Method for providing secure and private fine-grained access to outsourced data

Outsourcing data to the cloud for computation and storage has been on rise in recent years. In this paper we investigate the problem of supporting write operation on the outsourced data for clients using mobile devices. We consider the Attribute-based Encryption (ABE) scheme as it is well suited to support access control in outsourced cloud environment. Currently there is a gap in the literature on providing write access on the data encrypted with ABE. Moreover, since ABE is computationally expensive, it imposes processing burden on resource constrained mobile devices. Our work has two fold advantages. Firstly, we extend the single authority Ciphertext-Policy Attribute-based Encryption (CP-ABE) scheme to support write operations. Secondly, in achieving this goal, we move some of the expensive computations to a manager and remote cloud server by exploiting their high-end computational power. Our security analysis demonstrates that the security properties of system are not compromised.