A method and system for improving the reliability of blockchain differential authorization deduplication system

Abstract

The present invention is applicable to the field of blockchain technology improvement, and provides a method for improving the reliability of a blockchain differential authorization deduplication system, comprising: S1, adding an attribute list for the highest authority in the blockchain network and setting the number of attributes to n ; S2, select another n Each node keeps an attribute of the highest authority and sets a timeout time T for the system X ; S3, when the authority changes, the system will send a signature request to the highest authority; S4, determine the timeout time T X S5: If more than half of the committee members vote to pass the resolution, the attribute key of the highest authority is generated as a temporary signature key. This overcomes the problem of being unable to sign when the highest authority is not online. The attribute key set generated by the attribute agency that exceeds the threshold is used as the authority change signature, and the nodes involved in the generation of the attribute key are packaged and published on the blockchain as a transaction, ensuring the traceability of information.

Description

Technical Field

[0001] The present invention belongs to the field of blockchain technology improvement, and in particular relates to a method for improving the reliability of a blockchain differential authorization deduplication system. Background Art

[0002] With the continuous development of the big data era, big data technologies such as cloud computing and cloud storage have made great progress. Whether it is hardware equipment or a series of algorithms such as storage and transmission, new solutions are constantly emerging. In order to save unnecessary expenses on local resources, more and more users choose to store local data in the cloud, thereby alleviating the pressure on local server storage. At the same time, data stored in the cloud can also be shared more conveniently according to user needs. According to the Big Data White Paper (2020) released by the China Academy of Information and Communications Technology in December 2020, the amount of global cloud storage data is still growing at a rapid pace. At the end of 2020, the global cloud storage data reached 47ZB. It is predicted that by 2035, this data will explode to 2142ZB. Data resources have also officially become one of the five production factors, on par with labor, land, capital and technology, which reflects the importance that the country and society attach to data resources. In the scientific community, research on big data is also constantly moving forward. From 2012 to the present, the number of papers published in related fields with big data as the keyword has reached 64,739. Among them, China and the United States are far ahead with 18,216 and 16,241 papers respectively. These theoretical studies have also further promoted the continuous development of big data technology in the industry.

[0003] However, with the continuous surge in data on the cloud, a series of problems have also arisen, among which the first is the issue of data security. Many malicious attackers have targeted this thriving and lucrative industry and launched various attacks. According to the 2020 EMC Global Data Protection Index, data loss, server downtime and the resulting economic losses are very significant, causing serious consequences.

[0004] Another important issue is that in actual application scenarios, there may be many copies of data with the same content uploaded to the cloud server, which causes a lot of unnecessary overhead and waste of space, and also increases the storage and transmission costs of users when using cloud services. However, if the file data is directly stored in the cloud storage server, it is easy to face a series of risks such as data theft and leakage, so the ciphertext of the data should be stored in the cloud storage server. However, when storing ciphertext in the cloud storage server, since the nodes cannot fully trust each other or are even completely unfamiliar with each other, in the traditional encryption and decryption algorithm, the keys used by users to encrypt data are generated independently by users, which causes the uploaded identical data to become different after becoming ciphertext, and finally the duplicate data cannot be successfully deleted; if the cloud storage server generates a unified key to encrypt the data, it is easy to face the common centralization problem. Once the cloud storage server is maliciously attacked or the storage server itself becomes untrustworthy, the user's data security cannot be guaranteed.

[0005] In order to ensure data security and save storage space, many scholars have proposed many deduplication solutions. However, in these solutions, the focus is on how to achieve deduplication while ensuring data security, but they do not fully consider how to achieve trusted permission management when there are differences in permissions between users. Differential authorization between users is an issue that cannot be ignored in real scenarios. Users with different identities should have different operating permissions when facing data in cloud servers. How to achieve flexible differential authorization while ensuring the security of permission management has become an urgent problem to be solved. In the face of this problem, blockchain and attribute-based encryption signature technology are a good choice.

[0006] The Proof of Vote (PoV) consensus algorithm is a consensus mechanism based on voting. It relies on the golden rule of "the minority obeys the majority" to maintain the unity of organizational actions. Through the design of a specific consensus mechanism, it achieves good cooperation among multiple parties in collaboration. It is mainly used in alliance chain systems jointly maintained by alliances composed of enterprises or institutions in various regions of the world. Applications developed on this alliance chain can serve end users of the global network. PoV separates voting rights and execution rights. Compared with public chain consensus algorithms such as PoW and PoS, it abandons the proof of work method that relies on computing power, which can reduce block time while avoiding computing power waste. A network identity model based on four roles, namely committee members, housekeepers, housekeeper candidates, and ordinary accounts, is established. The design of the consensus algorithm verifies its security and correctness based on the basic requirements of scenic spot distribution theory and consensus theory, including meeting eventual consistency, activity (availability), and partition tolerance. In terms of performance, it meets high efficiency, low consumption, and fault tolerance. At the same time, PoV has proven that it can resist three common attacks on blockchains: double-flower attacks, witch attacks, and selfish mining. Compared with existing algorithms, PoV has the following advantages:

[0007] 1) In terms of compliance supervision, alliance nodes are allowed to fully control the generation and confirmation of transaction data. Compared with the public chain algorithm, the controllability of the system is reflected in the fact that only more than half of the committee members need to agree to maintain the on-chain data.

[0008] 2) In terms of transaction performance, PoV can achieve throughput processing that meets the transaction generation rate, and the transaction confirmation delay can reach 12.74s, which is better than most existing consensus mechanisms and meets the application requirements of the alliance chain.

[0009] 3) In terms of resource consumption, PoV ensures the security of the system through the credibility of the alliance committee nodes. There is no need for Nakamoto consensus-style computing power competition, and the power energy consumption is almost negligible.

[0010] 4) In terms of partition tolerance, PoV can ensure that as long as there are more than half of the members working normally and a normal steward node in the network, the system can continue to operate, and even if the nodes in the blockchain network are divided into two areas that cannot communicate with each other, the blockchain can still be guaranteed not to bifurcate. The security model is established using the characteristics of the alliance chain to maximize the security of PoV.

[0011] 5) In terms of consensus, PoV only needs to achieve the confirmation of more than half of the committee members in the network to reach the consensus of the block. The consensus has final consistency. The final validity of the transaction can be confirmed by waiting for only one block. Each block has finality. The final decision of the system node is consistent with more than half of the committee nodes to achieve system consistency. Compared with PoW, transaction confirmation is faster. Compared with PBFT, the election of the butler node reduces the communication overhead, which can reflect the efficiency of PoV.

[0012] 6) In terms of security, since the blocks generated by the housekeeper need to be verified by more than half of the committee members and obtain their signatures before they can be officially released, as long as more than half of the committee members are working normally, the correctness of the blockchain data can be guaranteed. The public chain lacks a regulatory mechanism in design, and any node can generate blocks, so it may be attacked by malicious nodes for double spending, that is, there are two incompatible transactions in the block. The PoV consensus algorithm adopts a committee supervision system, and the committee members need to verify the transactions in the block when verifying the block, so double spending attacks can be avoided.

[0013] PoV only allows one butler to generate blocks in each consensus cycle, and only one block is generated in each round of consensus, while other butlers are idle, so its block generation process is also serialized. However, since the communication complexity of PoV is O(3Nc), Nc is the number of committee members, the on-duty butler needs to send the generated blocks to all committee members for signature request. Therefore, when the number of committee nodes increases, the data throughput of PoV will decrease linearly, which has an adverse effect on the scalability of PoV.

[0014] In addition, since the next on-duty steward number in PoV is calculated by calculating the signatures of the committee members in the block, and the on-duty steward can arbitrarily arrange and combine these signatures when collecting signatures and storing them in the block header to change the next on-duty steward number, there is a possibility of selfish mining.

[0015] The blockchain-based differential authorization deduplication system consists of three parts, namely S-CSP (storage server provider), a private cloud server responsible for maintaining the user permission table, and users who upload and download files.

[0016] The workflow of uploading and downloading data in this system is as follows:

[0017] Before uploading and downloading data, initialization must be performed first. The purpose of this operation is to enable the system to complete some information necessary for operation, so as to facilitate communication and identity authentication between modules in the next step.

[0018] initialization:

[0019] The definition file F tag is A tag corresponds to a unique file data. In the improved system, S-CSP or users use file tags to identify or confirm a file, and different files have different tags. User permission sets use It is represented by , and its number is defined from small to large as the permission from high to low. It is also stipulated that high-level permission users can access files uploaded by low-level permission users and modify file permissions. In the initial state of the system, the first block of the blockchain will store a permission table. This permission table is signed with a negotiated private key S_kp of the highest permission owner P. This permission table is used to declare the permission level of each user. Any legitimate user in the system can use his public key P_k to view the permissions of each user. At the same time, the blockchain will also store the label of the file F And the encrypted file permissions It is convenient for S-CSP to query. Assume that user U wants to upload a file with permission The user's private key is S_kU, and S-CSP is initially empty.

[0020] Data upload:

[0021] If user U wants to upload a file F to a public cloud server, he needs to go through the following steps:

[0022] (1): The user sends the tag of the file to be uploaded encrypted by the private key S_kU to S-CSP User name U and its own permissions

[0023] (2): S-CSP will query whether there is a tag for the file on the blockchain And the file permissions

[0024] (3): This step can be divided into two different situations, namely, the file already exists and the file does not exist.

[0025] (3-1): If the file exists and its permissions are lower than or equal to the user's permissions The user needs to verify with the S-CSP using the POW algorithm to prove that he owns the file. At this time, the server will return a pointer to the user to indicate that the file already exists on the server and there is no need to upload it again. Note that if the file exists but the current file permissions are higher than the uploader, the user needs to decide whether to upload it again, because the user currently has no right to download the file from the cloud.

[0026] (3-2): If the file does not exist or the user does not have access to the file, the user needs to write the relevant information uploaded to the blockchain, that is, the file tag User name U, the user name U signed by its own private key S_kU, and the permission level at which the file can be accessed After verifying the identity of the user and S-CSP, the blockchain writes the record into a new block. At this time, the user can write a higher permission to the file for access by people with higher permissions. Then the user can send the data of the file encrypted by the convergent key to the S-CSP, such as Figure 1 shown.

[0027] Data download:

[0028] If user U wants to download file F to local computer, he needs to go through the following steps:

[0029] (1): The user sends the tag of the file to be downloaded to the S-CSP S-CSP will query whether the file exists.

[0030] (1-1): If the file does not exist, the S-CSP returns a prompt message to the user to inform the user that the file does not exist.

[0031] (1-2): If the file exists, user U sends the file tag User name U, username and permission information encrypted by own private key S_kU To S-CSP, S-CSP uses the user's public key P_kU to decrypt and obtain permissions.

[0032] (2): Use the public key of the highest authority to query the permission table to confirm whether the permissions match.

[0033] (2-1): If the permission is lower than the original permission of the file, the message "no permission to download" will be returned.

[0034] (2-2): If the permission is accessible, S-CSP will send a confirmation message to the blockchain. After verifying the identity of the user and S-CSP, the download record is saved in the block. S-CSP returns the file ciphertext C_F encrypted by the convergence key to the user, and the user uses the convergence key stored locally to decrypt the file.

[0035] Finally, when permissions change, you only need to write the changed information into the blockchain as a new transaction, such as Figure 2 shown.

[0036] During the actual operation of the deduplication solution, you may face the following situation: the highest authority is offline. At this time, if the permissions of a file or user are changed, and the change has been agreed upon by more than half of the other committee nodes, you need to wait for the highest authority to come online before signing and confirming and publishing it to the blockchain. At this time, the efficiency of permission changes will be affected. Summary of the invention

[0037] The purpose of the present invention is to provide a method for improving the reliability of a blockchain differential authorization deduplication system, aiming to solve the technical problem that when the highest authority is offline, the private key signature of the highest authority cannot be obtained in time when the authority changes.

[0038] The present invention is implemented as follows: a method for improving the reliability of a blockchain differential authorization deduplication system, the method for improving the reliability of a blockchain differential authorization deduplication system comprising the following steps:

[0039] S1. Add an attribute list for the highest authority in the blockchain network and set the number of attributes to n;

[0040] S2. Select n nodes to store an attribute of the highest authority and set a timeout time T for the system. X ;

[0041] S3. When the authority changes, the system will send a signature request to the person with the highest authority;

[0042] S4, determine the timeout period T X Whether the signature is obtained, if it is obtained, the highest authority is online and successfully uses his own private key to sign the updated permission table; if the highest authority private key S is not obtained, KH When a signed change list is created, a new round of consensus is initiated, and the committee members vote to decide whether to enable the attribute management agency to generate attribute keys to reach consensus on the change of permissions;

[0043] S5. If more than half of the committee members vote to approve the resolution, the attribute key of the person with the highest authority will be generated and used as a temporary signature key.

[0044] A further technical solution of the present invention is that the top manager in step S1 has two fields, identity and attribute

[0045] A further technical solution of the present invention is: the node that keeps an attribute of the person with the highest authority in step S2 is called an attribute management agency, which is responsible for generating the system public key and attribute key of its own corresponding attribute.

[0046] A further technical solution of the present invention is: in step S5, the system packages the consensus result as a new transaction and publishes it on the blockchain, and at the same time, the user acting as the attribute management agency generates a corresponding attribute key for the attribute of the highest authority managed by him / her.

[0047] A further technical solution of the present invention is that the highest authority in the system sets a threshold value, and the system public key can be decrypted when the attribute key set corresponding to more than m attributes is obtained, where m < n; when the authority changes in the system, the system will repeat steps S1 - S5, and the previous round of attribute keys is unavailable.

[0048] Another object of the present invention is to provide a system for improving the reliability of the blockchain differential authorization deduplication system. The system for improving the reliability of the blockchain differential authorization deduplication system includes

[0049] An attribute setting module, which is used to add an attribute list for the highest authority in the blockchain network and set the number of attributes to n;

[0050] A timeout setting module, which is used to select another n nodes to respectively store one attribute of the highest authority and set a timeout time T for the system X ;

[0051] A signature request module, which is used to send a signature request to the highest authority when the authority changes;

[0052] A signature acquisition judgment module, which is used to judge whether a signature is obtained within the set timeout time T X If a signature is obtained, the highest authority is online, and the updated authority list is signed using its own private key; if the change list signed by the private key S of the highest authority is not obtained KH a new round of consensus is initiated, and the committee votes to decide whether to enable the attribute management agency to generate attribute keys to conduct consensus on the change of authority;

[0053] An attribute key generation module, which is used to generate the attribute key corresponding to the highest authority as a temporary signature key if more than half of the committee members vote in favor of the resolution.

[0054] A further technical solution of the present invention is that the highest manager in the attribute setting module has two fields, identity and attribute

[0055] A further technical solution of the present invention is that the nodes storing one attribute of the highest authority in the timeout setting module are called attribute management agencies, which are responsible for generating the system public key and attribute keys corresponding to their respective attributes.

[0056] A further technical solution of the present invention is that in the attribute key generation module, the system packages the consensus result as a new transaction and publishes it on the blockchain. At the same time, the users acting as attribute management agencies will generate corresponding attribute keys for the attributes of the highest authority they manage.

[0057] A further technical solution of the present invention is that the highest - authority person in the system sets a threshold value, and when the attribute key set corresponding to more than m attributes is obtained, the system public key can be decrypted, where m < n; when the authority changes in the system, the system will repeat the actions in the attribute module, timeout setting module, signature request module, signature - obtained judgment module, and attribute key generation module, and the previous - round attribute keys are unavailable.

[0058] The beneficial effects of the present invention are as follows: adding an attribute list overcomes the problem that signature cannot be made when the highest - authority person is not online. Using the attribute key set with a quantity exceeding the threshold generated by the attribute institution as the signature for authority change, and at the same time, taking which nodes participated in the generation of this attribute key as a transaction and packaging and publishing it on the blockchain, ensuring the traceability of information.

[0059] In addition, since the highest - authority person has two fields, identity and attributes, and the private key generated by itself corresponding to the identity field has a higher priority, that is, when the highest - authority person is online, the committee members will not conduct consensus and allow the attribute institution to generate an attribute key set, so there is no need to worry about the collusion of the attribute institution. In addition, generating new attribute keys for each round of authority change further ensures the security of the system. Description of the Drawings

[0060] Figure 1 It is a schematic diagram of uploading data in the blockchain.

[0061] Figure 2 It is a schematic diagram of downloading data in the blockchain.

[0062] Figure 3 It is a flowchart of the method for improving the reliability of the blockchain differential - authorization deduplication system provided by the embodiment of the present invention. Detailed Embodiment

[0063] This solution focuses on improving the problem that when the highest - authority person is offline, the authority change cannot obtain its private - key signature in time, introduces attribute - based signature, and improves the system operation efficiency.

[0064] In the blockchain - based differential - authorization deduplication system, whether it is a file or a user, there are corresponding authorities. When the corresponding authority changes, this change needs to obtain the voting consensus of the committee members. In addition, in order to prevent tampering of the corresponding authority table, every time the authority changes, the committee member with the highest authority needs to sign the current change with the private key to ensure the authenticity and credibility of the authority table.

[0065] However, when the highest - authority person is offline, they cannot respond to the authority change in time, and then the duty steward cannot process and publish the change to the block, which will affect the system operation efficiency.

[0066] Therefore, we introduce the idea of ​​attribute signature and use the attribute key set to temporarily replace the identity of the highest authority, so as to ensure the normal operation of the system even when it is offline.

[0067] To address the problem of low system efficiency when the highest authority is not online, we consider adding an attribute list for the highest authority, with the number of attributes being n. In this case, the highest authority has two fields, identity and attribute. Set the highest authority user name to U H , whose signature private key is S KH , which is the private key used to sign the permission table during the normal operation process. In addition, n nodes are selected to keep U H At this time, these nodes can be regarded as attribute management agencies, responsible for generating system public keys and attribute keys for their corresponding attributes. In addition, the highest authority will also sign the members of the agency and the attributes they manage, and publish them on the blockchain for users to query.

[0068] It is worth noting that when permissions change, the system will first send a signature request to the highest authority. When the highest authority is online and successfully uses his or her own private key to sign the updated permission table, the attribute management agency cannot generate attribute keys at this time. If a collusion attack occurs, when the private key representing the identity exists, the system is set to not recognize the attribute key, that is, the private key representing the identity of the highest authority has a higher priority than the attribute key representing his or her attributes.

[0069] At the same time, a timeout period T is set for the system X If the S is not obtained within the timeout period, KH When a signed change list is created, a new round of consensus is initiated, and the committee members vote to decide whether to enable the attribute management agency to generate attribute keys to reach consensus on changes in permissions.

[0070] If more than half of the committee members vote to pass the resolution, the system will first package the consensus result as a new transaction and publish it on the blockchain. At the same time, the user who acts as the attribute management agency will generate the corresponding attribute key for the attribute of the highest authority under his management. The highest authority will set a threshold value, that is, when the attribute key set corresponding to more than m attributes is obtained, the system public key can be decrypted, and the key set can be used as a temporary signature key.

[0071] When the permissions change again, the system will repeat the above process, and the attribute key of the previous round cannot be used again to improve its security. The process is as follows Figure 3 shown.

[0072] The process can be formally described by the following pseudo code:

[0073]

[0074] This improvement overcomes the problem of being unable to sign when the highest authority is not online. The attribute key set generated by the attribute agency that exceeds the threshold is used as the authority change signature, and the nodes that participated in the generation of the attribute key are also packaged and published on the blockchain as a transaction, ensuring the traceability of information.

[0075] In addition, because the highest authority has two fields, identity and attribute, and the private key corresponding to the identity field has a high priority, that is, when the highest authority is online, the committee will not reach a consensus and allow the attribute agency to generate a set of attribute keys, so there is no need to worry about collusion of the attribute agency. In addition, each round of permission change will generate a new attribute key, which further ensures the security of the system.

[0076] The present invention aims to improve the problem that in a blockchain-based differential authorization deduplication solution, when user or file permissions change, the highest authority fails to use the private key to sign in a timely manner, thereby affecting the system operation efficiency.

[0077] The present invention introduces the idea of ​​attribute signature, separates the identity and attributes of the highest authority, and the identity has a higher priority than the attribute, and then uses several nodes to act as attribute agencies to generate attribute keys to act as temporary signature keys, thereby solving the problem that when the highest authority is not online, the change of authority cannot be processed in time, affecting subsequent user file access.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for improving the reliability of a blockchain differential authorization deduplication system, characterized in that: The method for improving the reliability of the blockchain differential authorization deduplication system comprises the following steps: S1. Add an attribute list for the highest authority in the blockchain network and set the number of attributes to n; S2. Select n nodes to store an attribute of the highest authority and set a timeout time T for the system. X ; S3. When the authority changes, the system will send a signature request to the person with the highest authority; S4, judging the timeout period T X Whether the signature is obtained, if it is obtained, the highest authority is online and successfully uses his own private key to sign the updated permission table; if the highest authority private key S is not obtained, KH When a signed change list is created, a new round of consensus is initiated, and the committee members vote to decide whether to enable the attribute management agency to generate attribute keys to reach consensus on the change of permissions; S5. If more than half of the committee members vote to pass the resolution, the attribute key corresponding to the highest authority will be generated and used as a temporary signature key.

2. The method for improving the reliability of the blockchain differential authorization deduplication system according to claim 1 is characterized in that: In step S1, the top manager has two fields, identity and attributes.

3. The method for improving the reliability of the blockchain differential authorization deduplication system according to claim 2 is characterized in that: The node that keeps an attribute of the highest authority in step S2 is called an attribute management agency, which is responsible for generating the system public key and attribute key of its own corresponding attribute.

4. The method for improving the reliability of the blockchain differential authorization deduplication system according to claim 3 is characterized in that: In step S5, the system packages the consensus result as a new transaction and publishes it on the blockchain. At the same time, the user acting as the attribute management agency will generate corresponding attribute keys for the attributes of the highest authority managed by him.

5. The method for improving the reliability of the blockchain differential authorization deduplication system according to claim 1 is characterized in that: The person with the highest authority in the system sets a threshold value, and when a set of attribute keys corresponding to more than m attributes is obtained, the system public key can be decrypted, where m < n; when the authority changes in the system, the system will repeat steps S1-S5, and the attribute keys of the previous round will not be available.

6. A system for improving the reliability of blockchain differential authorization deduplication system, characterized in that: The system for improving the reliability of the blockchain differential authorization deduplication system includes Set the attribute module, which is used to add an attribute list for the highest authority in the blockchain network and set the number of attributes to n; The timeout setting module is used to select n nodes to store an attribute of the highest authority and set a timeout time T for the system. X ; Signature request module, used to send a signature request to the highest authority when the authority changes; Obtain a signature judgment module to judge whether the signature is valid within the set timeout period T X Whether the signature is obtained, if it is obtained, the highest authority is online and successfully uses his own private key to sign the updated permission table; If the private key S of the highest authority is not obtained KH When a signed change list is created, a new round of consensus is initiated, and the committee members vote to decide whether to enable the attribute management agency to generate attribute keys to reach consensus on the change of permissions; The attribute key generation module is used to generate the attribute key of the corresponding highest authority as a temporary signature key if more than half of the committee members vote to pass the resolution.

7. The system for improving the reliability of the blockchain differential authorization deduplication system according to claim 6 is characterized in that: The top manager in the Set Attributes module has two fields, identity and attributes 8. The system for improving the reliability of the blockchain differential authorization deduplication system according to claim 7 is characterized in that: The node that keeps an attribute of the highest authority in the timeout setting module is called an attribute management agency, which is responsible for generating the system public key and attribute key of its own corresponding attribute.

9. The system for improving the reliability of the blockchain differential authorization deduplication system according to claim 8 is characterized in that: In the attribute key generation module, the system packages the consensus result as a new transaction and publishes it on the blockchain. At the same time, the user acting as the attribute management agency will generate corresponding attribute keys for the attributes of the highest authority managed by him.

10. The system for improving the reliability of the blockchain differential authorization deduplication system according to claim 9 is characterized in that: The person with the highest authority in the system sets the threshold value, and when a set of attribute keys corresponding to more than m attributes is obtained, the system public key can be decrypted, where m < n; when the authority changes in the system, the system will repeat the actions in the attribute module, timeout setting module, signature request module, signature judgment module, and attribute key generation module, and the previous round of attribute keys will be unavailable.

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