Efficient Hierarchical and Time-Sensitive Data Sharing with User Revocation in Mobile Crowdsensing

Recently, cloud-based mobile crowdsensing (MCS) has developed into a promising paradigm which can provide convenient data sensing, collection, storage, and sharing services for resource-constrained terminates. Nevertheless, it also inflicts many security concerns such as illegal access toward user secret and privacy. To protect shared data against unauthorized accesses, many studies on Ciphertext-Policy Attribute-Based Encryption (CP-ABE) have been proposed to achieve data sharing granularity. However, providing a scalable and time-sensitive data-sharing scheme across hierarchical users with compound attribute sets and revocability remains a big issue. In this paper, we investigate this challenge and propose a hierarchical and time-sensitive CP-ABE scheme, named HTR-DAC, which is characteristics of time-sensitive data access control with scalability, revocability, and high efficiency. Particularly, we propose a time-sensitive CP-ABE for hierarchical structured users with recursive attribute sets. Moreover, we design a robust revocable mechanism to achieve direct user revocation in our scheme. We also integrate verifiable outsourced decryption to improve efficiency and guarantee correctness in decryption procedure. Extensive security and performance analysis is presented to demonstrate the security requirement satisfaction and high efficiency for our data-sharing scheme in MCS.