WO2019178958A1

WO2019178958A1 - Data encryption method, data query method, data encryption apparatus, data query apparatus, device and storage medium

Info

Publication number: WO2019178958A1
Application number: PCT/CN2018/091912
Authority: WO
Inventors: 王翼
Original assignee: 平安科技（深圳）有限公司
Priority date: 2018-03-22
Filing date: 2018-06-20
Publication date: 2019-09-26
Also published as: CN108632248A; CN108632248B

Abstract

Disclosed are a data encryption method, a data query method, a data encryption apparatus, a data query apparatus, a device and a storage medium. The data encryption method comprises: acquiring a plaintext keyword of a plaintext file, and creating, based on the plaintext keyword, a file index of the plaintext file using a locality sensitive hashing function; acquiring a first random user key sent by a key management center; using the first random user key to respectively encrypt the plaintext file and the file index to acquire an encrypted file and an encrypted index; and sending the encrypted file and the encrypted index to a server side to instruct the server side to encrypt the encrypted file using a first random server side key sent by the key management center, so as to form a ciphertext file, wherein the first random user key is associated with the first random server side key. The data encryption method reduces the storage pressure of a system and improves the data security.

Description

Data encryption method, data query method, device, device and storage medium

This application is based on the Chinese Patent Application No. 201 810 239 555.X filed on Mar. 22, 2018, entitled "Data Encryption Method, Data Query Method, Apparatus, Apparatus, and Storage Medium", and claims priority.

Technical field

The present application relates to the field of data processing, and in particular, to a data encryption method, a data query method, an apparatus, a device, and a storage medium.

Background technique

With the development of cloud computing technology, more and more enterprises and individuals choose to store and manage data through the cloud server. For security reasons, users will choose to encrypt the data before uploading it to the cloud server. However, the encrypted data will bring difficulties to the retrieval of data, making the data query process inefficient. Currently, the cloud server mainly uses a fuzzy search algorithm to query data stored on the cloud server. The fuzzy search algorithm mainly relies on establishing an expandable keyword set as an index, which includes all users who may be misspelled. Keywords, this inevitably makes the size of the file index very large, increasing the storage overhead of the system.

Summary of the invention

The embodiment of the present application provides a data encryption method, device, device, and storage medium to solve the problem of occupying too much system storage space in data encryption.

The embodiment of the present application provides a data query method, device, device, and storage medium to solve the problem that the data query efficiency is not high.

The embodiment of the present application provides a data encryption method, including the following steps performed by the data owner:

Obtaining a plaintext keyword of the plaintext file, and establishing a file index of the plaintext file by using a local sensitive hash function based on the plaintext keyword;

Obtaining a first random user key sent by the key management center;

Encrypting the plaintext file and the file index by using a first random user key to obtain an encrypted file and an encrypted index;

And sending the encrypted file and the encrypted index to the server, to instruct the server to encrypt the encrypted file by using a first random server-side key sent by the key management center to form a ciphertext file;

The first random user secret key is associated with the first random server-side secret key.

The embodiment of the present application provides a data encryption apparatus, including:

a file index establishing module, configured to obtain a plaintext keyword of the plaintext file, and establish a file index of the plaintext file by using a local sensitive hash function based on the plaintext keyword;

a first random user key obtaining module, configured to acquire a first random user key sent by the key management center;

The encrypted file and the encrypted index obtaining module are configured to respectively encrypt the plaintext file and the file index by using a first random user key to obtain an encrypted file and an encrypted index;

And an encrypted file sending module, configured to send the encrypted file and the encrypted index to the server, to instruct the server to use the first random server-side key sent by the key management center to perform the encrypted file Encrypted to form a ciphertext file, wherein the first random user key is associated with the first random server-side key.

An embodiment of the present application provides a data query method, including the following steps performed by a server:

Obtaining a query keyword, and processing the query keyword by using a local sensitive hash function to form a query trapdoor;

Determining, by the query keyword and the query trapdoor, an encrypted index that successfully matches the query trapdoor as a target encryption index;

Determining, according to the target encryption index, a ciphertext file corresponding to the target encrypted index as a target ciphertext file; wherein the ciphertext file is owned by the first random server-side key sent by the key management center The encrypted file sent by the terminal is encrypted and formed;

Obtaining a second random server-side key sent by the key management center;

Decrypting the target ciphertext file based on the second random server-side key to obtain the target encrypted file;

And sending the target encrypted file to the authorized client, to instruct the authorized client to decrypt the target encrypted file by using a second random user key sent by the key management center, to obtain a corresponding plaintext file;

The second random user secret key is associated with the second random server end key.

An embodiment of the present application provides a data query apparatus, including:

Querying a trapdoor obtaining module, configured to obtain a query keyword, and processing the query keyword by using a local sensitive hash function to form a query trapdoor;

a target encryption index obtaining module, configured to use, as the target encryption index, an encrypted index that successfully matches the query trapdoor based on the query keyword and the query trapdoor;

a target ciphertext file obtaining module, configured to determine, according to the target encrypted index, a ciphertext file corresponding to the target encrypted index as a target ciphertext file; wherein the ciphertext file is sent by using a key management center a random server-side secret key is formed by encrypting an encrypted file sent by the data owner;

a second random server-side key acquisition module, configured to acquire a second random server-side key sent by the key management center;

The target encrypted file obtaining module is configured to decrypt the target ciphertext file based on the second random server-side key to obtain the target encrypted file;

a target encrypted file sending module, configured to send the target encrypted file to an authorized user end, to instruct the authorized user end to decrypt the target encrypted file by using a second random user key sent by the key management center, Obtaining a corresponding plaintext file, wherein the second random user secret key is associated with the second random server end key.

An embodiment of the present application provides a computer device including a memory, a processor, and computer readable instructions stored in the memory and executable on the processor, the processor implementing the computer readable instructions The following steps:

Obtaining a first random user key sent by the key management center;

Obtaining a second random server-side key sent by the key management center;

And sending the target encrypted file to the authorized client, to instruct the authorized user to decrypt the target encrypted file by using a second random user key sent by the key management center, to obtain a corresponding plaintext file;

Embodiments of the present application provide one or more non-volatile readable storage media storing computer readable instructions, when executed by one or more processors, causing the one or more processors Perform the following steps:

Obtaining a first random user key sent by the key management center;

Obtaining a second random server-side key sent by the key management center;

The details of one or more embodiments of the present invention are set forth in the accompanying drawings and the description of the claims.

DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the description of the embodiments of the present application will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the present application. Other drawings may also be obtained from those of ordinary skill in the art based on these drawings without the inventive labor.

1 is a schematic diagram of an application scenario in an embodiment of the present application;

2 is a flowchart of a data encryption method in Embodiment 1 of the present application;

Figure 3 is a flow chart of a specific embodiment of step S11 of Figure 2;

4 is a flow chart of a specific embodiment of step S13 in FIG. 2;

5 is a schematic diagram of a data encryption apparatus in Embodiment 2 of the present application;

6 is a flowchart of a data query method in Embodiment 3 of the present application;

Figure 7 is a flow chart of a specific embodiment of step S21 of Figure 6;

Figure 8 is a flow chart of a specific embodiment of step S22 of Figure 6;

9 is a schematic diagram of a data query device in Embodiment 4 of the present application;

Figure 10 is a schematic diagram of a computer device in Embodiment 6 of the present application.

detailed description

The technical solutions in the embodiments of the present application are clearly and completely described in the following with reference to the drawings in the embodiments of the present application. It is obvious that the described embodiments are a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present application without departing from the inventive scope are the scope of the present application.

The application example 1 to the embodiment 6 are applied to the application scenario shown in FIG. 1 , where the application scenario includes four terminals: a data ownership end, a secret key management center, a server end, and an authorized user end. The data owner refers to the terminal that owns the plaintext file. Authorized client refers to a terminal that is authorized to perform data query in the server. The Key Management Center (KMC) is an important part of the public key infrastructure. It is responsible for providing key generation, storage, backup, update, recovery, or query for the Certification Authority (CA) system. Key services to address key management issues associated with large-scale cryptographic applications in distributed enterprise applications. The server is mainly used for storing data and encrypting and decrypting data to interact with the client, so that the client can obtain corresponding data from the server, and the client includes but is not limited to the server-side communication. Terminals such as PCs and smartphones.

Data interaction can be performed between the data owner, the key management center, the server, and the authorized client. Specifically, the data possession end, the secret key management center, the server end, and the data authorization end can perform data interaction by means of Bluetooth, a network, or a local connection.

Example 1

Fig. 2 is a flow chart showing the data encryption method in this embodiment. The data encryption method is applied to various terminals to solve the problem of occupying too much system storage space in the data encryption process. As shown in FIG. 2, the data encryption method includes the following steps performed by the data owner:

S11: Obtain a plaintext keyword of the plaintext file, and use a local sensitive hash function to establish a file index of the plaintext file based on the plaintext keyword.

Among them, the plaintext file refers to the original file that is not encrypted. The Locality Sensitive Hashing (LSH) function is one of the Approximate Nearest Neighbor (ANN) searches to measure text similarity. Locally sensitive hash functions can mine similar data from massive data, which can be applied to text similarity detection, web search and other fields.

The plaintext file that needs to be uploaded to the server is pre-stored in the data owner. Before the plaintext file is uploaded to the server by the data owner, the plaintext keyword is obtained from the plaintext file, and the local sensitive hash function is used based on the plaintext keyword. Create a file index of the plaintext file.

In a specific implementation manner, the plaintext keyword of the plaintext file is obtained, and the file index of the plaintext file is established by using the local sensitive hash function based on the plaintext keyword, as shown in FIG. 3, which specifically includes the following steps:

S111: Extract plaintext keywords from the plaintext file, and convert the plaintext keywords into plaintext keyword vectors.

Extracting plaintext keywords from plaintext files can be implemented using textrank algorithm, rake algorithm, topic-model algorithm or TF-IDF algorithm. Specifically, the data from the end of the plaintext file has _{_{File = {file 1, file 2}} , ..., file n} plaintext extracted keywords and the keyword converted to a plaintext vector plaintext keyword _{_{W D = {w 1, w}} 2 ,...,w _n }, where File is a set of specified file files, file _n is a specified plaintext file element in the set of file files, W _D is a set of plaintext keyword vectors, and w _n is a set of plaintext keyword vectors Each plaintext keyword vector element, and, w _i ∈{0,1} ^26*26 . Specifically, the plaintext keyword is converted into a binary set consisting of two adjacent characters in the keyword, for example, the binary set of the keyword "network" is {ne, et, tw, wo, or, rk} . We use a vector of length 26*26 bits w _i ∈{0,1} ^26*26 to represent all possible binary sets. Each vector element represents one of 26*26 possible 2 letter combinations. If the corresponding element value is set to 1, it means that the corresponding letter combination exists in the given keyword. This vector-based keyword representation reduces the sensitivity of misspellings and misspellings. For example, the vector corresponding to the spelling method "netword", "nedwork" or "netwosk" is different from the original "network" vector by only 2 elements. Using this representation, even if a keyword may be mistakenly spelled into many forms, their vector representation will be close to the correct one, and this similarity can be measured using Euclidean distance. Alternatively, a 3 or 4 letter combination may also be used to represent the keyword vector, depending mainly on the actual degree of blur.

S112: Perform a hash conversion on each plaintext keyword vector by using a p-stable local sensitive hash function to obtain a corresponding plaintext hash value.

Among them, the p-stable local sensitive hash function refers to a locally sensitive hash function applied to the p-stable distribution. In this step, select one independent p-stable local sensitivity from the p-stable local sensitive hash function group H={h:{0,1} ^26*26 —>{0,1} ^m }} The Greek function h _i , l is a random number. Each plaintext keyword vector is hash-converted using the p-stable local-sensitive hash function h _i ∈H to obtain a corresponding plaintext hash value. Specifically, the p-stable locally sensitive hash function h _i can be:

Where a is an m-dimensional vector, b ∈ [0, c] is a real number, c is a fixed value, and the values of l and c can be determined according to the actual m. For example, when m=8000, l=30 and c=4 may be taken, and each plaintext keyword vector w _i is hash-converted by the p-stable local sensitive hash function h _i to obtain a corresponding plaintext hash. value.

S113: Insert each plaintext hash value into the Bloom filter for filtering to obtain a file index.

Among them, the Bloom Filter consists of a long binary vector and a series of random mapping functions. The Bloom filter can be used to retrieve whether an element is in a collection. Specifically, an n-bit Bloom filter is constructed for each plaintext file and each bit in the Bloom filter is initialized to zero. The file index is obtained by inserting the plaintext hash value obtained in step S112 into the corresponding Bloom filter.

In this embodiment, the plaintext keyword is first converted into a plaintext keyword vector, and then the plaintext keyword vector is hash-transformed by a p-stable local sensitive hash function and then filtered by a Bloom filter to directly form a file index. There is no need to expand the size of the index file, and it is not necessary to construct a fuzzy keyword set in advance, which reduces the storage pressure of the system and the complexity of subsequent query based on the file index, so as to improve the efficiency of data query.

S12: Acquire a first random user key sent by the key management center.

In this step, the data owner acquires the first random user key that is sent from the key management center for subsequent encryption of the related data (plain file and file index). The first random user secret key is a key generated by the key management center based on the private key and sent to the data owner.

In a specific embodiment, the first random user key sent by the key management center is generated during the initialization process of the key management center. The initialization of the key management center includes the following steps:

(1) The data owner sends the security parameter k to the key management center, and the key management center takes the security parameter k as an input, and outputs a cyclic group G, a prime number q, and a hash mapping function f, wherein the cyclic group G includes A generator element g.

Wherein, the cyclic group G means that if a group G can be generated by the element g, that is, for any b∈G, a ∈ Z exists, so that b=g ^a , then G=<g> is a cyclic group, and g is a generator of the cyclic group G. Where Z represents a set of all remaining classes of all prime numbers q, and this set constitutes an exchange group of order q under the addition of prime numbers q. The security parameter k belongs to a positive integer. Based on the security parameter k, the key management center selects a k-bit prime number q. In addition, the key management center also selects a hash mapping function f, which takes an arbitrarily long bit string as an input and outputs the elements on the cyclic group G as f: {0, 1} ^* →G.

(2) Select a random number x from Zq ^* and calculate h = g ^x , obtain the public key PK = (G, g, q, h, f), and the private key MSK = x.

Wherein, Z _q ^* _q represents a collection of the Z configuration of the remaining class q prime, i.e., the elements of Z _q ^* I under the same sense and q are smaller than the prime q positive integers, and therefore, Z _q ^* You can write the set Z _q ^* ={1,2,...,q-1}.

In this step, by selecting a random number x from Z _q ^* as the private key MSK=x, and after calculating h=g ^x , the corresponding public key PK=(G, g, q, h, f) is formed. .

(3) For the data possession i, the key management center randomly selects a number x _i1 from Z _q ^* and calculates x _i2 = xx _i1 .

(4) Using x _i1 as an input parameter, obtain SK=(M ₁ , M ₂ , S), where M ₁ , M ₂ ∈R ^m*m are invertible matrices, and S∈{0,1} ^m is a vector. Where x _i1 =m; thus obtaining the first random user secret key K _ui =(x _i1 , SK) and the first random server side key K _si =(i, x _i2 ).

(5) The key management center sends the first random user key K _ui = (x _i1 , SK) to the data owner i, and sends the first random server key K _si = (i, x _i2 ) to the server. end. After receiving the K _si =(i, x _i2 ), the server updates the first random user-key mapping relationship K _s =K _s ∪(i, x _i2 ) stored in the server.

In this embodiment, the key is generated by the key management center to generate a corresponding key, which improves the convenience of key generation and ensures the security of the key.

S13: encrypting the plaintext file and the file index by using the first random user key to obtain the encrypted file and the encrypted index.

After obtaining the first random user key K _ui , the data owner encrypts the plaintext file and the file index respectively by using the first random user key K _{ui to} obtain the corresponding encrypted file and the encrypted index.

In a specific implementation, the first random user key is used to encrypt the plaintext file and the file index respectively, and the encrypted file and the encrypted index are obtained. As shown in FIG. 4, step S13 specifically includes the following steps:

S131: Encrypt the plaintext file by using the ElGamal algorithm to obtain the encrypted file, based on the first random user key.

Among them, ElGamal algorithm is an asymmetric encryption algorithm. It is based on the public key cryptosystem and elliptic curve cryptosystem proposed in 1985. The ElGamal algorithm can be used for both data encryption and digital signature.

In this step, the data owner encrypts the plaintext file by using the ElGamal proxy encryption algorithm based on the first random user key K _ui = (x _i1 , SK), and obtains the encrypted file: C(file _i )=(g ^x , g ^rxi1 File _i ), where file _i is the plaintext file of data owner i.

S132: The first random user key is processed by using a hash mapping function based on the first random user secret key to generate a key K _I .

The hash mapping function is a hash mapping function f in the public key generated by the key management center. Based on the first random user key, the hash mapping function f is used to generate the key K _I =f(x _i1 ).

S133: Divide the file index I _D into two index vectors {I', I′′} as follows: For each element i _j ∈I _D , if S _j ∈S and S _j is equal to 1, set i _j ′ =i _j ′′=i _j ; otherwise, i _j '=1/2·i _j +r,i _j ′′=1/2·i _j −r, where r is a random number, S∈{0,1 } ^m .

In this step, the file index I _{D is} divided into two index vectors {I', I"} by SK = (M ₁ , M ₂ , S) in the key management center. Specifically, for the file index I _D One of the elements i _j ∈I _D first obtains the corresponding vector S _j from S. If S _j is equal to 1, the divided element i _j is {i _j ', i _j ′′}. If S _{j is} not equal to 1, the dividing element i _j is {1/2·i _j +r, 1/2·i _j -r}, where r is a random number, S ∈ {0, 1} ^m .

S134: Encrypt the file index based on the key K _I and the two index vectors {I', I′′}, and obtain an encrypted index: Enc _SK (I _D )={M ₁ ^T ·I′, M ₂ ^T ·I′′, Enc (K _I , fid _i )}, where fid _i is the file ID of the plaintext file, and M ₁ , M ₂ ∈R ^m*m are invertible matrices.

After dividing the index file into two index vectors, the file index is encrypted based on the key K _I and the two index vectors {I', I''}, and the encrypted index is obtained: Enc _SK (I _D )={M ₁ ^T ·I ', M ₂ ^T · I", Enc (K _I , fid _i )}.

In one embodiment, Enc can be implemented by AES or DES. Among them, AES refers to the Advanced Encryption Standard (English: Advanced Encryption Standard, abbreviation: AES), also known as Rijndael encryption in cryptography, is a block encryption standard adopted by the US federal government. DES is a symmetric cryptosystem in the cryptosystem, also known as the US data encryption standard. It is a symmetric cryptosystem encryption algorithm developed by IBM in 1972.

In a specific implementation, the first random user key is used to encrypt the plaintext file and the file index respectively, and the step of obtaining the encrypted file and the encrypted index (step S13) may also be performed on the server side, that is, the data owner sends the index file to Service-Terminal. At this time, the first random server-side key obtained by the server from the key management center is K _si = (i, x _i2 , SK). The server side divides the file index I _D into two index vectors {I', I′′} as follows: For each element i _j ∈I _D , if S _j ∈S and S _j is equal to 1, then i _j ′ is set =i _j ′′=i _j ; otherwise i _j ′=1/2·i _j +r,i _j ′′=1/2·i _j −r, where r is a random number, S∈{0,1} ^m . Encrypt the index vector to obtain the encrypted index: Enc _SK (I _D )={M ₁ ^T ·I', M ₂ ^T ·I′′}.

In this embodiment, the plaintext file and the file index are encrypted by the first random user key, which improves the security of the data.

S14: Send the encrypted file and the encrypted index to the server, to instruct the server to encrypt the encrypted file by using the first random server-side key sent by the key management center to form a ciphertext file, where the first random user secret The key is associated with the first random server-side key.

After obtaining the encrypted file and the encrypted index, the data owner sends the encrypted file and the encrypted index to the server. In this way, even if the data in the server side is stolen, since the server side lacks the decryption key corresponding to the encrypted file, there is no way to decrypt the encrypted file to obtain the corresponding plaintext file, which fully ensures the security of the data. In a specific embodiment, the step further includes sending the index file to the server.

After receiving the encrypted file sent by the data owner, the server encrypts the encrypted file by using the first random server-side key K _si = (i, x _i2 ) sent by the key management center to form a ciphertext file. Specifically, the server first finds the first random server-side key K _si =(i, x _i2 ) corresponding to the data owner i, and then encrypts the encrypted file by using the ElGamal algorithm based on x _i2 :

C*(file _i )=(g ^x ,(g ^r ) ^xi2 ·g ^rxi1 ·file _i )=(g ^x ,(g ^r ) ^xi2+xi1 ·file _i )=(g ^x ,g ^rx ·file _i ) ;

Therefore, the ciphertext file C*(file _i )=(g ^x , g ^rx file _i ) is finally obtained, where file _i ∈ File.

In this embodiment, the first random user secret key and the first random server side secret key are associated. Specifically, x _i1 user first random secret key _{_{K ui = (x i1, SK}} ) and the first random server-side secret key _{_{K si = (i, x i2}} ) by the private key x _i2 MSK = x Associated: x _i2 = xx _i1 .

In the data encryption method provided in this embodiment, the plaintext keyword of the plaintext file is first converted into a plaintext keyword vector, and then the plaintext keyword vector is hash-transformed by a local sensitive hash to form a file index, and the index file does not need to be extended. The size does not require pre-built fuzzy keyword sets, which reduces the system storage pressure and the complexity of subsequent queries. Moreover, the plaintext file is encrypted in advance when it is sent to the server, which improves the security of the data.

It should be understood that the size of the sequence of the steps in the above embodiments does not mean that the order of execution is performed. The order of execution of each process should be determined by its function and internal logic, and should not be construed as limiting the implementation process of the embodiments of the present application.

Example 2

Fig. 5 is a block diagram showing the principle of the data encryption apparatus corresponding to the data encryption method in the first embodiment. As shown in FIG. 2, the data encryption apparatus includes a file index establishing module 11, a first random user key obtaining module 12, an encrypted file and encrypted index obtaining module 13, and an encrypted file and encrypted index transmitting module 14. The file index establishing module 11, the first random user key obtaining module 12, the encrypted file and the encrypted index obtaining module 13, and the implementation function of the encrypted file and the encrypted index sending module 14 are the same as the data encryption method in the first embodiment. In order to avoid redundancy, the present embodiment is not described in detail.

The file index establishing module 11 is configured to obtain a plaintext keyword of the plaintext file, and use a local sensitive hash algorithm to establish a file index of the plaintext file based on the plaintext keyword.

The first random user key obtaining module 12 is configured to acquire a first random user key sent by the key management center.

The encrypted file and encryption index obtaining module 13 is configured to separately encrypt the plaintext file and the file index by using the first random user key to obtain the encrypted file and the encrypted index.

The encrypted file and the encrypted index sending module 14 is configured to send the encrypted file and the encrypted index to the server, to instruct the server to encrypt the encrypted file by using the first random server-side key sent by the key management center to form a ciphertext. A file, wherein the first random user key is associated with the first random server-side key.

Preferably, the file index establishing module 11 includes a plaintext keyword acquiring unit 111, a hash converting unit 112, and a file index acquiring unit 113.

The plaintext keyword obtaining unit 111 is configured to extract a plaintext keyword from the plaintext file, and convert the plaintext keyword into a plaintext keyword vector.

The hash conversion unit 112 is configured to perform hash conversion on each plaintext keyword vector by using a p-stable local sensitive hash function to obtain a corresponding plaintext hash value.

The file index obtaining unit 113 is configured to insert each plaintext hash value into the Bloom filter for filtering to obtain a file index.

Preferably, the encrypted file and encryption index acquisition module 13 includes an encrypted file acquisition unit 131, a key K _I generation unit 132, an index vector division unit 133, and an encryption index acquisition unit 134.

The encrypted file obtaining unit 131 is configured to encrypt the plaintext file by using the ElGamal algorithm based on the first random user secret key to obtain the encrypted file.

The key K _I generating unit 132 is configured to process the first random user key by using a hash mapping function based on the first random user key to generate a key K _I .

The index vector dividing unit 133 is configured to divide the file index I _D into two index vectors {I', I′′} as follows: for each element i _j ∈I _D , if S _j ∈S and S _j is equal to 1 , then i _j '=i _j ′′=i _j ; otherwise, i _j ′=1/2·i _j +r, i _j ′′=1/2·i _j −r, where r is a random number, S∈{0,1} ^m .

The encrypted index obtaining unit 134 is configured to encrypt the file index based on the key K _I and the two index vectors {I', I"} to obtain an encrypted index: Enc _SK (I _D )={M ₁ ^T ·I', M ₂ ^T · I′′, Enc(K _I , fid _i )}, where fid _i is the file ID of the plaintext file, and M ₁ , M ₂ ∈R ^m*m are reversible matrices.

Example 3

Fig. 6 is a flow chart showing the data query method in this embodiment. The data query method is applied to various terminals to solve the problem that the data query efficiency is not high. As shown in FIG. 6, the data query method includes the following steps performed by the server:

S21: Acquire a query keyword, and use a local sensitive hash function to process the query keyword to form a query trapdoor.

The query keyword refers to a keyword used to query a plaintext file. The query keyword is sent by the authorized client to the server. The server obtains the query keyword from the authorized user, and uses the local sensitive hash function to process the query keyword to form a query trap. Among them, the trapdoor is an "organ" set in a system or a file, which allows a violation of the security policy when providing specific input data. For example, a login processing subsystem allows processing of a particular user ID to bypass normal password checking.

In a specific implementation manner, the query keyword is obtained, and the query keyword is processed by using a local sensitive hash function to form a query trapdoor. As shown in FIG. 7, the method includes the following steps:

S211: Acquire a query keyword, and convert the query keyword into a query keyword vector.

After the server obtains the query keyword from the authorized user terminal j, the query keyword is converted into the query keyword vector, and the specific conversion process is similar to step S111, and details are not described herein again.

S212: Convert each query keyword vector by using a p-stable local sensitive hash function to obtain a corresponding query hash value.

The server obtains the query keyword sent by the authorized client j. Selecting one independent p-stable locally sensitive hash function h _j from the p-stable local sensitive hash function group H={h:{0,1} ^26*26 —>{0,1} ^m }} l is a random number. For each query keyword, each query keyword vector is hash-converted using the p-stable local-sensitive hash function h _j ∈H to obtain a corresponding query hash value. The specific hash conversion process is similar to step S112, and details are not described herein again.

S213: Insert each query hash value into the Bloom filter for filtering to obtain the query key value Q.

Specifically, an n-bit Bloom filter is constructed for each plaintext file and each bit in the Bloom filter is initialized to zero. The corresponding query hash value obtained in step S211 is inserted into the corresponding Bloom filter to obtain the query key value Q.

S214: Divide the query key value Q into two query vectors {Q', Q"} according to the following rules. For an element q _j ∈Q in the query key value Q, if S _j ∈S and S _j is equal to 1, then Set q _j '=q _j ′′=q _j ; otherwise, q _j ′=1/2·q _j +r′,q _j ′′=1/2·q _j −r′, where r′ is a random number , S∈{0,1} ^m .

In this step, the secret key management center _{_{SK = (M 1, M 2}} , S) query key value is divided into two queries Q vectors {Q ', Q "}. In particular, the key value for the query Q One of the elements q _j ∈Q first obtains the corresponding vector S _j from S. If S _j is equal to 1, the partition element q _j is {q _j ', q _j ′′}. If S _{j is} not equal to 1, the dividing element q _j is {1/2·q _j +r', 1/2·q _j -r'}, where r' is a random number, S∈{0,1 } ^m .

S215: Encrypt the query key value Q based on two query vectors {Q', Q"} to obtain a query trapdoor: Enc _SK (Q)={M ₁ ^-1 ·Q', M ₂ ^-1 ·Q"}, wherein , M ₁ , M ₂ ∈R ^m*m is an invertible matrix.

After dividing the query key value Q into two query vectors {Q', Q"}, the query key value Q is encrypted based on the two query vectors {Q', Q"}, and the query trapdoor is obtained: Enc _SK (Q)= {M ₁ ^-1 ·Q', M ₂ ^-1 ·Q"}.

In one embodiment, Enc can be implemented by AES or DES. Among them, AES refers to the Advanced Encryption Standard (English: Advanced Encryption Standard, abbreviation: AES), also known as Rijndael encryption in cryptography, is a block encryption standard adopted by the US federal government. The DES algorithm is a symmetric cryptosystem in the cryptosystem, also known as the US data encryption standard. It is a symmetric cryptosystem encryption algorithm developed by IBM in 1972.

In this embodiment, the local sensitive hash function is used to process the query keywords, and the query trapdoor is obtained to improve the efficiency of the data query and reduce the complexity in the data query.

In a specific implementation manner, the step of acquiring the query keyword and processing the query keyword by using the local sensitive hash function to form the query trapdoor (ie, step S21) may also be completed at the authorized user end, that is, the authorized user end obtains After the query trapdoor, the query trapdoor is sent to the server to reduce the query load on the server side and improve query efficiency.

S22: Based on the query keyword and the query trapdoor, the encrypted index that successfully matches the query trapdoor is used as the target encrypted index.

After obtaining the query trapdoor, the server queries the encrypted index based on the query trapdoor, and uses the encrypted index that matches the query trapdoor as the target encrypted index.

In a specific implementation, the encrypted index matching the query trapdoor is used as the target encryption index based on the query keyword and the query trapdoor. As shown in FIG. 8, the method includes the following steps:

S221: Acquire an inner product value of the query trapdoor and each encrypted index as a query inner product value.

Where inner product is a binary operation that accepts two vectors on a real number R and returns a real-valued scalar. The inner product value is the result value obtained by the inner product operation. Specifically, the inner product value of the two vectors a=[a ₁ , a ₂ , . . . , a _n ] and b=[ b ₁ , b ₂ , . . . , b _n ] is calculated as: a·b=a ₁ b ₁ + a ₂ b ₂ + ... + a _n b _n .

In this embodiment, by calculating the inner product value of the query trapdoor Enc _SK (Q) and each encryption index Enc _SK (I _D ), the inner product value of the query is obtained: M ₁ ^T I'·M ₁ ^-1 Q '+M ₂ ^T I′′·M ₂ ^-1 Q′′.

S222: Acquire an inner product value of the query keyword and each file index as the inner product value of the data.

The inner product value of the data is obtained by calculating the inner product value of the query keyword and each file index: I ^T · Q = I' ^T · Q' + I" ^T · Q".

S223: Obtain a difference between the inner product value of the query and the inner product value of the data. If the difference between the inner product value and the inner product value of the query is within a preset range, the query trapdoor and the encrypted index match successfully, and the encrypted index is targeted. Encrypt the index.

After obtaining the inner product value of the query and the inner product value of the data, calculating the difference between the inner product value of the query and the inner product value of the data, if the difference between the inner product value of the query and the inner product value of the query is within a preset range, the query The trapdoor and the corresponding encrypted index match successfully, and the encrypted index is used as the target encrypted index. The preset range may be a preset interval, which is set by actual needs. Preferably, the preset range may also be 0, that is, when the difference between the product value in the query query and the product value in the data is 0, the query trapdoor and the corresponding encrypted index match successfully.

In this embodiment, the server side obtains the difference between the inner product value of the query and the inner product value of the data based on the query keyword and the query trapdoor. If the difference between the inner product value and the inner product value of the query is within a preset range, Then the corresponding encrypted index is used as the target encryption index. In this way, the target encrypted index can be quickly located in the data query, which further improves the data query efficiency.

S23: Determine, according to the target encryption index, the ciphertext file corresponding to the target encrypted index as the target ciphertext file; wherein the ciphertext file is sent by the first random server-side key sent by the key management center to the data owner The encrypted file is formed after encryption.

After the target encrypted index is determined, the target ciphertext file is located according to the target encrypted index, and the ciphertext file is determined as the target ciphertext file. Specifically, the target encrypted index can be decrypted to obtain the file ID of the plaintext file: fid _i . The file ID of the plaintext file can be used to locate the corresponding ciphertext file. The ciphertext file is formed by encrypting the encrypted file sent by the data owner by using the first random server-side secret key sent by the key management center. After receiving the encrypted file sent by the data owner, the server encrypts the encrypted file by using the first random server-side key K _si = (i, x _i2 ) sent by the key management center to form a ciphertext file. Specifically, the server first finds the first server-side key K _si =(i, x _i2 ) corresponding to the data owner, and then encrypts the encrypted file by using the ElGamal algorithm based on x _i2 :

Therefore, the ciphertext file C*(file _i )=(g ^x , g ^rx file _i ), file _i ∈File is finally obtained.

S24: Acquire a second random server-side key sent by the key management center.

In this step, the server obtains the second random server-side key sent from the key management center for subsequent encryption of related data (plain file and file index).

In a specific embodiment, the second random server-side key sent by the key management center is generated during the initialization process of the key management center. The initialization of the key management center includes the following steps:

Wherein, the cyclic group G means that if a group G can be generated by the element g, that is, for any b∈G, a ∈ Z exists, so that b=g ^a , then G=<g> is a cyclic group, g Is a generator of the loop group G. Where Z represents a set of all remaining classes of all prime numbers q, and this set constitutes an exchange group of order q under the addition of prime numbers q. The security parameter k belongs to a positive integer. Based on the security parameter k, the key management center selects a k-bit prime number q. In addition, the key management center also selects a hash mapping function f, which takes an arbitrarily long bit string as an input, and uses the elements on the cyclic group G as the output hash function f, ie f:{ 0,1}*→G.

(2) Select a random number x from Zq ^* , calculate h = g ^x , obtain the public key PK = (G, g, q, h, f), and the private key MSK = x.

(3) For the authorized user terminal j, the key management center randomly selects a number x _j1 from Z _q ^* and calculates x _j2 = xx _j1 . The server-side key Ks _j = x _j2 and the user secret key Ku _j = x _j1 corresponding to the authorized client j are formed. The key management center sends the second random user key K _uj = (x _j1 , SK) to the authorized client j, and sends the second random server key K _sj = (j, x _j2 ) to the server. After receiving the K _sj , the server updates the second random user-key mapping relationship K _s =K _s K(j, x _j2 ) stored _thereon .

Alternatively, the initialization of the key management center in this embodiment may be performed simultaneously with the initialization of the key management center in Embodiment 1. In another embodiment, after the key management center completes the initialization in Embodiment 1, only the above step (3) is performed in the present embodiment, and steps (1) and (2) have been completed in Embodiment 1.

Further, when the second random user key is assigned to each authorized user, an authorized client ID is also generated, and the authorized client ID is in one-to-one correspondence with the second random user key of the authorized client. When the authorized client performs data query, the server selects the corresponding second random server-side key according to the authorized client ID for decryption.

Preferably, the password corresponding to the authorized client ID is also configured and authorized for the authorized client. In this way, the security of the data can be better ensured, even if the second random user key of the authorized client is stolen, if the authorized client ID and password corresponding to the authorized client are not available, the first hand cannot be successfully utilized. Two random user keys get data from the server.

In this embodiment, for the different authorized clients, the second random server-side key and the second random user key corresponding to the authorized client are generated and allocated, so that the security of the file can be increased at the same time. Achieve the purpose of sharing files with multiple authorized clients.

S25: Decrypt the target ciphertext file based on the second random server-side key to obtain the target encrypted file.

The server obtains the second random server-side key K _sj =x _j2 corresponding to the authorized client stored thereon, and decrypts the target ciphertext file C*(file _i ) by using x _j2 to obtain the target encrypted file. Specifically, the target encrypted file C'(file _i ) is:

C'(file _i )=(g ^r , g ^rx file _i ·(g ^r ) ^-xj2 )=(g ^r ,g ^(x-xj2)r file _i )=g ^rxj1 file _i .

S26: Send the target encrypted file to the authorized client to instruct the authorized client to decrypt the target encrypted file by using the second random user key sent by the key management center to obtain the corresponding plaintext file.

The server sends the obtained target encrypted file to the corresponding authorized user terminal j to instruct the authorized user terminal j to decrypt the target encrypted file by using the second random user key sent by the key management center to obtain the corresponding plaintext file. . Specifically, after receiving the target encrypted file sent by the server, the authorized user terminal j decrypts the target encrypted file by using the second random user key x _j1 to obtain a corresponding plaintext file: g ^rxj1 file _i ·(g ^r ) ^{- Xj1} =file _i to decrypt the encrypted file to get the final plaintext file.

In this embodiment, the second random user secret key and the second random server side secret key are associated. Specifically, the second random user secret key x _j1 and the second random server side secret key x _j2 are associated by the private key MSK=x: x _j2 = xx _j1 .

In the data query method provided in this embodiment, the local key sensitive hash function is used to process the query keywords to form a query trapdoor. And based on the query keyword and the query trapdoor, the corresponding target encrypted index is obtained to locate the corresponding target ciphertext file, thereby improving the efficiency of the data query and reducing the complexity of the data query. Moreover, the second plaintext file of the target ciphertext file can be obtained by the server and the authorized user to obtain the corresponding plaintext file, thereby improving the security of the data.

Example 4

FIG. 9 is a block diagram showing the principle of the data query device corresponding to the data query method in the first embodiment. As shown in FIG. 9, the data query device includes a query trapdoor acquisition module 21, a target encryption index acquisition module 22, a target ciphertext file acquisition module 23, a second random server-side key acquisition module 24, and a target encrypted file acquisition module 25. And the target encrypted file sending module 26. The implementation of the query trapdoor acquisition module 21, the target encryption index acquisition module 22, the target ciphertext file acquisition module 23, the second random server-side key acquisition module 24, the target encrypted file acquisition module 25, and the target encrypted file transmission module 26 The functions are in one-to-one correspondence with the steps corresponding to the data query method in the third embodiment. To avoid redundancy, the present embodiment is not described in detail.

The query trapdoor obtaining module 21 is configured to obtain a query keyword, and process the query keyword by using a local sensitive hash function to form a query trapdoor.

The target encryption index obtaining module 22 is configured to use the encrypted index that successfully matches the query trapdoor as the target encryption index based on the query keyword and the query trapdoor.

The target ciphertext file obtaining module 23 is configured to determine, according to the target encrypted index, the ciphertext file corresponding to the target encrypted index as the target ciphertext file; wherein the ciphertext file is the first random server sent by the key management center. The secret key is formed by encrypting the encrypted file sent by the data owner.

The second random server-side key acquisition module 24 is configured to acquire a second random server-side key sent by the key management center.

The target encrypted file obtaining module 25 is configured to decrypt the target ciphertext file based on the second random server-side key to obtain the target encrypted file.

The target encrypted file sending module 26 is configured to send the target encrypted file to the authorized user end, to indicate that the authorized user end decrypts the target encrypted file by using the second random user key sent by the key management center, and obtains the corresponding plaintext file. Wherein the second random user secret key is associated with the second random server side secret key.

Preferably, the query trapdoor acquisition module 21 includes a query keyword vector conversion unit 211, a query hash value acquisition unit 212, a query key value Q acquisition unit 213, a query vector division unit 214, and a query trapdoor acquisition unit 215.

The query keyword vector conversion unit 211 is configured to obtain a query keyword and convert the query keyword into a query keyword vector.

The query hash value obtaining unit 212 is configured to convert each query keyword vector by using a p-stable local sensitive hash function to obtain a corresponding query hash value.

The query key value Q obtaining unit 213 is configured to insert each query hash value into the Bloom filter for filtering, and obtain the query key value Q.

The query vector dividing unit 214 is configured to divide the query key value Q into two query vectors {Q′, Q′′} according to the following rules, for an element q _j ∈Q in the query key value Q, if S _j ∈S and S _j is equal to 1, the set _{_{q j '= q j "=}} q j; _{otherwise, q j' = 1/2} · q j + r ', q j" = 1/2 · q j -r', wherein r' is a random number, S∈{0,1} ^m .

The query trapdoor obtaining unit 215 is configured to encrypt the query key value Q based on the two query vectors {Q', Q"} to obtain the query trapdoor: Enc _SK (Q)={M ₁ ^-1 ·Q', M ₂ ^{- 1} · Q"}, wherein M ₁ , M ₂ ∈R ^m*m are invertible matrices.

Preferably, the target encryption index acquisition module 22 includes a query inner product value acquisition unit 221, a data inner product value acquisition unit 222, and a target encryption index acquisition unit 223.

The query inner product value obtaining unit 221 is configured to obtain an inner product value of the query trapdoor and each encrypted index as the inner product value of the query.

The data inner product value obtaining unit 222 is configured to obtain an inner product value of the query keyword and each file index as the data inner product value.

The target encryption index obtaining unit 223 is configured to obtain a difference between the inner product value of the query and the inner product value of the data. If the difference between the inner product value and the inner product value of the query is within a preset range, the query trapdoor and the encrypted index match. Successfully, the encrypted index is used as the target encryption index.

Example 5

The embodiment provides one or more non-volatile readable storage media having computer readable instructions that, when executed by one or more processors, cause the one or more processors to execute The data encryption method in Embodiment 1 or the data query method in Embodiment 3 is omitted. Alternatively, the computer readable instructions are executed by one or more processors such that when executed by the one or more processors, the functions of the modules/units in the data encryption apparatus of Embodiment 2 are implemented, or Embodiment 4 is implemented. The function of each module/unit in the data query device is not repeated here to avoid repetition. It will be understood that the computer readable storage medium may include any entity or device capable of carrying the computer readable instruction code, a recording medium, a USB flash drive, a removable hard drive, a magnetic disk, an optical disk, a computer memory, a read only memory ( ROM, Read-Only Memory), Random Access Memory (RAM), electrical carrier signals, and telecommunications signals.

Example 6

FIG. 10 is a schematic diagram of a computer device according to an embodiment of the present application. As shown in FIG. 10, computer device 60 of this embodiment includes a processor 61, a memory 62, and computer readable instructions 63 stored in memory 62 and executable on processor 61. The processor 61 executes the steps of the data encryption method in the first embodiment, such as steps S11 to S14 shown in FIG. 2, when the computer readable instructions 63 are executed. Alternatively, when the processor 61 executes the computer readable instructions 63, the functions of the modules/units in the data encryption apparatus in Embodiment 2 are implemented, such as the file index establishing module 11, the first random user key obtaining module 12, and the encryption shown in FIG. 5. The functions of the file and encryption index acquisition module 13 and the encrypted file and encryption index transmission module 14. Alternatively, the processor 61 implements the steps of the data query method in the above-described Embodiment 3 when the computer readable instructions 63 are executed, such as steps S21 to S26 shown in FIG. Alternatively, when the processor 61 executes the computer readable instructions 63, the functions of the modules/units in the data query device in Embodiment 4 are implemented. For example, as shown in FIG. 9, the query trapdoor acquisition module 21, the target encrypted index acquisition module 22, and the target secret are included. The functions of the file acquisition module 23, the second random server-side key acquisition module 24, the target encrypted file acquisition module 25, and the target encrypted file transmission module 26.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the division of each functional unit and module described above is exemplified. In practical applications, the above functions may be assigned to different functional units as needed. The module is completed by dividing the internal structure of the device into different functional units or modules to perform all or part of the functions described above. The above-mentioned embodiments are only used to explain the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still implement the foregoing embodiments. The technical solutions described in the examples are modified or equivalently replaced with some of the technical features; and the modifications or substitutions do not deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in Within the scope of protection of this application.

Claims

A data encryption method, comprising the following steps performed by a data owner:

Obtaining a plaintext keyword of the plaintext file, and establishing a file index of the plaintext file by using a local sensitive hash function based on the plaintext keyword;

Obtaining a first random user key sent by the key management center;

Encrypting the plaintext file and the file index by using a first random user key to obtain an encrypted file and an encrypted index;

And sending the encrypted file and the encrypted index to the server, to instruct the server to encrypt the encrypted file by using a first random server-side key sent by the key management center to form a ciphertext file;

The first random user secret key is associated with the first random server-side secret key.
The data encryption method according to claim 1, wherein the obtaining a plaintext keyword of the plaintext file, and establishing a file index of the plaintext file by using a local sensitive hash function based on the plaintext keyword, comprises:

Extracting the plaintext keyword from the plaintext file, and converting the plaintext keyword into a plaintext keyword vector;

Each plaintext keyword vector is converted by using a p-stable local sensitive hash function to obtain a corresponding plaintext hash value;

Each of the plaintext hash values is inserted into the Bloom filter for filtering to obtain a file index.
The data encryption method according to claim 1, wherein the encrypting the plaintext file and the file index by using the first random user key to obtain an encrypted file and an encrypted index, respectively, comprising:

Encrypting the plaintext file by using an ElGamal algorithm to obtain an encrypted file, based on the first random user key;

The first random user key is processed by using a hash mapping function to generate a key K I based on the first random user key;

The file index I D is divided into two index vectors {I', I"} as follows: For each element i j ∈ I D , if S j ∈ S and S j is equal to 1, then i j '= i is set j ′′=i j ; otherwise, i j ′=1/2·i j +r, i j ′′=1/2·i j −r, where r is a random number, S∈{0,1} m ;

Encrypted file index based on key K I and two index vectors {I', I''}, Enc SK (I D )={M 1 T ·I', M 2 T ·I′′, Enc(K I , fid i )}, where fid i is the file ID of the plaintext file, and M 1 , M 2 ∈R m*m is an invertible matrix.
A data query method, comprising the following steps performed by a server:

Obtaining a query keyword, and processing the query keyword by using a local sensitive hash function to form a query trapdoor;

Determining, by the query keyword and the query trapdoor, an encrypted index that successfully matches the query trapdoor as a target encryption index;

Determining, according to the target encryption index, a ciphertext file corresponding to the target encrypted index as a target ciphertext file; wherein the ciphertext file is owned by the first random server-side key sent by the key management center The encrypted file sent by the terminal is encrypted and formed;

Obtaining a second random server-side key sent by the key management center;

Decrypting the target ciphertext file based on the second random server-side key to obtain the target encrypted file;

And sending the target encrypted file to the authorized client, to instruct the authorized client to decrypt the target encrypted file by using a second random user key sent by the key management center, to obtain a corresponding plaintext file;

The second random user secret key is associated with the second random server end key.
The data query method according to claim 4, wherein the obtaining the query keyword, and processing the query keyword by using a local sensitive hash function to form a query trapdoor includes:

Obtain query keywords and convert query keywords into query keyword vectors;

Each query keyword vector is converted by using a p-stable local sensitive hash function to obtain a corresponding query hash value;

Inserting each of the query hash values into a Bloom filter for filtering to obtain a query key value Q;

The query key value Q is divided into two query vectors {Q', Q"} according to the following rules. For an element q j ∈Q in the query key value Q, if S j ∈S and S j is equal to 1, then q is set. j ′=q j ′′=q j ; otherwise, q j ′=1/2·q j +r′,q j ′′=1/2·q j —r′, where r′ is a random number, S ∈{0,1} m ;

The query key value Q is encrypted based on two query vectors {Q', Q"}, and the query trapdoor is obtained: Enc SK (Q)={M 1 -1 ·Q', M 2 -1 ·Q"}, where M 1 , M 2 ∈R m*m is an invertible matrix.
The data query method according to claim 4, wherein the encrypted index matching the query trapdoor is used as the target encryption index based on the query keyword and the query trapdoor, and specifically includes:

Obtaining an inner product value of the query trapdoor and each of the encrypted indexes as a query inner product value;

Obtaining an inner product value of the query keyword and each file index as an inner product value of the data;

Obtaining a difference between the inner product value of the query and the inner product value of the data. If the difference between the inner product value and the inner product value of the query is within a preset range, the query trapdoor and the encrypted index match successfully, and the encrypted index is used. Encrypt the index as a target.
A data encryption device, comprising:

a file index establishing module, configured to obtain a plaintext keyword of the plaintext file, and establish a file index of the plaintext file by using a local sensitive hash function based on the plaintext keyword;

a first random user key obtaining module, configured to acquire a first random user key sent by the key management center;

The encrypted file and the encrypted index obtaining module are configured to respectively encrypt the plaintext file and the file index by using a first random user key to obtain an encrypted file and an encrypted index;

And an encrypted file sending module, configured to send the encrypted file and the encrypted index to the server, to instruct the server to use the first random server-side key sent by the key management center to perform the encrypted file Encrypted to form a ciphertext file, wherein the first random user key is associated with the first random server-side key.
A data query device, comprising:

Querying a trapdoor obtaining module, configured to obtain a query keyword, and processing the query keyword by using a local sensitive hash function to form a query trapdoor;

a target encryption index obtaining module, configured to use, as the target encryption index, an encrypted index that successfully matches the query trapdoor based on the query keyword and the query trapdoor;

a target ciphertext file obtaining module, configured to determine, according to the target encrypted index, a ciphertext file corresponding to the target encrypted index as a target ciphertext file; wherein the ciphertext file is sent by using a key management center a random server-side secret key is formed by encrypting an encrypted file sent by the data owner;

a second random server-side key acquisition module, configured to acquire a second random server-side key sent by the key management center;

The target encrypted file obtaining module is configured to decrypt the target ciphertext file based on the second random server-side key to obtain the target encrypted file;

a target encrypted file sending module, configured to send the target encrypted file to an authorized user end, to instruct the authorized user end to decrypt the target encrypted file by using a second random user key sent by the key management center, Obtaining a corresponding plaintext file, wherein the second random user secret key is associated with the second random server end key.
A computer device comprising a memory, a processor, and computer readable instructions stored in the memory and operative on the processor, wherein the processor executes the computer readable instructions as follows step:

Obtaining a plaintext keyword of the plaintext file, and establishing a file index of the plaintext file by using a local sensitive hash function based on the plaintext keyword;

Obtaining a first random user key sent by the key management center;

Encrypting the plaintext file and the file index by using a first random user key to obtain an encrypted file and an encrypted index;

And sending the encrypted file and the encrypted index to the server, to instruct the server to encrypt the encrypted file by using a first random server-side key sent by the key management center to form a ciphertext file;

The first random user secret key is associated with the first random server-side secret key.
The computer device according to claim 9, wherein the obtaining a plaintext keyword of the plaintext file, and establishing a file index of the plaintext file by using a local sensitive hash function based on the plaintext keyword, comprises:

Extracting the plaintext keyword from the plaintext file, and converting the plaintext keyword into a plaintext keyword vector;

Each plaintext keyword vector is converted by using a p-stable local sensitive hash function to obtain a corresponding plaintext hash value;

Each of the plaintext hash values is inserted into the Bloom filter for filtering to obtain a file index.
The computer device according to claim 9, wherein the encrypting the plaintext file and the file index by using a first random user key to obtain an encrypted file and an encrypted index, respectively, comprising:

Encrypting the plaintext file by using an ElGamal algorithm to obtain an encrypted file, based on the first random user key;

The first random user key is processed by using a hash mapping function to generate a key K I based on the first random user key;

The file index I D is divided into two index vectors {I', I"} as follows: For each element i j ∈ I D , if S j ∈ S and S j is equal to 1, then i j '= i is set j ′′=i j ; otherwise, i j ′=1/2·i j +r, i j ′′=1/2·i j −r, where r is a random number, S∈{0,1} m ;

Encrypted file index based on key K I and two index vectors {I', I''}, Enc SK (I D )={M 1 T ·I', M 2 T ·I′′, Enc(K I , fid i )}, where fid i is the file ID of the plaintext file, and M 1 , M 2 ∈R m*m is an invertible matrix.
A computer device comprising a memory, a processor, and computer readable instructions stored in the memory and operative on the processor, wherein the processor executes the computer readable instructions as follows step:

Obtaining a query keyword, and processing the query keyword by using a local sensitive hash function to form a query trapdoor;

Determining, by the query keyword and the query trapdoor, an encrypted index that successfully matches the query trapdoor as a target encryption index;

Determining, according to the target encryption index, a ciphertext file corresponding to the target encrypted index as a target ciphertext file; wherein the ciphertext file is owned by the first random server-side key sent by the key management center The encrypted file sent by the terminal is encrypted and formed;

Obtaining a second random server-side key sent by the key management center;

Decrypting the target ciphertext file based on the second random server-side key to obtain the target encrypted file;

And sending the target encrypted file to the authorized client, to instruct the authorized client to decrypt the target encrypted file by using a second random user key sent by the key management center, to obtain a corresponding plaintext file;

The second random user secret key is associated with the second random server end key.
The computer device according to claim 12, wherein the obtaining a query keyword, and processing the query keyword by using a local sensitive hash function to form a query trapdoor comprises:

Obtain query keywords and convert query keywords into query keyword vectors;

Each query keyword vector is converted by using a p-stable local sensitive hash function to obtain a corresponding query hash value;

Inserting each of the query hash values into a Bloom filter for filtering to obtain a query key value Q;

The query key value Q is divided into two query vectors {Q', Q"} according to the following rules. For an element q j ∈Q in the query key value Q, if S j ∈S and S j is equal to 1, then q is set. j ′=q j ′′=q j ; otherwise, q j ′=1/2·q j +r′,q j ′′=1/2·q j —r′, where r′ is a random number, S ∈{0,1} m ;

The query key value Q is encrypted based on two query vectors {Q', Q"}, and the query trapdoor is obtained: Enc SK (Q)={M 1 -1 ·Q', M 2 -1 ·Q"}, where M 1 , M 2 ∈R m*m is an invertible matrix.
The computer device according to claim 12, wherein the encrypted index that successfully matches the query trapdoor is used as the target encryption index based on the query keyword and the query trapdoor, and specifically includes:

Obtaining an inner product value of the query trapdoor and each of the encrypted indexes as a query inner product value;

Obtaining an inner product value of the query keyword and each file index as an inner product value of the data;

Obtaining a difference between the inner product value of the query and the inner product value of the data. If the difference between the inner product value and the inner product value of the query is within a preset range, the query trapdoor and the encrypted index match successfully, and the encrypted index is used. Encrypt the index as a target.
One or more non-transitory readable storage mediums storing computer readable instructions, when executed by one or more processors, cause the one or more processors to perform the following steps:

Obtaining a plaintext keyword of the plaintext file, and establishing a file index of the plaintext file by using a local sensitive hash function based on the plaintext keyword;

Obtaining a first random user key sent by the key management center;

Encrypting the plaintext file and the file index by using a first random user key to obtain an encrypted file and an encrypted index;

And sending the encrypted file and the encrypted index to the server, to instruct the server to encrypt the encrypted file by using a first random server-side key sent by the key management center to form a ciphertext file;

The first random user secret key is associated with the first random server-side secret key.
The non-volatile readable storage medium according to claim 15, wherein the obtaining a plaintext keyword of the plaintext file, and establishing a file index of the plaintext file by using a local sensitive hash function based on the plaintext keyword ,include:

Extracting the plaintext keyword from the plaintext file, and converting the plaintext keyword into a plaintext keyword vector;

Each plaintext keyword vector is converted by using a p-stable local sensitive hash function to obtain a corresponding plaintext hash value;

Each of the plaintext hash values is inserted into the Bloom filter for filtering to obtain a file index.
The non-volatile readable storage medium according to claim 15, wherein the encrypting the plaintext file and the file index by using a first random user key to obtain an encrypted file and an encrypted index, respectively:

Encrypting the plaintext file by using an ElGamal algorithm to obtain an encrypted file, based on the first random user key;

The first random user key is processed by using a hash mapping function to generate a key K I based on the first random user key;

The file index I D is divided into two index vectors {I', I"} as follows: For each element i j ∈ I D , if S j ∈ S and S j is equal to 1, then i j '= i is set j ′′=i j ; otherwise, i j ′=1/2·i j +r, i j ′′=1/2·i j −r, where r is a random number, S∈{0,1} m ;

Encrypted file index based on key K I and two index vectors {I', I''}, Enc SK (I D )={M 1 T ·I', M 2 T ·I′′, Enc(K I , fid i )}, where fid i is the file ID of the plaintext file, and M 1 , M 2 ∈R m*m is an invertible matrix.
One or more non-transitory readable storage mediums storing computer readable instructions, when executed by one or more processors, cause the one or more processors to perform the following steps:

Obtaining a query keyword, and processing the query keyword by using a local sensitive hash function to form a query trapdoor;

Determining, by the query keyword and the query trapdoor, an encrypted index that successfully matches the query trapdoor as a target encryption index;

Determining, according to the target encryption index, a ciphertext file corresponding to the target encrypted index as a target ciphertext file; wherein the ciphertext file is owned by the first random server-side key sent by the key management center The encrypted file sent by the terminal is encrypted and formed;

Obtaining a second random server-side key sent by the key management center;

Decrypting the target ciphertext file based on the second random server-side key to obtain the target encrypted file;

And sending the target encrypted file to the authorized client, to instruct the authorized client to decrypt the target encrypted file by using a second random user key sent by the key management center, to obtain a corresponding plaintext file;

The second random user secret key is associated with the second random server end key.
The non-volatile readable storage medium according to claim 18, wherein the obtaining a query keyword, the local query-sensitive hash function is used to process the query keyword to form a query trapdoor, specifically including :

Obtain query keywords and convert query keywords into query keyword vectors;

Each query keyword vector is converted by using a p-stable local sensitive hash function to obtain a corresponding query hash value;

Inserting each of the query hash values into a Bloom filter for filtering to obtain a query key value Q;

The query key value Q is divided into two query vectors {Q', Q"} according to the following rules. For an element q j ∈Q in the query key value Q, if S j ∈S and S j is equal to 1, then q is set. j ′=q j ′′=q j ; otherwise, q j ′=1/2·q j +r′,q j ′′=1/2·q j —r′, where r′ is a random number, S ∈{0,1} m ;

The query key value Q is encrypted based on two query vectors {Q', Q"}, and the query trapdoor is obtained: Enc SK (Q)={M 1 -1 ·Q', M 2 -1 ·Q"}, where M 1 , M 2 ∈R m*m is an invertible matrix.
The non-volatile readable storage medium according to claim 18, wherein the encrypted index matching the query trapdoor is used as a target encrypted index based on the query keyword and the query trapdoor. Specifically include:

Obtaining an inner product value of the query trapdoor and each of the encrypted indexes as a query inner product value;

Obtaining an inner product value of the query keyword and each file index as an inner product value of the data;

Obtaining a difference between the inner product value of the query and the inner product value of the data. If the difference between the inner product value and the inner product value of the query is within a preset range, the query trapdoor and the encrypted index match successfully, and the encrypted index is used. Encrypt the index as a target.