User Data Security In Cloud Storage Service

Thanks to its high resorce utilization rate, low cost based on usage,easy to manage, scalability.etc, cloud computing becomes today’s hot topic.More and more people and enterprise starts to migrate their data orapplication onto cloud. However at the same time, cloud security becomesthe major concern. How to protect the sensitive user data, how to ensure theintegrity and availability of data and application, how to access data easilyand rapidly and how to safely share the data on cloud become themust-answer questions before cloud goes forward.This paper focuses on:(1) Analyse the framework, key techonology, security mechanism ofmajor Cloud Service provider, and extract the security problems andneeds.(2) Point out the key techonologies to solve the cloud security problems,including Attribute-Based-Encryption, Proof of Retrievability andProxy Re-Encryption.(3) Propose a framework of cloud user data security which integritesabove techonologies and secure cloud user data in terms ofConfidenciality, Integrity and Availability.(4) Work out a prototype of a cloud based data sharing system whichemploy Attribute-Based Encryption to implement fine-grained accesscontrol during sharing and secured search which protect sensitiveinformation (abstract, keywords) during search process.(5) Optmize the system in terms of efficiency and resorce utilization.(6) Analysis the performance of the system and figure out the bottleneck.Deploy and fully test the system, then compare its search performanceto the major search engines.(7) Analyse the defects of the system. Then point out future directions.