Security auditing method and device supporting data owner replacement, equipment, medium and product

Abstract

The invention discloses a safety auditing method and device supporting data owner replacement, equipment, a medium and a product, and relates to the field of auditing, and the method comprises the steps that if the data ownership is changed, an original data owner calculates a trap door parameter value based on a random number j and a private key of the original data owner; the new data owner calculates a conversion parameter value according to the trap door parameter value and a private key of the new data owner; the cloud server calculates the label of each data block after the data ownership is changed according to the conversion parameter value, the reciprocal of the random number j and the label of each data block before the data owner changes; the cloud server generates auditing evidences according to the labels of the data blocks and the inquiry information; the third-party auditor carries out safety auditing according to the auditing evidence and the inquiry information, and after the data ownership is changed, it can be ensured that the changed data owner can still ensure the continuity of data integrity verification under the condition that all the data are not downloaded.

Description

Technical Field

[0001] The present application relates to the field of auditing, and in particular to a security auditing method, apparatus, equipment, medium and product that supports data owner replacement. Background Art

[0002] The rapid development of cloud computing has made cloud storage services increasingly popular. However, when users store data in the cloud, they lose physical control of the data, making security and integrity a pressing concern. To address this issue, remote data integrity verification mechanisms have been proposed that can verify whether cloud data has been tampered with or corrupted without downloading all the data.

[0003] However, traditional public data integrity verification mechanisms mostly assume that the data owner remains unchanged and do not consider the frequent ownership transfer needs in the actual environment. However, in reality, during corporate mergers and acquisitions, Company A transfers the ownership of customer data stored in the cloud to Company B, and Company B needs to be able to verify the integrity and freshness of this data without downloading all the data to ensure that the data has not been tampered with or outdated.

[0004] Although data ownership transfer occurs frequently in cloud storage, how to ensure the continuity of data integrity verification after the data ownership changes without downloading all the data? Summary of the Invention

[0005] The purpose of this application is to provide a security audit method, device, equipment, medium and product that supports data owner replacement, which can ensure the continuity of data integrity verification for the changed data owner without downloading all data after the data ownership changes.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] In a first aspect, this application provides a security audit method that supports data owner replacement, including:

[0008] If the data ownership has not changed, the data owner divides the file stored in the cloud into multiple data blocks, generates labels for each data block before the data ownership change based on the data owner's private key, and sends the labels and each data block before the data ownership change to the cloud server;

[0009] If the data ownership changes, the original data owner selects a random number j and calculates a trapdoor parameter value based on the random number j and the original data owner's private key. The inverse of the random number j is then sent to the cloud server, which in turn sends the trapdoor parameter value to the new data owner. The new data owner calculates a conversion parameter value based on the trapdoor parameter value and the new data owner's private key, and sends the conversion parameter value to the cloud server. The cloud server calculates the labels of each data block after the data ownership change based on the conversion parameter value, the inverse of the random number j, and the labels of each data block before the data owner change.

[0010] The cloud server generates audit evidence based on the tags of each data block and the query information, and sends the audit evidence to the third-party auditor. The query information is generated by the third-party auditor. If the data ownership has not changed, the tags of each data block are the tags of each data block before the data ownership change. If the data ownership has changed, the tags of each data block are the tags of each data block after the data ownership change.

[0011] Third-party auditors conduct security audits on files stored in the cloud based on audit evidence and inquiry information.

[0012] In a second aspect, the present application provides a security audit device that supports data owner replacement, including:

[0013] A first label generation module is configured to, if the data ownership has not changed, divide the file stored in the cloud into multiple data blocks by the data owner, generate a label for each data block before the data ownership change based on the data owner's private key, and send the label of each data block before the data ownership change and each data block to the cloud server;

[0014] The second label generation module is configured to: if data ownership changes, the original data owner selects a random number j and calculates a trapdoor parameter value based on the random number j and the original data owner's private key; then sends the reciprocal of the random number j to the cloud server, and sends the trapdoor parameter value to the new data owner; the new data owner calculates a conversion parameter value based on the trapdoor parameter value and the new data owner's private key, and sends the conversion parameter value to the cloud server; the cloud server calculates the label of each data block after the data ownership change based on the conversion parameter value, the reciprocal of the random number j, and the label of each data block before the data owner change;

[0015] The audit evidence generation module is used by the cloud server to generate audit evidence based on the labels of each data block and the query information, and send the audit evidence to the third-party auditor. The query information is generated by the third-party auditor. If the data ownership has not changed, the label of each data block is the label of each data block before the data ownership change; if the data ownership has changed, the label of each data block is the label of each data block after the data ownership change.

[0016] The audit module is used by third-party auditors to conduct security audits on files stored in the cloud based on audit evidence and inquiry information.

[0017] In a third aspect, the present application provides a computer device comprising: a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the computer program to implement any of the above-described security audit methods supporting data owner replacement.

[0018] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-mentioned security audit methods supporting data owner replacement.

[0019] In a fifth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements any of the above-mentioned security audit methods supporting data owner replacement.

[0020] According to the specific embodiments provided in this application, this application has the following technical effects:

[0021] The present application provides a security audit method, apparatus, device, medium and product that supports the replacement of data owners. If the data ownership changes, the present application can achieve efficient transfer of cloud data owners after the data ownership changes, without the new data owner having to download all the data locally and ensuring the continuity of data integrity verification, with the help of trapdoor parameter D and conversion parameter θ. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A flowchart of a security audit method supporting data owner replacement provided in one embodiment of the present application;

[0024] Figure 2 A schematic diagram of a security audit method supporting data owner replacement provided in one embodiment of the present application;

[0025] Figure 3 Schematic diagram of the changes in the hash tree before and after the data block is modified;

[0026] Figure 4Schematic diagram of the changes in the hash tree before and after deleting the data block;

[0027] Figure 5 Schematic diagram of the changes in the hash tree before and after inserting the data block;

[0028] Figure 6 A schematic diagram of the functional modules of a security audit device that supports data owner replacement, provided in one embodiment of the present application;

[0029] Figure 7 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0031] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0032] In an exemplary embodiment, a security audit method supporting data owner replacement is provided, such as Figure 1 and Figure 2 As shown, the following steps are included:

[0033] Step 201: If the data ownership has not changed, the data owner divides the file stored in the cloud into multiple data blocks, generates a label for each data block before the data ownership change based on the data owner's private key, and sends the label of each data block before the data ownership change and each data block to the cloud server.

[0034] Step 202: If the data ownership changes, the original data owner selects a random number j and calculates a trapdoor parameter value based on the random number j and the private key of the original data owner, then sends the reciprocal of the random number j to the cloud server, and sends the trapdoor parameter value to the new data owner; the new data owner calculates a conversion parameter value based on the trapdoor parameter value and the private key of the new data owner, and sends the conversion parameter value to the cloud server; the cloud server calculates the label of each data block after the data ownership change based on the conversion parameter value, the reciprocal of the random number j and the label of each data block before the data owner change.

[0035] Step 203: The cloud server generates audit evidence based on the label of each data block and the query information, and sends the audit evidence to the third-party auditor; the query information is generated by the third-party auditor; if the data ownership has not changed, the label of each data block is the label of each data block before the data ownership change; if the data ownership has changed, the label of each data block is the label of each data block after the data ownership change.

[0036] Step 204: The third-party auditor performs a security audit on the files stored in the cloud based on the audit evidence and the inquiry information.

[0037] In actual applications, the data owner divides the cloud-stored file into multiple data blocks and sends the labels of each data block and each data block before the data ownership change to the cloud server. Specifically, the data owner divides the file F into n data blocks. Expressed as F={m1,m2....m n}, Represents the multiplication group modulo p (in the modulo p operation system, all addition, multiplication, and division operations are performed by taking the modulo p), which consists of all positive integers less than p and coprime to p. The data owner will Upload to the cloud server, where φ={σ i} 1≤i≤n , σ i Represents the label of the i-th data block before the data ownership change.

[0038] In another exemplary embodiment of the present application, if the data ownership has not changed, the data owner generates a label for each data block before the data ownership change based on the data owner's private key, specifically:

[0039] The key generation center randomly selects an element u in the multiplication cycle group and sends the element u to the data owner.

[0040] The data owner selects a random number r and then uses the formula Get the label σ of the i-th data block before the data ownership change i , where H() represents a hash function, FID∈G, FID represents a file identifier, i represents the sequence number of the data block, FID||i||r represents the concatenation of FID, i and r, and h R Represents the root hash value of the hash tree. The hash tree is formed by storing the hash values ​​of all data blocks in a tree structure, specifically a Merkle tree; m i Represents the i-th data block, Sp represents the private key of the data owner. When the data ownership has not changed, the random number r and hash root value h are embedded when the tag is generated. R, which can effectively resist replay attacks.

[0041] In another exemplary embodiment of the present application, the key generation center randomly selects an element u in the multiplication cycle group, specifically: the key generation center selects a bilinear pairing e:G×G→G T , e is a bilinear map acting on the multiplicative cyclic group G and the multiplicative cyclic group G, where the multiplicative cyclic group G and the multiplicative cyclic group G T are two multiplicative cyclic groups of order p, g∈G is the generator of the multiplicative cyclic group G. The key generation center selects the hash function H:{0,1} * →G, h:{0,1} * →G, and pick a random element u∈G. In practical applications, r∈g.

[0042] In another exemplary embodiment of the present application, before the data owner selects a random number r, the following steps are also included: the data owner selects his own private key And calculate your own public key as And store the private key confidentially.

[0043] The key generation center publishes the system public parameters params = (G, G T ,e,g,u,H,PK P ).

[0044] In another exemplary embodiment of the present application, if the data ownership changes, the original data owner selects a random number j and calculates the trapdoor parameter value based on the random number j and the private key of the original data owner, and the new data owner determines his own private key. At the same time, calculate and publish your own public key

[0045] In another exemplary embodiment of the present application, the original data owner selects a random number j and calculates a trapdoor parameter value based on the random number j and the original data owner's private key, specifically:

[0046] The original data owner selects a random number The data owner uses the formula Calculate the trapdoor parameter value, where D represents the trapdoor parameter.

[0047] In another exemplary embodiment of the present application, the new data owner calculates the conversion parameter value based on the trapdoor parameter value and the new data owner's private key, specifically:

[0048] The new data owner is based on the formula Calculate the conversion parameter value, where θ represents the conversion parameter.

[0049] In another exemplary embodiment of the present application, the cloud server calculates the label of each data block after the data ownership change based on the conversion parameter value, the reciprocal of the random number j, and the label of each data block before the data owner change, specifically including:

[0050] The cloud server calculates the label conversion factor value according to the conversion parameter value and the reciprocal of the random number j.

[0051] The cloud server calculates the label of each data block after the data ownership change based on the label conversion factor value and the label of each data block before the data owner change.

[0052] In another exemplary embodiment of the present application, the cloud server calculates the label conversion factor value according to the conversion parameter value and the inverse of the random number j, specifically: according to the formula Calculate the label conversion factor value, where T represents the label conversion factor.

[0053] In another exemplary embodiment of the present application, the cloud server calculates the label of each data block after the data ownership change based on the label conversion factor value and the label of each data block before the data owner change, specifically:

[0054] According to the formula Calculate the label σ′i of the i-th data block after data ownership conversion.

[0055] In another exemplary embodiment of the present application, the process of the third-party auditor generating the query information is as follows: if the data ownership has not changed, the third-party auditor randomly selects s ​​numbers in [1,n] to form a subset J, and generates a corresponding random number for each selected number v t Represents the random number corresponding to the number t selected before the data ownership change, where t∈J, and then generates the challenge information chal={s,v t} t∈J After the data owner changes, in order to ensure the validity of the audit and prevent malicious adversaries from launching replay attacks, the third-party auditor needs to regenerate the query information to obtain the query information after the data ownership is changed: chal′={s′,v′ t′} t′∈J′ , so if the data ownership changes, the third-party auditor randomly selects s′ numbers in [1,n] to form a subset J′ and generates a corresponding random number for each selected number v′ t′ The random number corresponding to the number t′ selected after the data ownership change is generated, and the challenge information chal′={s′,v′ t′} t′∈J′ .

[0056] In another exemplary embodiment of the present application, the audit evidence includes label evidence and data block evidence. The cloud server generates audit evidence based on the label of each data block and the query information as follows:

[0057] If the data ownership has not changed, the cloud server will Generate label evidence before data ownership changes According to the formula μ=∏ t∈J m t ·v t Generate data block evidence μ before the data ownership change, and finally obtain audit evidence before the data ownership change

[0058] If the data ownership changes, after receiving the challenge information sent by the third-party auditor, the cloud server will Computing label evidence after data ownership change According to the formula μ′=∏ t′∈J′ m t′ ·v′ t′ Calculate the data block evidence μ' after the data ownership change, and finally obtain the audit evidence after the data ownership change

[0059] In practical applications, because

[0060] Therefore, if the data ownership has not changed, the third-party auditor will conduct a security audit of the files stored in the cloud based on the audit evidence and the inquiry information. Specifically: The third-party auditor receives the audit evidence. Later, the correctness of P is verified by the following equation: If the equation holds true, it means that the file stored by the data owner in the cloud is correct and complete, and the third-party auditor returns 1; otherwise, it returns 0.

[0061] It is worth noting that the transfer of data ownership means that the label is updated without any impact on the data. i , does not affect file F, and because Therefore, during the integrity verification phase, if the data ownership changes, the third-party auditor will conduct a security audit of the cloud-stored files based on the audit evidence and the query information. Specifically, the third-party auditor will perform a security audit based on the equation Verifying audit evidence If the equation holds true, the third-party auditor returns 1, which means that the data stored in the cloud by the new data owner is correct and complete, and the data owner conversion is successful; otherwise, it returns 0.

[0062] In another exemplary embodiment of the present application, the security audit method supporting data owner replacement further includes:

[0063] When the data owner wants to update the i-th data block to the preset data block, the data owner sends a data block update request to the cloud server, updates the hash value corresponding to the i-th data block in the hash tree, obtains the updated hash tree, and calculates the root hash value of the updated hash tree; the hash tree is formed by storing the hash values ​​of all data blocks in a tree structure. Specifically, assuming that the data owner's i-th data block m i Needs to be updated to m′ i The data owner initiates a file block update request to the cloud server Doc req =(Doc,i,m′ i ,Ver′), where Doc represents the identifier of the file to be updated, Ver' represents the updated version number, and the hash value h(m′) of the corresponding node is updated at the same time i ||Ver′||n i ), n i Indicates the position number of the i-th data block in the hash tree, that is, the index value from left to right, h() represents the hash function used to generate the hash number of each node, m′ i ||Ver′||n i Indicates that m′ i , Ver′ and n i Splice them together and recalculate the root hash value h of the hash tree D-MHT R The diagram of the changes in the hash tree before and after the data block is modified is as follows: Figure 3 shown.

[0064] The data owner obtains the update tag of the i-th data block based on the root hash value of the updated hash tree and the preset data block, and initiates a data block update request to the cloud server again. Specifically, the data owner uses the formula Get the updated label σ of the i-th data block i ″, and send data update request Mod to the cloud server again req =(Mod,i,m′ i ,σ i ″), Mod represents the data block update request identifier. When the cloud server receives the data update request, the cloud server updates the data block information (m′ i ,σ i ″), S represents the private key of the data owner. If the data ownership does not change, S is Sp; if the data ownership changes, S is S N .

[0065] The cloud server modifies the i-th data block to the preset data block, and modifies the label of the i-th data block to the updated label of the i-th data block.

[0066] In another exemplary embodiment of the present application, the security audit method supporting data owner replacement further includes:

[0067] When the data owner wants to delete the i-th data block, the data owner sends a data block deletion request to the cloud server. Specifically: Assume that the i-th file block m i Need to be deleted, the data owner generates a data deletion request Del req =(Del,i,m i ) and sends it to the cloud server, where Del represents the data block deletion request identifier.

[0068] After receiving the deletion request, the cloud server deletes the i-th data block and the tag of the i-th data block from the file to obtain the updated file; deletes the hash value corresponding to the i-th data block in the hash tree to obtain the updated hash tree, and calculates the root hash value of the updated hash tree; the hash tree is formed by storing the hash values ​​of all data blocks in a tree structure. Specifically: the cloud server deletes the block information (m i ,σ i ) and the corresponding hash value h(m i ||Ver||n i ), and update the root hash value h of the hash tree D-MHT R , Ver represents the version number of the data block, m i ||Ver||n i Indicates that m i , Ver and n i The diagram of the change of the hash tree before and after deleting the data block is as follows: Figure 4 shown.

[0069] In another exemplary embodiment of the present application, the security audit method supporting data owner replacement further includes:

[0070] When the data owner wants to insert a preset file block after the i-th data block, the data owner initiates a data block insertion request to the cloud server. Specifically: Assume that the preset file block m y Needs to be inserted into the i-th file block m i After that, the data owner needs to send a data insertion request to the cloud server. req =(Ins,i,y,m y ,Ver), Ins represents the data block insertion request identifier, and y represents the subscript of the inserted data block.

[0071] The cloud server calculates the hash value corresponding to the preset file block in the hash tree, obtains the updated hash tree, and calculates the root hash value of the updated hash tree; the hash tree is formed by storing the hash values ​​of all data blocks in a tree structure. Specifically: the cloud server calculates the file block m y The hash value h(m y ||Ver||n y ), m y ||Ver||n y Indicates that m y , Ver and n y Splice it together, n y Indicates the preset file block m y The position number in the hash tree and the root hash value h of the hash tree D-MHT are updated R The diagram of the change of hash tree before and after inserting data block is as follows: Figure 5 shown.

[0072] The data owner obtains the update tag of the preset file block based on the root hash value of the updated hash tree and the preset file block, and sends the update tag of the preset file block to the cloud server. Specifically: the data owner is the file block m y Generate file tags And send it to the cloud server, which updates the inserted data block information (m y ,σ y ).

[0073] After the cloud server inserts the preset file block into the i-th data block, it inserts the update tag of the preset file block after the tag of the i-th data block.

[0074] Ensuring the freshness of cloud data helps improve the user experience and enhance the reliability and competitiveness of cloud storage services. Therefore, adding support for dynamic data operations is a hot topic in public auditing research. This application uses Merkle trees to support full dynamic data operations such as deletion, insertion, and modification. Before the data ownership changes, the data owner can delete, insert, and modify the file. After the data ownership changes, the new data owner can also delete, insert, and modify the file.

[0075] When there is a need to transfer the data owner, the new and old users jointly generate the trapdoor parameter D and the conversion parameter θ, and the cloud server calculates the conversion factor T. Without the need to re-download all the stored content, the label is updated in the cloud, that is, the owner of the file is changed from the original data owner to the new data owner.

[0076] Based on the same inventive concept, embodiments of the present application also provide a security audit device supporting data owner replacement for implementing the aforementioned security audit method supporting data owner replacement. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more embodiments of the security audit device supporting data owner replacement provided below can be found in the aforementioned limitations of the security audit method supporting data owner replacement and will not be further elaborated here.

[0077] In an exemplary embodiment, Figure 6 As shown, a security audit device supporting data owner replacement is provided, including:

[0078] A first label generation module is configured to, if the data ownership has not changed, divide the file stored in the cloud into multiple data blocks by the data owner, generate a label for each data block before the data ownership change based on the data owner's private key, and send the label of each data block before the data ownership change and each data block to the cloud server;

[0079] The second label generation module is configured to: if data ownership changes, the original data owner selects a random number j and calculates a trapdoor parameter value based on the random number j and the original data owner's private key; then sends the reciprocal of the random number j to the cloud server, and sends the trapdoor parameter value to the new data owner; the new data owner calculates a conversion parameter value based on the trapdoor parameter value and the new data owner's private key, and sends the conversion parameter value to the cloud server; the cloud server calculates the label of each data block after the data ownership change based on the conversion parameter value, the reciprocal of the random number j, and the label of each data block before the data owner change;

[0080] The audit evidence generation module is used by the cloud server to generate audit evidence based on the labels of each data block and the query information, and send the audit evidence to the third-party auditor. The query information is generated by the third-party auditor. If the data ownership has not changed, the label of each data block is the label of each data block before the data ownership change; if the data ownership has changed, the label of each data block is the label of each data block after the data ownership change.

[0081] The audit module is used by third-party auditors to conduct security audits on files stored in the cloud based on audit evidence and inquiry information.

[0082] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 7As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O) and a communication interface. The processor, memory and input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store security audit data that supports data owner replacement. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a security audit method that supports data owner replacement is implemented.

[0083] Those skilled in the art will understand that Figure 7 The structure shown in the figure is merely a block diagram of a portion of the structure related to the solution of the present application and does not constitute a limitation on the computer device to which the solution of the present application is applied. A specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement. In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the above-mentioned method embodiments when executing the computer program.

[0084] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, which implements the above-mentioned method embodiments when executed by a processor.

[0085] In an exemplary embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the above method embodiments are implemented.

[0086] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0087] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0088] The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may include, but are not limited to, general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic units, data processing logic units based on quantum computing, and the like.

[0089] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A security audit method supporting data owner replacement, characterized in that: The security audit method supporting data owner replacement includes: If the data ownership has not changed, the data owner divides the file stored in the cloud into multiple data blocks, generates labels for each data block before the data ownership change based on the data owner's private key, and sends the labels and each data block before the data ownership change to the cloud server; If the data ownership changes, the original data owner selects a random number j and calculates a trapdoor parameter value based on the random number j and the original data owner's private key. The inverse of the random number j is then sent to the cloud server, which in turn sends the trapdoor parameter value to the new data owner. The new data owner calculates a conversion parameter value based on the trapdoor parameter value and the new data owner's private key, and sends the conversion parameter value to the cloud server. The cloud server calculates the labels of each data block after the data ownership change based on the conversion parameter value, the inverse of the random number j, and the labels of each data block before the data owner change. The cloud server generates audit evidence based on the tags of each data block and the query information, and sends the audit evidence to the third-party auditor. The query information is generated by the third-party auditor. If the data ownership has not changed, the tags of each data block are the tags of each data block before the data ownership change. If the data ownership has changed, the tags of each data block are the tags of each data block after the data ownership change. Third-party auditors conduct security audits on files stored in the cloud based on audit evidence and inquiry information.

2. The security audit method supporting data owner replacement according to claim 1, characterized in that: The security audit method supporting data owner replacement further includes: When the data owner wants to update the i-th data block to the preset data block, the data owner sends a data block update request to the cloud server, updates the hash value corresponding to the i-th data block in the hash tree, obtains the updated hash tree, and calculates the root hash value of the updated hash tree; the hash tree is formed by storing the hash values ​​of all data blocks in a tree structure; The data owner obtains the update tag of the i-th data block based on the root hash value of the updated hash tree and the preset data block, and initiates a data block update request to the cloud server again; The cloud server modifies the i-th data block to the preset data block, and modifies the label of the i-th data block to the updated label of the i-th data block.

3. The security audit method supporting data owner replacement according to claim 1, characterized in that: The security audit method supporting data owner replacement further includes: When the data owner wants to delete the i-th data block, the data owner initiates a data block deletion request to the cloud server; After receiving the deletion request, the cloud server deletes the i-th data block and the label of the i-th data block from the file to obtain the updated file; deletes the hash value corresponding to the i-th data block in the hash tree to obtain the updated hash tree, and calculates the root hash value of the updated hash tree; the hash tree is formed by storing the hash values ​​of all data blocks in a tree structure.

4. The security audit method supporting data owner replacement according to claim 1, characterized in that: The security audit method supporting data owner replacement further includes: When the data owner wants to insert a preset file block after the i-th data block, the data owner initiates a data block insertion request to the cloud server; The cloud server calculates the hash value corresponding to the preset file block in the hash tree, obtains an updated hash tree, and calculates the root hash value of the updated hash tree; the hash tree is formed by storing the hash values ​​of all data blocks in a tree structure; The data owner obtains the update tag of the preset file block based on the root hash value of the updated hash tree and the preset file block, and sends the update tag of the preset file block to the cloud server; After the cloud server inserts the preset file block into the i-th data block, it inserts the update tag of the preset file block after the tag of the i-th data block.

5. The security audit method supporting data owner replacement according to claim 1, characterized in that: If the data ownership has not changed, the data owner generates the labels of each data block before the data ownership change based on the data owner's private key, specifically: The key generation center randomly selects an element u in the multiplication cycle group and sends the element u to the data owner; The data owner selects a random number r and then uses the formula Get the label σ of the i-th data block before the data ownership change i , where H() represents a hash function, FID represents a file identifier, i represents the sequence number of the data block, FID||i||r represents the concatenation of FID, i and r, and h R Represents the root hash value of the hash tree. The hash tree is formed by storing the hash values ​​of all data blocks in a tree structure. m i represents the i-th data block, and Sp represents the private key of the data owner.

6. The security audit method supporting data owner replacement according to claim 1, characterized in that: The cloud server calculates the labels of each data block after the data ownership change based on the conversion parameter value, the reciprocal of the random number j, and the labels of each data block before the data owner change, specifically including: The cloud server calculates the label conversion factor value according to the conversion parameter value and the reciprocal of the random number j; The cloud server calculates the label of each data block after the data ownership change based on the label conversion factor value and the label of each data block before the data owner change.

7. A security audit device that supports data owner replacement, characterized in that: The security audit device supporting data owner replacement includes: A first label generation module is configured to, if the data ownership has not changed, divide the file stored in the cloud into multiple data blocks by the data owner, generate a label for each data block before the data ownership change based on the data owner's private key, and send the label of each data block before the data ownership change and each data block to the cloud server; The second label generation module is configured to: if data ownership changes, the original data owner selects a random number j and calculates a trapdoor parameter value based on the random number j and the original data owner's private key; then sends the reciprocal of the random number j to the cloud server, and sends the trapdoor parameter value to the new data owner; the new data owner calculates a conversion parameter value based on the trapdoor parameter value and the new data owner's private key, and sends the conversion parameter value to the cloud server; the cloud server calculates the label of each data block after the data ownership change based on the conversion parameter value, the reciprocal of the random number j, and the label of each data block before the data owner change; The audit evidence generation module is used by the cloud server to generate audit evidence based on the labels of each data block and the query information, and send the audit evidence to the third-party auditor. The query information is generated by the third-party auditor. If the data ownership has not changed, the label of each data block is the label of each data block before the data ownership change; if the data ownership has changed, the label of each data block is the label of each data block after the data ownership change. The audit module is used by third-party auditors to conduct security audits on files stored in the cloud based on audit evidence and inquiry information.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the security audit method supporting data owner replacement as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the security audit method for supporting data owner replacement according to any one of claims 1 to 6 is implemented.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the security audit method for supporting data owner replacement described in any one of claims 1 to 6 is implemented.

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