Public Auditing Scheme of Dynamic Data Sharing Suiting for Cloud-Based EHR System

As a very popular application of cloud computing, CLOUD storage allows the users to outsource their data file to the cloud in order to share their data files. However, cloud storage server is an untrusted entity, it might neglect to keep or even deliberately remove the shared data which are rarely accessed. To ensure the integrity of their shared data in cloud, a number of data sharing auditing schemes have been proposed. However, these scheme only can achieve that multiple users edit the whole shared data, not realize that the specified user edits the specified portion of the shared data. In some cases, we need the specified user to revise the specified portion of the data file, such as EHR system. To achieve such function, in this paper we propose a novel public auditing scheme for the dynamic data sharing. It can achieve the specified data users edit the specific part of the shared data file. To the best of our knowledge, it is the first scheme which satisfies such function. Furthermore, the outstanding highlight of the scheme is that the auditor has constant communication cost and computational cost. By the detailed simulation and comparisons with the state-of-the-art scheme, The results demonstrate that the proposed scheme our scheme has many advantages in terms of data block updating, user revocation and integrity verification time. Finally, we formally prove the security of the proposed scheme, and evaluate the auditing performance.