Hybrid cloud-oriented multi-keyword Top-k ciphertext retrieval method and system of privacy protection

Abstract

The invention discloses a hybrid cloud-oriented multi-keyword Top-k ciphertext retrieval method and system of privacy protection. The method and system mainly solve the problem that retrieval efficiency is low. A scheme thereof includes: utilizing correlation relationships among keywords by a data providing end to generate a keyword dictionary sequence through clustering technology; and generatinga high-dimensional document vector and low-dimensional document filtering vectors by each document, then outsourcing ciphertext documents and encrypted document vectors to an unauthentic public cloudserver, and storing the plaintext document filtering vectors to an authentic private cloud server. In retrieval, a candidate document set is firstly calculated through the private cloud server, and then retrieval result Top-k document calculation is realized through the public cloud server. Aggregation characteristics of the correlation keywords in the keyword dictionary sequence improve a filtering effect of the private cloud server, and compress a size of the candidate document set. According to the method, a process is simple, security is high, realization is easy, and highly-efficient multi-keyword ciphertext retrieval processing can be realized in a hybrid-cloud environment through lower calculation overheads.

Description

technical field [0001] The invention relates to user data privacy protection, in particular to a hybrid cloud-oriented privacy protection multi-keyword Top-k ciphertext retrieval method and system. Background technique [0002] The idea of ​​service-oriented IT resources is becoming more and more popular, showing the trend of "everything is a service" (X as a Service, XaaS), and "service" has become the core concept of cloud computing. However, while cloud computing is booming, cloud security has also become a widely concerned issue. In the cloud environment, because users cannot directly control the data placed in the remote cloud server (Cloud Server, CS), they are worried that their outsourced data will be illegally obtained or abused by the cloud service provider, especially for sensitive data with high privacy requirements. Data, such as electronic medical records, bank transaction data, user emails, etc. Although cloud service providers claim that they will provide s...

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Problems solved by technology

[0004] Most methods in the prior art use public cloud services by default. Based on the assumption that public clouds provide services in a "semi-honest model", a series of multi-keyword ciphertext retrieval and processing methods in encrypted cloud environments are proposed. However, these methods There are one or more problems such as low retrieval efficiency, inaccurate retrieval results, complex index tree construction, etc.

[0005] In response to these problems, the Chinese invention patent application with application number 201710181664.6 discloses a fast multi-keyword semantic sorting search method for protecting data privacy in cloud computing. By adding a private cloud server, while creating a document vector for each document, create Corresponding to the identification vector, the encrypted document vector is outsourced to the public cloud server, the plaintext identification vector is stored in the private cloud server, and the preliminary filtering operation of the document set is realized through the private cloud server, reducing the number of document vectors calculated by the correlation score with the retrieval vector. However, due to the random distribution of keywords in the keyword dictionary in this method, the filtering effect of the private cloud server is not good, resulting in the need to calculate a large number of correlation scores between document vectors and retrieval vectors in the public cloud

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