A privacy-preserving cloud data integrity audit method, device, and medium

Abstract

The present invention relates to the field of information security, and discloses a privacy protection cloud data integrity audit method, device and medium. The method includes: the data holder sets ID∈{0,1} * The signature public key is sent to the key generation center KGC; the key generation center KGC generates a private key s based on the public key ID =H1(ID) α ; where α is a random number and H1 is a hash function; the data holder verifies the private key s to the cloud ID =H1(ID) α The legitimacy of the data is ensured; for legitimate data, a third-party auditor TPA performs an integrity audit on the cloud; the present invention ensures the integrity and privacy of cloud data during the cloud data integrity audit phase, and solves the technical problems that the existing technology can purify signatures without restriction, which easily causes security risks, and is easily attacked by TPA data recovery, and has the risk of privacy leakage.

Description

Technical Field

[0001] The present invention relates to the field of information security, and in particular to a privacy-preserving cloud data integrity audit method, device, and medium. Background Art

[0002] The era of big data has arrived. With the surge in data volumes, storing massive amounts of data locally has become a heavy burden for users. Consequently, more and more organizations and individuals are choosing to store and share data on cloud servers. However, data stored in the cloud can be damaged or lost due to inevitable software bugs, hardware failures, and human errors.

[0003] In order to verify whether the data is stored completely in the cloud, researchers have proposed many Provable Data Possession (PDP) schemes, in which a third-party auditor (TPA) conducts an integrity audit on the data stored in the cloud.

[0004] Most existing PDP solutions protect data in a holistic manner, without distinguishing data by sensitivity. This fails to guarantee the security of sensitive data, the efficiency of data integrity verification, and the ease of data sharing. Some solutions directly store and share data in plaintext, which can easily lead to the leakage of user sensitive information. Other solutions encrypt all data for storage and sharing to protect data confidentiality. However, for large amounts of non-sensitive information, this approach significantly reduces the efficiency of data integrity verification and the ease of data sharing. How to efficiently perform data integrity audits while ensuring data security and ease of use is a question worthy of research and exploration.

[0005] Sanitizable Signatures is a functional digital signature scheme that introduces an authorized sanitizer role on top of classic digital signatures. The sanitizer can make limited and controlled modifications to certain parts of a signed message and generate a new valid signature for the sanitized message, without interacting with the original signer. Sanitizable signatures can "sanitize" user information that does not need to be disclosed (for example, replacing it with "####") based on different application scenarios without affecting the validity of the signature for other parts of the information. This allows for efficient verification of the integrity of non-sensitive information while protecting sensitive user information.

[0006] In a public key infrastructure (PKI), the user's public key, used to verify signature validity, is managed by a digital certificate issued by a certificate authority (CA), which involves a series of cumbersome management processes such as certificate issuance, revocation, and querying. Identity-based cleansing signatures directly use the user's identity as the public key, while the private key is generated by a key generator center (KGC) based on the user's identity information. This effectively avoids the cumbersome certificate management issues inherent in PKI systems and is more suitable for lightweight applications.

[0007] The first identity-based purifiable signature scheme suitable for cloud auditing was proposed by Wenting Shen (see "Enabling Identity-Based Integrity Auditing and Data Sharing With Sensitive Information Hiding for Secure Cloud Storage," IEEE Transactions on Information Forensics and Security, Vol. 14, No. 2, February 2019). In this scheme, the purifier can purify signatures without restriction, which can easily lead to security risks. The integrity proof provided by the cloud server during the audit phase is generated by a simple linear combination of messages, making it vulnerable to data recovery attacks by TPAs ​​and posing a privacy risk. Summary of the Invention

[0008] The purpose of the present invention is to propose a privacy-preserving cloud data integrity audit method, device and medium. The method addresses the technical problem that the existing technology can purify signatures without restriction when conducting cloud data integrity audits, which easily causes security risks and is easily susceptible to data recovery attacks by TPA, and there is a risk of privacy leakage.

[0009] The present invention provides a privacy-preserving cloud data integrity audit method, comprising the following steps:

[0010] S1: The data holder sets ID∈{0,1} * Sent to the Key Generation Center KGC as the signature public key;

[0011] S2: The key generation center KGC generates a private key s based on the public key ID =H1(ID) α ; Where α is a random number and H1 is a hash function;

[0012] S3: The data holder verifies the private key s to the cloudID =H1(ID) α the legitimacy of

[0013] S4: For legitimate data, a third-party auditor, TPA, will conduct an integrity audit on the cloud.

[0014] A storage medium stores instructions and data for implementing a privacy-preserving cloud data integrity audit method.

[0015] A privacy-preserving cloud data integrity auditing device comprises: a processor and a storage medium; the processor loads and executes instructions and data in the storage medium to implement a privacy-preserving cloud data integrity auditing method.

[0016] The beneficial effects provided by the present invention are:

[0017] 1. Regarding the security of signatures, this invention is based on mathematical problems, which ensure that even if the adversary knows the public key and the signature-message pair, it cannot forge another signature;

[0018] 2. Regarding the restrictions of signatures, existing cleansing signature schemes in cloud auditing do not restrict the rights of the purifier. This invention ensures that the purifier can only purify messages in the set K;

[0019] 3. Regarding perfect privacy protection, the present invention adds a random number r in the cloud audit stage j , preventing curious TPAs ​​from recovering the message from the proof;

[0020] 4. Regarding the transparency of the purgeable signature, the purgeable signature scheme of the present invention is transparent, that is, the outside world cannot distinguish whether a signature is purgeable.

[0021] All of the above technical means jointly ensure the integrity and privacy of cloud data during the cloud data integrity audit phase of the present invention, and solve the technical problems that the existing technology can purify signatures without restriction, which easily causes security risks, is easily subject to TPA data recovery attacks, and has the risk of privacy leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a simplified flow chart of the method of the present invention;

[0023] Figure 2 It is a specific flow chart of the method of the present invention;

[0024] Figure 3 It is a flowchart of the cloud audit stage of the present invention;

[0025] Figure 4 It is a working diagram of the hardware device of the present invention. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0027] Before formally explaining the present invention, the scheme of the present invention is first generally explained for easy understanding.

[0028] The method of the present invention involves four entities: the key generation center (KGC), the data holder, the cloud, and the third-party auditor (TPA). The relationship between these four entities can be found in the background information and will not be elaborated here. These four entities can also be constructed into an identity-based distributed RSA digital signature generation system.

[0029] In order to better describe the method of the present invention, the present invention explains some concepts and parameters involved in the following text in advance as follows:

[0030] G1 and G2 are two multiplicative cyclic groups with order p, and g is a generator of G1. We call e:G1×G1→G2 a bilinear map, which has three properties:

[0031] 1. Bilinearity. For any u,v∈G1 and There is e(u a ,v b )=e(u ab ,v)=e(u,v ab )=e(u,v) ab .

[0032] 2. Computability. For any u, v ∈ G1, e(u, v) can be computed in polynomial time.

[0033] 3. Non-degenerate. e(g,g)≠1, where 1 is the identity element in G2.

[0034] In the following description of the present invention, H: {0,1} * →G1 represents a hash function that maps strings of arbitrary length to the multiplicative cyclic group G1; the multiplication symbols are omitted, for example: uv represents u×v, e(u,v)e(p,q) represents e(u,v)×e(p,q).

[0035] In addition, there are some set parameters in the present invention, which are generated by the key generation center KGC. The specific related operations are as follows:

[0036] Select two multiplicative cyclic groups G1 and G2, with order being a prime number q, and the generator of G1 being g;

[0037] Pick a random value is the system master private key, calculate the system master public key P pub =g α ;

[0038] Select a bilinear pairing e:G1×G1→G2; select two hash functions H1,H2:{0,1} * →G1; randomly select n elements u1,u2,…u in G1 n ;

[0039] The system's public parameters PP = (G1, G2, e, q, g, P pub ,H1,H2,u1,u2,…,u n ).

[0040] The above is the interpretation of all parameters and concepts involved in the present invention. The present application is explained in detail below.

[0041] Please refer to Figure 1-Figure 3 The present invention provides a privacy-preserving cloud data integrity audit method, comprising the following steps:

[0042] S1: The data holder sets ID∈{0,1} * Sent to the Key Generation Center KGC as the signature public key;

[0043] S2: The key generation center KGC generates a private key s based on the public key ID =H1(ID) α ; Where α is a random number and H1 is a hash function;

[0044] As an embodiment, steps S1 to S2 are specifically as follows:

[0045] Input random number α as the master private key and input data holder ID∈{0,1} * To the key generation center KGC; the key generation center KGC returns the private key s corresponding to the data holder ID ID =H1(ID) α To the data holder.

[0046] S3: The data holder verifies the private key s to the cloud ID =H1(ID) α the legitimacy of

[0047] It should be noted that the process of step S3 can also be called a signature algorithm, which mainly refers to the process in which, in the present invention, the user (data holder) is responsible for generating a signature, uploading the file, signature and some verification values ​​to the cloud, and then deleting the local storage.

[0048] The signature algorithm process is as follows:

[0049] S31. The data holder takes a file F and names it η, and divides the file F into n blocks, namely m:(m1,m2,…,m n ),in

[0050] S32. Regulations It is a set of subscripts that allow cloud purifiers to modify some file blocks;

[0051] It should be noted that in the present invention, the cloud is a purifier that purifies files without user interaction and generates valid signatures for the purified files. The cloud can only purify user-defined files. i |i∈K}.

[0052] Therefore, as an embodiment, in step S32, the cloud purifier purifies the file as follows:

[0053] S321, regulations It is the set of file indexes actually modified in the cloud. is the set of unmodified file indexes on the cloud, K1∪K2=K. is the purified file, then when i∈K1, When i∈K2,

[0054] S322, the cloud generates the signature of the i-th (i∈K) block file after purification

[0055] S323, verify the i-th file purification signature:

[0056] S33, select random value Calculate the verification value β = g r ; g is the generator of the multiplicative cyclic group;

[0057] S34. The signature for the i-th block of the file is:

[0058] S35. The data holder converts {F,σ={σ i} 1≤i≤n ,β,η,{(u i ) r |(i∈K)}} is sent to the cloud and local data is deleted;

[0059] S36. The cloud verifies the signature of the i-th file:

[0060] P pub is the master public key, and P pub =g α .

[0061] S4: For legitimate data, a third-party auditor, TPA, will conduct an integrity audit on the cloud.

[0062] It should be noted that step S4 is specifically as follows:

[0063] S41. The data holder issues an audit request, and the third-party auditor, TPA, runs a challenge generation algorithm and sends it to the cloud.

[0064] As an example, in step S41, the challenge generation algorithm is specifically as follows:

[0065] S411. The third-party auditor TPA randomly selects b blocks (1≤b≤n). The challenge query set is:

[0066] S412. The third-party auditor TPA selects b random values Then challenge chal={j,v j} j∈I Send to the cloud.

[0067] S42. The cloud runs the proof generation algorithm and sends the proof to the third-party auditor TPA;

[0068] As an embodiment, in step S42, the proof generation algorithm is specifically as follows:

[0069] S421, Cloud Computing λ j =m j v j +r j ,in are all different random values;

[0070] S422, Cloud Computing and

[0071] S423、The cloud will prove Sent to third-party auditor TPA.

[0072] S43. The third-party auditor runs the proof verification algorithm and sends the verification results to the data holder.

[0073] As an embodiment, in step S43, the proof verification algorithm is specifically as follows:

[0074] S431. Third-party auditor TPA verification equation:

[0075]

[0076] whether it is established;

[0077] S432. If established, the third-party auditor TPA audit is passed, otherwise it is not passed.

[0078] In summary, this paper designs a privacy-preserving cloud data integrity audit method based on sanitizable signatures, which is implemented through the following technical solutions:

[0079] The key generation center generates a private key s based on the user ID ID =H1(ID) α Sent to the user, α is a random value, the user verifies the validity of the private key: e(s ID ,g)=e(H1(ID),P pub ).

[0080] The user divides the file named η into n blocks, then generates a random value r and calculates β = g r , using the private key s ID Generate the signature of block i of the file: {F,σ={σ i} 1≤i≤n ,β,η,(u i ) r (i∈K)} is sent to the cloud, where K is the part allowed to be purified by the cloud.

[0081] Cloud signature verification: if Is the purified file, purify the i-th block file and the corresponding signature

[0082] During the cloud audit phase, TPA selects b blocks (1≤b≤n) and b random values ​​v j , send a challenge to the cloud chal = {j,v j} j∈I After receiving the challenge, the cloud generates a proof and calculates λ j =m j v j +r j , where r j are all different random values;

[0083] Then calculate and Will prove Send to TPA, TPA verification certificate:

[0084]

[0085] See Figure 4 , Figure 440 is a schematic diagram of the working of the hardware device of an embodiment of the present invention, wherein the hardware device specifically includes: a privacy protection cloud data integrity audit device 401, a processor 402 and a storage medium 403.

[0086] A privacy-preserving cloud data integrity auditing device 401: The privacy-preserving cloud data integrity auditing device 401 implements the privacy-preserving cloud data integrity auditing method.

[0087] Processor 402: The processor 402 loads and executes the instructions and data in the storage medium 403 to implement the privacy protection cloud data integrity audit method.

[0088] Storage medium 403: The storage medium 403 stores instructions and data; the storage medium 403 is used to implement the privacy protection cloud data integrity audit method.

[0089] The beneficial effects of the present invention are:

[0090] 1. Regarding the security of signatures, this invention is based on mathematical problems, which ensure that even if the adversary knows the public key and the signature-message pair, it cannot forge another signature;

[0091] 2. Regarding the restrictions of signatures, existing cleansing signature schemes in cloud auditing do not restrict the rights of the purifier. This invention ensures that the purifier can only purify messages in the set K;

[0092] 3. Regarding perfect privacy protection, the present invention adds a random number r in the cloud audit stage j , preventing curious TPAs ​​from recovering the message from the proof;

[0093] 4. Regarding the transparency of the purgeable signature, the purgeable signature scheme of the present invention is transparent, that is, the outside world cannot distinguish whether a signature is purgeable.

[0094] All of the above technical means jointly ensure the integrity and privacy of cloud data during the cloud data integrity audit phase of the present invention, and solve the technical problems that the existing technology can purify signatures without restriction, which easily causes security risks, is easily subject to TPA data recovery attacks, and has the risk of privacy leakage.

[0095] 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, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A privacy-preserving cloud data integrity audit method, characterized by: The method comprises the following steps: S1: Data holders will Sent to the Key Generation Center KGC as the signature public key; S2: The key generation center KGC generates a private key based on the public key ; where α is a random number, H 1 is the hash function; S3: The data holder verifies the private key to the cloud the legitimacy of Step S3 is as follows: S31. The data holder names a file F as , the file Divided into Block, that is ,in ; S32. Regulations It is a set of subscripts that allow cloud purifiers to modify some file blocks; S33, select random value , calculate the verification value ; is the generator of the multiplicative cyclic group; S34. The block's signature is: ; S35. Data holders will Send to the cloud and delete local data; S36, Cloud Verification Block file signature: ; is the master public key, and ; In step S32, the cloud purifier purifies the files as follows, where the cloud can only purify user-defined files. : S321, regulations It is the set of file indexes actually modified in the cloud. It is a collection of unmodified file indexes in the cloud. ,if If it is a purified file, then there is ; hour, ; S322, the cloud generates Signature of the cleaned block file = ; S323, verify Block file purification signature: ; S4: For legitimate data, a third-party auditor, TPA, will conduct an integrity audit on the cloud.

2. A privacy-preserving cloud data integrity auditing method according to claim 1, characterized in that: Steps S1 and S2 are as follows: Enter the random number α as the master private key and the data holder To the key generation center KGC; the key generation center KGC returns the private key corresponding to the data holder ID To the data holder.

3. The privacy-preserving cloud data integrity auditing method according to claim 1, wherein: Step S4 is specifically as follows: S41. The data holder issues an audit request, and the third-party auditor, TPA, runs a challenge generation algorithm and sends it to the cloud. S42. The cloud runs the proof generation algorithm and sends the proof to the third-party auditor TPA; S43. The third-party auditor runs the proof verification algorithm and sends the verification results to the data holder.

4. A privacy-preserving cloud data integrity auditing method according to claim 3, characterized in that: In step S41, the challenge generation algorithm is as follows: S411, third-party auditor TPA random selection Block , the challenge query set is: ; S412, Selection of Third-Party Auditor TPA Random values , then challenge Send to the cloud.

5. A privacy-preserving cloud data integrity auditing method according to claim 4, characterized in that: In step S42, the proof generation algorithm is as follows: S421, Cloud Computing ,in are all different random values; S422, Cloud Computing and ; S423、The cloud will prove Sent to third-party auditor TPA.

6. A privacy-preserving cloud data integrity auditing method according to claim 5, characterized in that: In step S43, the proof verification algorithm is as follows: S431. Third-party auditor TPA verification equation: whether it is established; S432. If established, the third-party auditor TPA audit is passed, otherwise it is not passed.

7. A storage medium, characterized in that: The storage medium stores instructions and data, and when the instructions and data are executed by the processor, they are used to implement a privacy-preserving cloud data integrity audit method as described in any one of claims 1 to 6.

8. A privacy-preserving cloud data integrity auditing device, characterized by: include: A processor and a storage medium; the processor loads and executes instructions and data in the storage medium to implement a privacy-preserving cloud data integrity audit method as described in any one of claims 1 to 6.

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