Research And Implementation Of Multi-user Cloud Storage Technology Supporting Access Mode Protection

Extensive use of cloud computing services especially cloud storage services faciliate people life vastly that there is an increasing number of Internet users using cloud storage services.Its data is stored in cloud storage services actively or passively when users employ it.In the meantime,the service provider have access to users' data without warranty which threatens their privacy.Data is usually encrypted and uploaded to cloud storage service to prevent service provider from stealing privacy,but user access pattern information like access location,frequency and mode can still be collected and be analyzed,causing privacy leaks.Oblivious Random Access Machine(ORAM)technology solved the problem of protecting access pattern information effectively.However,direct application of ORAM technology in multi-user scenarios may face many security problems because most of service scenarios are multi-user ones under cloud computing environment.Most service scenarios in a cloud storage environment are multi-user scenarios,and directly apply ORAM technology in a multi-user scenario will face many security issues.Under above-mentioned background,it causes wide attention of domestic and foreign scholars that how to design a ORAM scheme under multi-user scenarios.However,there are three main problems in existing multi-user ORAM schemes.First of all,the existing multi-user ORAM schemes usually assume that the request proxy security assumption is credible,which is not feasible in practical application scenarios.In addition,the problem of index synchronization among users is not taken into account,relevant data is not available to users,leading to low accuracy of user data requests.Finally,the schemes do not get index transformation optimized when data is rewritten,resulting in poor efficiency.To solve the above problems,this paper designs and implements a multi-user cloud storage scheme supporting access mode protection.The main contents and contributions of this paper are as follows:1.A multi-user cloud storage scheme supporting access mode protection is proposed.The scheme uses ring signature technology and P2 P network technology to generate dynamic proxy among data requester,which degrade the security assumption of proxy from trusted to semi-trust,and improves the practicability of the scheme.Besides,it solves the problem of index synchronization among users,updating the index at the end of each visit which improves the accuracy of user data requests.Finally,it improves the index transformation algorithm of data rewriting process,greatly improving the efficiency of data rewriting.2.According to the multi-user cloud storage scheme supporting access mode protection proposed in this paper,an online collaborative document editing system supporting access mode protection is designed.Users can use the system to edit documents online and invite other users to collaborate in editing documents or other users to apply for editing documents cooperatively.The system framework consists of communication layer,logic layer and interaction layer from bottom to top.It is divided into seven modules including node discovery,ciphertext communication,mail protocol,agent election,data sending and receiving,message pushing and display interface.In this paper,the system is designed and implemented in detail from three levels and its specific modules,and each module of the system is tested in detail.The system test results show that the system functions can be used normally.