Privacy Preserving Attribute Based Encryption for Multiple Cloud Collaborative Environment

In a Multiple Cloud Collaborative Environment (MCCE), cloud users and cloud providers interact with each other via a brokering service to request and provision cloud services. The brokering service considers several pieces of data to broker the best deal between users and providers which can subsequently risk the privacy and security of MCCE. In this paper, we propose a Privacy Preserving Attribute-Based Encryption (PPABE) scheme which protects MCCE from a compromised broker. The proposed encryption scheme preserves the privacy by employing data access policy over sets of attributes. The identifying attributes are anonymoized using pseudonyms. The data access policy is further anonymized so as it remains unknown to unauthorized parties. The PP-ABE achieves unlinkability between different data items which flows through the collaborative cloud environment and preserves the privacy of cloud users and cloud providers.