CN116566663A - Threat data dynamic processing and efficient sharing method suitable for industrial control system - Google Patents

Abstract

The invention discloses a method for dynamic processing and efficient sharing of threat data suitable for industrial control systems, comprising the following steps: 1) defining a data sharing system model; 2) preprocessing of shared data; 3) searching for sensitive keywords; 4) data Desensitization and sharing. This method has the functions of privacy protection, sensitive keyword security, trapdoor verification, and dynamic processing of sensitive data.

Description

Threat data dynamic processing and efficient sharing method suitable for industrial control system

technical field

The present invention relates to the technical field of data sharing, in particular to the realization of dynamic processing and efficient sharing of ciphertext data based on the identity and authority of visitors during the process of threat data sharing in industrial control systems. Efficient sharing method.

Background technique

With the continuous integration of industrialization and informationization, while the industrial control system is developing openly, the security threats it faces are also increasing. Threat intelligence data sharing can enhance the security protection capabilities and collaborative response capabilities of different organizations through threat data linkage and intelligence sharing, and has become one of the hot topics in cyberspace security construction. With the continuous operation and development of industrial control systems, the amount of industrial control data continues to increase. In order to alleviate the pressure on local servers, users usually choose to store data in cloud servers, but if they directly store plaintext data, there will be semi-trusted server leaks. Data at risk. Users usually choose to store data in the cloud server in the form of ciphertext. Since shared data may contain sensitive industrial or personal information, how to efficiently implement dynamic desensitization and sharing of data has become a difficult point in the face of visitors with different identities and permissions. There are two traditional desensitization sharing schemes. The first method is to first desensitize and then encrypt the data, and then upload it to the cloud server for other users to access. However, this static desensitization method cannot be implemented according to the permission level of different users Perform dynamic desensitization. The second method is to encrypt the data first and then upload it to the sharing system. This method requires desensitization on the basis of ciphertext, which is more difficult. In existing research, ciphertext retrieval technology can directly retrieve ciphertext data, which provides conditions for ciphertext desensitization. The homomorphic encryption algorithm allows users to calculate the encrypted data, and the result is the same as the result obtained by calculating the plaintext and then encrypting it, but this method requires high calculation costs. Differential privacy and anonymization are used in dynamic desensitization, which may affect the availability of data. Anonymization processing and adding noise may lead to data distortion or information loss. In addition, in order to protect privacy, it is necessary to add random noise to the data or perform some complex calculations, which may increase the calculation cost of the system.

The centralized architecture of traditional cloud servers has potential security risks. Once the server goes down or the system crashes, key data may be lost. In addition, centralized servers are easy to become the target of network attacks, which further leads to a decline in the credibility of data. In contrast, the blockchain has the characteristics of decentralization and non-tampering, which can effectively solve data security problems caused by server failures or network attacks. Maw et al. proposed a blockchain-based data security storage scheme, aiming to improve the security and traceability of operational data in industrial control systems. This scheme uses blockchain technology to build a decentralized data storage and Management system, and realize access control and audit of data through smart contracts, providing technical support for data security and operational traceability of industrial control systems. Aiming at the security challenges faced in the process of sharing device data between heterogeneous industrial networks, Yang et al. proposed a data sharing framework based on blockchain, which uses smart contract technology to achieve safe and efficient access to different levels of data control, thereby ensuring data security and privacy. However, there are some sensitive data in the data, which involves the privacy of data sharers or users, and constitutes a threat to data security. The traditional static data desensitization method has been unable to cope with the increasingly complex network environment and user authority differences. In contrast, dynamic desensitization technology can desensitize data in real time according to different user permission levels when users access data, thereby protecting data privacy. However, it is a difficult problem to complete the dynamic desensitization of ciphertext data without touching the plaintext of the data. For this reason, related technologies that can perform dynamic desensitization on ciphertext data include ciphertext retrieval technology, homomorphic encryption technology, differential privacy, and anonymization processing, etc., but these technologies need to bear high computing costs or may affect data security. availability. In terms of threats to data storage security, the traditional cloud server adopts a centralized architecture, which has security risks. Once the server goes down or the system crashes, critical data may be lost. In addition, centralized servers are easy to become the target of network attacks, which further leads to a decline in the credibility of data.

Contents of the invention

The purpose of the present invention is to provide a method for dynamic processing and efficient sharing of threat data suitable for industrial control systems against the deficiencies of the prior art. This method has the functions of privacy protection, sensitive keyword security, trapdoor verification, and dynamic processing of sensitive data.

The technical scheme that realizes the object of the present invention is:

A method for dynamic processing and efficient sharing of threat data suitable for industrial control systems, comprising the following steps:

1) Define the data sharing system model: Assume that there are three subjects in the data sharing system: data owner A, data visitor B, and cloud storage center. Data owner A and data visitor B are members of the threat data sharing system. All members Before joining the sharing system, it is necessary to go through strict user registration, login and authorization access procedures. The cloud storage center is a trusted network built by cloud servers and blockchain nodes, which mainly performs data storage, sensitive file search and data sharing. operation, where:

Data owner A, as the data provider, first extracts sensitive keywords from shared files, then uses public key encryption algorithm to encrypt shared files to generate ciphertext C, and performs searchable encryption on sensitive keywords to generate PEKS(PK, W ), upload C and PEKS (PK, W) to the cloud storage center, when the data visitor B needs to apply for an access credential from the data owner A before accessing the data uploaded by the data owner A, the data owner A according to the data The identity authority of visitor B selects sensitive keywords and generates trapdoors, and sends the trapdoors to data visitor B as access credentials. When receiving the desensitization request from the cloud storage center, the specified sensitive files need to be desensitized and encrypted, and then sent to the corresponding data visitor;

Before accessing the shared data of data owner A, data visitor B needs to apply for an access credential from data owner A, and then initiate a data access request to the cloud storage center with the credential. At this time, data visitor B may receive The file data of A and the cloud storage center, the content obtained directly from the data owner A is a file that has been desensitized and encrypted with the public key PK _B , and the data visitor B directly uses the private key SK _B to decrypt and obtain the desensitized file. The plaintext of the encrypted file, and the content obtained from the cloud storage center, due to the transformation of proxy re-encryption, the data visitor B can also use the private key SK _B to successfully decrypt and obtain the plaintext;

Cloud storage center: When the data owner A uploads the shared data ciphertext and keyword ciphertext, the cloud storage center first generates a data ID for the uploaded content, and then calls the smart contract to generate data ID, user ID, shared data ciphertext, key The key information of word ciphertext and time stamp is stored on the chain. When the access request of data visitor B is received, the access credentials carried by data visitor B will be verified first. If the access is not passed, the access will be rejected. Search for sensitive keywords on all files accessed, and then send all files containing sensitive information to data owner A, who will perform desensitization and sharing operations; for files that do not contain sensitive information, directly by The cloud storage center performs proxy re-encryption on it, converts it into a form that data visitor B can decrypt, and finally sends the twice-encrypted file to data visitor B;

2) Shared data preprocessing: data owner A may be eavesdropped or hijacked by an intermediary during the process of uploading shared data, and may be leaked by a semi-trusted server when the data is stored in the shared system. Therefore, before uploading data, it is necessary to Encrypt the data to ensure that the data is in the state of cipher text during transmission and storage, and use searchable encryption to process the shared data to prevent data leakage during transmission and storage, and also support the search function in the state of cipher text , assuming that the shared data file set of the data owner A is M={M ₁ , M ₂ , M ₃ ,...,M _n }, the preprocessing process of the shared data is as follows:

2-1) Generate an ECC asymmetric key pair (PK _A , SK _A ): first select a secure elliptic curve Ep(a, b), and then select a point from the curve as the base point G, then:

(PK _A , SK _A ) = KeyGen _ECC (Ep(a, b), G);

2-2) Extract sensitive data keywords from each file respectively, and generate a list of sensitive keywords: W _i = (w _i1 , w _i2 , w _i3 , ..., w _ik ), where 1≤i≤n , w _ij ∈ M _i , k is the number of sensitive keywords in file M _i , generate a public key searchable encryption key pair (A _pubi , A _privi ) for each sensitive keyword in W _i , where A _pubi = {Pub _i1 , Pub _i2 , Pub _i3 , ..., Pub _ik }, A _privi = {Priv _i1 , Priv _i2 , Priv _i3 , ..., Priv _ik };

2-3) Select k random character strings (Q _i1 , Q _i2 , Q _i3 , ..., Q _ik ), XOR each character string with the system parameter z, and obtain k new character strings (S _i1 , S _i2 , S _i3 ,..., S _ik ) perform searchable encryption on sensitive keywords to obtain ciphertext CK _i ,

CK _i =PEKS(Apub _i , W _i )

=([S _i1 , Encrypt(Pub _i1 , Q _i1 )], ([S _i2 , Encrypt(Pub _i2 , Q _i2 )],

[S _i3 , Encrypt(Pub _i3 , Q _i3 )], ..., ([S _ik , Encrypt(Pub _ik , Q _ik )];

2-4) Each file is encrypted, then:

C _i = Encrypt _ECC (PK _A , M _i );

2-5) Upload all file ciphertexts and sensitive keyword ciphertexts corresponding to the file ciphertexts to the cloud storage center. At this time, the ciphertexts can only be decrypted successfully with the private key SK _A of the data owner A, and the cloud storage center cannot To obtain the plaintext M, the proxy server calls the smart contract to file ciphertext C = (C ₁ , C ₂ , C ₃ , ..., C _n ), keyword ciphertext CK = (Ck ₁ , CK ₂ , CK ₃ , . .., CK _n ), data ID, data owner ID, threat data type, threat data description, and threat data upload time are stored in the blockchain, and the cloud storage center sends the dataID corresponding to the uploaded file to the data owner;

2-6) Use the private key of each sensitive keyword to generate a trapdoor:

Tw _ij =Trapdoor(Apriv _ij ,W _ij ),

3) Sensitive keyword search: In order to better realize dynamic desensitization and efficient sharing of threat data based on the identity and authority of the visitor, searchable encryption technology is used to ensure that the cloud storage center can complete the search for sensitive files without touching the plaintext , when the data visitor B needs to access the data shared by the data owner A, he first applies to the data owner A for a keyword trapdoor, and the data owner A according to the identity of the data visitor B (such as: authorized security analyst, operation and maintenance personnel, external users, etc.) to judge which of all the sensitive keywords are sensitive data invisible to the data visitor B, then generate the trapdoor list Tw _b and sign the trapdoor list Tw _b to obtain S _t , and then use the proxy server’s public The key PK _C encrypts S _t to obtain C _t , and returns C _t to B. The search process is as follows:

3-1) Data visitor B sends a data access request to the cloud storage center with trapdoor C _t and dataID_B, where dataID_B is the list of dataIDs corresponding to all the files that data visitor B wants to access, and the sharing center first requests the data visitor The identity of B is authenticated, and after passing the keyword search for the target data, first use the private key SK _C to decrypt the trapdoor C _t to obtain the signature S _t , then verify the signature, and finally obtain the trapdoor list of sensitive keywords, then : S _t = Decrypt _ECC (SK _C , c _t ),

3-2) Then call the smart contract, and read the file ciphertext set C' and the corresponding sensitive keyword ciphertext CK' that data visitor B applied for access according to dataID_B, where C' and CK' are C and CK respectively subset of

3-3) Search for sensitive keywords for each file ciphertext C′ _i in the set C′ to determine whether there is sensitive information in the file, and set the sensitive keyword ciphertext corresponding to C′ _i as CK′ _ij to traverse TW _b For each trapdoor t in , use t to decrypt the first element of CK' _ij to get:

s = Decrypt(CK' _ij [1], t),

Then XOR s with the system parameter Z to get s', if s'=CK' _ij [0], if the two are equal, the match is successful, indicating that there are sensitive keywords in the file, and the corresponding dataID is added to the sensitiveIDs set , when all trapdoors in Tw _b fail to match each keyword ciphertext of the file, it means that there is no sensitive keyword in the file, and its dataID is added to the securityIDs collection;

4) Data desensitization and sharing: After searching for sensitive keywords, the cloud storage center has identified whether each file that data visitor B applies for access contains sensitive information, and uses sensitiveIDs to record the corresponding dataIDs of all files containing sensitive information , securityIDs records the dataIDs corresponding to all files that do not contain sensitive information. Since the files containing sensitive information have not been desensitized, the cloud server needs to send the files corresponding to sensitiveIDs to data owner A, and data owner A will perform data processing on the data. Desensitized and then shared with data visitor B; for files without sensitive information, the cloud server can use proxy re-encryption technology to directly deliver to data visitor B, where:

4-1) Sensitive file processing: the cloud proxy server first uses the private key SK _C to sign the identity information of the data visitor B, and then signs S=Sign(SK _C , userIdB) and the file ciphertext C _sst recorded in sensitiveIDs Send to A:

S||(C _sst1 , C _sst2 , ..., C _sstd ),

Data owner A processes the file as follows:

4-1-1) The data owner A first verifies the signature S, and inputs the signature and the public key PK _C of the cloud proxy server, then the signature verification result is:

4-1-2) After the verification is passed, decrypt the file containing sensitive information, and then select the desensitization strategy R according to the identity authority of the data visitor B and perform the desensitization operation:

M _sst = (M _sst1 , M _sst2 , . . . , M _sstd )

=(Decrypt _ECC (SK _A , C _sst1 ), Decrypt _ECC (SK _A , C _sst2 ), . . . , Decrypt _ECC (SK _A , C _sstd ))

D=(D ₁ , D ₂ , . . . , D _d )

=(dataMask(R, M _sst1 ), dataMask(R, M _sst2 ), . . . , dataMask(R, M _sstd ));

4-1-3) After desensitization is completed, use the public key of data visitor B to encrypt the data and send it to data visitor B:

C _D = Encrypt _ECC (SK _B , D);

4-2) Non-sensitive file processing: Since the files for which securityIDs contain no sensitive information, the cloud proxy server can directly deliver them to the data visitor B, but at this time the file ciphertext is encrypted by the public key of the data owner A, In order for the data visitor B to successfully decrypt the final data, the proxy server also needs to re-encrypt the ciphertext to obtain the ciphertext C ^* , where the proxy re-encryption key K _AtoB is composed of the private key of the data owner A and Public key generation of data visitor B:

K _AtoB = GetRekey(SK _A , PK _B ),

C ^* = PreReEncrypt(K _AtoB , C _sec );

4-3) Data decryption: When the data visitor B accesses successfully, it will obtain _CD and C ^* from the data owner A and the cloud proxy server respectively, where _CD is directly decrypted by the data owner A after desensitizing the file. It is generated by encrypting with the public key ^of data visitor B, and data visitor B can successfully decrypt it with the private key and obtain _the desensitized plaintext data. The encryption key K _AtoB is encrypted, and the proxy re-encryption key K _AtoB is generated by the operation of SK _A and the public key PK _B of data visitor B. Therefore, data visitor B can also use the private key to decrypt:

M _D = GetDecryptedData(SK _B , C _D ),

M ^* = PreReDecrypt(SK _B , C ^* ).

This technical solution supports the data owner to implement dynamic desensitization based on the identity of the visitor to the sensitive files: when the data visitor requests the threat data from the cloud storage center, he needs to carry the trapdoor Tw _b , and Tw _b is determined by the data owner according to the data visitor’s The cloud storage center uses Tw _b to search out the ciphertext of the corresponding sensitive file, and then sends the ciphertext of the sensitive file and the identity information signature of the data visitor to the data owner, and the data owner decrypts the ciphertext of the sensitive file , desensitization and sharing operations.

This technical solution supports the "one-to-many" efficient sharing of non-sensitive files: the cloud storage center uses Tw _b to search out the ciphertext of the corresponding non-sensitive files. Sensitive operation, in the face of data requests from different visitors, the cloud storage center uses the re-encryption key provided by the data owner to re-encrypt non-sensitive files and convert them into a form that authorized visitors can decrypt to achieve "One-to-many" efficient sharing.

This technical solution can effectively protect the privacy of threat data: the cloud storage center and unauthorized visitors cannot decrypt the ciphertext, and the cloud storage center cannot calculate the sensitive keywords themselves through keyword ciphertext and trapdoors, and malicious visitors cannot Data cannot be obtained illegally by forging trapdoors.

This technical solution has the following advantages: 1) Privacy protection: this method can ensure the privacy of threat data, and ensure that only authorized data visitors can successfully decrypt and obtain the plaintext content of threat data, avoiding data privacy leakage;

2) Security of sensitive keywords: This method selects a random string for each sensitive keyword, and realizes the search for sensitive keywords by encrypting and verifying the random number. The cloud storage center can only access random strings, and does not know the sensitive keywords corresponding to random strings, thus ensuring the security of sensitive keywords;

3) Trapdoor verification: In this method, the cloud storage center needs to verify the source of the visitor's trapdoor, preventing malicious data visitors from forging trapdoors to obtain data illegally;

4) Dynamic processing of sensitive data: This method can ensure that the data owner can dynamically process and securely share the threat data ciphertext based on the identity and authority of the visitor.

This method has the functions of privacy protection, sensitive keyword security, trapdoor verification, and dynamic processing of sensitive data.

Description of drawings

Fig. 1 is the system structure schematic diagram in the embodiment;

Fig. 2 is the partition diagram of system function modules in the embodiment;

Fig. 3 is a schematic diagram of the system hierarchy in the embodiment.

Detailed ways

The content of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited.

Example:

A method for dynamic processing and efficient sharing of threat data suitable for industrial control systems, comprising the following steps:

1) Define the data sharing system model: As shown in Figure 1, suppose there are three subjects in the data sharing system: data owner A, data visitor B, and cloud storage center. Data owner A and data visitor B are threats to data sharing. Members of the system, all members need to go through strict user registration and login and authorization access procedures before joining the shared system. The cloud storage center is a trusted network built by cloud servers and blockchain nodes, which mainly performs data storage, Sensitive file search and data sharing operations, where:

Data owner A is the sharing party of threat data files such as industrial control vulnerabilities, attacker means, and attack paths. First, he extracts sensitive keywords from the shared files, and then uses public key encryption algorithm to encrypt the shared files to generate ciphertext C. Keywords are searchable and encrypted to generate PEKS (PK, W), and C and PEKS (PK, W) are uploaded to the cloud storage center. When data visitor B accesses the data uploaded by data owner A, he needs to first submit Data owner A applies for an access credential. Data owner A selects sensitive keywords based on the identity authority of data visitor B and generates a trapdoor, and sends the trapdoor to data visitor B as an access credential. When receiving the desensitization issued by the cloud storage center When requesting, the specified sensitive file needs to be desensitized and encrypted, and then sent to the corresponding data visitor;

Data visitor B represents visitors with different identities and permissions, such as industrial control security engineers, operation and maintenance personnel, and external users. Before accessing the shared data of data owner A, data visitor B needs to apply for access credentials from data owner A, and then bring the credentials to The cloud storage center initiates a data access request. At this time, the data visitor B may receive file data from both the data owner A and the cloud storage center. The content obtained directly from the data owner A is desensitized and desensitized. For files encrypted with the public key PK _B , the data visitor B directly uses the private key SK _B to decrypt the plaintext of the desensitized file, and the content obtained from the cloud storage center, due to the transformation of the proxy re-encryption, the data visitor B B also uses the private key SK _B to successfully decrypt and obtain the plaintext;

Cloud storage center: When the data owner A uploads the shared data ciphertext and keyword ciphertext, the cloud storage center first generates a data ID for the uploaded content, and then calls the smart contract to generate data ID, user ID, shared data ciphertext, key The key information of word ciphertext and time stamp is stored on the chain. When the access request of data visitor B is received, the access credentials carried by data visitor B will be verified first. If the access is not passed, the access will be rejected. Search for sensitive keywords on all files accessed, and then send all files containing sensitive information to data owner A, who will perform desensitization and sharing operations; for files that do not contain sensitive information, directly by The cloud storage center performs proxy re-encryption on it, converts it into a form that data visitor B can decrypt, and finally sends the twice-encrypted file to data visitor B;

2) Divide the system function modules and hierarchical structure: the schematic diagram of the application system structure in the embodiment is shown in Figure 2, and the modular design is carried out in combination with the requirements in the industrial control threat data sharing process and the main functions of the specific business, specifically, including the user identity There are four modules: management, threat data upload, threat data search, and threat data query. The schematic diagram of the system hierarchy architecture in the embodiment is shown in Figure 3. The system architecture is divided into 5 layers: front-end layer, back-end layer, middle layer, persistence layer and collection layer;

3) Shared data preprocessing: data owner A may be eavesdropped or hijacked by an intermediary during the process of uploading shared data, and may be leaked by a semi-trusted server when the data is stored in the shared system. The data is encrypted to ensure that the data is in the state of ciphertext during transmission and storage, and the shared data is processed with searchable encryption to prevent data leakage during transmission and storage. At the same time, it can also support the search function in the state of ciphertext. Assuming that the shared data file set of data owner A is M={M ₁ , M ₂ , M ₃ ,...,M _n }, the preprocessing process of the shared data is as follows:

3-1) Generate an ECC asymmetric key pair (PK _A , SK _A ): first select a secure elliptic curve Ep(a, b), and then select a point from the curve as the base point G, then:

(PK _A , SK _A ) = KeyGen _ECC (Ep(a, b), G);

3-2) Extract sensitive data keywords from each file respectively, and generate a list of sensitive keywords: W _i = (w _i1 , w _i2 , w _i3 , ..., w _ik ), where 1≤i≤n , w _ij ∈ M _i , k is the number of sensitive keywords in file M _i , generate a public key searchable encryption key pair (A _pubi , A _privi ) for each sensitive keyword in W _i , where A _pubi = {Pub _i1 , Pub _i2 , Pub _i3 , . . . , Pub _ik }, A _privi = {Priv _i1 , Priv _i2 , priv _i3 , . . . , Priv _ik };

3-3) Select k random character strings (Q _i1 , Q _i2 , Q _i3 , ..., Q _ik ), XOR each character string with the system parameter Z, and obtain k new character strings (S _i1 , S _i2 , S _i3 ,..., S _ik ) perform searchable encryption on sensitive keywords to obtain ciphertext CK _i ,

CK _i =PEKS(Apub _i , W _i )

=([S _i1 , Encrypt(Pub _i1 , Q _i1 )], ([S _i2 , Encrypt(Pub _i2 , Q _i2 )],

[S _i3 , Encrypt(Pub _i3 , Q _i3 )]..., ([S _ik , Encrypt(Pub _ik , Q _ik )];

3-4) Each file is encrypted, then:

C _i = Encrypt _ECC (PK _A , M _i );

3-5) Upload all file ciphertexts and sensitive keyword ciphertexts corresponding to the file ciphertexts to the cloud storage center. At this time, the ciphertexts can only be decrypted successfully with the private key SK _A of the data owner A, and the cloud storage center cannot To obtain the plaintext M, the proxy server calls the smart contract to file ciphertext C = (C ₁ , C ₂ , C ₃ , ..., C _n ), keyword ciphertext CK = (CK ₁ , CK ₂ , CK ₃ , . .., CK _n ), data ID, data owner ID, threat data type, threat data description, and threat data upload time are stored in the blockchain, and the cloud storage center sends the dataID corresponding to the uploaded file to the data owner;

3-6) Use the private key of each sensitive keyword to generate a trapdoor:

Tw _ij = Trapdoor(Apriv _ij , W _ij );

4) Sensitive keyword search: In order to better realize dynamic desensitization and efficient sharing of threat data based on the identity and authority of the visitor, searchable encryption technology is used to ensure that the cloud storage center can complete the search for sensitive files without touching the plaintext , when data visitor B needs to access the data shared by data owner A, he first applies to data owner A for a keyword trapdoor, and data owner A judges which of all sensitive keywords are data based on the identity of data visitor B Sensitive data invisible to visitor B, then generate trapdoor list Tw _b and sign trapdoor list Tw _b to get S _t , then use proxy server’s public key PK _C to encrypt S _t to get C _t , and C _t Back to B, the search process is as follows:

4-1) Data visitor B carries the trapdoor C _t and dataID_B to send a data access request to the cloud storage center, where dataID_B is the list of dataIDs corresponding to all the files that data visitor B wants to access, and the sharing center first requests the data visitor The identity of B is authenticated, and after passing the keyword search for the target data, first use the private key SK _C to decrypt the trapdoor C _t to obtain the signature S _t , then verify the signature, and finally obtain the trapdoor list of sensitive keywords, then : S _t = Decrypt _ECC (SK _C , c _t ),

{Tw _b , ⊥}=Verify(PK _A , S _t );

4-2) Then call the smart contract, and read the file ciphertext set C' and the corresponding sensitive keyword ciphertext CK' that data visitor B applied for access according to dataID_B, where C' and CK' are C and CK respectively subset of

4-3) Search for sensitive keywords for each file ciphertext C' _i in the set C', and determine whether there is sensitive information in the file, and set the sensitive keyword ciphertext corresponding to C' _i as CK' _ij traversal Tw _b For each trapdoor t in , use t to decrypt the first element of CK' _ij to get:

s = Decrypt(CK' _ij [1], t),

Then XOR s with the system parameter Z to get s', if s'=CK' _ij [0], if the two are equal, the match is successful, indicating that there are sensitive keywords in the file, and the corresponding dataID is added to sensitiveID□ In the collection, when all the trapdoors in Tw _b fail to match each keyword ciphertext of the file, it means that there is no sensitive keyword in the file, and its dataID is added to the securityIDs collection;

5) Data desensitization and sharing: After searching for sensitive keywords, the cloud storage center has identified whether each file that data visitor B applies for access contains sensitive information, and uses sensitiveIDs to record the dataIDs corresponding to all files containing sensitive information , securityIDs records the dataIDs corresponding to all files that do not contain sensitive information. Since the files containing sensitive information have not been desensitized, the cloud server needs to send the files corresponding to sensitiveIDs to data owner A first, and data owner A desensitizes the data before sharing it with data visitor B; Files with sensitive information can be directly delivered to data visitor B by the cloud server using proxy re-encryption technology, where:

5-1) Sensitive file processing: the cloud proxy server first uses the private key SK _c to sign the identity information of the data visitor B, and then signs s=Sign(SK _c , userIdB) and the file ciphertext C _sst recorded in sensitivrIDs Send to A:

S||(C _sst1 , C _sst2 , ..., C _sstd ), data owner A processes the file as follows:

5-1-1) The data owner A first verifies the signature S, and inputs the signature and the public key PK _c of the cloud proxy server, then the signature verification result is:

{userIdB, ⊥} = Verify(PK _c , S);

5-1-2) After the verification is passed, decrypt the file containing sensitive information, and then select the desensitization strategy R according to the identity authority of the data visitor B and perform the desensitization operation:

M _sst = (M _sst1 , M _sst2 , . . . , M _sstd )

=(Decrypt _ECC (SK _A , C _sst1 ), Decrypt _ECC (SK _A , C _sst2 ), . . . , Decrypt _ECC (SK _A , C _sstd ))

D=(D ₁ , D ₂ , . . . , D _d )

=(dataMask(R, M _sst1 ), dataMask(R, M _sst2 ), . . . , dataMask(R, M _sstd ));

5-1-3) After desensitization is completed, use the public key of data visitor B to encrypt the data and send it to data visitor B:

C _D = Encrypt _ECC (SK _B , D);

5-2) Non-sensitive file processing: Since the files for which securityIDs contain no sensitive information, the cloud proxy server can directly deliver them to the data visitor B, but the ciphertext of the file at this time is encrypted by the public key of the data owner A. In order to enable data visitor B to successfully decrypt and obtain the final data, the proxy server also re-encrypts the ciphertext to obtain the ciphertext C ^* , where the proxy re-encryption key K _AtoB is obtained from the private key of the data owner A and the data The public key of visitor B is generated:

K _AtoB = GetRekey(SK _A , PK _B ),

C ^* = PreReEncrypt(K _AtoB , C _sec );

5-3) Data decryption: When the data visitor B accesses successfully, it will obtain _CD and C ^* from the data owner A and the cloud proxy server respectively. Among them, _CD is directly decrypted by the data owner A after desensitizing the file. It is generated by encrypting with the public key of data visitor B. Data visitor B successfully decrypts with the private key and obtains the desensitized plaintext data. Since C ^* has successively experienced data owner A’s public key SK _A and proxy re-encryption The key K _AtoB is encrypted, and the proxy re-encryption key K _AtoB is generated by the operation of SK _A and the public key PK _B of the data visitor B, and the data visitor B can also use the private key to decrypt:

M _D = GetDecryptedData(SK _B , C _D ),

M ^* = PreReDecrypt(SK _B , C ^* ).

Claims (1)

1. the threat data dynamic processing and efficient sharing method suitable for the industrial control system is characterized by comprising the following steps of:

1) Defining a data sharing system model: assuming that three main bodies of a data owner A, a data visitor B and a cloud storage center exist in the data sharing system, the data owner A and the data visitor B are members threatening the data sharing system, and before all members join the sharing system, strict user registration login and authorization admission flow are needed, the cloud storage center is a trusted network constructed by a cloud server and a blockchain node, and mainly performs data storage, sensitive file searching and data sharing operations, wherein:

the data owner A is used as a data provider, sensitive keywords are firstly extracted from a shared file, then a public key encryption algorithm is adopted to encrypt the shared file to generate ciphertext C, searchable encryption is carried out on the sensitive keywords to generate PEKS (PK, W), the C and the PEKS (PK, W) are uploaded to a cloud storage center, before a data visitor B accesses data uploaded by the data owner A, the data owner A needs to apply for an access certificate, the data owner A selects the sensitive keywords according to the identity authority of the data visitor B and generates a trapdoor, the trapdoor is sent to the data visitor B to serve as the access certificate, and when a desensitization request sent by the cloud storage center is received, the designated sensitive file needs to be desensitized and encrypted, and then the designated sensitive file needs to be sent to a corresponding data visitor;

before the data visitor B accesses the shared data of the data owner A, the data visitor B needs to apply for access credentials to the data owner A, then initiates a request for accessing the data to the cloud storage center with the credentials, at this time, the data visitor B may receive file data from both the data owner A and the cloud storage center, and the content obtained directly from the data owner A is desensitized and uses the public key PK _B Encrypted file, data visitor B directly uses private key SK _B Decrypting to obtain the desensitized file plaintext, and obtaining the content from the cloud storage center, wherein the data visitor B adopts the private key SK as the content is subjected to the conversion of proxy re-encryption _B The plaintext can be successfully obtained after decryption;

cloud storage center: when a data owner A uploads a shared data ciphertext and a keyword ciphertext, a cloud storage center firstly generates a data ID for uploading content, then invokes an intelligent contract to store the data ID, a user identity ID, the shared data ciphertext, the keyword ciphertext and time stamp key information on a chain, when an access request of a data visitor B is received, firstly, the access credential carried by the data visitor B is verified, if the access credential does not pass, access is refused, if the access credential passes, sensitive keyword search is carried out on all accessed files, then all files containing sensitive information are sent to the data owner A, and the data owner A executes desensitization and sharing operations; for files which do not contain sensitive information, directly performing agent re-encryption on the files by a cloud storage center, converting the files into a form which can be decrypted by a data visitor B, and finally sending the files subjected to secondary encryption to the data visitor B;

2) Shared data preprocessing: the data owner A encrypts the data before uploading the data, adopts searchable encryption to process the shared data, and sets the shared data file set of the data owner A as M= { M ₁ ，M ₂ ，M ₃ ，…，M _n The shared data preprocessing procedure is as follows:

2-1) Generation of ECC asymmetric Key Pairs (PKs) _A ，SK _A ): firstly, a safe elliptic curve Ep (d, b) is selected, then a point is selected from the curve as a base point G, and then:

(PK _A ，SK _A )＝KeyGen _ECC (Ep(a，b)，G)；

2-2) extracting sensitive data keywords from each file respectively to generate a sensitive keyword list: w (W) _i ＝(w _i1 ，w _i2 ，w _i3 ，…，w _ik ) Wherein i is more than or equal to 1 and less than or equal to n, w _ij ∈M _i K is the file M _i The number of sensitive keywords in the Chinese character is W _i Generates a public key searchable encryption key pair (a _pubi ，A _privi ) Wherein A is _pubi ＝{Pub _i1 ，Pub _i2 ，Pub _i3 ，…，Pub _ik }，A _privi ＝{Priv _i1 ，Priv _i2 ，Priv _i3 ，…，Priv _ik }；

2-3) selecting k random strings (Q) _i1 ，Q _i2 ，Q _i3 ，…，Q _ik ) Each character string is exclusive-ored with the system parameter Z to obtain k new character strings (S _i1 ，S _i2 ，S _i4 ，…，S _ik ) The sensitive keywords are subjected to searchable encryption to obtain ciphertext CK _i ，

CK _i ＝PEKS(Apub _i ，W _i )

＝([S _i1 ，Encrypt(Pub _i1 ，Q _i1 )]，([S _i2 ，Encrypt(Pub _i2 ，Q _i2 )]，[S _i3 ，Encrypt(Pub _i3 ，Q _i3 )]，...，([S _ik ，Encrypt(Pub _ik ，Q _ik )]；

2-4) encrypt each file, then:

C _i ＝Encrypt _ECC (PK _A ，M _i )；

2-5) uploading all file ciphertexts and sensitive keyword ciphertexts corresponding to the file ciphertexts to a cloud storage center, wherein the ciphertexts only use the private key SK of the data owner A _A Can the decryption succeed, the cloud storage center cannot acquire the plaintext M, and the proxy server calls the intelligent contract to document ciphertext c= (C) ₁ ，C ₂ ，C ₃ ，...，C _n ) Keyword ciphertext Ck= (CK) ₁ ，CK ₂ ，CK ₃ ，…，CK _n ) The cloud storage center sends the dataID corresponding to the uploaded file to the data owner;

2-6) generating trapdoors using the private key of each sensitive keyword:

3) Sensitive keyword search: adopting a searchable encryption technology to ensure that a cloud storage center is sensitive under the condition of not contacting with plaintextSearching files, when a data visitor B needs to access data shared by a data owner A, firstly applying a keyword trapdoor to the data owner A, judging which of all sensitive keywords are invisible sensitive data of the data visitor B according to the identity of the data visitor B, and then generating a trapdoor list Tw _b And for trapdoor list Tw _b Signing to obtain S _t Public key PK of proxy server is then adopted _C For S _t Encryption is carried out to obtain C _t C is carried out by _t Returning to B, the search process is as follows:

3-1) data visitor B carries trapdoor C _t The data access request is sent to the cloud storage center by the data ID_B, wherein the data ID_B is a data ID list corresponding to all files which the data visitor B wants to access, the sharing center firstly authenticates the identity of the data visitor B, performs keyword search on target data after passing the identity authentication, and firstly adopts a private key SK _C Opposite trap door C _t Decryption is carried out to obtain signature S _t And then verifying the signature, and finally obtaining a sensitive keyword trapdoor list, wherein:

S _t ＝Decrypt _ECC (SK _C ，c _t )，

{Tw _b ，⊥}＝Verify(PK _A ，S _t )；

3-2) then calling an intelligent contract, and reading a file ciphertext set C 'and a corresponding sensitive keyword ciphertext CK' which are applied to be accessed by a data visitor B according to the dataID_B, wherein C 'and CK' are subsets of C and CK respectively;

3-3) ciphertext C 'for each file in collection C' _i Searching sensitive keywords, judging whether sensitive information exists in the file, and setting C' _i The corresponding sensitive keyword ciphertext is CK' _ij Traversal Tw _b T pairs of CK 'are used for each trapdoor t' _ij Decryption of element 1 of (c):

s＝Decrypt(CK’ _ij [1]，t)，

then, s is exclusive-ored with the system parameter Z to obtain s ', if s' =CK '' _ij [0]If the two are equal, the matching is successful, which indicates that the file existsSensitive keywords, adding corresponding dataID into the set of sendeids, when Tw _b When all trapdoors in the file fail to be matched with each keyword ciphertext of the file, indicating that no sensitive keywords exist in the file, and adding the dataID of the sensitive keywords into a security ids set;

4) Data desensitization and sharing: after searching the sensitive keywords, the cloud storage center already recognizes whether each file which is applied to be accessed by the data visitor B contains sensitive information, dataID, securityIDs which is corresponding to all files containing the sensitive information is recorded by adopting sendeids, dataIDs which are corresponding to all files not containing the sensitive information are recorded, the files corresponding to the sendeids are sent to the data owner A, and the data owner A desensitizes the data and then shares the data to the data visitor B; for files without sensitive information, the files can be directly delivered to the data visitor B by a cloud server through a proxy re-encryption technology, wherein:

4-1) sensitive file processing: the cloud proxy server first uses the private key SK _C Signing the identity information of the data visitor B, and then signing s=sign (SK _C userIdB) and file ciphertext C recorded in sendiiids _sst And (3) sending the data to A:

S||(C _sst1 ，C _sst2 ，…，C _sstd )，

the data owner a processes the file as follows:

4-1-1) data owner A first verifies signature S, inputs signature and public key PK of cloud proxy server _C The result of the signature verification is:

{userIdB，⊥}＝Verify(PK _C ，S)；

4-1-2) after verification, decrypting the file containing the sensitive information, then selecting a desensitization strategy R according to the identity authority of the data visitor B and executing desensitization operation:

M _sst ＝(M _ss21 ，M _sst2 ，…，M _sstd )

＝(Decrypt _ECC (SK _A ，C _sst1 )，Decrypt _ECC (SK _A ，C _sst2 )，...，Decrypt _ECC (SK _A ，C _sstd ))

D＝(D ₁ ，D ₂ ，...，D _d )

＝(dataMask(R，M _sst1 )，dataMask(R，M _sst2 )，…，dataMask(R，M _sstd ))；

4-1-3) after the desensitization is finished, encrypting the data by using the public key of the data visitor B and then sending the encrypted data to the data visitor B: c (C) _D ＝Encrypt _ECC (SK _B ，D)；

4-2) non-sensitive file processing: the cloud proxy server directly gives the file ciphertext to the data visitor B, but the file ciphertext is encrypted by the public key of the data owner A, and the proxy server further re-encrypts the ciphertext to obtain ciphertext C ^* Wherein the proxy re-encrypts the key K _AtoB Generated by the private key of data owner a and the public key of data visitor B:

K _AtoB ＝GetRekey(SK _A ，PK _B )，

C ^* ＝PreReEncrypt(K _AtoB ，C _sec )；

4-3) data decryption: when the data visitor B accesses successfully, C is obtained from the data owner A and the cloud proxy server respectively _D And C ^* Wherein C _D Is generated by the data owner A directly encrypting the file by using the public key of the data visitor B after desensitizing the file, the data visitor B successfully decrypts by using the private key, and the desensitized plaintext data is obtained, because of C ^* Which in turn goes through the public key SK of the data owner a _A And proxy re-encryption key K _AtoB While the proxy re-encrypts the key K _AtoB Is made of SK _A And public key PK of data visitor B _B The operation generation, the data visitor B can also decrypt using the private key:

M _D ＝GetDecryptedData(SK _B ，C _D )，

M ^* ＝PreReDecrypt(SK _B ，C ^* )。