An Efficient Secure Data Sharing Framework for Public Cloud Based Group Sharing

Many of the public cloud computing services have appeared for data storage in group applications. Two important problems that arises when sharing group data in public cloud are the privacy and security of group member's data. Cloud service providers are separate administrative entities and users don't have access to the cloud internal operational details. Because of the semi trust nature of cloud service provider, the traditional security technologies cannot be directly applied to the public cloud based group data sharing applications. We propose an efficient secure framework for public cloud based group application. This framework combines proxy signature scheme, incremental proxy re-encryption scheme and cipher text policy attribute based encryption together into a protocol. The group leader can choose one or more of the group members for the management of the group by adopting proxy signature scheme. Incremental proxy re-encryption scheme is used to simplify the file modification by the data owner by dividing the file into different data blocks. Cipher text policy attribute based encryption is used to perform encryption on data blocks.