Research And Application On Attribute-Based Public Key Encryption Scheme In Cloud Environment

With the continuous development and application of cloud computing technology,cloud storage service as a component of cloud computing has become an important way for enterprises and individuals to store and manage data.However,the unreliability of cloud storage services may lead to data privacy leaks.In fact,in order to avoid data leakage of cloud users,the data can be encrypted,but how to quickly find the target ciphertext in a large amount of encrypted data,and how to ensure the user’s dynamic access rights is a problem to be solved.In addition,because the traditional cloud storage model operates in a centralized storage mode,a single point of failure may cause the system to crash,and there are hidden security risks in centralized management.In response to the above problems,blockchain technology provides a unique opportunity for constructing a safe and reliable data management and sharing system with its characteristics of non-tampering,public verification,and non-forgery.Based on the attribute encryption technology,this paper focuses on the functions of attribute revocation,data verification and multi-keyword search,combined with the safe storage and data sharing of personal privacy information in medical systems and wearable devices,and the following research results are obtained:(1)Considering most existing attribute-based searchable encryption schemes only support single-keyword search,user attributes may change frequently,and cloud servers are not completely loyal,a practical multi-keyword searchable encryption scheme is proposed.The scheme supports multi-keyword search which avoids the cloud server yield ample irrelevant documents by narrowing the search scope.At the same time,the ciphertext update is entrusted to a powerful cloud server,which effectively realizes the attribute revocation function.In addition,the introduction of third-party auditing uses verification algorithms to ensure the accuracy of search results and reduce the amount of calculations for end users.Security analysis shows that the scheme can resist selective plaintext attacks and selective keyword attacks.(2)Considering the potential privacy problems and security vulnerabilities in the current personal health data storage and sharing system,we proposed a novel user-centered personal health data sharing scheme by using the blockchain technology,attribute-based encryption,and searchable encryption methods.In this scheme,the data owner encrypts and saves the personal health data collected from the wearable device to the cloud server,and at the same time saves the hash value of the health record to the blockchain to ensure the integrity,security and traceability of the health data.In addition,the scheme sets an authorization control ciphertext.Only authorized users can obtain this ciphertext,and use the ciphertext to generate effective trapdoors for data search.Finally,the efficiency analysis shows that the scheme has a small amount of computation,high efficiency,and can quickly carry out a keyword search and verify search results in the huge data environment.(3)Considering the safe storage and sharing of patients’electronic medical records in the current medical system,a distributed electronic-medical-records secure storaging and sharing scheme was proposed by leveraging blockchain and smart contract technology.Firstly,storing electronic medical records metadata’s hash value in the blockchain is used to ensure its integrity and authenticity.Secondly,storing encrypted medical data files in the InterPlanetary File System can solve the problem of centralized data storage on the servers of various medical institutions.Futhermore,the encrypted keyword index information of electronic medical records was stored on the blockchain,meanwhile a smart contract deployed in the blockchain is used to realize keyword search.Finally,our performance analysis and security analysis show that the scheme is secure and efficient.