Symmetrical searchable encryption method based on keyword retrieval and related components

Abstract

The invention discloses a symmetric searchable encryption method based on keyword retrieval and related components, and relates to the technical field of data retrieval, and the method comprises the following steps: receiving a document query request sent by a data user side; the document query request is a request generated based on an encrypted target keyword, a data user key and an index coding parameter; generating response information corresponding to the document query request by using the server key, the index coding parameter and the coded database, and sending the response information to the data user side, so that the data user side decrypts the response information to obtain document identification information containing the target keyword; the encoded database comprises keywords in a plurality of documents in the form of encoded key-value pairs and corresponding security indexes. By means of the scheme, the cloud server can respond to the query request under the condition that decryption is not conducted, and the search mode of a user is effectively hidden. And an attacker is prevented from speculating sensitive information of the user by analyzing an access mode.

Description

Technical Field

[0001] The present invention relates to the technical field of data retrieval, and in particular to a symmetric searchable encryption method based on keyword retrieval and related components. Background Art

[0002] Searchable encryption technology supports retrieval of ciphertext data without decryption, which can effectively solve the problem of ciphertext retrieval in open environments such as cloud storage. Symmetric searchable encryption is popular due to its simple scheme, rich search functions and high computational efficiency, but it often leaks search patterns and access patterns. If these pattern information is used by malicious attackers, it will also pose a threat to the keyword content of the document. Therefore, it is necessary to design a highly secure symmetric searchable encryption scheme that hides search patterns and access patterns under malicious security models.

[0003] Currently, there are very few symmetric searchable encryption schemes that can hide search patterns and access patterns. The only schemes mainly include two types of methods. One is to hide search patterns by using keyword classification and shared index items, and the same plaintext corresponds to multiple ciphertext copies. The other is to combine homomorphic encryption and polynomial interpolation technology to achieve randomization of search traps and keyword matching. However, the former requires data users to store a query table locally, and its computational burden, storage burden, and communication burden will increase sharply with the increase of data volume. The latter data users need the data owner to assist in decryption online during the query process, and the query user needs to store the keyword dictionary and even all document identifiers. Therefore, there are many restrictions on data users, and the storage and computational burdens are also heavy. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a symmetric searchable encryption method based on keyword retrieval and related components, which can hide the user's search mode and access mode during the search process and have higher security strength. The specific scheme is as follows:

[0005] In a first aspect, the present application discloses a symmetric searchable encryption method based on keyword retrieval, which is applied to a cloud server, comprising:

[0006] Receiving a document query request sent by a data user; wherein the document query request is a request generated based on the encrypted target keyword, the data user key, and the index encoding parameter;

[0007] Response information corresponding to the document query request is generated using a server key, index encoding parameters, and an encoded database, and the response information is sent to the data user end so that the data user end decrypts the response information to obtain document identification information containing the target keyword; wherein the encoded database includes keywords in several documents in the form of encoded key-value pairs and corresponding security indexes.

[0008] Optionally, the symmetric searchable encryption method based on keyword retrieval further includes:

[0009] A mapping relationship between keywords in each document and document identifiers of corresponding documents is established through the data user end to obtain a corresponding inverted index;

[0010] The inverted indexes are indexed and encrypted by the data user terminal to obtain corresponding security indexes, and the security indexes and document ciphertext sets are sent to the cloud server so that the cloud server can encode the security indexes to obtain corresponding index encoding parameters and an encoded database; wherein the document ciphertext set is a ciphertext set formed after each document is encrypted.

[0011] Optionally, the encrypting each of the inverted indexes by the data user terminal to obtain a corresponding security index includes:

[0012] The data user terminal calculates the keywords in each of the inverted indexes by using a pseudo-random permutation function and a pseudo-random permutation key encryption to obtain a corresponding keyword tag;

[0013] Encrypting the document identifiers and keywords in each of the inverted indexes by using a pseudo-random function and a pseudo-random key through the data user terminal to obtain corresponding encrypted index items;

[0014] A corresponding security index is constructed through the data user terminal according to the keyword tag and the encrypted index item.

[0015] Optionally, before generating a document query request based on the encrypted target keyword, data user key, and index encoding parameter, the following is further included:

[0016] The target keyword is calculated and encrypted by using a pseudo-random permutation function and a pseudo-random permutation key through the data user end to obtain an encrypted target keyword.

[0017] Optionally, the decrypting the response information to obtain document identification information containing the target keyword includes:

[0018] Performing a primary decryption process on the response information by the data user terminal and using a preset decryption algorithm, index encoding parameters and the data user key to obtain a target encrypted index item;

[0019] The target encrypted index item is decrypted twice by the data user terminal using a pseudo-random function and a pseudo-random key to obtain document identification information containing the target keyword.

[0020] Optionally, after obtaining the document identification information containing the target keyword, the method further includes:

[0021] The corresponding target document ciphertext is obtained from the document ciphertext set stored in the cloud server through the data user terminal and using the document identification information, and the target document ciphertext is decrypted to obtain the corresponding target document.

[0022] Optionally, before receiving the document query request sent by the data user, the method further includes:

[0023] A pseudo-random replacement key, a pseudo-random key, a data user key and a server key are generated through the data user terminal based on security parameters, and the server key is sent to the cloud server.

[0024] In a second aspect, the present application discloses a symmetric searchable encryption device based on keyword retrieval, which is applied to a cloud server, comprising:

[0025] A request receiving module, used to receive a document query request sent by a data user terminal; wherein the document query request is a request generated based on the encrypted target keyword, the data user key, and the index encoding parameter;

[0026] A document search module is used to generate response information corresponding to the document query request using a server key, index encoding parameters, and an encoded database, and send the response information to the data user end so that the data user end can decrypt the response information to obtain document identification information containing the target keyword; wherein the encoded database includes keywords in several documents in the form of encoded key-value pairs and corresponding security indexes.

[0027] In a third aspect, the present application discloses an electronic device, comprising:

[0028] Memory, used to store computer programs;

[0029] A processor is used to execute the computer program to implement the steps of the aforementioned disclosed symmetric searchable encryption method based on keyword retrieval.

[0030] In a fourth aspect, the present application discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, the steps of the aforementioned disclosed symmetric searchable encryption method based on keyword retrieval are implemented.

[0031] It can be seen that the present application discloses a symmetric searchable encryption method based on keyword retrieval, which is applied to a cloud server, including: receiving a document query request sent by a data user terminal; wherein the document query request is a request generated based on an encrypted target keyword, a data user key, and an index encoding parameter; using a server key, an index encoding parameter, and an encoded database to generate a response message corresponding to the document query request, and sending the response message to the data user terminal, so that the data user terminal decrypts the response message to obtain document identification information containing the target keyword; wherein the encoded database includes keywords in a number of documents in the form of encoded key-value pairs and corresponding security indexes. It can be seen that the data user terminal retrieves documents containing keywords through a search trap of querying keywords, and during the retrieval process, the cloud server cannot obtain specific plaintext keyword information. At the same time, during the process of matching documents with plaintext keywords, that is, during the search process, the cloud server can complete the response to the query request without decryption, effectively hiding the user's search mode. Both the query request from the data user and the response information generated by the cloud server are encrypted, making it difficult for malicious attackers to infer the user's query intentions and interests. In this way, by using blind storage technology for documents and hiding access patterns during index retrieval, the user's access behavior to documents is further protected, preventing attackers from inferring the user's sensitive information by analyzing access patterns. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0033] Figure 1 A flowchart of a symmetric searchable encryption method based on keyword retrieval disclosed in this application;

[0034] Figure 2 A schematic diagram of a single-user searchable encryption system framework disclosed in this application;

[0035] Figure 3 A flow chart of a search method based on a single-user searchable encryption system disclosed in this application;

[0036] Figure 4 A schematic diagram of the structure of a symmetric searchable encryption device based on keyword retrieval disclosed in this application;

[0037] Figure 5 This is a structural diagram of an electronic device disclosed in this application. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0039] Searchable encryption technology supports retrieval of ciphertext data without decryption, which can effectively solve the problem of ciphertext retrieval in open environments such as cloud storage. Symmetric searchable encryption is popular due to its simple scheme, rich search functions and high computational efficiency, but it often leaks search patterns and access patterns. If these pattern information is used by malicious attackers, it will also pose a threat to the keyword content of the document. Therefore, it is necessary to design a highly secure symmetric searchable encryption scheme that hides search patterns and access patterns under malicious security models.

[0040] Currently, there are very few symmetric searchable encryption schemes that can hide search patterns and access patterns. The only schemes mainly include two types of methods. One is to hide search patterns by using keyword classification and shared index items, and the same plaintext corresponds to multiple ciphertext copies. The other is to combine homomorphic encryption and polynomial interpolation technology to achieve randomization of search traps and keyword matching. However, the former requires data users to store a query table locally, and its computational burden, storage burden, and communication burden will increase sharply with the increase of data volume. The latter data users need the data owner to assist in decryption online during the query process, and the query user needs to store the keyword dictionary and even all document identifiers. Therefore, there are many restrictions on data users, and the storage and computational burdens are also heavy.

[0041] To this end, the present invention provides a symmetric searchable encryption scheme based on keyword retrieval, which can hide the user's search mode and access mode during the search process and has higher security strength.

[0042] Reference Figure 1 As shown, the embodiment of the present invention discloses a symmetric searchable encryption method based on keyword retrieval, which is applied to a cloud server and includes:

[0043] Step S11: receiving a document query request sent by a data user terminal; wherein the document query request is a request generated based on the encrypted target keyword, data user key, and index encoding parameters.

[0044] In this embodiment, before receiving a document query request, a single-user searchable encryption system framework is pre-built between the cloud server and the data user end, wherein a mapping relationship between keywords in each document and the document identifier of the corresponding document is established by the data user end to obtain a corresponding inverted index; the data user end performs index encryption on each inverted index to obtain a corresponding security index, and sends the security index and the document ciphertext set to the cloud server so that the cloud server encodes the security index to obtain a corresponding index encoding parameter and an encoded database; wherein the document ciphertext set is a ciphertext set formed after each document is encrypted. It can be understood that the data user end is both the data owner and the data user. In the data upload stage, the data user end is responsible for encrypting documents, generating security indexes, and uploading the two to the cloud server; in the data search stage, the data user end generates a search trap for the query keyword and uploads it to the cloud server, and finally decrypts the returned search results. The cloud server is responsible for storing the encrypted documents, security indexes, and system public parameters uploaded by the data user, and provides search services for the data user in the search stage. Therefore, at the data user end, an inverted index of "keyword-document" in each plaintext document is first established, and then the inverted index of the plaintext document is encrypted to obtain a secure index, and finally the secure index is uploaded to the cloud server. Among them, the index encryption of each inverted index by the data user end to obtain a corresponding security index includes: using the data user end and using a pseudo-random permutation function and a pseudo-random permutation key to encrypt and calculate the keywords in each inverted index to obtain a corresponding keyword tag; using the data user end and using a pseudo-random function and a pseudo-random key to encrypt the document identifiers and keywords in each inverted index to obtain a corresponding encrypted index item; and using the data user end and building a corresponding security index based on the keyword tags and the encrypted index items. The specific operations are as follows:

[0045] Create an inverted index: The union of the keyword sets of all plaintext documents is the keyword dictionary , where m is the number of keywords and the document set The set of identifiers of all documents containing keyword w in dictionary W is denoted as DB(w). , build the corresponding index item , , Then we get the plaintext index table .

[0046] Encrypted index: Using pseudo-random permutation function π to calculate keyword tags , using pseudo-random function f to construct pseudo-random sequence encryption index items ,Right now , where ⊕ represents an XOR operation, and then the security index table is obtained .

[0047] Security index encoding: After receiving the data uploaded by the user, the cloud server stores the document ciphertext set and the security index. Then the cloud server calls the encoding algorithm to encode the security index and obtains ,in, It represents the encoded database, prms represents the index encoding parameters, and the index encoding parameters prms are returned to the data user.

[0048] like Figure 2 As shown in the figure, the single-user searchable encryption system includes two entity participants and two data processing stages. The two entity participants include the data user and the cloud server, and the two data processing stages include data upload and data search. The data user stores the encrypted personal documents and indexes on the cloud server, and then retrieves them through the search trap of the query keyword. During the whole process, the cloud server cannot obtain the plaintext information of the documents and query keywords. The single-user searchable encryption system is suitable for application scenarios where data is exclusive, such as personal cloud disks.

[0049] In this embodiment, before receiving the document query request sent by the data user terminal, it also includes: generating a pseudo-random permutation key, a pseudo-random key, a data user key and a server key through the data user terminal and based on the security parameters, and sending the server key to the cloud server. It can be understood that in the process of creating the system framework, the system initialization processing of the created system is also required, wherein the purpose of system initialization is to generate all encryption keys, that is, input security parameters, output data user keys and the server key Specifically, the system selects a pseudo-random permutation function and pseudorandom functions , where λ represents the security parameter and * represents the length of the set of binary strings. The data user generates a key based on the security parameter λ. ,in, With the pseudo-random permutation function π, With the pseudo-random function f, the key and By running generate. The cloud server stores the key, while the other keys are stored by the user. This key separation makes it impossible for the cloud server to decrypt the user's query request alone.

[0050] In this embodiment, before generating a document query request based on the encrypted target keyword, the data user key, and the index encoding parameter, the method further includes: encrypting and calculating the target keyword by the data user terminal using a pseudo-random permutation function and a pseudo-random permutation key to obtain the encrypted target keyword. It can be understood that after the data user terminal in the system framework completes the step of uploading data, further, in the data search phase, when the data user terminal queries the keyword w, it first calculates , to obtain the encrypted target keyword, corresponding to the keyword tag in the data upload phase, and then call the query algorithm to generate a document query request ,Right now Here, the target keyword is encrypted by a pseudo-random permutation function π, so that the query request received by the cloud server is in an encrypted form and the plain text information of the target keyword cannot be directly obtained, thereby hiding the user's search mode.

[0051] Step S12: Generate response information corresponding to the document query request using the server key, index encoding parameters, and the encoded database, and send the response information to the data user end so that the data user end decrypts the response information to obtain document identification information containing the target keyword; wherein the encoded database includes keywords in several documents in the form of encoded key-value pairs and corresponding security indexes.

[0052] In this embodiment, when the cloud server receives the document query request, it generates a response message corresponding to the document query request, wherein the cloud server receives the document query request After that, the response algorithm is called to generate a response, that is, , and returns the response information to the data user. In this process, the cloud server uses the stored server key , index encoding parameter prms, encoded database and encrypted query request To generate response information. Since the cloud server cannot obtain the plain text information of the target keywords and documents during the whole process and can only perform calculations based on the encrypted information, the generated response will not leak the user's search mode and access mode.

[0053] In this embodiment, the data user terminal uses a preset decryption algorithm, index encoding parameters and the data user key to perform a primary decryption process on the response information to obtain a target encrypted index item; the data user terminal uses a pseudo-random function and a pseudo-random key to perform a secondary decryption process on the target encrypted index item to obtain document identification information containing the target keyword. It can be understood that the data user terminal calls the decryption algorithm of keywordPIR to decrypt the response information. Perform parsing and initial decryption to obtain the target encrypted index item , and then further decrypt to get the identifier information plaintext , and then get the identifiers of all documents containing the target keyword w.

[0054] In this embodiment, after obtaining the document identification information containing the target keyword, the method further includes: obtaining the corresponding target document ciphertext from the document ciphertext set stored in the cloud server through the data user terminal and using the document identification information, and decrypting the target document ciphertext to obtain the corresponding target document. It can be understood that if the document identification information is obtained by secondary decryption, the corresponding target document ciphertext is obtained from the document ciphertext set stored in the cloud server according to the document identification information, and is decrypted locally on the data user terminal to finally obtain the required document plaintext content.

[0055] like Figure 3 As shown in the figure, the main process of the single-user searchable encryption scheme based on keyword private information retrieval (KWPIR) is shown. The core content is as follows: 1. Data user operation, including: 1. System establishment: data users generate a key set based on security parameters , where the server key The key is saved by the cloud server, and other keys are saved by the data user. 2. Security index construction: Establish an inverted index of "keyword-document", encrypt the inverted index of the plaintext document to obtain a security index, including operations such as determining the keyword dictionary, building index items, and encrypting the index. The security index and encrypted document are sent to the cloud server so that the cloud server can perform 3. Encoding processing on them , to obtain the security index code. 4. Generate query request: When querying keyword w, first calculate the encrypted keyword , and then call the query algorithm to generate a query request And send it to the cloud server, the cloud server executes 5. Call the response algorithm to generate a response 6. Decryption: The data user calls the decryption algorithm to decrypt the response returned by the cloud server, obtains the plaintext identifier information, and then downloads the document ciphertext from the cloud server through the identifier and decrypts it locally.

[0056] The entire process is designed through encryption and specific algorithms to ensure that the user's search mode and access mode can be hidden during data storage and retrieval on the cloud server, providing data users with a safe and efficient single-user searchable encryption service, which is especially suitable for data-exclusive application scenarios such as personal cloud drives.

[0057] It can be seen that the present application discloses a symmetric searchable encryption method based on keyword retrieval, which is applied to a cloud server, including: receiving a document query request sent by a data user terminal; wherein the document query request is a request generated based on an encrypted target keyword, a data user key, and an index encoding parameter; using a server key, an index encoding parameter, and an encoded database to generate a response message corresponding to the document query request, and sending the response message to the data user terminal, so that the data user terminal decrypts the response message to obtain document identification information containing the target keyword; wherein the encoded database includes keywords in a number of documents in the form of encoded key-value pairs and corresponding security indexes. It can be seen that the data user terminal retrieves documents containing keywords through a search trap of querying keywords, and during the retrieval process, the cloud server cannot obtain specific plaintext keyword information. At the same time, during the process of matching documents with plaintext keywords, that is, during the search process, the cloud server can complete the response to the query request without decryption, effectively hiding the user's search mode. Both the query request from the data user and the response information generated by the cloud server are encrypted, making it difficult for malicious attackers to infer the user's query intentions and interests. In this way, by using blind storage technology for documents and hiding access patterns during index retrieval, the user's access behavior to documents is further protected, preventing attackers from inferring the user's sensitive information by analyzing access patterns.

[0058] Reference Figure 4 As shown, the present invention also discloses a symmetric searchable encryption device based on keyword retrieval, which is applied to a cloud server and includes:

[0059] The request receiving module 11 is used to receive a document query request sent by a data user terminal; wherein the document query request is a request generated based on the encrypted target keyword, the data user key, and the index encoding parameter;

[0060] The document search module 12 is used to generate response information corresponding to the document query request using a server key, index encoding parameters, and an encoded database, and send the response information to the data user end so that the data user end decrypts the response information to obtain document identification information containing the target keyword; wherein the encoded database includes keywords in several documents in the form of encoded key-value pairs and corresponding security indexes.

[0061] It can be seen that the present application discloses the following: receiving a document query request sent by a data user terminal; wherein the document query request is a request generated based on an encrypted target keyword, a data user key, and an index encoding parameter; using a server key, an index encoding parameter, and an encoded database to generate a response message corresponding to the document query request, and sending the response message to the data user terminal so that the data user terminal decrypts the response message to obtain document identification information containing the target keyword; wherein the encoded database includes keywords in a number of documents in the form of encoded key-value pairs and corresponding security indexes. It can be seen that the data user terminal retrieves documents containing keywords through a search trap of query keywords, and during the retrieval process, the cloud server cannot obtain specific plaintext keyword information. At the same time, during the process of matching documents with plaintext keywords, that is, during the search process, the cloud server can complete the response to the query request without decryption, effectively hiding the user's search mode. Both the query request from the data user and the response information generated by the cloud server are encrypted, making it difficult for malicious attackers to infer the user's query intentions and interests. In this way, by using blind storage technology for documents and hiding access patterns during index retrieval, the user's access behavior to documents is further protected, preventing attackers from inferring the user's sensitive information by analyzing access patterns.

[0062] Furthermore, the present application also discloses an electronic device. Figure 5 This is a structural diagram of an electronic device 20 according to an exemplary embodiment. The content in the diagram cannot be regarded as any limitation on the scope of use of the present application.

[0063] Figure 5 A schematic diagram of the structure of an electronic device 20 provided in an embodiment of the present application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. The memory 22 is used to store a computer program, which is loaded and executed by the processor 21 to implement the relevant steps in the symmetric searchable encryption method based on keyword retrieval disclosed in any of the aforementioned embodiments. In addition, the electronic device 20 in this embodiment may specifically be an electronic computer.

[0064] In this embodiment, the power supply 23 is used to provide working voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and the external device, and the communication protocol it follows is any communication protocol that can be applied to the technical solution of the present application, and is not specifically limited here; the input and output interface 25 is used to obtain external input data or output data to the outside world, and its specific interface type can be selected according to specific application needs and is not specifically limited here.

[0065] Among them, the processor 21 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 21 can be implemented in at least one hardware form of DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), and PLA (Programmable Logic Array). The processor 21 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a CPU (Central Processing Unit); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 21 may be integrated with a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 21 may also include an AI (Artificial Intelligence) processor, which is used to process computing operations related to machine learning.

[0066] In addition, the memory 22, as a carrier for storing resources, can be a read-only memory, a random access memory, a disk or an optical disk, etc. The resources stored thereon can include an operating system 221, a computer program 222, etc., and the storage method can be temporary storage or permanent storage.

[0067] Among them, the operating system 221 is used to manage and control the hardware devices and computer programs 222 on the electronic device 20, so as to realize the operation and processing of the massive data 223 in the memory 22 by the processor 21, which can be Windows Server, Netware, Unix, Linux, etc. In addition to including a computer program that can be used to complete the symmetric searchable encryption method based on keyword retrieval performed by the electronic device 20 disclosed in any of the aforementioned embodiments, the computer program 222 can further include a computer program that can be used to complete other specific tasks. In addition to data transmitted from an external device received by the electronic device, the data 223 can also include data collected by its own input and output interface 25, etc.

[0068] Furthermore, the present application also discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, the aforementioned disclosed symmetric searchable encryption method based on keyword retrieval is implemented. For the specific steps of the method, reference may be made to the corresponding contents disclosed in the aforementioned embodiments, and no further description will be given here.

[0069] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0070] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application. The steps of the method or algorithm described in conjunction with the embodiments disclosed herein can be implemented directly with hardware, a software module executed by a processor, or a combination of the two. The software module can be placed in a random access memory RAM (Random Access Memory), memory, read-only memory ROM (Read Only Memory), electrically programmable EPROM (Electrically Programmable Read Only Memory), electrically erasable programmable EEPROM (ElectricErasable Programmable Read Only Memory), register, hard disk, removable disk, CD-ROM (CompactDisc-Read Only Memory), or any other form of storage medium known in the technical field.

[0071] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0072] The scheme provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A symmetric searchable encryption method based on keyword retrieval, characterized in that: Applied to cloud servers, including: Receiving a document query request sent by a data user; wherein the document query request is a request generated based on the encrypted target keyword, the data user key, and the index encoding parameter; Response information corresponding to the document query request is generated using a server key, index encoding parameters, and an encoded database, and the response information is sent to the data user end so that the data user end decrypts the response information to obtain document identification information containing the target keyword; wherein the encoded database includes keywords in several documents in the form of encoded key-value pairs and corresponding security indexes.

2. The symmetric searchable encryption method based on keyword retrieval according to claim 1 is characterized in that: Also includes: A mapping relationship between keywords in each document and document identifiers of corresponding documents is established through the data user end to obtain a corresponding inverted index; The inverted indexes are indexed and encrypted by the data user terminal to obtain corresponding security indexes, and the security indexes and document ciphertext sets are sent to the cloud server so that the cloud server can encode the security indexes to obtain corresponding index encoding parameters and an encoded database; wherein the document ciphertext set is a ciphertext set formed after each document is encrypted.

3. The symmetric searchable encryption method based on keyword retrieval according to claim 2 is characterized in that: The step of encrypting each of the inverted indexes by the data user terminal to obtain a corresponding security index includes: The data user terminal calculates the keywords in each of the inverted indexes by using a pseudo-random permutation function and a pseudo-random permutation key encryption to obtain a corresponding keyword tag; Encrypting the document identifiers and keywords in each of the inverted indexes by using a pseudo-random function and a pseudo-random key through the data user terminal to obtain corresponding encrypted index items; A corresponding security index is constructed through the data user terminal according to the keyword tag and the encrypted index item.

4. The symmetric searchable encryption method based on keyword retrieval according to claim 1, characterized in that: Before generating a document query request based on the encrypted target keyword, data user key, and index encoding parameter, it also includes: The target keyword is calculated and encrypted by using a pseudo-random permutation function and a pseudo-random permutation key through the data user end to obtain an encrypted target keyword.

5. The symmetric searchable encryption method based on keyword retrieval according to claim 1, characterized in that: The decrypting process of the response information to obtain document identification information containing the target keyword includes: Performing a primary decryption process on the response information by the data user terminal and using a preset decryption algorithm, index encoding parameters and the data user key to obtain a target encrypted index item; The target encrypted index item is decrypted twice by the data user terminal using a pseudo-random function and a pseudo-random key to obtain document identification information containing the target keyword.

6. The symmetric searchable encryption method based on keyword retrieval according to claim 5 is characterized in that: After obtaining the document identification information containing the target keyword, the method further includes: The corresponding target document ciphertext is obtained from the document ciphertext set stored in the cloud server through the data user terminal and using the document identification information, and the target document ciphertext is decrypted to obtain the corresponding target document.

7. The symmetric searchable encryption method based on keyword retrieval according to any one of claims 1 to 6, characterized in that: Before receiving the document query request sent by the data user terminal, the method further includes: A pseudo-random replacement key, a pseudo-random key, a data user key and a server key are generated through the data user terminal based on security parameters, and the server key is sent to the cloud server.

8. A symmetric searchable encryption device based on keyword retrieval, characterized in that: Applied to cloud servers, including: A request receiving module, used to receive a document query request sent by a data user terminal; wherein the document query request is a request generated based on the encrypted target keyword, the data user key, and the index encoding parameter; A document search module is used to generate response information corresponding to the document query request using a server key, index encoding parameters, and an encoded database, and send the response information to the data user end so that the data user end can decrypt the response information to obtain document identification information containing the target keyword; wherein the encoded database includes keywords in several documents in the form of encoded key-value pairs and corresponding security indexes.

9. An electronic device, characterized in that: include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the steps of the symmetric searchable encryption method based on keyword retrieval as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: Used to store computer programs; wherein, when the computer program is executed by a processor, the steps of the symmetric searchable encryption method based on keyword retrieval as described in any one of claims 1 to 7 are implemented.

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