CN104980437A - Identity-based authorized third party data integrity proving method - Google Patents

Abstract

The invention discloses an identity-based authorized third party data integrity proving method. The method is designed based on double-line pair and identity encryption technologies. By embedding user authorization evidence into generation of a data block tag to be stored, the purpose that only the third party with user authorization can complete remote data integrity checking is achieved. The invention puts forward an identity-based authorized third party proving method beyond the existing remote data private verification and public verification, and meets the need for privacy protection while realizing user-entrusted verification. In addition, the method ensures the fairness between a data owning party and a data storing party. The data storing party inspects a data block-tag pair uploaded by the data owning party in order to prevent malicious users from uploading wrong data and unreasonable claim over the storing party caused thereby.

Description

An Identity-Based Authorized Third-Party Data Integrity Proof Method

technical field

The present invention relates to information security technology.

Background technique

Cloud computing is an important direction for the development of information technology and a basic technology in the era of big data. It has become a hot spot in the development of the current information industry due to its powerful computing and storage capabilities and its ability to provide users with on-demand services, and it has been gradually applied in practice.

As an important part of cloud computing, cloud storage has begun to be widely accepted and used. Users can store data on remote cloud servers according to their own needs, so as to reduce the burden of hardware purchase and maintenance, and at the same time gain the convenience of accessing at any time. However, precisely because users do not actually store data, this uncontrollability brings data security risks to users.

The cloud service provider may not store user data correctly and completely due to its own interests or other reasons, and how to perform remote data integrity verification becomes very important at this time.

According to different verifiers, the current cloud data integrity verification scheme can be divided into private verification and public verification. Private verification can only be verified by the data owner itself, while public verification supports any third party to verify. However, when the user cannot complete the verification process by himself and does not want any third party to verify his own data, the above two types of solutions will not be able to meet the user's needs.

In addition, most of the existing verification schemes are based on the traditional public key certificate architecture. When users or third parties perform data integrity verification, they need to query the public key certificate first, which brings additional communication overhead and implementation complexity to the verification. At the same time, the management and maintenance of the certificate library is also costly.

Contents of the invention

The technical problem to be solved by the present invention is to provide an identity-based, safe and effective remote data integrity inspection method that can be completed by a third party designated by the user.

The technical solution adopted by the present invention to solve the above problems is to provide an identity-based authorized third-party data integrity verification method, which is characterized in that it includes the following steps.

1. Key and authorization generation.

The private key generation center (PKG) selects the system private key and calculates the system public key, and then generates a public-private key pair corresponding to its ID according to the ID of each participant in the system, and sends it to all parties. In addition, the authorization proof is generated by the user and the authorization is signed.

2. Generation of data block-label pairs. the

The user divides the file F into n data blocks, and uses his own private key to generate a label for each data block, and embeds authorization evidence into each label. Then the user sends the data block-label pair to the cloud storage server for storage, and sends the authorization evidence to the third party for authorization.

3. Authorize third parties to initiate challenges.

After receiving the user's authorization, the third party can initiate a data integrity verification challenge to the cloud server according to the agreement. The challenge information includes the number of blocks to be challenged, the key value of the permutation function and the key value of random number generation for each block. Then authorize the third party to send the challenge information along with its own authorization to the cloud server.

4. Challenge response.

After receiving the challenge from the third party, the cloud server first calculates the block to be challenged and the random value of each block through the sent challenge value, permutation function and pseudo-random function. Then, the cloud server aggregates the proof containing the challenged block and block label information and returns it to the challenger.

5. Proof verification.

After receiving the proof information from the cloud server, the challenger uses his authorization, parameters in the system and known public key to verify the integrity of the data. The verification is completed by calculating whether an equation constructed by a bilinear pair is established. Since the verification of the equation requires authorization information, only an authorized third party can complete the verification. Finally, the authorized third party informs the user of the verification result.

The purpose of the present invention is achieved like this.

In the present invention, the user generates evidence for the third party to be authorized, and embeds the authorization evidence into the tag generated for each data block. When performing remote data integrity verification, only a third party with authorization evidence can complete the verification process, thereby realizing authorized third-party data integrity verification. In addition, the present invention adopts an identity-based secret key system, which reduces the burden of certificate query, management and maintenance brought to users by the traditional public key infrastructure (PKI), and reduces the computing and communication expenses of users.

The beneficial effect of the present invention is that it not only satisfies the requirement of lightweight users to realize remote data integrity inspection through a third party, but also prohibits any third party from performing inspection, thus protecting user privacy and making up for the shortcomings of existing solutions. At the same time, the invention reduces the calculation and communication overhead in the verification process.

Detailed ways

The present invention will be specifically described below.

1.1 Preliminary knowledge - bilinear mapping. the

Let G ₁ be a factorial cyclic group of p (p is a large prime number) whose generator is g, and G ₂ be a multiplicative cyclic group of the same order. A bilinear pair is a mapping ^[26] e that satisfies the following properties: G ₁ ×G ₁ →G ₂ .

(1) Bilinearity: for any There is e(g ₁ ² , g ₂ ^b )=e(g ₁ , g ₂ ) ^ab .

(2) Non-degenerate: e(g, g)≠1.

(3) Computability: There is always an efficient algorithm to compute the mapping e.

1.2 Meaning of symbols used.

H, H ₁ , h is an encrypted hash function, is a pseudorandom function, and S is a random permutation function.

1.3 Identity-based authorized third-party data integrity certification protocol, including 5 stages.

1. Key and authorization generation.

The private key generation center (PKG) selects a random number As the system master private key, calculate the system public key M=g ^m at the same time, disclose M as a system parameter, and keep m secret.

Then PKG calculates the three-party key according to the three-party identity id∈{0, 1} ^* of the user (User), authorized third party (ATP), and cloud service provider (CSP), and obtains the public key of User: U=H(User _id ), private key: u=mU; ATP public key: A=H(ATP _id ), private key: a=mA; CSP public key: C=H(CSP _id ), private key: c=mC.

After receiving the key sent by PKG from the secure channel, the three parties respectively use the equations: g ^u = M ^U , g ^a = M ^A , g ^c = M ^c to confirm the correctness of the key, and if the equation is established, they will receive key, otherwise request resend.

After receiving the correct key, User generates authorization v, and signs S _v = Sig _u (v) on the authorization.

2. Data block label generation.

The user divides the file F into n file blocks Then generate a signature for each block in the following way: Calculation ①k=H(e(M ^A , M ^C ) ^u , v); ②Calculation θ _i =f _k (i); ③Calculation of label where r ∈ G ₁ is chosen and made public by the user.

The user assigns the block-label pair and v are sent to CSP for storage, and (v, S _v ) is sent to ATP for authorization. Afterwards, the user can delete local data and block-label pairs.

After the CSP receives the data sent by the user, it checks the correctness of the block-label pair. The process is as follows: ①Calculate k′=H(e(M ^U , M ^A ) ^c , v); ②Calculate θ _i ′=f _k ′(i); ③If the equation If established, the block-label pair is accepted, otherwise retransmission is required.

After receiving the authorization from the user, ATP runs the AuthVerify algorithm to confirm the authorization. If it is correct, it accepts the authorization, otherwise it requests re-authorization.

3. Authorize third parties to initiate challenges.

After receiving user authorization, ATP initiates a challenge to CSP according to user requirements. ATP first selects x (1≤x≤n) blocks to be challenged, and selects a random number As the key value of the pseudo-random permutation function S to ensure the randomness of the challenge.

ATP will then challenge the information Sent to the CSP with its authorization (v, S _v ).

4. Challenge response.

After the CSP receives the challenge from the ATP, it first judges the validity of the ATP authorization, if it is legal, it accepts the challenge from the ATP and generates a certificate.

CSP first calculates the block of ATP request challenge: i _w = S _λ (w), and calculates a random parameter for each block: where 1≤w≤x.

The CSP then calculates the aggregated proof and And send (T,X) to ATP.

5. Proof verification.

After receiving the proof from CSP, ATP runs the algorithm to check the correctness of the proof, and first calculates: k″=H(e(M ^U , M ^C ) ^a , v).

Then ATP verifies the equation Whether it is established or not is used to judge data integrity. If the equation is established, it proves that the data is complete, otherwise it means that the data is wrong.

The verification formula is derived as follows.

From H( ^e (MA,MC)u,v)=H(e(MU,MA)c,v)=H(e(MU,Mc)a,v)=H(e(g,g) ^auc , v) It can be known that k=k'=k".

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Claims (5)

1. An identity-based authorized third-party data integrity certification method, characterized in that it comprises the following steps: 1. Key and authorization generation; The private key generation center (PKG) selects the system private key and calculates the system public key, and then generates a public-private key pair corresponding to its ID according to the ID of each participant in the system, and sends it to all parties; in addition, the user generates an authorization Evidence, and sign the authorization; 2. Data block tag generation; The user divides the file F into n data blocks, and uses his own private key to generate a label for each data block, and embeds the authorization evidence into each label; then the user sends the data block-label pair to the cloud storage server for storage, and Send proof of authorization to a third party for authorization; 3. Authorize third parties to initiate challenges; After receiving the authorization from the user, the third party can initiate a data integrity verification challenge to the cloud server according to the agreement. The three parties send the challenge information to the cloud server along with their own authorization; 4. Challenge response; After the cloud server receives the challenge from the third party, it first calculates the block to be challenged and the random value of each block through the sent challenge value, replacement function and pseudo-random function; then, the cloud server aggregates the challenged block and block label Proof of information returned to the challenger; 5. Proof verification; After receiving the proof information from the cloud server, the challenger uses his authorization, system parameters and known public key to verify the integrity of the data; the verification is completed by calculating whether an equation constructed by bilinear pairing is established, because The verification of the equation requires authorization information, so only an authorized third party can complete the verification; finally, the authorized third party informs the user of the verification result. 2. A kind of identity-based authorizing third-party data integrity proof method as claimed in claim 1, is characterized in that, the specific method of secret key generation is: First, a random number is selected by the private key generation center (PKG) As the system master private key, calculate the system public key M=g ^m at the same time; then PKG calculates the user (User), authorized third party (ATP) and cloud service provider (CSP) according to the identity id ∈ {0, 1} ^* Key, get User’s public key: U=H(User _id ), private key: u=mU; ATP’s public key: A=H(ATP _id ), private key: a=mA; CSP’s public key: C =(CSP _id ), private key: c=mC; after receiving the key sent by PKG from the secure channel, the three parties respectively use the equations: g ^u = M ^U , g ^a = M ^A , g ^c = M ^C Confirm the correctness of the key, receive the key if the equation is established, otherwise request resend. 3. An identity-based authorized third-party data integrity certification method as claimed in claim 1, wherein the authorization must be embedded in the block label, and the specific method of authorization and label generation is: After receiving the correct key, the user generates an authorization v, and signs the authorization Sv=Sig _u (v); then the user divides the file F into n blocks And generate a signature for each block in the following way: ①Calculate k=H(e(M ^A , M ^C ) ^u , v); ②Calculate θ _i =f _k (i); ③Calculate label where r ∈ G ₁ is selected and made public by the user; finally the user will block-label pair and v are sent to CSP for storage, and (v, S _v ) is sent to ATP for authorization. 4. An identity-based authorized third-party data integrity certification method as claimed in claim 1, wherein the specific method of challenge and response generation is: After receiving user authorization, ATP initiates a challenge to CSP according to user needs; ATP first selects x (1≤x≤n) blocks to be challenged, and selects a random number as the key value of the pseudo-random permutation function S; then, ATP will challenge the information and authorization (v, S _v ) are sent to CSP; after receiving the challenge, CSP first judges the legality of ATP authorization, and if it is legal, then generates a certificate. The specific process is as follows: CSP calculates the block of ATP request challenge: i _w = S _λ (w), and calculate the random parameters for each block: where 1≤w≤x; then the CSP calculation and And return (T,X) to ATP as evidence. 5. An identity-based authorized third-party data integrity certification method according to claim 1 or 3, characterized in that authorization evidence must be used for certification verification, and the specific method is: After receiving the response from CSP, ATP first calculates: k ⁿ =H(e(M ^U , M ^C ) ^a , v), and then verifies the equation: Whether it is established, if it is established, it proves that the data is complete, otherwise it means that the user data is stored incorrectly.