Data transmission method, system, sensor and base station based on wavelet transform

Abstract

The present invention provides a data transmission method, system, sensor and base station based on wavelet transform. When the method is applied to the sensor, it includes: generating a fragile watermark based on sensor information; performing discrete wavelet decomposition on the measurement value data of the sensor to obtain high-frequency coefficients and low-frequency coefficients; selectively encrypting and embedding the fragile watermark in the high-frequency coefficient based on the parity of the low-frequency coefficient to form encrypted data; performing inverse wavelet transform on the encrypted data to obtain encrypted measurement value data, and sending the encrypted measurement value data to the base station. The present invention encrypts a fragile watermark in the measurement data, the fragile watermark carries the information of the sender, and uses the sensitivity of the fragile watermark to tampering and data modification to verify the integrity of the measurement data, effectively ensuring the secure transmission of data.

Description

Technical Field

[0001] The present invention relates to the technical field of communication systems, and in particular to the technical field of data transmission security. Background Art

[0002] Under the architecture of the Industrial Internet of Things, the Internet of Things is connected to the "smart" terminals of the Internet to form an ecosystem. The sensors measure the data of the environment and transmit the data to the control center of the base station through the network. Since the communication network is vulnerable to network attacks, attackers can destroy or tamper with normal measurement data by invading the network, affecting normal data transmission. These attacks may affect the integrity of the data, which may seriously damage the system or lead to dangerous consequences. Therefore, it is crucial to provide effective and feasible data encryption and authentication to ensure the secure transmission of data and filter out erroneous data.

[0003] Most early solutions use traditional encryption techniques (such as symmetric and asymmetric encryption) to ensure secure data transmission. However, they are still subject to the following limitations: 1) Resource-constrained sensors have limited memory, functionality, and computing power, which often makes it difficult to deploy standard highly secure encryption mechanisms because the large number of mathematical operations performed to achieve high security incurs huge overhead; 2) All original data is changed into ciphertext, and the base station needs to decrypt the ciphertext into plaintext after receiving the data, which increases the task of the base station.

[0004] There are also some other mechanisms to protect data and filter out erroneous data. For example, software attestation, anomaly detection techniques, signature-based techniques or watermarking techniques are used. However, most of these mechanisms have their limitations and cannot be effectively used to provide confidentiality and integrity. Software attestation techniques require special hardware. Anomaly detection techniques require a large amount of labeled data for training, involve additional steps to establish the distribution of normal behavior, and may have a high false alarm rate. Signature-based techniques are computationally complex. Watermarking technology is used in many applications. In the watermarking process, the sensor will embed each data together with a unique watermark into the sensor node before sending it. The access point can then verify its integrity.

[0005] Two implementation schemes of the prior art of the present invention are as follows:

[0006] 1) Generate a watermark by combining the length of the measured value data, the frequency of the number, and the data capture time of the sensor node, and encrypt the watermark using a shared key. The sensor embeds the encrypted watermark at the end of the detected data before sending it to the base station. However, this method increases the size of the reported data by embedding it at the end of the data, and is vulnerable to many security vulnerabilities when the entire network uses a shared secret key that is exposed as one key.

[0007] 2) A watermarking method based on linear interpolation is proposed, which does not generate any extra bits for the watermark. However, it uses fixed watermark parameters for all nodes in the system, which provides a security vulnerability for attackers.

[0008] The existing technology currently has the following problems:

[0009] 1) When data is encrypted and the original format / size of the data is changed / increased, the base station needs to decrypt all data into plain text before use, which consumes additional bandwidth.

[0010] 2) Use symmetric / asymmetric keys for encryption. When the key is shared publicly, attackers can calculate or eavesdrop on the key, making it vulnerable to many security vulnerabilities.

[0011] 3) Solve the problem that the watermark with fixed parameters for encryption embedding is vulnerable to being cracked by attackers and becomes invalid. Summary of the invention

[0012] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a data transmission method, system, sensor and base station based on wavelet transform, so as to solve the problems of large bandwidth consumption and poor data security in the prior art.

[0013] To achieve the above-mentioned purpose and other related purposes, the present invention provides a data transmission method based on wavelet transform, which is applied to sensors, including: generating a fragile watermark based on sensor information; performing discrete wavelet decomposition on the measurement value data of the sensor to obtain high-frequency coefficients and low-frequency coefficients; selectively encrypting and embedding the fragile watermark in the high-frequency coefficient based on the parity of the low-frequency coefficient to form encrypted data; performing inverse wavelet transform on the encrypted data to obtain encrypted measurement value data, and sending the encrypted measurement value data to a base station.

[0014] In one embodiment of the present invention, the fragile watermark is generated by, for example: obtaining the reserved information of the sensor; and generating a fixed-length binary sequence watermark based on the MD5 information digest algorithm and the reserved information of the sensor.

[0015] In one embodiment of the present invention, the data fields of the various retained information of the sensor are spliced ​​to generate unified and complete retained information; the retained information includes: a unique unit identifier of the sensor, a timestamp and a sensor unit address.

[0016] In one embodiment of the present invention, the discrete wavelet decomposition of the sensor's measurement data to obtain high-frequency coefficients and low-frequency coefficients includes: performing discrete wavelet decomposition on the sensor's measurement data and the low-frequency components after decomposition of a preset layer layer by layer through mutually orthogonal high-frequency filters and low-frequency filters to obtain the high-frequency coefficients and low-frequency coefficients of the preset layer.

[0017] In one embodiment of the present invention, the selective encryption and embedding of the fragile watermark in the high-frequency coefficient based on the parity of the low-frequency coefficient to form encrypted data includes: when the low-frequency coefficient is an even number, the high-frequency coefficient is converted into binary; when the low-frequency coefficient is an odd number, four bits at a specified position in the fragile watermark are taken, and the four bits at the specified position replace the following four bits of the high-frequency coefficient, and the high-frequency coefficient with the replaced four bits is converted into decimal to form encrypted data.

[0018] In one embodiment of the present invention, performing an inverse wavelet transform on the encrypted data to obtain the encrypted measurement value data includes: applying an inverse DWT operation to convert the encrypted data from the frequency domain to the time domain to obtain the encrypted measurement value data.

[0019] The present invention also provides a sensor, comprising a memory for storing a computer program; and a processor for running the computer program to implement the steps of the wavelet transform-based data transmission method applied in the sensor.

[0020] The present invention also provides a data transmission method based on wavelet transform, which is applied to a base station, including: splicing various retained information data fields of the sensor stored in the base station to generate unified and complete retained information; generating a fragile watermark identical to that of the sensor; performing discrete wavelet decomposition on the encrypted measurement value data received from the sensor layer by layer to obtain high-frequency coefficients and low-frequency coefficients; extracting the fragile watermark based on the parity of the low-frequency coefficients and the high-frequency coefficients; and verifying the extracted fragile watermark based on the generated fragile watermark.

[0021] The present invention also provides a base station, comprising a memory for storing a computer program; and a processor for running the computer program to implement the steps of the data transmission method based on wavelet transform applied in the base station.

[0022] The present invention also provides a data transmission system based on wavelet transform, comprising: the sensor as described above and the base station as described above.

[0023] As described above, the data transmission method, system, sensor and base station based on wavelet transform of the present invention have the following beneficial effects:

[0024] 1. The present invention encrypts a fragile watermark in the measurement data. The fragile watermark carries the information of the sender and uses the sensitivity of the fragile watermark to tampering and data modification to verify the integrity of the measurement data and effectively ensure the secure transmission of data.

[0025] 2. The present invention encrypts and embeds a watermark in the high-frequency coefficients of the measurement data without increasing or changing the original reading form, so that the base station does not need to decrypt it into plain text, reducing the computing pressure of the base station. The time information of the sensor collecting data is added to the watermark information, and the time information is constantly changing with each communication between the sensor and the base station. Therefore, the dynamic change of the watermark increases the difficulty of watermark cracking. The present invention does not use a shared key but uses the MD5 information digest algorithm to encrypt and generate the watermark, which increases the security and dynamism of the watermark. In addition, the present invention determines the watermark embedding through the low-frequency coefficient, which increases the randomness of the watermark encryption embedding. The embedded watermark at a random position will make it more difficult for attackers to inject false data.

[0026] 2. The present invention solves the problem that the original reading form is increased or changed after encryption, and the base station needs to consume additional bandwidth due to decryption operations. It also solves the problem that the shared key is easily monitored or cracked by attackers when the shared key is open. It also solves the problem that the encryption embedding using a watermark with fixed parameters is easily cracked by attackers. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 It is a schematic diagram of the overall process of a data transmission method based on wavelet transform in one embodiment of the present application when it is applied to a sensor.

[0029] Figure 2 Shown is a schematic diagram of the watermark generation process when the wavelet transform-based data transmission method in one embodiment of the present application is applied to a sensor.

[0030] Figure 3 It shows a specific wavelet decomposition and encryption process diagram when the wavelet transform-based data transmission method in one embodiment of the present application is applied to a sensor.

[0031] Figure 4 It is a schematic diagram of the overall process of a data transmission method based on wavelet transform in an embodiment of the present application when it is applied in a base station.

[0032] Figure 5Shown is a principle block diagram of a sensor in one embodiment of the present application.

[0033] Figure 6 Shown is a principle block diagram of a base station in an embodiment of the present application.

[0034] Figure 7 Shown is a schematic diagram of the communication process of a wavelet transform-based data transmission system in one embodiment of the present application. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0036] The purpose of this embodiment is to provide a data transmission method, system, sensor and base station based on wavelet transform, which are used to solve the problems of large bandwidth consumption and poor data security in the prior art. The data transmission method based on wavelet transform provided in this embodiment encrypts a fragile watermark in the measurement data, and the fragile watermark carries the information of the sender. The fragile watermark is used to verify the integrity of the measurement data and ensure the secure transmission of the data by using the sensitivity of the fragile watermark to tampering and data modification. That is, when an attacker tampers with the measurement value encrypted with the fragile watermark by invading the transmission network, the encrypted embedded watermark will be destroyed. The base station can determine whether the data has been tampered by verifying the integrity of the encrypted embedded watermark. If the watermark information is destroyed and the verification fails, the base station considers that the received data is unsafe.

[0037] The principles and implementation methods of the wavelet transform-based data transmission method, system, sensor and base station of the present invention will be described in detail below, so that those skilled in the art can understand the wavelet transform-based data transmission method, system, sensor and base station of the present invention without creative work.

[0038] Example 1

[0039] Figure 1 The figure shows the overall flow chart of the data transmission method based on wavelet transform in this embodiment when it is applied to the sensor. Figure 1 As shown, this embodiment provides a data transmission method based on wavelet transform, which is applied to a sensor. The data transmission method based on wavelet transform includes:

[0040] Step S11, generating a fragile watermark based on sensor information;

[0041] Step S12, performing discrete wavelet decomposition on the sensor's measurement data to obtain high-frequency coefficients and low-frequency coefficients;

[0042] Step S13, selectively encrypting and embedding the fragile watermark in the high frequency coefficient based on the parity of the low frequency coefficient to form encrypted data;

[0043] Step S14, performing inverse wavelet transform on the encrypted data to obtain encrypted measurement data, performing discrete wavelet decomposition on the measurement data of the sensor to obtain high-frequency coefficients and low-frequency coefficients, and sending the encrypted measurement data to the base station.

[0044] The following specifically describes steps S11 to S14 of the data transmission method based on wavelet transform in this embodiment.

[0045] Step S11, generating a fragile watermark based on the sensor information.

[0046] In this embodiment, the fragile watermark is generated in the sensor, and the sensor data can be divided into two categories: reserved information and measured value data. The reserved information refers to the unique unit identification and unit address of the sensor, which is sent to the base station control center when it is first connected to the control center and stored by the control center. Therefore, in this embodiment, it is assumed that subsequent communications do not need to transmit this part of information to the base station control center again. The measured value data is the data collected by the sensor and needs to be transmitted to the base station control center regularly.

[0047] Specifically, in this embodiment, the fragile watermark is generated by, for example: obtaining the reserved information of the sensor; and generating a fixed-length binary sequence watermark based on the MD5 information digest algorithm and the reserved information of the sensor.

[0048] The data fields of the various retained information of the sensor are spliced ​​to generate unified and complete retained information; the retained information includes: a unique unit identification of the sensor, a timestamp and a sensor unit address.

[0049] Figure 2 The diagram shows a schematic diagram of the watermark generation process when the wavelet transform-based data transmission method in this embodiment is applied to a sensor. Figure 2 As shown, the fragile watermark is generated as follows:

[0050] 1) Concatenate the data fields of each sensor's reserved information to generate a unified and complete reserved information m=uid&ts&addr.

[0051] 2) Use the MD5 information digest algorithm to calculate and obtain a fixed-length binary watermark w=G(m)=MD5(m), where w is a 128-bit binary {0, 1} sequence.

[0052] Where uid is the unique unit identifier of the sensor, ts is the timestamp, addr is the sensor unit address, & is the string concatenation operation, G(m) is the watermark generation algorithm form, and MD5(m) is the MD5 information digest algorithm.

[0053] Step S12: performing discrete wavelet decomposition on the sensor's measurement data to obtain high-frequency coefficients and low-frequency coefficients.

[0054] Discrete wavelet transform (DWT) is a technique for processing discrete data in signal and image processing, in which the signal is converted from its spatial domain to the frequency domain. More precisely, it is a linear transformation performed on a given signal, decomposing it into coefficients at different levels, where the low-frequency coefficients reflect the approximate information of the data and the high-frequency coefficients reflect the detailed information of the data. According to the sensitivity requirements of the fragile watermark, the high-frequency coefficients of the wavelet decomposition are selected to encrypt the watermark by replacing the last 4 significant bits (4LSB) with the watermark. In addition, in order to enhance the randomness of the watermark embedding encryption, whether the watermark is embedded or not will be determined by the low-frequency coefficients, that is, if the low-frequency coefficient at the corresponding position is an even number, the 4LSB watermark encryption is performed on the relatively high-frequency coefficient, otherwise it is not encrypted on the corresponding high-frequency coefficient. After the watermark is embedded, the inverse wavelet transform is performed to reconstruct the data to obtain the measurement value data of the encrypted embedded watermark.

[0055] In this embodiment, the discrete wavelet decomposition of the sensor's measurement data to obtain high-frequency coefficients and low-frequency coefficients includes: using mutually orthogonal high-frequency filters and low-frequency filters, performing discrete wavelet decomposition on the sensor's measurement data and the low-frequency components after decomposition of a preset layer layer by layer to obtain the high-frequency coefficients and low-frequency coefficients of the preset layer.

[0056] Figure 3 The figure shows the specific wavelet decomposition and encryption process when the data transmission method based on wavelet transform in this embodiment is applied to the sensor. Figure 3 As shown, the specific wavelet decomposition and encryption includes the following steps:

[0057] Through mutually orthogonal high-frequency filters and low-frequency filters, the measured value data x = [x1, x2, ..., x n ] and the low-frequency components after i-layer decomposition Apply k wavelet decomposition to obtain the wavelet decomposition coefficients of the original measurement data x [L k , H k , H k-1 , ..., H2, H1], where L i , Hi are the low-frequency coefficients and high-frequency coefficients of the i-th layer of wavelet decomposition respectively.

[0058] Step S13: selectively encrypt and embed the fragile watermark in the high frequency coefficients based on the parity of the low frequency coefficients to form encrypted data.

[0059] Specifically, in this embodiment, the selectively encrypting and embedding the fragile watermark in the high-frequency coefficients based on the parity of the low-frequency coefficients to form encrypted data includes:

[0060] When the low-frequency coefficient is an even number, the high-frequency coefficient is converted into binary; when the low-frequency coefficient is an odd number, the four bits at the specified position in the fragile watermark are taken, and the four bits at the specified position replace the following four bits of the high-frequency coefficient, and the high-frequency coefficient that replaces the following four bits is converted into decimal to form encrypted data.

[0061] Specifically, in this embodiment, selectively encrypting and embedding the fragile watermark in the high-frequency coefficients based on the parity of the low-frequency coefficients to form encrypted data includes:

[0062] 1) Determine the low-frequency coefficient L k，j Is it an even number? If it is an even number, the corresponding H k，j Convert to binary, if it is an odd number, then j=j+1, and proceed to step 2).

[0063] 2) Take 4 bits from the (j-1)*4+1th bit to the (j-1)*4+4th bit in the watermark w sequence. If the watermark sequence reaches 128 bits, repeat starting from the 1st bit of the watermark w sequence.

[0064] 3) Use the four bits taken from 3) to replace H k，j The last four bits of binary, and then H k，j Convert to decimal.

[0065] 4) j starts from 1, and then 2), 3), 4) until j = n / m, then it ends and the wavelet decomposition coefficients after watermark encryption are obtained It is the high-frequency coefficient of the kth layer of wavelet decomposition after watermark encryption.

[0066] Step S14, performing inverse wavelet transform on the encrypted data to obtain encrypted measurement data, performing discrete wavelet decomposition on the measurement data of the sensor to obtain high-frequency coefficients and low-frequency coefficients, and sending the encrypted measurement data to the base station.

[0067] In this embodiment, performing an inverse wavelet transform on the encrypted data to obtain the encrypted measurement value data includes: applying an inverse DWT operation to convert the encrypted data from the frequency domain to the time domain to obtain the encrypted measurement value data.

[0068] Specifically, in this embodiment, L k , H k-1 , ..., H2, H1] applies the inverse DWT operation to convert the measurement values ​​from their frequency domain to the original time domain measurement values ​​containing the encrypted watermark information without transforming the data form and size, which is almost close to the reading of the original measurement value.

[0069] The principle of the wavelet transform based data transmission method applied in the base station is that it is carried out after the base station receives the watermark encrypted data sent from the sensor. The process is roughly the same as the encryption process, except that it retrieves and extracts the watermark bits instead of hiding them.

[0070] Figure 4 The diagram shows a schematic diagram of the watermark generation process when the wavelet transform-based data transmission method in this embodiment is applied to a base station. Specifically, Figure 4 As shown, this embodiment provides a data transmission method based on wavelet transform, which is applied in a base station. The data transmission method based on wavelet transform includes:

[0071] Step S21, splicing the data fields of the sensor retention information stored in the base station to generate unified and complete retention information;

[0072] Step S22, generating a fragile watermark identical to that of the sensor;

[0073] Step S23, performing discrete wavelet decomposition layer by layer on the encrypted measurement data received from the sensor to obtain high-frequency coefficients and low-frequency coefficients;

[0074] Step S24, extracting a fragile watermark based on the parity of the low-frequency coefficients and the high-frequency coefficients;

[0075] Step S25: verifying the extracted fragile watermark based on the generated fragile watermark.

[0076] The specific steps include:

[0077] 1) Concatenate the data fields of the sensor's reserved information stored in the base station to generate unified and complete reserved information m=uid&ts&addr;

[0078] 2) Use the MD5 information digest algorithm to obtain a fixed-length binary watermark w=G(m)=MD5(m) that is the same as the one generated by the sensor end, where w is a 128-bit binary {0, 1} sequence;

[0079] 3) Through mutually orthogonal high-frequency filters and low-frequency filters, the received measurement data is filtered layer by layer. and the low-frequency component after decomposition of layer i Apply wavelet decomposition to obtain wavelet decomposition coefficients in They are the watermark encrypted measurement data x received by the base station. w The low-frequency coefficients and high-frequency coefficients of the i-th layer of wavelet decomposition;

[0080] 4) Determine the low frequency coefficient Is it an even number? If it is an even number, the corresponding Convert to binary and extract the last four bits, which is w e From the (j-1)*4+1th to the (j-1)*4+4th in the sequence, if it is an odd number, then j=j+1, and continue with step 4);

[0081] 5) j starts from 1, repeat 2), 3), 4) until j = n / m, then end, and the extracted complete watermark w is obtained e ;

[0082] 6) By verifying w and w e The similarity is used to verify the integrity of the fragile watermark to determine whether the data integrity verification is completed. Here, in order to evaluate the integrity of the extracted watermark, the similarity is carefully checked by using the bit error rate (BER):

[0083]

[0084] Br is w and w e Compared with the number of error bits, Bt is the total number of bits. The lower the BER, the greater the difference between w and w. e The higher the similarity, the higher the BER, and the e The lower the similarity.

[0085] When the BER is higher than the preset threshold, the watermark is considered to be damaged, the data is not safe, and the data verification fails. When it is lower than the preset threshold, the watermark is considered to be complete, the data has not been damaged or tampered with, the base station accepts the data, and due to x w The format and size of the original measurement data will not be changed, and the reading is almost close to the original measurement value. After the base station verifies the data, it can be directly used in subsequent calculations without the need to decrypt it into plain text.

[0086] As can be seen from the above, the data transmission method based on wavelet transform in this embodiment encrypts and embeds the watermark in the high-frequency coefficients of the measured value data, and does not increase or change its original reading form, so that the base station does not need to decrypt it into plain text, which reduces the computing pressure of the base station. The time information of the sensor collecting data is added to the watermark information, and the time information is constantly changing with each communication between the sensor and the base station. Therefore, the dynamic change of the watermark increases the difficulty of watermark cracking. The present invention does not use a shared key but uses the MD5 information digest algorithm to encrypt and generate the watermark, which increases the security and dynamism of the watermark. In addition, the present invention determines the watermark embedding through the low-frequency coefficient, which increases the randomness of the watermark encryption embedding. The embedded watermark at a random position will make it more difficult for attackers to inject false data. The present invention solves the problem of increasing or changing the original reading form after encryption, and the base station needs to decrypt the operation and consume additional bandwidth. It solves the problem that the shared key is easily monitored or cracked by attackers when the shared key is open, and solves the problem that the watermark with fixed parameters is easily cracked by attackers for encryption embedding.

[0087] Example 2

[0088] like Figure 5 As shown, this embodiment provides a sensor 101, and the sensor 101 includes: a processor 1001 and a memory 1002; the memory 1002 is used to store a computer program; the processor 1001 is used to execute the computer program stored in the memory 1002, so that the sensor 101 performs the steps of the data transmission method based on wavelet transform in Example 1. Since the specific implementation process of the steps of the data transmission method based on wavelet transform applied to the sensor has been described in detail in Example 1, it will not be repeated here.

[0089] The processor 1001 is a central processing unit. The memory 1002 is connected to the processor 1001 through a system bus and communicates with each other. The memory 1002 is used to store computer programs, and the processor 1001 is used to run computer programs so that the processor 1001 executes the data transmission method based on wavelet transform. The memory 1002 may include a random access memory (Random Access Memory, referred to as RAM), and may also include a non-volatile memory (non-volatile memory), such as at least one disk storage.

[0090] Example 3

[0091] like Figure 6As shown, this embodiment provides a base station 201, and the base station 201 includes: a processor 2001 and a memory 2002; the memory 2002 is used to store a computer program; the processor 2001 is used to execute the computer program stored in the memory 2002, so that the base station 201 performs the steps of the data transmission method based on wavelet transform in Example 1. Since the specific implementation process of the steps of the data transmission method based on wavelet transform applied in the base station has been described in detail in Example 1, it will not be repeated here.

[0092] The processor 2001 is a central processing unit. The memory 2002 is connected to the processor 2001 through a system bus and communicates with each other. The memory 2002 is used to store computer programs, and the processor 2001 is used to run computer programs so that the processor 1001 executes the data transmission method based on wavelet transform. The memory 1002 may include a random access memory (Random Access Memory, referred to as RAM), and may also include a non-volatile memory (non-volatile memory), such as at least one disk storage.

[0093] Example 4

[0094] like Figure 6 As shown, this embodiment provides a data transmission system based on wavelet transform, and the data transmission system based on wavelet transform includes: the sensor as described in Example 2 and the base station as described in Example 3. Figure 7 It is a schematic diagram showing the communication process of the wavelet transform-based data transmission system in this embodiment.

[0095] In this embodiment, the sensor realizes the functions of data collection and watermark encryption embedding, while the base station mainly realizes the functions of watermark extraction and watermark verification.

[0096] The wavelet transform-based data transmission system 100 in this embodiment aims at the end-to-end data security transmission problem. First, a fragile watermark is generated at the sending end (sensor). The fragile watermark is a fixed-length binary sequence output by the MD5 information digest algorithm with the retained information of the sensor end as input; secondly, the sending end performs discrete wavelet decomposition on the measurement data to obtain high-frequency coefficients and low-frequency coefficients, and selectively encrypts and embeds the fragile watermark in the high-frequency coefficient according to the parity of the low-frequency coefficient. After encryption, an inverse wavelet transform is performed to obtain the encrypted measurement data with embedded watermark, and the encrypted measurement data is sent to the base station.

[0097] When the data is transmitted to the base station, the base station has the right to know the retained information of the sensors in the entire network and the method of embedding encryption. Therefore, the base station can verify the integrity of the watermark by comparing the extracted watermark with the generated original watermark, and determine whether the data has been tampered with or destroyed.

[0098] The technical features specifically implemented by the wavelet transform-based data transmission system 100 of this embodiment are substantially the same as those of the wavelet transform-based data transmission method in the aforementioned embodiment 1, and the technical contents that are common between the embodiments will not be repeated.

[0099] In addition, this embodiment further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by the processor 1001, the steps of the data transmission method based on wavelet transform applied to the sensor or applied to the base station in Embodiment 1 are implemented. Embodiment 1 has already described the data transmission method based on wavelet transform in detail, which will not be repeated here.

[0100] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to the computer program. The aforementioned computer program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes.

[0101] In summary, the present invention encrypts a fragile watermark in the measurement data, and the fragile watermark carries the information of the sender. The fragile watermark uses the sensitivity of the fragile watermark to tampering and data modification to verify the integrity of the measurement data and effectively ensure the secure transmission of the data. The present invention encrypts and embeds the watermark in the high-frequency coefficient of the measurement data, and does not increase or change its original reading form, so that the base station does not need to decrypt it into plain text, which reduces the computing pressure of the base station. The time information of the sensor collecting data is added to the watermark information, and the time information is constantly changing with each communication between the sensor and the base station. Therefore, the dynamic change of the watermark increases the difficulty of watermark cracking. The present invention does not use a shared key but uses the MD5 information digest algorithm to encrypt and generate the watermark, which increases the security and dynamism of the watermark. In addition, the present invention determines the watermark embedding through the low-frequency coefficient, which increases the randomness of the watermark encryption embedding. The embedded watermark at a random position will make it more difficult for an attacker to inject false data. The present invention solves the problem that the original reading form is increased or changed after encryption, and the base station needs to decrypt the operation and consume additional bandwidth. It solves the problem that the shared key is easily monitored or cracked by an attacker when the shared key is open, and solves the problem that the encryption embedding of a watermark with fixed parameters is easily cracked by an attacker. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0102] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A data transmission method based on wavelet transform, applied to a sensor, characterized in that: include: Generate fragile watermark based on sensor information; Perform discrete wavelet decomposition on the sensor's measured value data to obtain high-frequency coefficients and low-frequency coefficients; Based on the odd or even number of the low-frequency coefficient, the low-frequency coefficient is selectively applied to the sensor in the high-frequency coefficient to encrypt and embed the fragile watermark to form encrypted data, including: when the low-frequency coefficient is an even number, the high-frequency coefficient is converted into binary; when the low-frequency coefficient is an odd number, four bits at a specified position in the fragile watermark are taken, and the four bits at the specified position are replaced by the four bits at the specified position. The high-frequency coefficient that replaces the four bits at the rear is converted into a decimal system to form encrypted data; The encrypted data is subjected to inverse wavelet transform to obtain encrypted measurement data, and the measurement data of the sensor is subjected to discrete wavelet decomposition to obtain high-frequency coefficients and low-frequency coefficients, and the encrypted measurement data is sent to a base station; the discrete wavelet decomposition of the measurement data of the sensor to obtain high-frequency coefficients and low-frequency coefficients comprises: performing discrete wavelet decomposition on the measurement data of the sensor and the low-frequency components after decomposition of a preset layer layer by layer through mutually orthogonal high-frequency filters and low-frequency filters to obtain high-frequency coefficients and low-frequency coefficients of the preset layer.

2. The data transmission method based on wavelet transform according to claim 1, characterized in that: The fragile watermark is generated as follows: Get the sensor's retention information; A fixed-length binary sequence watermark is generated based on the MD5 information digest algorithm and the reserved information of the sensor.

3. The data transmission method based on wavelet transform according to claim 2 is characterized in that: In the generation of the fixed-length binary sequence watermark, the data fields of the various retained information of the sensor are spliced ​​to generate unified and complete retained information; The reserved information includes: a unique unit identification of the sensor, a timestamp and a sensor unit address.

4. The data transmission method based on wavelet transform according to claim 1 is characterized in that: The performing inverse wavelet transform on the encrypted data to obtain the encrypted measurement value data comprises: The encrypted data is converted from the frequency domain to the time domain using an inverse DWT operation to obtain encrypted measurement value data.

5. A sensor, characterized in that: It comprises a memory for storing a computer program; and a processor for running the computer program to implement the steps of the data transmission method based on wavelet transform as claimed in any one of claims 1 to 4.

6. A data transmission method based on wavelet transform, applied in a base station, characterized in that: include: The data fields of the sensor retention information stored in the base station are spliced ​​to generate unified and complete retention information; Generates the same fragile watermark as the sensor; Perform discrete wavelet decomposition layer by layer on the encrypted measurement data received from the sensor to obtain high-frequency coefficients and low-frequency coefficients; Extracting a fragile watermark based on the parity of the low frequency coefficients and the high frequency coefficients; verifying the extracted fragile watermark based on the generated fragile watermark; Specifically, it includes: 1) Concatenate the data fields of the sensor's reserved information stored in the base station to generate unified and complete reserved information m=uid&ts&addr; 2) Use the MD5 information digest algorithm to obtain a fixed-length binary watermark w=G(m)=MD5(m) that is the same as the one generated by the sensor end, where w is a 128-bit binary {0, 1} sequence; 3) Through mutually orthogonal high-frequency filters and low-frequency filters, the received measurement data is filtered layer by layer. and the low-frequency component after decomposition of layer i Apply wavelet decomposition to obtain wavelet decomposition coefficients in They are the watermark encrypted measurement data x received by the base station. w The low-frequency coefficients and high-frequency coefficients of the i-th layer of wavelet decomposition; 4) Determine the low frequency coefficient Is it an even number? If it is an even number, the corresponding Convert to binary and extract the last four bits, which is w e From the (j-1)*4+1th to the (j-1)*4+4th in the sequence, if it is an odd number, then j=j+1, and continue with 4); 5) j starts from 1, repeat 2), 3), 4) until j = n / m, then end, and the extracted complete watermark w is obtained e .

7. A base station, characterized in that: It comprises a memory for storing a computer program; and a processor for running the computer program to implement the steps of the data transmission method based on wavelet transform as claimed in claim 6.

8. A data transmission system based on wavelet transform, characterized in that: include: A sensor as claimed in claim 5 and a base station as claimed in claim 7.

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