Decentralized attribute-based encryption and data sharing scheme in cloud storage

In this paper, we consider the problems of data sharing between multiple distrusted authorities. Prior solutions rely on trusted third parties such as CAs, or are susceptible to collusion between malicious authorities, which can comprise the security of honest ones. In this paper, we propose a new multi-authority data sharing scheme — Decentralized Multi-Authority ABE (DMA), which is derived from CP-ABE that is resilient to these types of misbehavior. Our system distinguishes between a data owner (DO) principal and attribute authorities (AAs): the DO owns the data but allows AAs to arbitrate access by providing attribute labels to users. The data is protected by policy encryption over these attributes. Unlike prior systems, attributes generated by AAs are not user-specific, and neither is the system susceptible to collusion between users who try to escalate their access by sharing keys. We prove our scheme correct under the Decisional Bilinear Diffie-Hellman (DBDH) assumption; we also include a complete end-to-end implementation that demonstrates the practical efficacy of our technique.