Blockchain-Based Privacy-Preserving Authentication With Hierarchical Access Control Using Polynomial Commitment for Mobile Cloud Computing

Blockchain-based authentication, as a distributed system, is a significant method to achieve secure service access and provision for the distributed mobile cloud computing (MCC) environment. However, owing to the transparency of blockchain, it remains a challenge to protect users’ access behavior from disclosure. Besides, billions of users in the MCC system may cause storage bottlenecks to the blockchain network. To overcome these challenges, this article designs two blockchain-based privacy-preserving authentication schemes supporting hierarchical access control for the MCC environment. Both schemes allow users to access multiple services with different permissions after a single registration. To address the challenges of privacy disclosure, we use polynomial commitment (PC) to replace the plaintext on the blockchain. Meanwhile, a new verification and updating of the access permission method is proposed using the homomorphic property of PC. The first scheme works toward reducing computation costs, which is more suitable for systems with a limited number of service providers (SPs). On the other hand, the second scheme aims to reduce the storage requirements of blockchain, and it provides more efficient hierarchical access control for large-scale scenarios without requiring more storage space. Then, the security analysis demonstrates that the two schemes satisfy multiple security requirements. Finally, a comparative summary is presented to show that our schemes have good performance in computation and communication efficiency and are well suited to the MCC system.