Research On ORAM-based Privacy Perserving Data Sharing Scheme

With the development of cloud computing,cloud storage services like DropBox and Goggle Driver emerged as the times require.The control of sensitive data is transferred to the third party,causing data security and individual privacy become the major concerns for users.The scandals of Information disclosure that occurred frequently in recent years suggest that the concerns are by no means groundless and honest service provides are not enough because hacking has been the main attak means.Searchable encryption allows the ciphertext of data to be stored in cloud,in which users can search intended data while data contents will not be revealed to cloud.Nevertheless,some researches show that access pattern cloud observes probably discloses sensitive information even though data contents are encrypted using encryption schemes with semantic security[1].Therefore,hiding access pattern is the increasingly significant consideration when designing privacy preserving schemes.Focusing on single user mode in the scene of cloud storage,in which user can retrieve or write data from cloud,the first work of this paper delves into two models including private information retrieval(PIR)and oblivious random access memory(ORAM),analyzing the characteristics of two models,summarizing effective means hiding access pattern and drawing comparisons among the results of these methods.I personally think this part could be a useful guide for researches of privacy preserving schemes in cloud storage.The second work of the article concentrates on application scenario of data sharing in cloud storage.ORAM is the best choice of protecting access pattern for users' read and write but computational complexity has been a bottleneck of designing ORAM.Data sharing is one of the basic applications for cloud storage,which is inherently suitable for scalability and multitenancy feature of cloud computing,and its demand of privilege control increases the level of challenge for implementing data sharing schemes meeting the requirements of hiding access pattern.Currently known ORAM-based privacy preserving schemes involve various deficiences,either in high complexity or heavy reliance of complex cryptography primitives.The thesis designs a data sharing scheme with high security guarantee and high efficiency using Path ORAM,permitting data holder to distribute access rights to other users and preventing evil users from illegally read or write data.Shuffle Correctness Proof after each access protect data from falsification as well as lightening the load on data holder.Analysis shows that.Analysis shows that the scheme has the optimal computation and communication complexity.