DABE-PU: Decentralized Attribute-Based Data Sharing Scheme with Policy Update Privacy

Ciphertext policy attribute-based encryption (CP-ABE) is one of the most widely used encryption schemes for cloud data sharing due to its ability to protect data confidentiality and access controllability. However, most of the traditional CP-ABE schemes face challenges of distributed deployment difficulties and privacy leakage due to the fact that the attribute key is distributed by a central attribute authority, and the access policy is stored in plaintext. In this paper, we design a decentralized attribute encryption scheme (DABE-PU) with policy update privacy for data sharing. DABE-PU effectively integrates policy privacy and updating while avoiding the single point of failure risk arising from a single attribute authority. Therefore, DABE-PU helps to achieve data sharing that can be implemented in a distributed deployment and supports privacy for policy updating. In addition, DABE-PU ensures that users can complete ciphertext updating with low computation and communication overhead. Finally, we performed a formal security analysis and performance analysis of DABE-PU. The results show that DABE-PU can guarantee the privacy of policy updating as well as efficient ciphertext updating.