CN103377458A - Geographic space data watermarking method based on byte streams - Google Patents

Abstract

The present invention relates to a geospatial data watermarking method based on byte streams. The method is based on the fact that geospatial data is organized in units of byte streams in the process of computer carrier access and circulation, and introduces the idea of data encryption into In the design of the watermark algorithm, the idea of mathematical mapping is used to construct the watermark mapping function, that is, to establish the function of locating the watermark information bit according to the byte itself, so that the byte and the watermark information bit maintain a many-to-one mapping relationship, which is determined by the established mapping relationship The embedding position of the watermark information bit, and then embed the watermark information into the data byte by quantization. In watermark detection, the optimal watermark information is restored according to the principle of maximum membership degree. This method can not only effectively control the quality and accuracy of geospatial data, reduce the availability of geospatial data, but also effectively protect the copyright of geospatial data in the process of circulation, and play a role in tracking the source of data outflow.

Description

A Geospatial Data Watermarking Method Based on Byte Stream

technical field

The invention relates to the technical field of geographic information copyright protection, in particular to a byte stream-based geospatial data watermarking method. the

Background technique

Geospatial data is an indispensable strategic resource in national economy and national defense construction, and a supporting achievement of national infrastructure construction and earth science research. In recent years, as the process of digitization and networking of geospatial data has been accelerated, its dissemination and circulation in different places have become more and more convenient, which has also led to increasingly serious phenomena such as illegal use of geospatial data and copyright disputes. Therefore, how to effectively manage the use rights of geospatial data in the circulation process, protect its copyright and even track its use has become an important issue that needs to be solved urgently in the current geospatial information security. As an emerging data security technology in recent years, digital watermarking shows great potential in this respect. the

As a new information security technology, digital watermarking technology provides a feasible solution for the security protection of geospatial data. Digital watermarking refers to embedding watermark information in digital data, integrating watermark information with source data, and becoming an inseparable part of source data. This is used to determine the copyright owner, verify ownership, track infringement, authenticate the authenticity of the source of digital content, identify buyers, and provide other additional information about digital content, etc. At the same time, it plays an important role in strengthening the sense of responsibility, deterring illegal acts, and having evidence-based and fast investigations. The role of digital watermarking technology in military security and national security has been highly valued by national government agencies. the

Digital watermarking has been widely used in the security protection of image, graphics, video, audio and other fields, and it has also been used in surveying and mapping related fields in recent years. the

At present, there have been many researches on the digital watermarking technology of geospatial data. These researches have achieved some results, but they mainly focus on the copyright protection, use tracking and content authentication of digital watermarking technology in geospatial data. The solutions proposed by these researches are all based on the traditional digital watermarking idea, which is a passive data copyright management and usage tracking mechanism, which cannot control the use rights of geospatial data in the circulation process, and cannot actively control users to correct data. The purpose of geospatial data access rights does not take into account the diversity of geospatial data sources, and the complexity of watermark embedding methods for different characteristic data. the

Based on the analysis of the current geospatial data digital watermark embedding method, the present invention solves the problems of the use authority control and flow tracking of the geospatial data in the circulation process, and better protects the security of the geospatial data. the

Contents of the invention

The purpose of the present invention is to introduce the idea of data encryption into the design of watermark embedding method according to the circulation characteristics of geospatial data, which can not only effectively control the quality and precision of geospatial data, reduce the usability of geospatial data, but also Effectively protect the copyright of geospatial data in circulation and play a role in tracking the source of data outflow. It better solves the problems of access control and flow tracking of geospatial data in the circulation process. the

In order to achieve the above-mentioned invention, the technical solution adopted by the present invention is: based on the characteristic that geographic spatial data is organized in units of byte streams in the computer carrier access and circulation process, the idea of data encryption is introduced into the watermarking method. In the design, the mathematical mapping idea is adopted to construct the watermark mapping function, that is, to establish the function of locating the watermark information bit according to the byte itself, so that the byte and the watermark information bit maintain a many-to-one mapping relationship, and the watermark information bit is determined through the established mapping relationship The embedding position, and then embed the watermark information into the data bytes by quantization. In order to realize the above-mentioned purpose of the invention, the technical scheme that the present invention takes is:

A method for geospatial data watermarking based on byte stream, characterized in that it comprises the following steps:

(1) Watermark information generation

Step 1: Generate a random number, which is unique and forms a one-to-one relationship with each user;

Step 2: Based on the random number, use the random sequence generator to generate a pseudo-random binary sequence, and convert the pseudo-random binary sequence into watermark information to be embedded composed of -1 and 1;

Step 3: Associate this random number with meaningful copyright information such as data ownership, circulation direction and other relevant information, and establish a watermark relationship mapping table for use in watermark detection and legal removal of watermark information.

(2) Watermark embedding process

Step 1: Read data; read geospatial data in the form of a byte stream, and convert all bytes in the geospatial data byte stream into corresponding values;

Step 2: preprocessing; performing bit inversion and scrambling on the bytes in the byte stream;

，采用多对一映射的思想，按照字节所对应的数值映射到

上，形成多个字节对应某个水印信息位的关系，令映射函数为

，

为字节本身所对应的数值，水印信息为

 ，即要求

； Step 3: Determine the embedding position of the watermark information bit in the byte stream; suppose the length of the watermark information is

, using the idea of many-to-one mapping, according to the value corresponding to the byte is mapped to

On the above, the relationship between multiple bytes corresponding to a certain watermark information bit is formed, and the mapping function is

,

is the value corresponding to the byte itself, and the watermark information is

, which requires

;

应尽量均匀的把

映射到

上；嵌入水印后所引起的变化不会显著影响到水印信息位所对应的字节个数，从而保证水印嵌入后不会影响到字节数值所对应的水印信息位。基于此，构建的映射函数如下所示： In order to establish a many-to-one mapping relationship, the watermark information bits are repeatedly embedded in the corresponding value of the byte; considering the watermark robustness of the method,

should be spread as evenly as possible

map to

superior; The changes caused by embedding the watermark will not significantly affect the number of bytes corresponding to the watermark information bits, so as to ensure that the watermark embedding will not affect the watermark information bits corresponding to the byte values. Based on this, the built mapping function looks like this:

、

为字节的最大值、最小值，

为映射步长； in

,

is the maximum and minimum value of bytes,

is the mapping step;

Step 4: Determination of watermark information embedding rules; based on the space domain, the additive law is used to embed the watermark information into the byte stream in a quantized manner. When the watermark information bit is -1, the corresponding byte quantization rule is :

表示映射步长； in Represents a byte value,

Indicates the mapping step;

Step 5: When the watermark information bit is 1, the watermark information is embedded according to the following quantization rules:

表示字节值，

表示映射步长； in

Represents a byte value,

Indicates the mapping step;

Step 6: Save the geospatial data after embedding the watermark information.

(3) Watermark information detection and removal

Step 1: Read data; read geospatial data containing watermark information in the form of byte stream, and convert all bytes in the geospatial data byte stream into corresponding values;

Step 2: Data preprocessing; perform inverse inversion, inverse scrambling, etc. on the bytes in the byte stream;

Step 3: Extract the watermark information; find the corresponding watermark information bits for each byte according to the mapping function, and refer to the quantization rules for watermark information extraction to judge the watermark information bits. The specific judgment rules are:

Since the embedding of watermark information adopts a many-to-one mapping relationship, the same watermark information bit has multiple extractions;

，

，

为水印信息长度，

为单个水印信息位所提取的次数。对含水印地理空间数据按照字节为单位取出并转换为其对应数值，令： Step 4: Discrimination of watermark information; discriminate the extracted watermark information according to the principle of maximum membership degree of fuzzy pattern recognition, and define the watermark detection sequence ,in

,

,

is the length of the watermark information,

The number of extractions for a single bit of watermark information. Extract the watermarked geospatial data in units of bytes and convert it to its corresponding value ,make:

表示水印信息的检测法则，

，因此

。然后依据最大隶属度原则获取水印信息

。定义第

位水印信息在空间上对1的隶属度为：

;第

位水印信息

在空间上对-1隶属度为：

，根据最大隶属度原则，来确定第

位水印信息

是

还是

，而后对提取出的水印信息进行如下处理： in

Indicates the detection rule of the watermark information,

,therefore

. Then obtain the watermark information according to the principle of maximum membership degree

. definition

bit watermark information The degree of membership to 1 in space is:

;

bit watermark information

The degree of membership to -1 in space is:

, according to the principle of maximum membership degree, to determine the first

bit watermark information

yes

still

, and then process the extracted watermark information as follows:

                                                                              

                                                    

In this way, the watermark information is extracted;

Step 5: detection of watermark information; Correlation detection is performed between the obtained binary watermark information and the original binary watermark information corresponding to the random number stored in the watermark relationship mapping table, and judging whether the data to be tested contains watermark information according to the correlation coefficient;

Step 6: When it is detected that the geospatial data contains watermark information, if it is a data authorized user, it means that the user has the right to use the geospatial data, then remove the watermark information, restore the data, and the user obtains the correct geospatial data , the process of removing watermark information is the inverse process of embedding watermark information; otherwise, it means that the user illegally obtained the geospatial data and cannot use the correct geospatial data;

Step 7: Obtain relevant information such as data flow and copyright based on the extracted watermark information, so as to protect the copyright of the data and track the source of illegal data outflow.

The characteristics and technical advantages of this method are:

(1) The most critical thing in this method is to determine the corresponding relationship between the watermark information bit and the byte in the byte stream. By constructing the mapping function, the embedded position of the watermark information bit is determined by the byte itself, that is, the byte itself and The embedded watermark information bits maintain a synchronous relationship, so that it is possible to realize the blind detection of watermark information by the embedding method.

(2) This method can effectively reduce the quality and accuracy of geospatial data, and can better resist attacks such as byte loss, byte shift, and byte addition and deletion that are common in the circulation process of geospatial data. Problems such as access control and flow tracking of geospatial data in the circulation process are solved. the

Description of drawings

Fig. 1 is a flow chart of embedding watermark information in the method of the present invention. the

Fig. 2 is a flow chart of watermark information detection in the method of the present invention. the

Fig. 3 is an original digital grid map in the prior art. the

Figure 4 is the watermarked digital raster map after correlation correction. the

Detailed ways

The invention will be described in further detail below in conjunction with the accompanying drawings. the

Embodiment one

In the embodiment of the present invention, the digital raster map is selected as the experimental data, and the whole process of data reading, preprocessing, watermark information generation, watermark embedding, watermark data storage, watermark detection, detection result output, and watermark removal is given. An embodiment of the present invention is presented, and the present invention is further described in detail.

As shown in FIG. 3 and FIG. 4 , in this embodiment, a digital grid map with a size of 698×654 is selected as the experimental data. For this piece of data, the mapping step size N is set to 8. the

1. The watermark information generation of the present invention:

Step 1: Generate a random number, which is unique and forms a one-to-one relationship with each user;

Step 2: Based on the random number, use the random sequence generator to generate a pseudo-random binary sequence, and convert the pseudo-random binary sequence into watermark information to be embedded composed of -1 and 1;

Step 3: Associate this random number with meaningful copyright information such as data ownership, circulation direction and other relevant information, and establish a watermark relationship mapping table for use in watermark detection and legal removal of watermark information.

2. The watermark information embedding of the present invention:

Step 1: Read data; read geospatial data in the form of a byte stream, and convert all bytes in the geospatial data byte stream into corresponding values;

Step 2: preprocessing; performing bit inversion and scrambling on the bytes in the byte stream;

，根据映射函数确定字节所对应的水印信息位； Step 3: Determine the embedding position of the watermark information bit in the byte stream; here the length of the watermark information used is

, determine the watermark information bit corresponding to the byte according to the mapping function;

Step 4: Determination of watermark information embedding rules; based on the space domain, the additive law is used to embed the watermark information into the byte stream in a quantized manner. When the watermark information bit is -1, according to the quantization rules:

Embed the watermark information, here set the quantization step to 4;

Step 5: When the watermark information bit is 1, embedding the watermark information according to the quantization rule;

Step 6: Save the geospatial data after embedding the watermark information.

3. Watermark detection and removal of the present invention:

Step 1: Read data; read geospatial data containing watermark information in the form of byte stream, and convert all bytes in the geospatial data byte stream into corresponding values;

Step 2: Data preprocessing; perform inverse inversion, inverse scrambling, etc. on the bytes in the byte stream;

Step 3: Extraction of watermark information; find the corresponding watermark information bit of each byte according to the mapping function, and extract the watermark according to the watermark information extraction rules. The specific judgment rules are:

Since the embedding of watermark information adopts a many-to-one mapping relationship, the same watermark information bit has multiple extractions;

位水印信息

是

还是

，而后对提取出的水印信息进行如下处理： Step 4: Discrimination of watermark information; discriminate the extracted watermark information according to the principle of maximum membership degree of fuzzy pattern recognition, and determine the first watermark information according to the principle of maximum membership degree

bit watermark information

yes

still

, and then process the extracted watermark information as follows:

                                                                              

                                                    

In this way, the watermark information is extracted;

Step 5: detection of watermark information; Correlation detection is performed between the obtained binary watermark information and the original binary watermark information corresponding to the random number stored in the watermark relationship mapping table, and judging whether the data to be tested contains watermark information according to the correlation coefficient;

Step 6: When it is detected that the geospatial data contains watermark information, if it is a data authorized user, it means that the user has the right to use the geospatial data, then remove the watermark information, restore the data, and the user obtains the correct geospatial data , the process of removing watermark information is the inverse process of embedding watermark information; otherwise, it means that the user illegally obtained the geospatial data and cannot use the correct geospatial data;

Step 7: Obtain relevant information such as data flow and copyright based on the extracted watermark information, so as to protect the copyright of the data and track the source of illegal data outflow.

4. The characteristics and technical advantages of this method:

(1) The most critical thing in this method is to determine the corresponding relationship between the watermark information bit and the byte in the byte stream. By constructing the mapping function, the embedded position of the watermark information bit is determined by the byte itself, that is, the byte itself and The embedded watermark information bits maintain a synchronous relationship, so that it is possible to realize the blind detection of watermark information by the embedding method.

(2) This method can effectively reduce the quality and accuracy of geospatial data, and can better resist attacks such as byte loss, byte shift, and byte addition and deletion that are common in the circulation process of geospatial data. Problems such as access control and flow tracking of geospatial data in the circulation process are solved. the

5. Test and analysis of the present invention:

The method proposed by the invention is a watermark method specially aimed at geographic space data, and the method can effectively protect the use authority of the original vector geographic data.

Geospatial data is unavailable after using this method to embed watermark information, and users cannot use the data files normally. Considering that illegal users can analyze the geographical data containing watermarks to perform relevant processing, such as reverse scrambling, forcibly correcting relevant data parameters, etc., so as to access the data information contained in it. the

Perform inverse scrambling on the watermarked raster map and correct the relevant attribute parameters of the header file to open the data. As shown in Figure 4, more than 50% of the data has changed, and the data quality and accuracy have changed greatly, affecting When the user obtains the relevant geographic information from the geospatial data, thereby controlling the user's access to the correct data, but the legitimate user can use the correct geographic data by removing the watermark. After the watermark is removed, the data is consistent with the original data. 100%. the

For geospatial data in the process of data circulation and access, such attacks as byte loss, byte shift and byte addition and deletion are often encountered, the method has good robustness, so that it can effectively protect data in the circulation Geospatial data copyright, and play a role in tracking the source of data outflow. the

Embodiment two

As shown in Figure 1 and Figure 2, the purpose of the present invention is: the solutions proposed by the current watermarking technology research institute are all based on the traditional digital watermarking idea, which is a passive data copyright management and usage tracking mechanism, and cannot control geographical space The use authority of data in the process of circulation cannot achieve the purpose of actively controlling the user's access to correct geospatial data. It does not take into account the diversity of geospatial data sources, and the watermark embedding method is applicable to the complexity of different characteristic data. Aiming at this problem, a new type of geospatial data watermarking method based on byte stream is invented. This watermarking method has better robustness, and can effectively reduce the availability of geospatial data, and better solve the problem of geospatial data. Issues such as access control and flow tracking in the circulation process.

In order to realize the above-mentioned purpose of the invention, the technical scheme that the present invention takes is:

A method for geospatial data watermarking based on byte stream, characterized in that it comprises the following steps:

(1) Watermark information generation

Step 1: Generate a random number, which is unique and forms a one-to-one relationship with each user;

Step 2: Based on the random number, use the random sequence generator to generate a pseudo-random binary sequence, and convert the pseudo-random binary sequence into watermark information to be embedded composed of -1 and 1;

Step 3: Associate this random number with meaningful copyright information such as data ownership, circulation direction and other relevant information, and establish a watermark relationship mapping table for use in watermark detection and legal removal of watermark information.

(2) Watermark embedding process

Step 1: Read data; read geospatial data in the form of a byte stream, and convert all bytes in the geospatial data byte stream into corresponding values;

Step 2: preprocessing; performing bit inversion and scrambling on the bytes in the byte stream;

，采用多对一映射的思想，按照字节所对应的数值映射到

上，形成多个字节对应某个水印信息位的关系，令映射函数为

，

为字节本身所对应的数值，水印信息为

 ，即要求

； Step 3: Determine the embedding position of the watermark information bit in the byte stream; suppose the length of the watermark information is

, using the idea of many-to-one mapping, according to the value corresponding to the byte is mapped to

On the above, the relationship between multiple bytes corresponding to a certain watermark information bit is formed, and the mapping function is

,

is the value corresponding to the byte itself, and the watermark information is

, which requires

;

应尽量均匀的把

映射到

上；

嵌入水印后所引起的变化不会显著影响到水印信息位所对应的字节个数，从而保证水印嵌入后不会影响到字节数值所对应的水印信息位。基于此，构建的映射函数如下所示： In order to establish a many-to-one mapping relationship, the watermark information bits are repeatedly embedded in the corresponding value of the byte; considering the watermark robustness of this method,

should be spread as evenly as possible

map to

superior;

The changes caused by embedding the watermark will not significantly affect the number of bytes corresponding to the watermark information bits, so as to ensure that the watermark embedding will not affect the watermark information bits corresponding to the byte values. Based on this, the built mapping function looks like this:

、

为字节的最大值、最小值，

为映射步长； in

,

is the maximum and minimum value of bytes,

is the mapping step;

Step 4: Determination of watermark information embedding rules; based on the space domain, the additive law is used to embed the watermark information into the byte stream in a quantized manner. When the watermark information bit is -1, the corresponding byte quantization rule is :

表示字节值，表示映射步长； in

Represents a byte value, Indicates the mapping step;

Step 5: When the watermark information bit is 1, the watermark information is embedded according to the following quantization rules:

表示字节值，

表示映射步长； in

Represents a byte value,

Indicates the mapping step;

Step 6: Save the geospatial data after embedding the watermark information.

(3) Watermark information detection and removal

Step 1: Read data; read geospatial data containing watermark information in the form of byte stream, and convert all bytes in the geospatial data byte stream into corresponding values;

Step 2: Data preprocessing; perform inverse inversion, inverse scrambling, etc. on the bytes in the byte stream;

Step 3: Extract the watermark information; find the corresponding watermark information bits for each byte according to the mapping function, and refer to the quantization rules for watermark information extraction to judge the watermark information bits. The specific judgment rules are:

Since the embedding of watermark information adopts a many-to-one mapping relationship, the same watermark information bit has multiple extractions;

，其中，，为水印信息长度，

为单个水印信息位所提取的次数。对含水印地理空间数据按照字节为单位取出并转换为其对应数值

，令： Step 4: Discrimination of watermark information; discriminate the extracted watermark information according to the principle of maximum membership degree of fuzzy pattern recognition, and define the watermark detection sequence

,in , , is the length of the watermark information,

The number of extractions for a single bit of watermark information. Extract the watermarked geospatial data in units of bytes and convert it to its corresponding value

,make:

表示水印信息的检测法则，，因此

。然后依据最大隶属度原则获取水印信息

。定义第

位水印信息

在空间上对1的隶属度为：

;第

位水印信息

在空间上对-1隶属度为：

，根据最大隶属度原则，来确定第位水印信息

是

还是

，而后对提取出的水印信息进行如下处理： in

Indicates the detection rule of the watermark information, ,therefore

. Then obtain the watermark information according to the principle of maximum membership degree

. definition

bit watermark information

The degree of membership to 1 in space is:

;

bit watermark information

The degree of membership to -1 in space is:

, according to the principle of maximum membership degree, to determine the first bit watermark information

yes

still

, and then process the extracted watermark information as follows:

                                                                             

In this way, the watermark information is extracted;

Step 5: detection of watermark information; Correlation detection is performed between the obtained binary watermark information and the original binary watermark information corresponding to the random number stored in the watermark relationship mapping table, and judging whether the data to be tested contains watermark information according to the correlation coefficient;

Step 6: When it is detected that the geospatial data contains watermark information, if it is a data authorized user, it means that the user has the right to use the geospatial data, then remove the watermark information, restore the data, and the user obtains the correct geospatial data , the process of removing watermark information is the inverse process of embedding watermark information; otherwise, it means that the user illegally obtained the geospatial data and cannot use the correct geospatial data;

Step 7: Obtain relevant information such as data flow and copyright based on the extracted watermark information, so as to protect the copyright of the data and track the source of illegal data outflow.

Claims (5)

1. a geospatial data watermark method based on byte stream, is characterized in that: comprise the steps: (1) Generation of watermark information; Step 1: Generate a random number, which is unique and forms a one-to-one relationship with each user; Step 2: Based on the random number, use the random sequence generator to generate a pseudo-random binary sequence, and convert the pseudo-random binary sequence into watermark information to be embedded composed of -1 and 1; Step 3: Associate this random number with meaningful copyright information such as data ownership and circulation direction information, and establish a watermark relationship mapping table for use in watermark detection and legal removal of watermark information; (2), watermark embedding process; Step 1: Read data; read geospatial data in the form of a byte stream, and convert all bytes in the geospatial data byte stream into corresponding values; Step 2: preprocessing; performing bit inversion and scrambling on the bytes in the byte stream; Step 3: Determine the embedding position of the watermark information bit in the byte stream; suppose the length of the watermark information is

, using the idea of many-to-one mapping, according to the value corresponding to the byte is mapped to

On the above, the relationship between multiple bytes corresponding to a certain watermark information bit is formed, and the mapping function is

, is the value corresponding to the byte itself, and the watermark information is , which requires

; In order to establish a many-to-one mapping relationship, the watermark information bits are repeatedly embedded in the corresponding value of the byte; considering the robustness of the watermark method,

should be spread as evenly as possible map to

superior;

The changes caused by embedding the watermark will not significantly affect the number of bytes corresponding to the watermark information bits, so as to ensure that the watermark embedding will not affect the watermark information bits corresponding to the byte values. Based on this, the mapping function constructed is as follows Shown: in

, is the maximum and minimum value of bytes,

is the mapping step; Step 4: Determination of watermark information embedding rules; based on the space domain, the additive law is used to embed the watermark information into the byte stream in a quantized manner. When the watermark information bit is -1, the corresponding byte quantization rule is :

in

Represents a byte value,

Indicates the mapping step; Step 5: When the watermark information bit is 1, the watermark information is embedded according to the following quantization rules:

in

Represents a byte value,

Indicates the mapping step; Step 6: Save the geospatial data after embedding the watermark information; (3) Watermark information detection and removal; Step 1: Read data; read geospatial data containing watermark information in the form of byte stream, and convert all bytes in the geospatial data byte stream into corresponding values; Step 2: Data preprocessing; perform inverse inversion and inverse scrambling of the bytes in the byte stream; Step 3: Extract the watermark information; find the corresponding watermark information bits for each byte according to the mapping function, and refer to the quantization rules for watermark information extraction to judge the watermark information bits. The specific judgment rules are:

Since the embedding of watermark information adopts a many-to-one mapping relationship, the same watermark information bit has multiple extractions; Step 4: Discrimination of watermark information; discriminate the extracted watermark information according to the principle of maximum membership degree of fuzzy pattern recognition, and define the watermark detection sequence

,in

,

,

is the length of the watermark information,

The number of extraction times for a single watermark information bit; for watermarked geospatial data, it is extracted in bytes and converted to its corresponding value

,make:

in

Indicates the detection rule of the watermark information,

,therefore

, and then obtain the watermark information according to the principle of maximum membership degree

, define the first

bit watermark information

The degree of membership to 1 in space is:

;

bit watermark information

The degree of membership to -1 in space is:

, according to the principle of maximum membership degree, to determine the first

bit watermark information

yes

still

, and then process the extracted watermark information as follows:                         

                                                     In this way, the watermark information is extracted; Step 5: detection of watermark information; Correlation detection is performed between the obtained binary watermark information and the original binary watermark information corresponding to the random number stored in the watermark relationship mapping table, and judging whether the data to be tested contains watermark information according to the correlation coefficient; Step 6: When it is detected that the geospatial data contains watermark information, if it is a data authorized user, it means that the user has the right to use the geospatial data, then remove the watermark information, restore the data, and the user obtains the correct geospatial data , the process of removing watermark information is the inverse process of embedding watermark information; otherwise, it means that the user illegally obtained the geospatial data and cannot use the correct geospatial data; Step 7: Obtain data flow and copyright-related information based on the extracted watermark information, thereby protecting data copyright and tracking the source of illegal data outflow. 2. A kind of geospatial data watermarking method based on byte stream according to claim 1, it is characterized in that: based on the circulation characteristics of geospatial data, data encryption idea is introduced in the design of watermarking method, by mapping idea Watermark information is embedded in data bytes in a quantized manner. 3. A geospatial data watermarking method based on byte stream, characterized in that: Watermark information generation; Step 1: Generate a random number, which is unique and forms a one-to-one relationship with each user; Step 2: Based on the random number, use the random sequence generator to generate a pseudo-random binary sequence, and convert the pseudo-random binary sequence into watermark information to be embedded composed of -1 and 1; Step 3: Associate this random number with meaningful copyright information such as data ownership and circulation direction information, and establish a watermark relationship mapping table for use in watermark detection and legal removal of watermark information. 4. A geospatial data watermarking method based on byte stream, characterized in that: watermark embedding process; Step 1: Read data; read geospatial data in the form of a byte stream, and convert all bytes in the geospatial data byte stream into corresponding values; Step 2: preprocessing; performing bit inversion and scrambling on the bytes in the byte stream; Step 3: Determine the embedding position of the watermark information bit in the byte stream; suppose the length of the watermark information is , using the idea of many-to-one mapping, according to the value corresponding to the byte is mapped to On the above, the relationship between multiple bytes corresponding to a certain watermark information bit is formed, and the mapping function is

,

is the value corresponding to the byte itself, and the watermark information is

, which requires

; In order to establish a many-to-one mapping relationship, the watermark information bits are repeatedly embedded in the corresponding value of the byte; considering the watermark robustness of this method,

should be spread as evenly as possible map to superior;

The changes caused by embedding the watermark will not significantly affect the number of bytes corresponding to the watermark information bits, so as to ensure that the watermark embedding will not affect the watermark information bits corresponding to the byte values. Based on this, the mapping function constructed is as follows Shown: in

, is the maximum and minimum value of bytes,

is the mapping step; Step 4: Determination of watermark information embedding rules; based on the space domain, the additive law is used to embed the watermark information into the byte stream in a quantized manner. When the watermark information bit is -1, the corresponding byte quantization rule is : in Represents a byte value, Indicates the mapping step; Step 5: When the watermark information bit is 1, the watermark information is embedded according to the following quantization rules:

in

Represents a byte value,

Indicates the mapping step; Step 6: Save the geospatial data after embedding the watermark information. 5. A geospatial data watermarking method based on byte stream, characterized in that: Watermark information detection and removal; Step 1: Read data; read geospatial data containing watermark information in the form of a byte stream, and convert all bytes in the geospatial data byte stream into corresponding values; Step 2: data preprocessing; perform inverse inversion and inverse scrambling of the bytes in the byte stream; Step 3: Extract the watermark information; find the corresponding watermark information bits for each byte according to the mapping function, and refer to the quantization rules for watermark information extraction to judge the watermark information bits. The specific judgment rules are:

Since the embedding of watermark information adopts a many-to-one mapping relationship, the same watermark information bit has multiple extractions; Step 4: Discrimination of watermark information; discriminate the extracted watermark information according to the principle of maximum membership degree of fuzzy pattern recognition, and define the watermark detection sequence

,in

,

, is the length of the watermark information, The number of extraction times for a single watermark information bit, for geospatial data containing watermarks, it is extracted in units of bytes and converted to its corresponding value

,make:

in

Indicates the detection rule of the watermark information,

,therefore

, and then obtain the watermark information according to the principle of maximum membership degree

, define the first

bit watermark information

The degree of membership to 1 in space is:

;

bit watermark information

The degree of membership to -1 in space is:

, according to the principle of maximum membership degree, to determine the first

bit watermark information

yes

still

, and then process the extracted watermark information as follows:                         

                                                     In this way, the watermark information is extracted; Step 5: detection of watermark information; Correlation detection is carried out between the obtained binary watermark information and the original binary watermark information corresponding to the random number stored in the watermark relationship mapping table, and judging whether the data to be tested contains watermark information according to the correlation coefficient; Step 6: When it is detected that the geospatial data contains watermark information, if it is a data authorized user, it means that the user has the right to use the geospatial data, then remove the watermark information, restore the data, and the user obtains the correct geospatial data , the process of removing watermark information is the reverse process of embedding watermark information; otherwise, it means that the user illegally obtained the geospatial data and cannot use the correct geospatial data; Step 7: Obtain data flow and copyright-related information based on the extracted watermark information, thereby protecting data copyright and tracking the source of illegal data outflow.

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