Privacy protection cloud data integrity auditing method, equipment and medium

Abstract

The invention relates to the field of information security, and discloses a privacy protection cloud data integrity auditing method and device and a medium, the method comprises the following steps: a data holder sends an ID (Identity) belongs to {0, 1} * as a signature public key to a key generation center KGC; the key generation center KGC generates a private key sID = H1 (ID) alpha according to the public key; wherein alpha is a random number, and H1 is a hash function; the data holder verifies the legality of the private key sID = H1 (ID) alpha to the cloud; for legal data, a third-party auditor TPA performs integrity auditing on the cloud; according to the method, the integrity and privacy of the cloud data in the cloud data integrity auditing stage process are guaranteed, and the technical problems that in the prior art, signatures can be purified without limitation, potential safety hazards are likely to be caused, data recovery attacks of TPA are likely to happen, and potential privacy leakage hazards exist are solved.

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 volume, it has become a heavy burden for users to store massive amounts of data locally. Therefore, more and more organizations and individuals choose to store data on cloud servers and share data through the cloud. However, data stored in the cloud may be damaged or lost due to inevitable software defects, 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 an overall manner without distinguishing the sensitivity of data, and cannot guarantee the security of sensitive data, the efficiency of data integrity verification, and the convenience of data sharing. Some solutions directly store and share data in plain text, which can easily lead to the leakage of user sensitive information; other solutions encrypt and store and share all data to protect the confidentiality of data. For a large amount of non-sensitive information, this method greatly reduces the efficiency of data integrity verification and the convenience of data sharing. How to perform efficient integrity audits on data while ensuring data security and ease of use is an issue worthy of research and discussion.

[0005] Sanitizable Signatures is a functional digital signature scheme that introduces an authorized purifier role based on classic digital signatures. The purifier can make limited and controlled modifications to certain parts of the signed message and generate a new valid signature for the sanitized message without interacting with the original signer in the process. Sanitizable signatures can "purify" user information that does not need to be disclosed according to different application scenarios (for example, replace it with "####") without affecting the validity of the signature of other parts of the information. In this way, the integrity of non-sensitive information can be efficiently verified while protecting user sensitive information.

[0006] In the Public Key Infrastructure (PKI), the user's public key used to verify the validity of the signature is managed by a digital certificate issued by a Certificate Authority (CA), which involves a series of cumbersome management processes such as the issuance, revocation, and query of certificates. Identity-based purifiable signatures directly use the user's identity as the public key, and the private key is generated by the Key Generator Center (KGC) based on the user's identity information, which can effectively avoid the cumbersome certificate management problem in the PKI system and is more suitable for lightweight application scenarios.

[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 the signature without restriction, which may cause security risks; the integrity proof provided by the cloud server during the audit phase is generated by a simple linear combination of messages, which is vulnerable to data recovery attacks by TPA and poses a risk of privacy leakage. 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, in order to address the technical problems that the prior art can purify signatures without restriction when conducting cloud data integrity audits, which easily causes security risks and is easily subject to data recovery attacks by TPA, and has the risk of privacy leakage.

[0009] The present invention provides a privacy protection 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 legality of

[0013] S4: For legitimate data, a third-party auditor, TPA, conducts 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 audit device comprises: a processor and the storage medium; the processor loads and executes instructions and data in the storage medium to implement a privacy-preserving cloud data integrity audit method.

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

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

[0018] 2. Regarding the restriction of signatures, the existing purifiable signature schemes in cloud auditing do not restrict the rights of purifiers. The present invention ensures that purifiers can only purify messages in set K;

[0019] 3. Regarding perfect privacy protection, the present invention adds a random number r in the cloud audit stage j , preventing a curious TPA 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 purified.

[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 data recovery attacks by TPA, 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 schematic diagram of the process of the present invention;

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

[0025] Figure 4 It is a working schematic 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 describing the present invention, the scheme of the present invention is first generally described for easy understanding.

[0028] The method of the present invention includes four entities, namely, the key generation center KGC, the data holder, the cloud, and the third-party auditor TPA; the relationship between the four entities can be found in the relevant content of the background technology, and will not be repeated here. The above 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 being a prime number, and g being the 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 calculated 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 a string of arbitrary length to the multiplicative cyclic group G1; the multiplication symbol is 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 are the definitions of all parameters and concepts involved in the present invention. The present application will be 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 master private key and 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 legality 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, named 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, which purifies files without interacting with users 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 in the cloud, K1∪K2=K. is a purified file, then when i∈K1, When i∈K2,

[0054] S322, the cloud generates the signature of the i-th (i∈K) block of files 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 will {F,σ={σ i} 1≤i≤n ,β,η,{(u i ) r |(i∈K)}} is sent to the cloud and the local data is deleted;

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

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

[0061] S4: For legitimate data, a third-party auditor, TPA, conducts 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 the 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), and 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 will pass, otherwise it will fail.

[0078] In general, the present invention designs a privacy-preserving cloud data integrity audit method based on a purifiable signature, which is implemented through the following technical solutions:

[0079] The key generation center generates a private key based on the user ID ID =H1(ID) α Sent to the user, α is a random value, and 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 private key s ID Generate the signature of the i-th block 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 for cloud purification.

[0081] Cloud signature verification: if is the purified file, purifying the i-th block of files and the corresponding signature

[0082] In 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 also Figure 4 , Figure 4It is a working diagram of the hardware device of an embodiment of the present invention, and 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 the signature, the present invention is based on mathematical problems to ensure that even if the adversary knows the public key and the signature-message pair, he cannot forge another signature;

[0091] 2. Regarding the restriction of signatures, the existing purifiable signature schemes in cloud auditing do not restrict the rights of purifiers. The present invention ensures that purifiers can only purify messages in set K;

[0092] 3. Regarding perfect privacy protection, the present invention adds a random number r in the cloud audit stage j , preventing a curious TPA 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 purified.

[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 data recovery attacks by TPA, 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A privacy-preserving cloud data integrity audit method, characterized by: The method comprises the following steps: S1: The data holder sets ID∈{0,1} * Sent to the key generation center KGC as the signature public key; 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; S3: The data holder verifies the private key s to the cloud ID =H1(ID) α the legality of S4: For legitimate data, a third-party auditor, TPA, conducts an integrity audit on the cloud.

2. A privacy-preserving cloud data integrity audit method as claimed in claim 1, characterized in that: Steps S1 to S2 are as follows: Input random number α as master private key and 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.

3. A privacy-preserving cloud data integrity audit method as claimed in claim 1, characterized in that: Step S3 is as follows: S31. The data holder takes a file F, named η, and divides the file F into n blocks, namely m:(m1,m2,…,m n ),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 β = g r ; g is the generator of the multiplicative cyclic group; S34. The signature for the i-th block of the file is: S35, the data holder will {F,σ={σ i } 1≤i≤n ,β,η,{(u i ) r |(i∈K)}} is sent to the cloud and the local data is deleted; S36. Cloud verifies the signature of the i-th file: P pub is the primary public key, and P pub =g α .

4. A privacy-preserving cloud data integrity audit method as claimed in claim 1, characterized in that: In step S32, the cloud purifier purifies the files as follows, where the cloud can only purify user-defined files {m i |i∈K}: S321, regulations It is the set of file indexes actually modified in the cloud. is the set of unmodified file indexes in the cloud, K1∪K2=K. is a purified file, then when i∈K1, When i∈K2, S322, the cloud generates the signature of the purified i-th (i∈K) block file S323, verify the i-th file purification signature:

5. A privacy-preserving cloud data integrity audit method as claimed in claim 1, characterized in that: Step S4 is specifically as follows: S41. The data holder issues an audit request, and the third-party auditor TPA runs the 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.

6. A privacy-preserving cloud data integrity audit method as claimed in claim 5, characterized in that: In step S41, the challenge generation algorithm is as follows: S411. The third-party auditor TPA randomly selects b blocks (1≤b≤n), and the challenge query set is: S412, the third-party auditor TPA selects b random values Then challenge chal = {j,v j } j∈I Send to the cloud.

7. A privacy-preserving cloud data integrity audit method as claimed in claim 6, characterized in that: In step S42, the proof generation algorithm is specifically as follows: S421, Cloud Computing λ j =m j v j +r j ,in are all different random values; S422, Cloud Computing and S423, the cloud will prove Sent to third-party auditor TPA.

8. A privacy-preserving cloud data integrity audit method as claimed in claim 1, 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 will pass, otherwise it will fail.

9. A storage medium, characterized in that: The storage medium stores instructions and data for implementing a privacy-preserving cloud data integrity audit method as described in any one of claims 1 to 8.

10. A privacy-preserving cloud data integrity auditing device, characterized in that: include: Processor and 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 8.

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