New Multiple-replica Storage And Provable Data Possession Schemes In Cloud Computing

Cloud computing, which is regarded as the core technology in IT sector, has been promoting and developing very quickly for a long time and is becoming one of the most profound technologies that influence around the world. The key factors of cloud computing are centralized architecture and shared services.The cloud gathers massive sharing resources together to provide services to the world. And the resources can not only be used by a large number of users, but also can be reassigned to any other users once they are free from a user. As a result, any user can enjoy the services provided by the cloud,thus realizing the shared services and max imization of resource utilization.This thesis introduces the concept, characteristics, developing history, deployment models and the service modes of cloud computingin details.Then, it researches and analyzes the cloud storage services provided by the main cloud service providers(CSP) in nowadays. Next, it summarizes the main problems faced by the cloud computing services. In cloud computing service,due to the separation of data and its owner, the owner has a natural sense of in security to his data stored in the cloud, which is the main obstacle that restricts the use of the cloud computing technology. Therefore, studying the security issues in cloud computing and eliminating the users’ security concerns is necessary and urgent, which has great academic and application values for the promotion and development of cloud computing technology.This thesis takes the data security issue which is cared about most by the users as research subject. Based on the low space utilization ratio problem, data security issue and CSP trust issue in cloud storage services,it proposes schemes to solve those problems. Specifically, first, according to the data security issue and low space utilization ratio problem in today’s storage service, it puts forward a multiple-replica storage scheme which is based on secret sharing scheme.This thesis introduces in detail the corresponding research background, basic idea, system model and design goals of this scheme.And then it explains the process of data storage, back-up, download and other dynamic operations in this scheme. Finally, it carries on a detailed discussion and analysis on the proposed scheme, which showing the effectiveness of the scheme. Second,based on a fact that the CSP is not completely credible and the current provable data possessing(PDP) schemes have too many shortcomings, this thesis comes up with a new multiple-replica PDP scheme which is based on homomorphic validation tags.It introduces in detail the corresponding research background, basic idea, design goals and architecture of the proposed PDP scheme. Next it also explains the details of each operation during the verifying process. In the end, it discusses and analyzes the proposed PDP scheme, which proving the practicality of the scheme.