Efficient Revocable Storage Attribute-based Encryption With Arithmetic Span Programs in Cloud-Assisted Internet of Things

Revocable storage and efficient description of the access policy are necessary to enhance the practicality of the attribute-based encryption (ABE) in real-life scenarios, such as cloud-assisted Internet of Things (IoT). Nevertheless, existing ABE works fail to balance the two vital factors. In this paper, we construct an efficient revocable storage ciphertext-policy attribute-based encryption with arithmetic span programs (RS-CPABE-ASP). The arithmetic span program (ASP) is elegantly utilized as the access structure to reduce the unnecessary cost for defining access policy. Combining the indirect revocation and the ciphertext update mechanism, our work prevents the revoked user unable to access the newly generated data and the old data that can be accessed before. As shown in the outsourced version of RS-CPABE-ASP, the costly part for users to decrypt the data can be outsourced to powerful cloud servers. In this way, users in our RS-CPABE-ASP are able to access their data in a more efficient way by merely one exponential operation. Finally, we carry out detailed theoretical analysis and experimental simulations to evaluate the performance of our work. The results fairly show that our proposed work is efficient and feasible in cloud-assisted IoT.