embedding is then processed by adding `Num` to each element value to generate a signature `S'` containing the secret information. The system sends the newly generated signature field and plaintext to the plaintext and signature table in the intelligence recipient's database.

[0017] Furthermore, during the implementation of the function `EmbedSign(Message, Sk, Secret, LenSecret)` in the signature method containing secret information, the intelligence sender connects to the backend database. The intelligence sender selects the private key used for signing from the private key data table. The intelligence sender inputs the message `Message` to be signed, and the system signs the message `Message` to generate a signature `S`. The intelligence sender inputs the secret information to be transmitted `Secret` and the length of the secret information `LenSecret`. The function `DE_HS_n_H(Carrier, Secret)` is used to embed information into the obtained signature `S` to obtain a new signature `S′`, where signature `S` serves as the carrier `Carrier`. The system encapsulates the message `Message`, the new signature `S′`, and other descriptive information and sends them to the plaintext and signature tables in the intelligence receiver's database. The other descriptive information includes the length of the secret information `LenSecret`, and the length of the secret information embedded is not zero.

[0018] Furthermore, in the implementation of the differential expansion extraction function DE_HS_n_E(S), the intelligence receiver selects a signature S′ containing embedded secret information from the plaintext and signature table. The system preprocesses the elements in the signature S′, which is in the form of a square matrix. Each element in the square matrix is ​​subtracted from Num. Two LSBs are extracted from the four corner elements of the square matrix of the signature S′ in order, concatenated to form Delta, and the difference matrix H′ and mean matrix I′ are calculated. The difference range of the embedded secret information is determined based on Delta. The grouping of the embedded secret information is determined according to the raster scanning order, and the expansion bit depth is calculated accordingly. M extracts and concatenates the secret information according to the differential expansion recovery formula to form Secret′. After extraction, the group is subjected to histogram inverse shift operation to restore the histogram. The restored group is restored to the signature matrix after histogram inverse shift to generate S″. The system extracts the last eight bits of binary information of Secret′, and the rest is the secret information Secret. The last eight bits of LSB information are restored to S″ in order to generate the original signature S. Finally, the system groups the secret information Secret into 8-bit groups, converts them into decimal ASCII code, and returns the embedded secret information.

[0019] The present invention has the following advantages and effects compared with the prior art:

[0020] (1) This invention can both correctly verify the authenticity of the signature and correctly extract the encrypted information.

[0021] (2) In this invention, the theoretical maximum embedding bit rate of the traditional differential expansion scheme is 0.5, while this invention can exceed this maximum embedding bit rate when selecting 2 and 4 embedding bits. Therefore, under the premise of selecting an appropriate number of embedding bits and the element distribution range being relatively small, this information hiding scheme can embed a large amount of data on a small carrier.

[0022] (3) This invention implements an intelligence transmission method based on the signature field of a lattice cryptography protocol, wherein the secret information carrier is the signature field of the lattice cryptography protocol. It ensures that even if irreversible distortion is caused to the signature field, the signature can still be successfully verified and the secret information can be extracted, and makes the operation of embedding secret messages less likely to be detected by a man in the middle. Attached Figure Description

[0023] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0024] Figure 1 This is a logical structure diagram of an intelligence transmission system based on lattice cryptography signature field information hiding disclosed in an embodiment of the present invention;

[0025] Figure 2 This is a flowchart of a client subsystem based on lattice cryptography signature field information hiding disclosed in an embodiment of the present invention;

[0026] Figure 3 This is an example of a histogram after preprocessing (n=128) in a lattice-ciphertext domain intelligence transmission method disclosed in an embodiment of the present invention;

[0027] Figure 4 This is an example of a histogram after embedding information in a lattice-based ciphertext field intelligence transmission method disclosed in this embodiment of the invention;

[0028] Figure 5 This is a flowchart of a secret information embedding process based on lattice cryptography signature field information hiding disclosed in an embodiment of the present invention;

[0029] Figure 6 This is a flowchart of a secret information extraction process based on lattice cryptography signature field information hiding disclosed in an embodiment of the present invention;

[0030] Figure 7 This is a flowchart of a client subsystem public key sending program based on lattice cryptography signature field information hiding, as disclosed in an embodiment of the present invention.

[0031] Figure 8This is a flowchart of a client subsystem for sending information signatures without secret information based on lattice cryptography signature field information hiding, as disclosed in an embodiment of the present invention.

[0032] Figure 9 This is a flowchart of an information signature sending procedure for a client subsystem based on lattice cryptography signature field information hiding, which is disclosed in an embodiment of the present invention.

[0033] Figure 10 This is a flowchart of a client subsystem verification procedure based on lattice cryptography signature field information hiding, as disclosed in an embodiment of the present invention.

[0034] Figure 11 This is a flowchart of a client subsystem extraction procedure based on lattice cryptography signature field information hiding, as disclosed in an embodiment of the present invention.

[0035] Figure 12 This is a flowchart of an intelligence transmission method based on lattice cryptography signature field information hiding disclosed in an embodiment of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0037] Example 1

[0038] With the continuous development of cryptographic technology, more and more enterprises and individuals need a dedicated, absolutely secure intranet-based intelligence transmission system. This type of system does not connect to the network, but it can cause some distortion to the transmission medium, making hidden information easier to detect. Therefore, reversible information hiding methods have been proposed. However, in reality, such reversible information hiding methods are very costly, and with the development of quantum cryptography, they pose a threat to traditional cryptographic protocols for information transmission. Therefore, how to ensure that the embedding of secret information is imperceptible and that the transmission system is more secure and reliable directly affects the practicality of intelligence transmission systems in various fields.

[0039] This embodiment addresses the above problems by studying the signature field generated by the lattice cipher hash-and-sign algorithm, proposing an information hiding function DE_HS_n for the signature field, and designing an intelligence transmission method based on lattice cipher signature field information hiding. This algorithm transfers the principle of image information hiding to signature field information hiding. By converting the signature field into two dimensions, extracting the LSB information at the corresponding positions and concatenating them into an information extraction key, secret information can be directly extracted without providing an additional key. Furthermore, the original image information is stored within the secret information. Through secret information extraction, lossless recovery of the signature can be achieved, ensuring that the embedding of secret information does not affect the signature field itself. This achieves both error-free transmission of the original signature and embedding a significant amount of secret information into the signature field.

[0040] The following is combined Figure 1-11 This embodiment provides a detailed explanation of the specific process of an intelligence transmission method based on lattice cryptography signature field information hiding.

[0041] When establishing communication between the two parties, the hash-and-sign algorithm of lattice cipher based on the fault-tolerant learning problem (LWE) and the short integer solution problem (SIS) is selected to construct the signature field. The parameters of the key generation algorithm are N=512 and q=1024.

[0042] A method for information-hidden intelligence transmission based on lattice cipher signature fields includes the following steps:

[0043] S1. The intelligence sender uses the system establishment algorithm Setup(Info) to establish the system. Info is the input, which is the identity information of the intelligence sender. After the identity information is successfully verified, the system is established and run. The intelligence sender is both the sender of intelligence and the producer of public and private keys and the sender of public keys.

[0044] S2. The intelligence receiver uses the system establishment algorithm Setup(Inf0) to establish the system. Info is the input, which is the identity information of the intelligence receiver. After the identity information is successfully verified, the system is established and run. The intelligence receiver is both the receiver of intelligence and the receiver of public key.

[0045] The following will combine Figure 1 Describe the implementation process of the system algorithm Setup(Inf0):

[0046] T1. Connect to the backend database;

[0047] T2. The intelligence recipient or intelligence sender enters their personal identification information Info.

[0048] T3. Verify the personal identification information (Info) with the backend database information;

[0049] T4. If the verification is successful, the intelligence receiver or intelligence sender system will be established, generating an intelligence receiver database and an intelligence sender database. The system functions can then be used. The intelligence receiver database includes a public key data table and a plaintext and signature table, while the intelligence sender database includes a private key data table. If the verification fails, the system cannot be established, and the information-hidden intelligence transmission method cannot be started.

[0050] Figure 1 The document indicates that the entire system will consist of three objects: a server, an intelligence receiver, and an intelligence sender, each with a corresponding backend database. The server uses the backend database to authenticate and manage users, while the intelligence receiver and sender transmit intelligence information based on the backend database.

[0051] S3. The intelligence sender uses the SendPKE function to generate a public key Pk and a private key Sk, keeps the private key Sk private, and sends the public key Pk to the intelligence receiver.

[0052] The following will combine Figure 7 The process description of the implementation of the public key sending function SendPKE is as follows:

[0053] D1. Connect to the backend database;

[0054] D2. The system generates random public-private key pairs; both the public and private keys are in matrix form, and the elements in the matrix are all decimal numbers.

[0055] D3. The system transmits the generated public key to the public key data table of the intelligence receiver, while the private key is stored in the private key data table of the intelligence sender. The public key data table stores all the public keys received by the intelligence receiver, and the private key data table stores all the private keys saved by the intelligence sender.

[0056] S4. The intelligence sender selects the desired transmission method for intelligence transmission. There are two transmission methods: a signature method without secret information and a signature method with secret information. If the intelligence sender selects the signature method without secret information, the sender uses its self-generated private key Sk as the signing key and calls the function NoSecretSign(Message, Sk) to sign the plaintext Message, generating a signature S. The system then sends the plaintext and the generated signature to the intelligence receiver. The input to the function NoSecretSign(Message, Sk) is the plaintext Message and the private key Sk, and the output is the signature S. The signature S belongs to the signature field and is in matrix form. Each element in the matrix stores the corresponding data element, and each data element is stored in decimal in the matrix. If the intelligence sender selects the signature method with secret information, the function Embed is called. The `Sign(Message,Sk,Secret,LenSecret)` function generates a signature `S`, and then uses the differential extended steganography function `DE_HS_n_H(Carrier,Secret)` to hide information on the signature, generating a signature `S′`. The plaintext and the new signature `S′` are then sent to the intelligence recipient. The inputs of the function `EmbedSign(Message,Sk,Secret,LenSecret)` are the plaintext `Message`, the private key `Sk`, the secret message `Secret`, and the length of the secret message `LenSecret`, and the output is the signature `S`. The inputs of the differential extended steganography function `DE_HS_n_H(Carrier,Secret)` are the carrier `Carrier` and the secret message `Secret`. The carrier `Carrier` corresponds to the signature `S`, and the secret message `Secret` corresponds to the information to be hidden. The output is the new signature `S′`.

[0057] The following will combine Figure 8 Describe the process by which the intelligence sender sends a NoSecretSign(Message, Sk) message without a secret signature:

[0058] E1. Connect to the backend database;

[0059] E2. The intelligence sender selects the private key used for signing from the private key data table;

[0060] E3. Enter the message to be signed (Message);

[0061] E4. The system signs the information and generates a signature S;

[0062] E5. Encapsulate the message Message, signature S, and other descriptive information and send them to the plaintext and signature table in the intelligence recipient's database. The other descriptive information includes the length of the secret information LenSecret. The length of the secret information in the signature information without secret information is 0.

[0063] The following will combine Figure 9 Describe the implementation process of the EmbedSign(Message, Sk, Secret, LenSecret) function, which sends secret information using a signature method:

[0064] G1, Connect to the backend database;

[0065] G2. The intelligence sender selects the private key used for signing from the private key data table;

[0066] G3, The intelligence sender enters the message to be signed;

[0067] G4. The system signs the message Message to generate a signature S;

[0068] G5. The intelligence sender inputs the secret information to be transmitted, Secret, and the length of the secret information, LenSecret. The information is embedded using DE_HS_n_H(Carrier,Secret) on the obtained signature S to obtain a new signature S′, where the signature S serves as the carrier.

[0069] G6. The system encapsulates the message Message, the new signature S′, and other descriptive information and sends them to the plaintext and signature table in the intelligence receiver's database. The other descriptive information includes the secret message length LenSecret, and the length of the secret message embedded with the secret message is not 0.

[0070] The following will combine Figure 3 , Figure 5 To describe the process of the differential extended steganography function DE_HS_n_H(Carrier, Secret):

[0071] H1. Concatenate the first and last elements of the signature matrix S = {S1, S2} into an N-dimensional square matrix. First, preprocess each element by adding a constant Num (Num = 128 or 256). Then, group adjacent elements in each preprocessed row pairwise. Each row contains... There are 1 group, with a total of 1 group. There are 1 group, where N is the dimension of the square matrix formed by concatenating matrices S1 and S2 end to end. Calculate the difference h and mean i for each group, construct the difference matrix H and mean matrix I, and draw the difference distribution histogram.

[0072] H2. Convert the hidden information Secret into binary information according to ASCII code format, and calculate the length of the binary information LenSecret. According to the raster scan order, select the group with the smaller absolute value of the difference from the difference histogram and expandable with M bits of all 1 secret information. M is a constant with a limited value range, M = 1, 2, 4 or 8. Determine the maximum absolute value of the selected difference Delta, and shift the histogram accordingly. Retain the two LSBs of the four corner elements of the shifted matrix. The LSBs are the least significant bits. They are retained at the end of the hidden information Secret in order to generate Secret'. Convert Delta into an 8-bit binary number and embed it into the two least significant bits of the four corner elements in order. Then split Secret' into groups of M bits. M is a constant with a limited value range, M = 1, 2, 4 or 8. According to the raster scan order, embed a secret information group into each selected difference group.

[0073] H3. The signature generated after embedding is further processed, that is, Num is added to the value of each element to generate a signature S′ with secret information.

[0074] H4. The system sends the newly generated signature field and plaintext to the plaintext and signature table in the intelligence recipient's database.

[0075] Figure 5 Embedding secret information into the process.

[0076] S5. After receiving the plaintext and signature, the intelligence receiver selects the desired processing method to verify the information. There are two verification methods: direct verification and verification after extracting secret information. If direct verification is selected, the direct verification function Verify(S, Message, Pk) is called to directly verify and obtain the verification result. The input of the function Verify(S, Message, Pk) is the signature S, the plaintext Message, and the public key Pk, and the output is the verification result. If verification after extracting secret information is selected, the differential extension extraction function DE_HS_n_E(S) is first called to extract the secret information. The input of the function DE_HS_n_E(S) is the signature S, and the output is the secret information. Then, the function Verify(S, Message, Pk) is called to obtain the verification result.

[0077] The following will combine Figure 10 Describe the process of the direct verification function Verify(S, Message, Pk):

[0078] F1: Connect to the backend database;

[0079] F2. The intelligence receiver selects the message to be verified (Message) and the signature (S) from the plaintext and signature information table, and selects the public key corresponding to the signature from the public key data table.

[0080] F3. The system uses signature S to verify message Message, obtains the verification result, and outputs it.

[0081] The following will combine Figure 6 and Figure 11 To describe the process of the differential expansion extraction function DE_HS_n_E(S):

[0082] N1. The intelligence recipient selects a signature S′ containing secret information from the plaintext and signature table;

[0083] N2. The system preprocesses the elements in the S′ square matrix by subtracting Num from each element. The four corner elements of the square matrix S′ are then extracted in order, their two LSBs are extracted, concatenated to form Delta, and the difference matrix H′ and the mean matrix I′ are calculated.

[0084] N3. Based on Delta, determine the difference range of the embedded secret information, determine the group of embedded secret information according to the grating scanning order, extract and splice the secret information according to the differential expansion recovery formula based on the extension bit M, and form Secret′. After extraction, perform histogram reverse shift operation on the group and restore the histogram; restore the restored group to the signature matrix after histogram reverse shift to generate S″.

[0085] N4. The system extracts the last eight bits of binary information from Secret′, generates the original secret information Secret, and restores them into S″ in order to generate the original signature S;

[0086] N5. The system groups the secret information (Secret) into 8-bit blocks, converts them into decimal ASCII codes, and returns the embedded secret information.

[0087] Figure 6 This is the process for extracting classified information.

[0088] Figure 11 This describes the process for extracting and verifying signatures containing embedded secret information.

[0089] Example 2

[0090] In Example 2, except for step H2, the same steps as in Example 1 are taken. In step H2 of Example 2, groups of extended 1, 2, 4, and 8 all-1 secret information are selected respectively.

[0091] Table 1. Average capacity of embedding different bit lengths after shift strategy improvement

[0092] Embedded bits Embeddable location Theoretical capacity Actual capacity Embedding bit rate 1 512.0 512 512 0.5000 2 511.99 1024 1022.92 0.9990 4 376.19 1626.92 1201.64 1.1734 8 28.17 186.96 111.52 0.1089

[0093] To achieve the maximum embedding capacity and embedding bit rate, experimental results from the embodiments show that the optimal embedding bit length in this invention should be 4 bits as described in this invention. Table 1 shows that after improving the histogram shifting strategy, this invention significantly improves both the theoretical and actual capacity, and the actual embedding bit rate reaches over 1, far exceeding the maximum embedding bit rate of 0.5 of the traditional differential extension scheme, thus greatly improving the information embedding capacity. Figure 4 The histogram of embedded information after the shift strategy improvement shows that the histogram has become more compact, avoiding difference and element overflow.

[0094] In a company intranet environment, a specific example of implementing an intelligence transmission mechanism based on lattice cryptographic signature field information hiding is as follows: Figure 1 As shown in the diagram. This diagram contains three entities, and each entity performs the following operations.

[0095] (1) Intelligence Sender. This is the sender of intelligence information, using the intelligence client subsystem to sign and hide the intelligence information before sending it to the connected client subsystem. Since the sending client needs to store the private key used by the signature algorithm, which comes from itself, a database needs to be established and managed for this client.

[0096] (2) Intelligence Receiver. This is the recipient of intelligence information, using the intelligence client subsystem to extract and verify secret information from the data. Since it needs to store the received information and the public key used by the verification algorithm (which originates from the intelligence sender), a database needs to be established and managed for this client.

[0097] (3) Server side. Manage client users and record all information about system usage to control access to the system and ensure system security.

[0098] In summary, to resist quantum cryptography attacks and overcome the drawbacks of traditional information hiding methods, the above embodiments construct an intelligence transmission method based on lattice cryptography signature fields. This invention supports the use of lattice cryptography protocols in intelligence transmission systems to achieve communication between two parties. The information communicated by both parties is signed before transmission to ensure information security. S is the signature generated using a lattice cryptographic hash-and-sign signature algorithm, overcoming the threat of quantum cryptography. Simultaneously, this invention chooses the signature field S as the information hiding carrier and uses an N-bit differential extended steganography scheme with histogram shift for information hiding. This invention does not require an additional key and can directly extract secret information. Furthermore, this invention can achieve lossless signature recovery, ensuring that the embedding of secret information does not affect the signature field itself, thus achieving error-free transmission of the original signature while embedding a significant amount of secret information into the signature field.

[0099] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for information hiding and intelligence transmission based on lattice cipher signature fields, characterized in that, The information-hidden intelligence transmission method includes the following steps: S1. The intelligence sender uses the system establishment algorithm Setup(Info) to establish the system. Info is the input, which is the identity information of the intelligence sender. After the identity information is successfully verified, the system is established and run. The intelligence sender is both the sender of intelligence and the producer of public and private keys and the sender of public keys. S2. The intelligence receiver uses the system establishment algorithm Setup(Info) to establish the system. Info is the input, which is the identity information of the intelligence receiver. After the identity information is successfully verified, the system is established and run. The intelligence receiver is both the receiver of intelligence and the receiver of public key. S3. The intelligence sender uses the SendPKE function to generate a public key Pk and a private key Sk, keeps the private key Sk private, and sends the public key Pk to the intelligence receiver. S4. The intelligence sender selects the desired transmission method for intelligence transmission. There are two transmission methods: a signature method without secret information and a signature method with secret information. If the intelligence sender selects the signature method without secret information, the sender uses its self-generated private key Sk as the signature key and calls the function NoSecretSign(Message, Sk) to sign the plaintext Message, generating a signature S. The system then sends the plaintext and the generated signature to the intelligence receiver. The input to the function NoSecretSign(Message, Sk) is the plaintext Message and the private key Sk, and the output is the signature S. The signature S belongs to the signature field and is in matrix form. Each element in the matrix stores the corresponding data element, and each data element is stored in decimal in the matrix. If the intelligence sender selects the signature method with secret information, the function EmbedSign(Message, Sk, Secret, LenSecret) is called to generate the signature S. The differential extended steganography function DE_HS_n_H(Carrier, Secret) is then used to hide the information on the signature before generating the final signature. Named S′, the plaintext and the new signature S′ are sent to the intelligence recipient. The function EmbedSign(Message, Sk, Secret, LenSecret) takes plaintext Message, private key Sk, secret information Secret and the length of secret information LenSecret as inputs and outputs signature S. The differential extended steganography function DE_HS_n_H(Carrier, Secret) takes carrier Carrier and secret information Secret as inputs. Carrier corresponds to signature S and secret information Secret corresponds to the information to be hidden. The output is the new signature S′. S5. After receiving the plaintext and signature, the intelligence receiver selects the desired processing method to verify the information. There are two verification methods: direct verification and verification after extracting secret information. If direct verification is selected, the direct verification function Verify(S,Message,Pk) is called to directly verify and obtain the verification result. The input of the function Verify(S,Message,Pk) is the signature S, the plaintext Message, and the public key Pk, and the output is the verification result. If verification after extracting secret information is selected, the differential extension extraction function DE_HS_n_E(S) is first called to extract the secret information. The input of the function DE_HS_n_E(S) is the signature S, and the output is the secret information. Then, the function Verify(S,Message,Pk) is called to obtain the verification result.

2. The information-hiding intelligence transmission method based on lattice cryptographic signature fields according to claim 1, characterized in that, The system establishes the algorithm Setup(Info), and the implementation process is as follows: T1. Connect to the backend database; T2. The intelligence recipient or intelligence sender enters their personal identification information Info. T3. Verify the personal identification information (Info) with the backend database information; T4. If the verification is successful, the system of the intelligence receiver or the intelligence sender will be established, generating an intelligence receiver database and an intelligence sender database, and the system functions will be invoked. The intelligence receiver database includes a public key data table and a plaintext and signature table, while the intelligence sender database includes a private key data table. If the verification fails, the system cannot be established and the information hiding intelligence transmission method cannot be started.

3. The information-hiding intelligence transmission method based on lattice cryptographic signature fields according to claim 2, characterized in that, The implementation process of the SendPKE function for sending public keys is as follows: D1. Connect to the backend database; D2. The system generates random public-private key pairs; both the public and private keys are in matrix form, and the elements in the matrix are all decimal numbers. D3. The system transmits the generated public key to the public key data table of the intelligence receiver, while the private key is stored in the private key data table of the intelligence sender. The public key data table stores all the public keys received by the intelligence receiver, and the private key data table stores all the private keys saved by the intelligence sender.

4. The information-hiding intelligence transmission method based on lattice cipher signature field according to claim 3, characterized in that, The process of the intelligence sender sending NoSecretSign(Message, Sk) without a secret signature is as follows: E1. Connect to the backend database; E2. The intelligence sender selects the private key used for signing from the private key data table; E3. Enter the message to be signed (Message); E4. The system signs the information and generates a signature S; E5. Encapsulate the message Message, signature S, and other descriptive information and send them to the plaintext and signature table in the intelligence recipient's database. The other descriptive information includes the length of the secret message LenSecret, and the length of the secret message in the signature information without secret information is 0.

5. The information-hiding intelligence transmission method based on lattice cryptographic signature fields according to claim 4, characterized in that, The direct verification function Verify(S,Message,Pk) works as follows: F1: Connect to the backend database; F2. The intelligence receiver selects the message to be verified (Message) and the signature (S) from the plaintext and signature information table, and selects the public key corresponding to the signature from the public key data table. F3. The system uses signature S to verify message Message, obtains the verification result, and outputs it.

6. The information-hiding intelligence transmission method based on lattice cipher signature field according to claim 5, characterized in that, The differential extended steganography function DE_HS_n_H(Carrier, Secret) is implemented as follows, where the input carrier Carrier is the signature S, and Secret is the information to be hidden: H1. Concatenate the first and last elements of the signature matrix S = {S1, S2} into an N-dimensional square matrix. First, preprocess each element by adding a constant Num (Num = 128 or 256). Then, group adjacent elements in each preprocessed row pairwise. Each row has... There are 1 group, with a total of 1 group. There are 1 group, where N is the dimension of the square matrix formed by concatenating matrices S1 and S2 end to end. Calculate the difference h and mean i for each group, construct the difference matrix H and mean matrix I, and draw the difference distribution histogram. H2. Convert the hidden information Secret into binary information according to ASCII code format, and calculate the length of the binary information LenSecret. According to the raster scan order, select the group with the smaller absolute value of the difference from the difference histogram and expandable with M bits of all 1 secret information. M is a constant with a limited value range, M = 1, 2, 4 or 8. Determine the maximum absolute value of the selected difference Delta, and shift the histogram accordingly. Retain the two LSBs of the four corner elements of the shifted matrix. LSB represents the least significant bit. Retain them in order at the end of the hidden information Secret to generate Secret'. Convert Delta into an 8-bit binary number and embed it into the two least significant LSBs of the four corner elements in order. Then split Secret' into groups of M bits. M is a constant with a limited value range, M = 1, 2, 4 or 8. According to the raster scan order, embed a secret information group into each selected difference group. H3. The signature generated after embedding is further processed, that is, Num is added to the value of each element to generate a signature S′ with secret information. H4. The system sends the newly generated signature field and plaintext to the plaintext and signature table in the intelligence recipient's database.

7. The information-hiding intelligence transmission method based on lattice cipher signature field according to claim 6, characterized in that, The implementation process of the EmbedSign(Message, Sk, Secret, LenSecret) function, which sends secret information using a signature method, is as follows: G1, Connect to the backend database; G2. The intelligence sender selects the private key used for signing from the private key data table; G3, The intelligence sender enters the message to be signed; G4. The system signs the message Message to generate a signature S; G5. The intelligence sender inputs the secret information to be transmitted, Secret, and the length of the secret information, LenSecret. The information is embedded in the obtained signature S using the function DE_HS_n_H(Carrier,Secret) to obtain a new signature S′, where the signature S serves as the carrier. G6. The system encapsulates the message Message, the new signature S′, and other descriptive information and sends them to the plaintext and signature table in the intelligence receiver's database. The other descriptive information includes the secret message length LenSecret, and the length of the secret message embedded with the secret message is not 0.

8. The information-hiding intelligence transmission method based on lattice cipher signature field according to claim 7, characterized in that, The implementation process of the differential expansion extraction function DE_HS_n_E(S) is as follows: N1. The intelligence recipient selects a signature S′ containing secret information from the plaintext and signature table; N2. The system preprocesses the elements in the signature S′. The signature S′ is in the form of a square matrix. Each element in the square matrix is ​​subtracted from Num. The four corner elements of the signature S′ square matrix are extracted in order, and two LSBs are extracted respectively. They are concatenated to form Delta, and the difference matrix H′ and the mean matrix I′ are calculated. N3. Based on Delta, determine the difference range of embedded secret information, determine the grouping of embedded secret information according to the grating scanning order, extract and splice the secret information according to the differential expansion recovery formula based on the extension bit M, and form Secret′. After extraction, perform histogram reverse shift operation on the grouping and restore the histogram. The recovered groups are restored to the signature matrix after the histogram is shifted in reverse, generating S. ″ ; N4. The system extracts the last eight bits of the binary information of Secret', and the remaining bits are the secret information Secret. The last eight LSB bits are then restored to their corresponding S bits in sequence. ″ In the process, the original signature S is generated; N5. The system groups the secret information (Secret) into 8-bit blocks, converts them into decimal ASCII codes, and returns the embedded secret information.

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