Multi-group data security sharing method and system supporting traceability and revocation

Abstract

The invention discloses a multi-group data security sharing method and system supporting traceability and revocation. A trusted key generation center generates parameters required by system operation; generating an attribute private key and a puncturable private key; the data owner uses a pre-formulated access control strategy to encrypt data to be shared by adopting puncturable attribute-based encryption; the group administrator formulates a new access control strategy, and generates a re-encryption key based on an attribute private key of the group administrator; the cloud server performs re-encryption on the original ciphertext according to the proxy re-encryption key; and the group administrator decrypts the original ciphertext according to the attribute private key and the puncturable private key, and the user in the group decrypts the re-encrypted ciphertext according to the attribute private key, the puncturable private key and the authorized private key to obtain the plaintext of the data to be shared. According to the method, the user decryption key is divided into the attribute private key, the puncturable private key and the authorized private key, the group user identity can be uniquely determined through combination of the three types of keys, and refined tracing is achieved.

Description

Technical Field

[0001] This invention relates to the field of network security technology, and more specifically, to a method and system for secure sharing of multi-group data that supports traceability and revocation. Background Technology

[0002] With the rapid development of cloud computing, the demand for shared data stored on outsourced servers is constantly increasing among users from different groups. Typically, each group consists of an administrator and multiple users within the group, where the administrator is responsible for managing access control permissions for the data, as this data may be sensitive. For example, patients from multiple hospitals may encrypt their medical data and upload it to a cloud server for research use, while the department head (i.e., the administrator) must stipulate who can access this data, such as doctors or nurses.

[0003] To achieve fine-grained data sharing in the cloud, most research employs Attribute-Based Encryption (ABE). In this mechanism, data is encrypted according to an access policy defined by the data owner, and only users whose attribute set matches the predefined policy can decrypt the data. However, in data sharing scenarios, this mechanism faces the problem of key abuse: attackers may compromise the device storing the keys or obtain leaked keys from publicly available databases. We primarily focus on the latter, i.e., the situation where leaked keys are publicly disclosed. Specifically, the keys used by legitimate authorized administrators or users within a group to access data on a cloud server may be exposed to unauthorized entities, who may then maliciously publish these keys. Once these keys are obtained, attackers can decrypt multiple pieces of sensitive data on the cloud server, potentially leading to user privacy breaches and reducing users' willingness to share.

[0004] Therefore, we can see that there are two technical problems in multi-group data sharing scenarios: First, after the key is leaked due to multiple groups, it is difficult to locate the group and role (administrator or user) to which the user belongs; Second, multiple user attributes make it difficult to ensure that a specific attribute group corresponds to multiple users, making it difficult to implement fine-grained security permission revocation for specific users while ensuring the legitimate user's permissions. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a method and system for secure data sharing across multiple groups that supports traceability and revocation. Specifically, each group administrator obtains an attribute private key and a piercing private key from a key generation center. Unlike the group administrator, users within the group need to obtain an attribute private key from the key generation center and a piercing private key and an authorization private key from their respective group administrator. When sharing data with a specific user, the group administrator delegates the task of proxy re-encryption to a cloud server. The cloud server uses a piercing attribute-based encryption method to encrypt the original ciphertext and generate new ciphertext. Simultaneously, users within the group must possess the attribute private key, the piercing private key, and the authorization private key to correctly decrypt the new ciphertext. In the event of key leakage, the key generation center can locate the specific leaking user by tracing the piercing private key and the authorization private key, and revoke their corresponding access permissions, thereby mitigating the risk of key misuse in a multi-group environment.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for secure sharing of multi-group data that supports traceability and revocation, comprising: The trusted key generation center generates the parameters required for system operation, including the system public key and the system master key; The trusted key generation center generates corresponding attribute private keys and puncturable private keys based on the user's identity information and attributes. If the user is a user within the group, the corresponding attribute private key is returned; if the user is a group administrator, the corresponding attribute private key and puncturable private key are returned. The data owner uses a pre-defined access control policy and employs puncturable attribute-based encryption to encrypt the data to be shared, obtaining the original ciphertext; The group administrator formulates a new access control policy and generates a re-encryption key based on their own attribute private key. The re-encryption key includes the proxy re-encryption key sent to the cloud server and the authorization private key sent to users in the group. The cloud server re-encrypts the original ciphertext using the proxy's re-encryption key; The group administrator decrypts the original ciphertext using the obtained attribute private key and puncture-enabled private key to obtain the plaintext of the data to be shared; users in the group decrypt the re-encrypted ciphertext using the obtained attribute private key, puncture-enabled private key, and authorization private key to obtain the plaintext of the data to be shared. The puncture-enabled private key of each user in the group is obtained from the corresponding group administrator.

[0007] In one implementation, the method further includes a malicious user tracing step, comprising: Tracing malicious group administrators and malicious users within the group involves extracting pre-bound identity information from the group administrator's spoofable private key to trace the malicious group administrator's identity. Tracing malicious users within the group involves extracting pre-bound user identity information from the user's authorized private key and extracting pre-bound group administrator identity information from the spoofable private key to obtain the user's group and specific identity.

[0008] In one implementation, the method further includes a user undo step, comprising: The revocation process involves both group administrator and user revocation. For group administrator revocation, the key generation center sends an encryption puncture command to the group administrator, which includes a puncture tag. The group administrator obtains an updated puncturable key based on the puncture tag and randomly selected elements within the group. For user revocation, the group administrator does not assign authorized private keys to users within the group, generates a new re-encryption key, and entrusts the cloud server to perform proxy re-encryption.

[0009] In one implementation, the trusted key generation center generates the parameters required for the system to operate, including: The trusted key generation center receives the user's identity information and its own attributes; Elements are randomly selected from the set of real numbers, and attribute private keys and puncturable private keys are generated based on identity information and user ownership attributes. The attribute private keys include a first attribute private key subkey, a second attribute private key subkey, and a third attribute private key subkey, and the puncturable private keys include a first puncturable private key subkey, a second puncturable private key subkey, a third puncturable private key subkey, a fourth puncturable private key subkey, and a fifth puncturable private key subkey.

[0010] In one implementation, the pre-defined access control policy includes a secret-sharing-based access control structure. The data owner uses the pre-defined access control policy to encrypt the data to be shared using puncturable attribute-based encryption, including: The data owner encrypts the data to be shared based on the system's public key, the data to be shared, the access control structure based on secret sharing, and a tag associated with the ciphertext, thus obtaining the ciphertext.

[0011] In one implementation, the group administrator formulates a new access control policy and generates a re-encryption key based on their own attribute private key, including: The group administrator formulates a new access control policy that satisfies the users in the sharing group based on the attribute information of the users to be shared; Based on the group administrator's attribute private key, the new access control policy for users within the shared group, and the identity information of users who need to be shared within the group, a re-encryption key for the server and an authorization private key for the shared users are generated.

[0012] In one implementation, the cloud server performs re-encryption on the original ciphertext based on the proxy re-encryption key, including: Set valid attributes to participate in the mapping set; Based on the valid attributes participating in the mapping set, the agent re-encrypts the key to calculate the new ciphertext; The re-encrypted ciphertext is obtained based on the new ciphertext, the original ciphertext, the access control structure based on secret sharing, and the set of tags associated with the ciphertext.

[0013] Based on the same inventive concept, a second aspect of the present invention provides a multi-group data secure sharing system that supports traceability and revocation, comprising: The system initialization module is used to support the trusted key generation center in generating the parameters required for system operation, including the system public key and the system master key; The user key generation module is used to support the trusted key generation center in generating corresponding attribute private keys and piercing private keys based on user identity information and attributes. Specifically, if the user is a user within a group, the corresponding attribute private key is returned; if the user is a group administrator, the corresponding attribute private key and piercing private key are returned. The data encryption module is used to support data owners in using pre-defined access control policies and employing puncturable attribute-based encryption to encrypt the data to be shared, obtaining the original ciphertext. The proxy re-encryption key generation module is used to support group administrators in formulating new access control policies and generating re-encryption keys based on their own attribute private keys. The re-encryption keys include the proxy re-encryption key sent to the cloud server and the authorization private key sent to users in the group. The proxy re-encryption module is used to support cloud servers in re-encrypting the original ciphertext based on the proxy re-encryption key; The data decryption module is used to support group administrators in decrypting the original ciphertext using the obtained attribute private key and puncture-enabled private key to obtain the plaintext of the data to be shared; group users can also decrypt the re-encrypted ciphertext using the obtained attribute private key, puncture-enabled private key, and authorization private key to obtain the plaintext of the data to be shared. The puncture-enabled private key for each group user is obtained from the corresponding group administrator.

[0014] In one implementation, the system further includes a malicious user tracing module for tracing malicious group administrators and malicious users within the group. Tracing malicious group administrators includes extracting pre-bound identity information from the group administrator's pierceable private key to trace the identity of the malicious group administrator. Tracing malicious users within the group includes extracting pre-bound user identity information from the user's authorized private key and extracting pre-bound group administrator identity information from the pierceable private key to obtain the user's group and specific identity.

[0015] In one implementation, the system further includes a user revocation module for revoking the group administrator's account and revoking the account of users within the group. Revocation of the group administrator's account includes the key generation center sending an encryption piercing instruction to the group administrator, wherein the encryption piercing instruction includes a piercing tag, and the group administrator obtains an updated piercing key based on the piercing tag and randomly selected elements within the group. Revocation of the account of users within the group includes the group administrator not distributing authorized private keys to users within the group, while simultaneously generating a new re-encryption key and entrusting the cloud server to perform proxy re-encryption.

[0016] Compared with the prior art, the advantages and beneficial technical effects of the present invention are as follows: This invention discloses a method and system for secure sharing of multi-group data that supports traceability and revocation. By introducing a multi-dimensional key segmentation mechanism, the user decryption key is divided into three parts: an attribute private key, a puncturable private key, and an authorization private key. The puncturable private key is bound to the group administrator's identity and is used to identify the group; the authorization private key is bound to the group user's identity and is used to identify the user's identity. The combination of these three types of keys can uniquely identify group users, enabling fine-grained traceability. For revocation operations, this invention proposes a differentiated revocation strategy based on adaptive key manipulation encryption, applicable to both group administrator and group user revocation scenarios. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a multi-group data secure sharing method in an embodiment of the present invention; Figure 2 This is a flowchart illustrating a method for securely sharing traceable and revocable multi-group data in another embodiment of the present invention. Figure 3This is an architecture diagram of a multi-group data security sharing system that supports traceability and revocation in an embodiment of the present invention. Detailed Implementation

[0019] Key aspects of this invention include: 1. An efficient group user tracing scheme was designed, supporting tracing of both group administrators and users within the group. The scheme introduces the concept of multi-dimensional key segmentation, dividing the decryption key into attribute private keys, puncture private keys, and authorization private keys. Different private keys are bound to different user identity information, and tracing different private keys can pinpoint specific users.

[0020] 2. Design an adaptive group user revocation scheme that supports revocation by both group administrators and group users. To address the potential for policy conflicts during the revocation process, different revocation methods will be used for different roles.

[0021] 3. A multi-group data security sharing system supporting traceability and revocation was designed. Notably, the system's traceability and revocation mechanisms are specifically designed for group administrators and group users. Different methods are implemented based on the characteristics of different roles. Therefore, a user traceability and secure revocation mechanism can be effectively implemented.

[0022] Example 1 This embodiment provides a method for securely sharing multi-group data that supports traceability and revocation. Please refer to [link to relevant documentation]. Figure 1 ,include: S1: The trusted key generation center generates the parameters required for system operation, including the system public key and the system master key.

[0023] Specifically, S1 is the system initialization step. The trusted key generation center generates the public key and system master key required by the system based on security parameters. Input system security parameters. The maximum number of attribute tags associated with the ciphertext (The number of attributes in the system) and the number of columns in the linear secret sharing matrix. Output system public key and system master key .

[0024] In the specific implementation process, firstly, select an input group. An output group And they are all multiplicative cyclic groups, calculating bilinear operations. Randomly select the set of real numbers elements in and shared matrix The position corresponds to an element in the multiplication cyclic group. Set up three functions Then, select a depth of polynomial ,make ,calculate At the same time, set up polynomials Choose an initial label that can be recognized. Finally, the system public key and system master key are output as follows: , ; in, It is a generator.

[0025] S2: The trusted key generation center generates corresponding attribute private keys and puncturable private keys based on the user's identity information and attributes. If the user is a user within the group, the corresponding attribute private key is returned. If the user is a group administrator, the corresponding attribute private key and puncturable private key are returned.

[0026] Specifically, S2 is the user key generation step. The user sends their identity information and the attributes they possess to the trusted key generation center. The key generation center then returns different information based on the user's identity. If the user is a group administrator, the center returns the attribute private key and the puncturable private key. Otherwise, the center only returns the attribute private key.

[0027] S2 can be implemented in the following way: S2.1: The trusted key generation center receives the identity information sent by the user and the attributes it possesses; S2.2: Randomly select elements from the set of real numbers and generate attribute private keys and puncturable private keys based on identity information and user ownership attributes. The attribute private keys include a first attribute private key subkey, a second attribute private key subkey, and a third attribute private key subkey. The puncturable private keys include a first puncturable private key subkey, a second puncturable private key subkey, a third puncturable private key subkey, a fourth puncturable private key subkey, and a fifth puncturable private key subkey.

[0028] In practice, if the user is a group administrator, then the input is... yes (Group administrator ID), if you are a group user, please enter this. yes (Group User ID). Registered users will use their unique identity. and the set of attributes possessed Send it to the trusted key generation center, and then generate the user attribute private key. and pierceable private key Specifically, random selection And calculate the attribute private key and the puncturable private key, wherein the attribute private key includes the first attribute private key subkey. Second attribute: private key / subkey Second attribute: private key The calculation method is as follows:

[0029] in, The number of rows in the shared matrix. This is the row index of the shared matrix.

[0030] A stabable private key includes: a first stabable private key subkey. Second puncturable private key Third puncturable private key Fourth, a puncturable private key And the fifth puncturable private key The calculation method is as follows:

[0031]

[0032] , It is a random number. This is the group administrator's ID.

[0033] Finally, if the registered user is a group administrator, the trusted key generation center will be sent to them. If the user is in the group, then only send... .

[0034] S3: The data owner uses a pre-defined access control policy and employs puncturable attribute-based encryption to encrypt the data to be shared, obtaining the original ciphertext.

[0035] Specifically, S3 is the data encryption step. The data owner uses a predefined access control policy and employs puncturable attribute-based encryption to encrypt the data to be shared, obtaining the encrypted ciphertext (original ciphertext), and then uploads the ciphertext to the cloud for storage.

[0036] S3 can be implemented in the following way: The data owner encrypts the data to be shared based on the system's public key, the data to be shared, the access control structure based on secret sharing, and a tag associated with the ciphertext, thus obtaining the ciphertext.

[0037] In the specific implementation process, input the system public key. Plaintext data Access control structure based on secret sharing and a set of tags related to the ciphertext. ,in For shared matrices, This is a mapping function that maps the corresponding row to an attribute. The data owner is randomly selected. ,in It is The matrix, randomly selected Form a vector Then calculate the original ciphertext, where the original ciphertext is... Including the first ciphertext Second ciphertext Third ciphertext Fourth ciphertext The calculation method is as follows:

[0038]

[0039] in, for The exponentiation of the corresponding attribute element; Finally, the ciphertext is output. .

[0040] S4: The group administrator formulates a new access control policy and generates a re-encryption key based on their own attribute private key. The re-encryption key includes the proxy re-encryption key sent to the cloud server and the authorization private key sent to users in the group.

[0041] Specifically, S4 is the re-encryption key generation step. The group administrator formulates a new access control policy based on the attribute information of the users to be shared, and generates a re-encryption key based on their own attribute private key, including the proxy re-encryption key sent to the cloud server and the authorization private key sent to the users in the group.

[0042] S4 can be implemented in the following way: S4.1: The group administrator formulates a new access control policy that satisfies the users in the sharing group based on the attribute information of the users to be shared; S4.2: Based on the group administrator's attribute private key, the new access control policy for users within the shared group, and the identity information of users within the group that need to be shared, generate the server's re-encryption key and the authorization private key for the shared users.

[0043] In the specific implementation process, the group administrator's private key is entered. To meet the new access control policies for users within the shared group. Users need to share their identities within the group. Output the cloud server re-encryption key and shared user authorization private key , For the new shared matrix, For the new mapping function.

[0044] Specifically, randomly select a random number Calculate identity binding value Cloud server re-encryption key Including the first encryption subkey Second encryption subkey Third encryption subkey and the fourth encryption subkey The specific calculation method is as follows: .

[0045] Then, choose a random vector. Then calculate the authorized private key for the shared user, where the authorized private key... Including the first authorized private key subkey Second authorized private key Third-party authorized private key and the fourth authorized private key The calculation method is as follows: .

[0046] Finally Send to the cloud server, Send to the relevant users in the shared group.

[0047] S5: The cloud server performs re-encryption on the original ciphertext based on the agent's re-encryption key.

[0048] Specifically, S5 is a proxy re-encryption step. The cloud server performs a re-encryption operation on the original ciphertext based on the received re-encryption key, changing the access control policy of the original ciphertext without revealing its privacy.

[0049] S5 can be implemented in the following ways: S5.1: Set valid attributes to participate in the mapping set; S5.2: Calculate new ciphertext based on the valid attributes participating in the mapping set and the proxy re-encryption key; S5.3: Obtain the re-encrypted ciphertext based on the new ciphertext, the original ciphertext, the access control structure based on secret sharing, and the set of tags associated with the ciphertext.

[0050] Enter re-encryption key and the original ciphertext Output the re-encrypted ciphertext Define valid attributes to participate in the mapping set. , Attributes exist Corresponding share value , making Among them, the Lagrange coefficient It is possible to reconstruct the shared key. ; Then calculate the new ciphertext. Finally, the re-encrypted ciphertext is obtained. .

[0051] S6: The group administrator decrypts the original ciphertext using the obtained attribute private key and puncture-enabled private key to obtain the plaintext of the data to be shared; the group users decrypt the re-encrypted ciphertext using the obtained attribute private key, puncture-enabled private key and authorization private key to obtain the plaintext of the data to be shared. The puncture-enabled private key of the group users is obtained from the corresponding group administrator.

[0052] Specifically, S6 is the data decryption step, which is mainly divided into two cases: group administrator decryption and group user decryption. The group administrator uses their own attribute private key and puncturable encryption key to decrypt the original ciphertext; while group users need to use their own attribute private key, puncturable private key, and authorization private key to decrypt the re-encrypted ciphertext and finally obtain the plaintext.

[0053] In practice, the decryption algorithm can be divided into two cases depending on the decryption target: decryption by the group administrator and decryption by users within the group.

[0054] The group administrator decrypts the data by entering the system public key. Attribute set Attribute private key and ciphertext and the set of attributes associated with the ciphertext Finally, output plaintext. The calculation and decryption of part A is as follows: For a puncture encryption key, there exists a set of coefficients. This makes the following formula true: Then, the decryption part B is calculated as follows: and .

[0055] Users within the group need to decrypt the code by entering the system's public key. Attribute set Attribute private key, puncturable private key, and authorized private key, as well as ciphertext. and the set of attributes associated with the ciphertext Finally, output plaintext. The identity binding value is calculated as follows: Then calculate the decryption part B: .

[0056] In one implementation, the method further includes a malicious user tracing step, comprising: Tracing malicious group administrators and malicious users within the group involves extracting pre-bound identity information from the group administrator's spoofable private key to trace the malicious group administrator's identity. Tracing malicious users within the group involves extracting pre-bound user identity information from the user's authorized private key and extracting pre-bound group administrator identity information from the spoofable private key to obtain the user's group and specific identity.

[0057] Specifically, tracing malicious users includes tracing malicious group administrators and malicious users within the group. Tracing malicious group administrators involves verifying their identity by extracting the identity information from the spoofable private key; while tracing malicious users within the group requires combining the spoofable private key and the authorization private key to uniquely identify their identity.

[0058] In the specific implementation process, two different scenarios are used to trace the leaked encryption keys of group administrators and users within the group. For tracing the leak of a group administrator's vulnerable encryption key, the input is the vulnerable encryption key, the user identity table maintained by the key server, and public parameters. The output is the identity of the group administrator whose key was leaked. To output the formula that satisfies the above formula. .

[0059] To trace the leakage of decryption keys among users within a group, the input includes the decryption key, the user identity table maintained by the key server, and common parameters. The output is the identity of the user whose key was leaked. Output the formula that satisfies the above formula. .

[0060] In one implementation, the method further includes a user undo step, comprising: The revocation process involves both group administrator and user revocation. For group administrator revocation, the key generation center sends an encryption puncture command to the group administrator, which includes a puncture tag. The group administrator obtains an updated puncturable key based on the puncture tag and randomly selected elements within the group. For user revocation, the group administrator does not assign authorized private keys to users within the group, generates a new re-encryption key, and entrusts the cloud server to perform proxy re-encryption.

[0061] Please see Figure 2 The flowchart below illustrates a method for secure sharing of multi-group data that supports traceability and revocation, as provided in an embodiment of the present invention.

[0062] Specifically, user revocation mainly covers two scenarios: revocation for group administrators and revocation for users within the group. Revocation for group administrators can be achieved through puncturable encryption; while for revocation for users within the group, the group administrator first stops assigning authorization private keys and generates a new re-encryption key, which is then delegated to a cloud server to perform proxy re-encryption, thereby achieving the revocation of users within the group.

[0063] In practice, the revocation algorithm is executed by the group administrator. It mainly involves revocation of the pierceable encryption key for the group administrator and revocation of the key for other users within the group. For revocation targeting the administrator in a collaborative group, the key generation center sends a pierceable encryption command, including a pierce tag 't', to the administrator, who then randomly selects an element within the group. The updated puncture-enabled key includes: the first updated puncture-enabled key subkey. The second update allows for the penetration of key subkeys. After the third update, the key subkey can be pierced. The fourth update allows for the penetration of key subkeys. After the fifth update, the key and sub-key can be pierced. After the sixth update, the key subkey can be pierced. After the seventh update, the key and sub-key can be pierced. And the piercing key subkey after the eighth update The specific calculation method is as follows: , , , , .

[0064] The process involves revoking the access control of users in a collaborative group, the group administrator selecting a new access control policy that makes the malicious user's attributes no longer meet the new policy, and then invoking a re-encryption key generation algorithm to generate a new re-encryption key. ,Will Send to the cloud server, the cloud server processes the encrypted text. Perform a re-encryption operation to generate new ciphertext. At the same time, new authorization private keys will no longer be issued. Send to users who maliciously revoked the contract.

[0065] Example 2 Based on the same inventive concept, this embodiment discloses a multi-group data secure sharing system that supports traceability and revocation, including: The system initialization module is used to support the trusted key generation center in generating the parameters required for system operation, including the system public key and the system master key; The user key generation module is used to support the trusted key generation center in generating corresponding attribute private keys and piercing private keys based on user identity information and attributes. Specifically, if the user is a user within a group, the corresponding attribute private key is returned; if the user is a group administrator, the corresponding attribute private key and piercing private key are returned. The data encryption module is used to support data owners in using pre-defined access control policies and employing puncturable attribute-based encryption to encrypt the data to be shared, obtaining the original ciphertext. The proxy re-encryption key generation module is used to support group administrators in formulating new access control policies and generating re-encryption keys based on their own attribute private keys. The re-encryption keys include the proxy re-encryption key sent to the cloud server and the authorization private key sent to users in the group. The proxy re-encryption module is used to support cloud servers in re-encrypting the original ciphertext based on the proxy re-encryption key; The data decryption module is used to support group administrators in decrypting the original ciphertext using the obtained attribute private key and puncture-enabled private key to obtain the plaintext of the data to be shared; group users can also decrypt the re-encrypted ciphertext using the obtained attribute private key, puncture-enabled private key, and authorization private key to obtain the plaintext of the data to be shared. The puncture-enabled private key for each group user is obtained from the corresponding group administrator.

[0066] like Figure 3 The diagram shown is an architecture diagram of a multi-group data security sharing system that supports traceability and revocation in an embodiment of the present invention. The entities involved in the system include a key generation center, data owners, cloud servers, and users (group administrators and group users).

[0067] In one implementation, the system further includes a malicious user tracing module for tracing malicious group administrators and malicious users within the group. Tracing malicious group administrators includes extracting pre-bound identity information from the group administrator's pierceable private key to trace the identity of the malicious group administrator. Tracing malicious users within the group includes extracting pre-bound user identity information from the user's authorized private key and extracting pre-bound group administrator identity information from the pierceable private key to obtain the user's group and specific identity.

[0068] In one implementation, the system further includes a user revocation module for revoking the group administrator's account and revoking the account of users within the group. Revocation of the group administrator's account includes the key generation center sending an encryption piercing instruction to the group administrator, wherein the encryption piercing instruction includes a piercing tag, and the group administrator obtains an updated piercing key based on the piercing tag and randomly selected elements within the group. Revocation of the account of users within the group includes the group administrator not distributing authorized private keys to users within the group, while simultaneously generating a new re-encryption key and entrusting the cloud server to perform proxy re-encryption.

[0069] This invention can provide users with a private, secure, traceable, and revocable sharing method in more fields such as data sharing and cloud storage.

[0070] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0071] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0072] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various modifications and variations to the embodiments of the invention without departing from the spirit and scope of the invention. Thus, if these modifications and variations of the embodiments of the invention fall within the scope of the claims of the invention and their equivalents, the invention also intends to include these modifications and variations.

Claims

1. A method for secure data sharing across multiple groups, characterized in that, include: The trusted key generation center generates the parameters required for system operation, including the system public key and the system master key; The trusted key generation center generates corresponding attribute private keys and puncturable private keys based on the user's identity information and attributes. If the user is a user within the group, the corresponding attribute private key is returned; if the user is a group administrator, the corresponding attribute private key and puncturable private key are returned. The data owner uses a pre-defined access control policy and employs puncturable attribute-based encryption to encrypt the data to be shared, obtaining the original ciphertext; The group administrator formulates a new access control policy and generates a re-encryption key based on their own attribute private key. The re-encryption key includes the proxy re-encryption key sent to the cloud server and the authorization private key sent to users in the group. The cloud server re-encrypts the original ciphertext using the proxy's re-encryption key; The group administrator decrypts the original ciphertext using the obtained attribute private key and puncture-enabled private key to obtain the plaintext of the data to be shared; users in the group decrypt the re-encrypted ciphertext using the obtained attribute private key, puncture-enabled private key, and authorization private key to obtain the plaintext of the data to be shared. The puncture-enabled private key of each user in the group is obtained from the corresponding group administrator.

2. The method for secure sharing of multi-group data as described in claim 1, characterized in that, The method also includes a malicious user tracing step, including: Tracing malicious group administrators and malicious users within the group involves extracting pre-bound identity information from the group administrator's spoofable private key to trace the malicious group administrator's identity. Tracing malicious users within the group involves extracting pre-bound user identity information from the user's authorized private key and extracting pre-bound group administrator identity information from the spoofable private key to obtain the user's group and specific identity.

3. The method for secure sharing of multi-group data as described in claim 2, characterized in that, The method also includes a user cancellation step, including: The revocation process involves both group administrator and user revocation. For group administrator revocation, the key generation center sends an encryption puncture command to the group administrator, which includes a puncture tag. The group administrator obtains an updated puncturable key based on the puncture tag and randomly selected elements within the group. For user revocation, the group administrator does not assign authorized private keys to users within the group, generates a new re-encryption key, and entrusts the cloud server to perform proxy re-encryption.

4. The method for secure sharing of multi-group data as described in claim 1, characterized in that, The trusted key generation center generates the parameters required for the system to run, including: The trusted key generation center receives the user's identity information and its own attributes; Elements are randomly selected from the set of real numbers, and attribute private keys and puncturable private keys are generated based on identity information and user ownership attributes. The attribute private keys include a first attribute private key subkey, a second attribute private key subkey, and a third attribute private key subkey, and the puncturable private keys include a first puncturable private key subkey, a second puncturable private key subkey, a third puncturable private key subkey, a fourth puncturable private key subkey, and a fifth puncturable private key subkey.

5. The method for secure sharing of multi-group data as described in claim 1, characterized in that, Predefined access control policies include a secret-sharing-based access control structure. Data owners use these policies to encrypt the data to be shared using puncturable attribute-based encryption, including: The data owner encrypts the data to be shared based on the system's public key, the data to be shared, the access control structure based on secret sharing, and a tag associated with the ciphertext, thus obtaining the ciphertext.

6. The method for secure sharing of multi-group data as described in claim 1, characterized in that, The group administrator sets up a new access control policy, generating a re-encryption key based on their own attribute private key, including: The group administrator formulates a new access control policy that satisfies the users in the sharing group based on the attribute information of the users to be shared; Based on the group administrator's attribute private key, the new access control policy for users within the shared group, and the identity information of users who need to be shared within the group, a re-encryption key for the server and an authorization private key for the shared users are generated.

7. The method for secure sharing of multi-group data as described in claim 5, characterized in that, The cloud server performs re-encryption on the original ciphertext based on the proxy re-encryption key, including: Set valid attributes to participate in the mapping set; Based on the effect attribute, participate in the mapping set and calculate the new ciphertext using the proxy re-encryption key; The re-encrypted ciphertext is obtained based on the new ciphertext, the original ciphertext, the access control structure based on secret sharing, and the set of tags associated with the ciphertext.

8. A multi-group data secure sharing system, characterized in that, include: The system initialization module is used to support the trusted key generation center in generating the parameters required for system operation, including the system public key and the system master key; The user key generation module is used to support the trusted key generation center in generating corresponding attribute private keys and piercing private keys based on user identity information and attributes. Specifically, if the user is a user in the group, the corresponding attribute private key is returned; if the user is a group administrator, the corresponding attribute private key and piercing private key are returned. The data encryption module is used to support data owners in using pre-defined access control policies and employing puncturable attribute-based encryption to encrypt the data to be shared, obtaining the original ciphertext. The proxy re-encryption key generation module is used to support group administrators in formulating new access control policies and generating re-encryption keys based on their own attribute private keys. The re-encryption keys include the proxy re-encryption key sent to the cloud server and the authorization private key sent to users in the group. The proxy re-encryption module is used to support cloud servers in re-encrypting the original ciphertext based on the proxy re-encryption key; The data decryption module is used to support group administrators in decrypting the original ciphertext using the obtained attribute private key and puncture-enabled private key to obtain the plaintext of the data to be shared; group users can also decrypt the re-encrypted ciphertext using the obtained attribute private key, puncture-enabled private key, and authorization private key to obtain the plaintext of the data to be shared. The puncture-enabled private key of each group user is obtained from the corresponding group administrator.

9. The multi-group data secure sharing system as described in claim 8, characterized in that, The system also includes a malicious user tracing module, used to trace malicious group administrators and malicious users within the group. Tracing malicious group administrators includes extracting pre-bound identity information from the group administrator's pierceable private key to trace the identity of the malicious group administrator. Tracing malicious users within the group includes extracting pre-bound user identity information from the user's authorized private key and extracting pre-bound group administrator identity information from the pierceable private key to obtain the user's group and specific identity.

10. The method for secure sharing of multi-group data as described in claim 8, characterized in that, The system also includes a user revocation module for revoking the rights of group administrators and users within the group. Revocation of group administrators involves the key generation center sending an encryption piercing command to the group administrator, which includes a piercing tag. The group administrator obtains an updated piercing key based on the piercing tag and randomly selected elements within the group. Revocation of users within the group involves the group administrator not distributing authorized private keys to users within the group, generating a new re-encryption key, and entrusting the cloud server to perform proxy re-encryption.

Images