An Efficiently Revocable Cloud-based Access Control Using Proxy Re-encryption and Blockchain

Existing cloud-based access control schemes employing ciphertext-policy attribute-based encryption (CP-ABE) generally achieve secure and fine-grained data sharing. However, most works have not taken the full support of both user and attribute revocation with the auditability of revocation transactions in their core contributions. In this paper, we proposed a blockchain-assisted cloud-based access control scheme composing a set of cryptographic protocols leveraging CP-ABE and blockchain technology to deliver an optimized user and attribute revocation cost which is capable of efficiently handling both users and attribute revocation with the auditable feature. Specifically, we devised cryptographic protocols to work with the blockchain and smart contracts to handle user authentication checking, cryptographic processes, and revocation management for data outsourced in the cloud. To evaluate the efficiency of our proposed scheme, we run experiments to show that the performance of ciphertext re-encryption and key update is efficient and implementable.

I. Introduction

Cloud computing has been utilized by countless application services as it provides a scalable, resilient, cost-saving, and efficient platform for system development, system hosting, data sharing, and service delivery. Although the cloud provides numerous benefits, security, and privacy are the issues that most organizations are reluctant to use the cloud. Specifically, the privacy and security of their data will be outsourced to the cloud. Basically, cloud service providers (CSPs) provide basic security perimeters such as authentication methods and access logs for their enterprise customers. However, the security and privacy of data outsourced have not been fully assured. Therefore, data owners need to implement additional data privacy-preserving solutions, such as encryption, to protect the content of their data. Nonetheless, implementing both an access control environment and encryption requires double operations and key management costs.