CN115002754B - Lightweight data sharing method based on vehicle social network - Google Patents

Abstract

The invention discloses a lightweight data sharing method based on a vehicle social network, which is characterized in that the method includes: system initialization, key generation, data encryption, user trapdoor generation, data matching, re-encryption key generation, re-encryption Steps such as generation of encrypted ciphertext and decryption by the user. If the user is unwilling to decrypt the decryption by the user, the cloud server will generate a re-encrypted ciphertext for the next data user, and the next user will decrypt it. And so on, until there is a data user willing to decrypt in the sharing path. Compared with the prior art, the present invention realizes the lightness of calculation efficiency in data matching and data sharing, especially the calculation overhead of the user end, protects the privacy of the data owner's search keyword and the privacy of shared data, and supports multiple Data owner and multiple data consumers, especially for vehicle social networks.

Description

A lightweight data sharing method based on vehicle social network

Technical Field

The present invention relates to the technical field of data encryption, and in particular to a method for lightweight data sharing based on a vehicle social network.

Background Art

Vehicular social networks (VSNs) include social networks and vehicle-mounted networks (VANETs), providing data sharing between vehicles and vehicles or roadside units (RSUs) to reduce traffic congestion, travel time, and even provide comprehensive social services. With the development of wireless sensor networks (WSNs) and cloud computing, more and more VSN data can be conveniently collected from heterogeneous mobile devices, such as onboard units (OBUs), passengers, and drivers. These data from heterogeneous sources (e.g., smart mobile data owners, RSUs) are aggregated and sent to a trusted vehicle cloud for remote storage and access. However, the outsourced data usually contains some sensitive information (e.g., user's identity, traffic information, and vehicle information). Therefore, data confidentiality is crucial in VSNs.

To protect data privacy, data owners need to encrypt data with their public key before outsourcing. However, public key encryption technology complicates data utilization in VSNs, especially data sharing and data retrieval. As a promising primitive, proxy re-encryption (PRE) allows a trusted vehicle cloud (i.e., a trusted agent) to convert ciphertext encrypted under the public key of the data owner into ciphertext that can be decrypted by data users without learning the plaintext. However, before sharing data in the VSN scenario, the data owner may not know who will be interested in her/his data. Therefore, the data owner needs an effective mechanism to solve the data retrieval problem in PRE. Due to the accuracy requirements of users for data acquisition and massive data, efficient retrieval becomes a key issue for VSN. In the case that the cloud cannot obtain the corresponding ciphertext, public key encryption by keyword search (PEKS) can be used to achieve ciphertext retrieval on the cloud server through the trapdoor information generated by the user. Nevertheless, the cloud server in PEKS can only search for ciphertext encrypted with the same public key. Therefore, PKES is not suitable for VSN scenarios. In order to achieve multi-user ciphertext matching, Yang et al. proposed a PKE-ET construction, in which the cloud server can test whether ciphertexts encrypted with the same and different public keys are from the same plaintext without learning the plaintext information.

In summary, the data matching in the prior art basically adopts time-consuming bilinear pairing operations to match the data, which undoubtedly reduces the computational efficiency of the system and is not suitable for vehicle social networks.

Summary of the invention

The purpose of the present invention is to design a lightweight data sharing method based on vehicle social network in view of the deficiencies of the prior art. The method adopts a data sharing method with ciphertext search, integrates PRE into PKE-ET construction, uses PKE-ET to match some suitable data users for data owners, shares encrypted data with corresponding users in order of priority, realizes data search and sharing while ensuring the confidentiality of data, effectively solves the problem of limited computing power of mobile devices in vehicle social network, not only ensures the data privacy, interest privacy and query privacy of data owners, but also resists unauthorized access to data by semi-trusted cloud servers. The method uses equality test based on public key encryption to realize ciphertext matching between data owners and users, and uses multi-hop proxy re-encryption to share the encrypted data of users. The method is particularly suitable for vehicle social network environment, can realize fine-grained access control and data privacy protection, and has the advantages of simple method, practicality, fastness, high computing efficiency and small storage space.

The object of the present invention is achieved by: a lightweight data sharing method based on vehicle social network, which is characterized in that the method uses PKE-ET to match some suitable data users for the data owner, and then shares the encrypted data with the corresponding users in order of priority, specifically including the following steps:

(I) System initialization

The trusted authority (TA) randomly selects a set of parameters under the bilinear library, randomly selects a generator under the two multiplication cycle groups _G1 and _Gt , then selects the system security parameters and generates a strong unforgeable signature algorithm, defines 8 hash functions, and executes the Setup(1 ^λ )→par algorithm to generate the public parameter pp for the system.

(II) Key Generation

The trusted authority (TA) executes the KeyGen(pp,i/j)→(pk _i ,sk _i )/(pk _j ,sk _j ) algorithm to select a random number and generate a pair of public/private keys for the user (data owner and data user).

(III) Data encryption

The data owner encrypts the shared data and keywords to generate data ciphertext, and the data user encrypts the keywords of the interest data to generate interest ciphertext, wherein the data ciphertext includes: the data ciphertext of the shared data and keywords.

(IV) Trapdoor Generation

算法生成的密文作为输入，执行

算法生成关键字的陷门，然后与密文一起上传给云服务器。Users (data owners and data users) use their own private keys and

The ciphertext generated by the algorithm is used as input and executed

The algorithm generates a trapdoor for the keyword and then uploads it to the cloud server together with the ciphertext.

(V) Data Matching

算法，检查数据拥有者和数据使用者上传的关键字密文是否匹配，并将匹配成功的数据使用者的公钥和声誉值σ_i返回给数据所有者。When the cloud server finds a message/interest pair, it executes

The algorithm checks whether the keyword ciphertexts uploaded by the data owner and the data user match, and returns the public key and reputation value σ _i of the successfully matched data user to the data owner.

(VI) Re-encryption key generation

然后执行

算法，为数据分享路径Pa_i中的用户生成重加密密钥，并将重加密密钥分发给云服务器。The data owner establishes a data sharing path based on the user's reputation value σ _i

Then execute

The algorithm generates re-encryption keys for users in the data sharing path Pa _i and distributes the re-encryption keys to the cloud servers.

(VII) Re-encrypted ciphertext generation

算法，为数据分享路径Pa_i的用户依次生成重加密密文。After receiving the proxy re-encryption key, the shared path Pa _i, and the ciphertext of the shared data, the cloud server executes

The algorithm generates re-encrypted ciphertexts for users of the data sharing path Pa _i in sequence.

(VIII) User Decryption

算法解密重加密密文，得到数据拥有者分享的数据后，信用度高的数据拥有者可以具有解密优先级，如果信用高的数据拥有者不能完成解密，云服务器则将自动委托给下一个信用较高的数据使用者。The user executes with his own private key

After the algorithm decrypts and re-encrypts the ciphertext and obtains the data shared by the data owner, the data owner with high credit can have decryption priority. If the data owner with high credit cannot complete the decryption, the cloud server will automatically delegate it to the next data user with higher credit.

The algorithm used in the present invention is described as follows:

The Setup(1 ^λ )→par algorithm is executed by a trusted authority (TA) and generates a system public parameter pp based on the security parameter λ.

The KeyGen(pp,i/j)→( _pki , _ski )/( _pkj , _skj ) algorithm generates a public key _pki and a private key _ski . KeyGen is executed by a trusted authority (TA), and takes as input the system public parameter pp and the identity information of the data owner user (i represents the identity of the data owner, and j represents the identity of the data user). The public _/ private key pair (pki, _ski ) of the data owner or the public/private key pair ( _pkj , _skj ) of the data user is output.

算法由用户(数据拥有者和数据使用者)实现，并生成一个属于数据拥有者的密文

输入系统公共参数pp、数据拥有者的公钥pk_i、关键字ωk_i和消息m。同理，数据使用者的密文为

其中j表示数据使用者的身份。Said

The algorithm is implemented by the user (data owner and data user) and generates a ciphertext belonging to the data owner.

Input the system public parameter pp, the data owner's public key _pki , the keyword _ωki and the message m. Similarly, the ciphertext of the data user is

Where j represents the identity of the data user.

算法用于生成用户i的陷门

作为输出，公共参数par、数据拥有者的私钥sk_i和密文

作为输入。同理，数据使用者的陷门为

Said

The algorithm is used to generate a trapdoor for user i

As output, the public parameter par, the data owner's private key sk _i and the ciphertext

As input. Similarly, the trapdoor for data users is

该算法在云服务器中执行，输出值为0或1。算法的输入为公共参数par、密文

和对应的陷门

以及兴趣密文

和对应的陷门

其中，

是数据使用者的密文，

是数据使用者产生的陷门。Said

The algorithm is executed in the cloud server and the output value is 0 or 1. The input of the algorithm is the public parameter par, the ciphertext

and the corresponding trapdoor

And interest ciphertext

and the corresponding trapdoor

in,

is the ciphertext of the data user,

It is a trapdoor created by the data user.

该算法输出l个重加密密钥、

并以安全的方式将它们发送到相应的云服务器中。RKGen由用户i 执行，输入包括一个自主路径Pa_i、数据拥有者的私钥sk_i和系统的公共参数pp。Said

The algorithm outputs l re-encryption keys,

And send them to the corresponding cloud servers in a secure way. RKGen is executed by user i, and the input includes an autonomous path Pa _i , the private key sk _i of the data owner, and the public parameters pp of the system.

为重新加密的算法，ReEnc由云服务器执行，并输出重新加密的密文

系统的公共参数pp、指定分享路径Pa_i、从数据使用者j到j+1的重新加密密钥

和密文

作为输入，

为数据拥有者i到数据使用者j的重加秘密密文。Said

ReEnc is the re-encryption algorithm. It is executed by the cloud server and outputs the re-encrypted ciphertext.

The system's public parameters pp, the specified sharing path Pa _i , and the re-encryption key from data user j to j+1

and ciphertext

As input,

It is the re-added secret ciphertext from data owner i to data user j.

为解密算法，Dec由用户j执行，输入系统公共参数par、密文

和用户j的私钥sk_j，然后输出消息m或错误信息符号⊥。在解密成功后，数据使用者D_j中会获得数据拥有者的分享信息。如果用户不愿意解密，云服务器将为下一个数据使用者生成重加密密文，由下一个用户解密。依次类推，直到分享路径Pa_i中有数据使用者愿意解密为止。Said

The decryption algorithm, Dec, is executed by user j, and inputs the system public parameters par, the ciphertext

and the private key sk _j of user j, and then outputs the message m or the error message symbol ⊥. After the decryption is successful, the data user D _j will obtain the shared information of the data owner. If the user is unwilling to decrypt, the cloud server will generate a re-encrypted ciphertext for the next data user, who will decrypt it. And so on, until there is a data user in the sharing path Pa _i who is willing to decrypt.

Compared with the prior art, the present invention can realize data search and sharing while ensuring the confidentiality of data, effectively solving the problem of limited computing power of mobile devices in vehicle social networks, not only ensuring the data privacy, interest privacy and query privacy of data owners, but also resisting unauthorized access to data by semi-trusted cloud servers. The method uses equality test based on public key encryption to realize ciphertext matching between data owners and users, and uses multi-hop proxy re-encryption to share the user's encrypted data. It is particularly suitable for vehicle social network environments, and can realize fine-grained access control and data privacy protection. It has the advantages of simple method, practicality, speed, high computing efficiency and small storage space.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a system diagram of the present invention;

FIG. 2 is a flow chart of the present invention.

DETAILED DESCRIPTION

1. Description of the mathematical theory used in the present invention:

1. Bilinear mapping

Let G be a multiplicative cyclic group of order prime p. The mapping e:G×G-→ _GT is a linear mapping if it satisfies the following three conditions:

1) Bilinear, for all u,v∈G,a,b∈Z _p , e(u^a,v^b)＝e(u,v) ^ab ;

2) Non-degeneracy, there exists e(g,g)≠1, otherwise e(g,g) ^ab≡1 ;

3) Computability: For all u, v, there exists an efficient algorithm to calculate e(u, v).

In the present invention, the bilinear pairing e:G×G-→ _GT is a mapping that satisfies bilinearity, non-degeneracy and computability, and maps the operation of two elements on the multiplicative cyclic group of prime numbers to an element in the multiplicative cyclic group _GT .

2. Shamir Secret Sharing

The Shamir key sharing algorithm is based on the Lagrange difference and vector method. The basic idea is that the distributor divides the private information into n encrypted information fragments through the encryption polynomial, among which a certain amount of encrypted information can reproduce the ciphertext, and any part of the ciphertext cannot be obtained through any small amount of encrypted information. The specific steps are as follows:

2-1: Setup(λ): When the security parameter λ is input, a large random prime number q will be output as the public parameter pp.

2-2: Generation (pp, s): When the public parameter pp and a secret value s∈Z _q are input, the following operations are performed:

2-1-1: Select a random polynomial f(x) of order (t-1): f(x) = a ₀ + a ₁ x + … + a _k-1 x ^t-1 (modq), where the private information s = a ₀ = f(0), a ₀ , a ₁ , …, a _k-1 ∈ Z _q .

2-1-2: Calculate all shared data: s _i = f( _xi ) mod q, in which x _i ∈ _Zq , i = 1, 2,…, n.

2-1-3: Finally, the algorithm outputs a list of n points, {(x ₁ ,y ₁ ),(x ₂ ,y ₂ ),…,(x _n ,y _n )}, and each s _i is assigned to the corresponding information sharer.

当输入公共参数pp和任意t个点时，算法可以重构f(x)并输出的密文

其中

中的i 是拉格朗日插值系数，且

2-2:

When the public parameter pp and any t points are input, the algorithm can reconstruct f(x) and output the ciphertext

in

where i is the Lagrange interpolation coefficient, and

3. Proxy Re-Encryption (PRE)

In PRE, users can authorize semi-trusted servers and then convert ciphertext encrypted under the user's public key into ciphertext that a certain user can decrypt. It is worth noting that the cloud server cannot learn the plaintext and private key during the conversion process. The specific algorithm is as follows:

A one-way multi-hop proxy re-encryption scheme in a traditional PKI environment includes the following algorithms:

1) Key generation algorithm KeyGen(par)→(pk;sk): Input the system public parameter par, and the algorithm outputs (pk,sk) as a user's public-private key pair.

2) Encryption algorithm Enc(par,M,pk)→C ₍₀₎ : Input system public parameter par, plaintext M in message space, and public key pk of a user. The algorithm outputs ciphertext C ₍₀₎ encrypted by public key pk, where 0 indicates that ciphertext C has not been re-encrypted. C ₍₀₎ is also called original ciphertext.

3) The conversion key generation algorithm RekeyGen(par, sk _i , pk _j )→rk _i→j inputs the system public parameter par, the private key sk _i of the authorized user, and the public key pk _j of the authorized user. The algorithm outputs the conversion key rk _i→j for one-way re-encryption from the authorized user to the authorized user.

4) Re-encryption algorithm ReEnc(par,rk _i→j ,C _i(n) )→C _j(n+1) : Input system public parameter par, conversion key rk _i→j from user pk _i to user pk _j , and ciphertext C _i(n) under user pk _i , where n represents the number of times ciphertext C _i(n) has been re-encrypted. The algorithm outputs ciphertext C _{j(n+1) under} user pk _j , which has been re-encrypted n+1 times, or ⊥ indicates that ciphertext C _i(n) is illegal.

5) Decryption algorithm Dec ₂ (par, sk _j , C _j(n+1) )→M: Input system public parameter par, user private key sk _j , and ciphertext C _j(n+1) under user pk _j . The algorithm outputs the corresponding plaintext M, or ⊥ indicates that the ciphertext C _j(n+1) is illegal.

4. Public Key Encryption Ciphertext Equivalence Test (PKE-ET)

Ciphertext equivalence test based on public key encryption is an encryption technology that can directly determine whether two ciphertexts contain the same message without decryption. In PKE-ET, given two ciphertexts c ₁ and c ₂ generated under public keys pk ₁ and pk ₂ respectively, the function test Test(c, td, c′, td′) returns 1 if and only if c ₁ and c ₂ encrypt the same message. The specific steps are as follows:

4-1: Setup(λ)→pp: Initialize the algorithm, input security parameter λ, and output system parameter pp.

4-2: KeyGen(pp)→(pk,sk): key generation algorithm, input system parameter pp, output public key and private key (pk,sk).

4-3: Enc(m,pk)→c: encryption algorithm, inputs the plaintext m to be encrypted and the public key pk, and outputs the ciphertext c.

4-4: Dec(c,sk)→m: Decryption algorithm, input the ciphertext c∈C to be decrypted and the private key sk, and output the ciphertext m.

4-5: Aut(sk,·)→td: authorization generation algorithm, input private key sk, etc., output authorization trapdoor td.

4-6: Test(c ₁ ,td ₁ ,c ₂ ,td ₂ )→(0,1): Ciphertext equivalence test algorithm, input two sets of ciphertext and the corresponding authorization (c ₁ ,td ₁ ) and (c ₂ ,td ₂ ), and output the matching result: if the plaintext corresponding to c ₁ and c ₂ is the same, output 1; otherwise output 0.

2. Implementation process of the present invention

Referring to Figure 1, the present invention uses two access control structures. One is the equality test, which is used for data matching in vehicle social networks. Only data users with the same keyword as the data owner can decrypt. The other is the proxy re-encryption (PRE), which is used to define data sharing and hide the information of the data owner. In addition, the concept of self-organizing path is introduced, so that the delegate (data user) is assigned by the delegator (data owner), which not only guarantees the privacy of the data owner but also prevents the collusion between the data user and the cloud server. In addition, the trapdoor will not leak the user's information, ensuring the privacy of the keywords of the data owner and the data user. At the same time, our method uses a hybrid encryption method to improve efficiency.

In order to understand the technical means, technical features, objectives and effects achieved by the present invention, the present invention will be further described below in conjunction with specific embodiments.

Example 1

Referring to FIG. 2 , lightweight data sharing in a vehicle social network specifically includes the following steps:

(I) System initialization

TA selects a security parameter λ as the input and output of the system public parameter pp. The specific operation is as follows:

H₁:G₁→(0,1)^3λ,H₂:G₁×G_t×(0,1)^3λ→(0,1)^4λ,H₃:(0,1)^λ→Z_q,H₄:(0,1)^λ→Z_q,H₅:(0,1)^λ→Z_q, H₆:(0,1)^λ→Z_q,H₇:(0,1)^λ→Z_q,H₈:(0,1)^3λ→Z_q。最后这些系统公开参数由pp＝ (G₁,G_t,P₁,P₂,q,H₁,H₂,H₃,H₄,H₅,H₆,H₇,H₈,H₀)来表示。1-1: Setup(1 ^λ )→par.TA selects two groups G ₁ and G _t with the same prime number q, where P ₁ is taken from G ₁ and P ₂ is taken from G _t . Assume that 1 ^λ is the system security parameter, Sig＝(G,S,V) is a one-time signature algorithm with strong unforgeability, and L _s ＝L _sig (1 ^λ ) is the length of the verification key. Secondly, TA defines some hash functions H ₀ :

H ₁ : G ₁ →(0,1) ^3λ ,H ₂ : G ₁ ×G _t ×(0,1) ^3λ →(0,1) ^4λ ,H ₃ :(0,1) ^λ →Z _q ,H ₄ :(0,1) ^λ →Z _q ,H ₅ :(0,1) ^λ →Z _q , H ₆ :(0,1) ^λ →Z _q ,H ₇ :(0,1) ^λ →Z _q ,H ₈ :(0,1) ^3λ →Z _q . Finally, the public parameters of these systems are represented by pp = (G ₁ ,G _t ,P ₁ ,P ₂ ,q,H ₁ ,H ₂ ,H ₃ ,H ₄ ,H ₅ ,H ₆ ,H ₇ ,H ₈ ,H ₀ ).

(II) Key Generation

TA uses the following method to generate a pair of public and private keys for each user in the system:

其中

KeyGen( _pp )→( _pki , _skj ). The algorithm takes the public parameter pp as input, then randomly selects a private key _skj = _ai∈Zq , and calculates the public key

in

(III) Data encryption

The data owner and data user each use the following steps to encrypt their data and keywords and upload the ciphertext to the cloud server.

让m∈(0,1)^λ表示数据拥有者U_i的分享数据明文，ωk_i∈(0,1)^λ表示m的关键字。然后，选择四个随机数(r₁,r₂,x_i-1,x_i-2)∈Z_q并生成密文

算法过程如下：

Let m∈(0,1) ^λ denote the shared data plaintext of data owner U _i and ωk _i∈ (0,1) ^λ denote the keyword of m. Then, select four random numbers (r ₁ ,r ₂ ,xi _-1 ,xi _-2 )∈Z _q and generate the ciphertext

The algorithm process is as follows:

Step 1: Choose a one-time signature key pair G(1 ^λ )→(svk,ssk) and set

以及

Step 2: Calculation

as well as

表示的密文中间值：Step 3: Given three points p ₁ = (H ₃ ( _ωki ), H ₄ ( _ωki )), p ₂ = (H ₅ ( _ωki ), H ₆ ( _ωki )), p ₃ = (H ₇ ( _ωki ), ID _RSU ) construct an interpolation polynomial f(x) of degree 2. Then calculate the two point values yi _-1 = f(xi _-1 ), yi _-2 = f(xi _-2 ) and generate the following

The intermediate value of the ciphertext represented by:

Step 4: Calculation

Step 5: Run the signature algorithm

以及

被上传到云服务器，c_j(m^*)被数据使用者D_j由加密算法生成。Step 6: Finally, the ciphertext

as well as

Uploaded to the cloud server, c _j (m ^* ) is generated by the data user D _j using an encryption algorithm.

(IV) Trapdoor Generation

The data owner and the data user each generate a trapdoor through the trapdoor algorithm.

数据拥有者为每个加密数据

生成一个陷门

并上传给云服务器。同样的，数据使用者为了每个加密数据

生成一个陷门

并上传到云服务器。

The data owner shall encrypt each

Create a trapdoor

And upload to the cloud server. Similarly, data users need to

Create a trapdoor

And upload to the cloud server.

(V) Data Matching

为数据拥有者匹配合适的数据使用者，其算法执行如下述步骤：After receiving the matching request from the data owner and the data user, the cloud server runs the test algorithm

To match the data owner with the appropriate data user, the algorithm performs the following steps:

验证信息

中关于

的签名S_i。然后，检查

如果检查失败，则终止方案，否则继续进行下述步骤2。5-1: By execution

Verification Information

About

_Then , check

If the check fails, terminate the scheme, otherwise proceed to step 2 below.

5-2: Calculation

之后，使用点(x_i-1,y_i-1)， (x_i-2,y_i-2)，(x_j-1,y_j-1)重新构造函数f(x)，使用点(x_j-1,y_j-1)，(x_j-2,y_j-2)，(x_i-1,y_i-1)重新构造函数f′(x)。如果f(0)＝f′(0)，则输出1；否则，输出0。

Afterwards, use the points (xi _-1 , yi _-1 ), (xi _-2 , yi _-2 ), (xj _-1 , _yj-1 ) to reconstruct the function f(x), and use the points (xj _-1 , yj _-1 ), (xj _-2 , yj _-2 ), ( _xi-1 , yi _-1 ) to reconstruct the function f′(x). If f(0) = f′(0), output 1; otherwise, output 0.

5-3: Finally, the cloud server sends the data user’s public key pk _j and reputation value rυ _j to the data owner.

(VI) Generation of re-encryption keys

其中：Pa_i是一个长度为l，按D_j的信誉值排序的公钥序列，并且(i₁,…,i_l)∈(1,…,j)。然后，U_i使用下面的方式为共享路径Pa_i中的每个数据使用者生成重加密密钥。RKGen算法的具体步骤如下：Assume that a data owner U _i can successfully match l data users within a period of time, then U _i will generate an ordered sharing path based on the reputation value of each data user

Where: Pa _i is a public key sequence of length l, sorted by the reputation value of D _j , and (i ₁ ,…,i _l )∈(1,…,j). Then, U _i generates a re-encryption key for each data user in the shared path Pa _i using the following method. The specific steps of the RKGen algorithm are as follows:

U_i选取随机数

为Pa_i中的每个数据使用者计算一个重加密的密钥

6-1:

U _i selects a random number

Calculate a re-encryption key for each data user in Pa _i

in:

然后，将

和Pa_i上传到云服务器上。

Then,

and Pa _i uploaded to the cloud server.

(VII) Ciphertext Re-encryption

后，云服务器执行重加密算法，将数据拥有者的密文c_i(m) 转换为重加密的密文

并且对应的数据使用者可以解密，其算法具体如下：Receive these re-encryption keys

After that, the cloud server executes the re-encryption algorithm to convert the data owner's ciphertext c _i (m) into the re-encrypted ciphertext

And the corresponding data user can decrypt it, and the algorithm is as follows:

该算法首先检查是否满足

如果不满足，则输出⊥。然后通过执行

去验证信息

中关于

的签名S_i，并且检测

如果存在检查失败，则终止方案，否则，使用云服务器计算

最后，输出

7-1:

The algorithm first checks whether

If it is not satisfied, then output ⊥. Then by executing

To verify information

About

The signature S _i of

If there is a check failure, the solution is terminated, otherwise, the cloud server is used to calculate

Finally, the output

(VIII) Data Decryption

后，Pa_i中的数据使用者D_j可以通过执行Dec算法来解密重加密后的密文

其算法具体如下：Receive the re-encrypted ciphertext from the cloud server

After that, the data user _Dj in _Pai can decrypt the re-encrypted ciphertext by executing the Dec algorithm.

The specific algorithm is as follows:

8-1:

8-2: D _j calculation

进行解密，获取原文的明文m和r₁，如果

以及

成立，则m被接受，否则，不会被接受。8-3: Then through

Decrypt and obtain the original plaintext m and r _1. If

as well as

If it holds, m is accepted, otherwise, it is not accepted.

8-4: After the decryption is successful, the data user _Dj will obtain the data owner's sharing information. If the user is unwilling to decrypt, the cloud server will generate a re-encrypted ciphertext for the next data user, who will decrypt it. And so on, until there is a data user in the sharing path _Pai who is willing to decrypt.

The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention, and those skilled in the art should understand. Without departing from the purpose and scope of the present invention as defined in the appended claims, the present invention can be modified in various forms and details. The embodiments should be considered only as illustrative, not mandatory. Therefore, the detailed description of the present invention does not limit the scope of the present invention, the scope of the present invention should be defined by the appended claims, and all distinguishing technical features within the scope of the present invention should be understood to be included in the present invention.

Claims (3)

1. A lightweight data sharing method based on a vehicle social network, characterized in that the method specifically comprises the following steps: (I) System initialization The trusted institution TA selects a set of parameters arbitrarily under the bilinear library, randomly selects a generator under the two multiplication cycle groups _G1 and _Gt , then selects the system security parameters and generates a strong unforgeable signature algorithm, and defines 8 hash functions, and executes the Setup(1 ^λ )→par algorithm to generate a public parameter pp for the system. The execution of the Setup(1 ^λ )→par algorithm is as follows: 1-1: Setup(1 ^λ )→pp.TA selects two groups G ₁ and G _t with the same prime number q, where P ₁ is taken from G ₁ and P ₂ is taken from G _t . Assume that 1 ^λ is the system security parameter, Sig＝(G,S,V) is a one-time signature algorithm with strong unforgeability, and L _s ＝L _sig (1 ^λ ) is the length of the verification key. Secondly, TA defines some hash functions

H ₁ : G ₁ →(0,1) ^3λ , H ₂ : G ₁ ×G _t ×(0,1) ^3λ →(0，1) ^4λ , H ₃ :(0，1) ^λ →Z _q , H ₄ :(0，1) ^λ →Z _q , H ₅ :(0，1) ^λ →Z _q , H ₆ :(0,1) ^λ →Z _q , H ₇ :(0,1) ^λ →Z _q , H ₈ :(0,1) ^3λ →Z _q , finally these system public parameters are represented by pp=(G ₁ ,G _t ,P ₁ ，P ₂ ,q,H ₁ ,H ₂ ,H ₃ ，H ₄ ,H ₅ ，H ₆ ，H ₇ ，H ₈ ,H ₀ ); Wherein, TA: is a trusted authority; q is a prime number used to construct the G1 and _Gt groups; _G1 and Gt are respectively multiplication cyclic groups; _P1 and _P2 are respectively a random element in the _G1 and _Gt groups; pp is a public parameter of the system; G is a function in the one-time signature algorithm with strong unforgeability; S is the signature algorithm in the one-time signature algorithm with strong unforgeability; V is the verification algorithm in the one-time signature algorithm with strong unforgeability; (II) Key Generation The trusted institution executes the KeyGen(pp, i/j)→( _pki , _skj )/( _pki , _skj ) algorithm to select random numbers and generate a pair of public and private keys for the data owner and the data user. The KeyGen(pp)→( _pki , _skj ) algorithm uses the public parameter pp as input, then randomly selects the private key _skj = _ai∈Zq , and calculates the public _key

in

Wherein, i/j is the number of the data owner/data user; (sk _j , pk _j ) is the public key and private key of the jth data user; (sk _i , pk _i ) is the public key and private key of the i-th data owner;

It is a component of the public key of the i-th data owner; (III) Data encryption The data user encrypts the shared data and the keyword to generate data ciphertext, and the data user encrypts the keyword of the interest data to generate interest ciphertext, wherein the data ciphertext includes: the data ciphertext of the shared data and the keyword; (IV) Trapdoor Generation Data owners and data users use their own private keys and

The ciphertext generated by the algorithm is used as input and executed

The algorithm generates a keyword trapdoor, which is then uploaded to the cloud server together with the ciphertext.

The algorithm is that the data owner encrypts each data

Create a trapdoor

And upload to the cloud server, similarly, data users need to encrypt data for each

Create a trapdoor

And upload to the cloud server; Where, (sk _i ,pk _i ): the public key and private key of the i-th data owner; m is the plaintext data that the data owner wants to share; ωk _i is the plaintext keyword that the data owner i wants to share;

is the ciphertext of m and _ωki , that is, the ciphertext of the data and its keywords that the data owner wants to share;

The ciphertext of the data and keywords that the data user wants to share;

For the data owner in the ciphertext

The trapdoor generated below;

For the data owner in the ciphertext

The trapdoor generated by the following; a _i is the private key of the data owner; b _j is a random number selected by the data user and used as his own private key;

for

The median value of

for

The median value of

A random number selected by the data user during the encryption phase; (V) Data Matching When the cloud server finds a message/interest pair, it executes

The algorithm checks whether the keyword ciphertext uploaded by the data owner and the data user matches, and returns the public key and reputation value σ _i of the successfully matched data user to the data owner.

The algorithm is executed as follows: 5-1: By execution

Verification Information

About

Then _, check

If the check fails, terminate the scheme, otherwise proceed to step 5-2 below; 5-2: Calculation

Afterwards, use the points (xi _-1 , yi _-1 ), (xi _-2 , yi _-2 ), (xj _-1 , _yj-1 ) to reconstruct the function f(x), and use the points (xj _-1 , yj _-1 ), (xj _-2 , yj _-2 ), ( _xi-1 , yi _-1 ) to reconstruct the function f′(x). If f(0) = f′(0), output 1; otherwise, output 0. 5-3: Finally, the cloud server sends the data user’s public key pk _j and reputation value rυ _j to the data owner; Among them, pk _i is the public key of data owner i;

is a component of pk _i ; m is the plaintext data that the data owner wants to share;

is the ciphertext of m and _ωki , that is, the ciphertext of the data and its keywords that the data owner wants to share;

The ciphertext of the data and keywords that the data user wants to share;

for

The constituent elements of ; sυk _i and sυk _j are random numbers, respectively, which are used as the signature private key of the data owner in the strong unforgeable one-time signature algorithm; S _i is a signature generated by the data owner; ν() is the verification function in the strong unforgeable one-time signature algorithm; x _i-1 , x _i-2 , y _i-1 , y _i-2 are 4 random numbers selected by the data owner; x _j-1 , x _j-2 , y _j-1 , y _j-2 are 4 random numbers selected by the data user; f(x) is a polynomial function; (VI) Re-encryption key generation The data owner establishes an orderly sharing path based on the reputation value σ _i of the data user

implement

The algorithm generates a re-encryption key for the data user in the sharing path Pa _i and distributes the re-encryption key to the cloud server.

The algorithm is that the data owner U _i selects a random number

Calculate a re-encryption key for each data user in Pa _i

in:

Then,

and Pa _i are uploaded to the cloud server; Pa _i is an ordered sharing path generated by the data owner based on the reputation value of the data user, consisting of the public key of the data user;

is the ciphertext of the data and its keywords that the data owner wants to share; sk _i is the private key of the i-th data owner; pk _j is the public key of the data user; U _i is an identity identifier of the data owner;

Generate

The resulting intermediate value; (VII) Re-encrypted ciphertext generation After receiving the re-encryption key, sharing path Pa _i and the ciphertext of the shared data, the cloud server executes

The algorithm generates a corresponding re-encrypted ciphertext for each data user in the sharing path Pa _i ;

The algorithm is executed by the cloud server, first checking whether

If it is not satisfied, then output ⊥; then execute

To verify information

About

The signature S _i of

If there is a check failure, the solution is terminated, otherwise, the cloud server is used to calculate

Finally, the output

in,

is a component of pk _i ;

is the public key of the jth data user in Pa _i ;

is the public key of the j+1th data user in Pa _i ;

is the re-encrypted ciphertext generated by the cloud server for the jth data user in Pa _i ;

is the re-encrypted key generated by the j+1th data user in Pa _i ; ⊥ is the protocol termination symbol; (VIII) Data Decryption After receiving the re-encrypted ciphertext, the data user uses his own private key to execute

The algorithm decrypts the re-encrypted ciphertext and obtains the shared information of the data owner. If the data user cannot complete the decryption, the cloud server will generate a re-encrypted ciphertext for the next data user, and the next data user will decrypt it, and so on, until a data user in the sharing path Pa _i completes the decryption.

The algorithm is executed as follows: 8-1:

8-2: D _j calculation

8-3: Then through

Decrypt and obtain the original plaintext m and r _1. If

as well as

If it holds, then m is accepted, otherwise, it will not be accepted; 8-4: After the decryption is successful, the data user _Dj will obtain the sharing information of the data owner. If the data user is unwilling to decrypt, the cloud server will generate a re-encrypted ciphertext for the next data user, who will decrypt it, and so on, until there is a data user in the sharing path _Pai who is willing to decrypt; in,

is the re-encrypted ciphertext generated by the j+1th data user in Pa _i ; D _j is an identity identifier of the data user; sk _j is the private key of the data user; r ₁ , r ₂ are two random numbers selected by the data owner during the encryption phase;

To generate

The resulting intermediate value. 2. According to claim 1, the lightweight data sharing method based on vehicle social network is characterized in that the data owner adopts a hybrid encryption mode to encrypt the data to be shared, and the ciphertext of the shared data includes the ciphertext of relevant keywords. The data owner encrypts the keywords of the shared data and generates a corresponding trapdoor for the keyword ciphertext. At the same time, the data user encrypts the keywords of the interest data and generates a corresponding trapdoor for the interest keyword ciphertext. The cloud server determines whether the two keywords are equal and will not disclose the privacy of the keywords. The data owner adopts a public key-based equality test to achieve data matching in the vehicle social network. 3. According to claim 1, the lightweight data sharing method based on vehicle social network is characterized in that the cloud server uses proxy re-encryption technology to realize data sharing in the vehicle social network. The delegator does not trust the secondary delegate and adopts the autonomous path method. The data owner generates an ordered sharing path according to the reputation value of the data user, and then generates a re-encrypted ciphertext for the data user in the path and sends it to the cloud server. After receiving the sharing path and the re-encryption key, the cloud server converts the ciphertext into a re-encrypted ciphertext that can be decrypted by the data user.

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