Secure and Light Weight Fine-grained Access Mechanism for Outsourced Data

In this paper we explore the problem of providing selective read/write access to the outsourced data for clients using mobile devices in an environment that supports users from multiple domains and where attributes are generated by multiple authorities. We consider Ciphertext-Policy Attribute-based Encryption (CP-ABE) scheme as it can provide access control on the encrypted outsourced data. One limitation of CP-ABE is that users can modify the access policy specified by the data owner if write operations are introduced in the scheme. We propose a protocol for providing different levels of access to outsourced data that permits the authorized users to perform write operation without altering the access policy specified by the data owner. Our scheme provides fine-grained read/write access to the users, accompanied with a light weight signature scheme and computationally inexpensive user revocation mechanism suitable for resource-constrained mobile devices. The security analysis demonstrates the robustness of the proposed scheme.