Fully Constant-Size CP-ABE with Privacy-Preserving Outsourced Decryption for Lightweight Devices in Cloud-Assisted IoT

Zhishuo Zhang,Wei Zhang,Zhiguang Qin,Chien-Ming Chen

doi:10.1155/2021/6676862

Abstract

In recent years, ciphertext-policy attribute-based encryption (CP-ABE) has been recognized as a solution to the challenge of the information privacy and data confidentiality in cloud-assisted Internet-of-Things (IoT). Since the devices in cloud-assisted IoT are generally resource-constrained, the lightweight CP-ABE is more suitable for the cloud-assisted IoT. So how to construct the lightweight CP-ABE for the cloud-assisted IoT to achieve the fine-grained access control and ensure the privacy and confidentiality simultaneously is a prominent challenge. Thus, in this paper, we propose a constant-size CP-ABE scheme with outsourced decryption for the cloud-assisted IoT. In our scheme, the ciphertexts and the attribute-based private keys for users are both of constant size, which can alleviate the transmission overhead and reduce the occupied storage space. Our outsourced decryption algorithm is privacy-protective, which means the proxy server cannot know anything about the access policy of the ciphertext and the attributes set of the user during performing the online partial decryption algorithm. This will prevent the privacy from leaking out to the proxy server. And we rigorously prove that our scheme is selectively indistinguishably secure under the chosen ciphertext attacks (IND-CCA) in the random oracle model (ROM). Finally, by evaluating and implementing our scheme as well as other CP-ABE schemes, we can observe that our scheme is more suitable and applicable for cloud-assisted IoT.

Highlights

IoT has been recognized as a new paradigm in the network and information area in recent years [1, 2]
By means of the widespread deployment of spatially distributed devices, such as sensors, radio-frequency identification (RFID), wireless devices, and smartphones, IoT has the perfect sensing and actuation capabilities and makes the existing information system intelligent. ough IoT gives a new dimension to the Internet and has envisioned a future in which digital and physical entities can be linked in anywhere [3,4,5], security is still a critical obstacle for enabling the widespread adoption of the cloud-assisted IoT
In traditional cloud-assisted IoT system, data owners transmit the data to the cloud server over the transmission media and the users download the data from the cloud storage

Summary

Introduction

IoT has been recognized as a new paradigm in the network and information area in recent years [1, 2]. To make CP-ABE applicable for the lightweight devices in the cloud-assisted IoT, in this paper, we propose a lightweight CP-ABE scheme with both constant-size ciphertexts and private keys. One way is to construct the lightweight CP-ABE to mitigate the transmission overhead of the system Another way is outsourcing the decryption phase to proxy server to relieve the computing burden of the users used IoT devices. Emura et al [23] build a fully constant-size CP-ABE scheme with both constant-size ciphertexts and private keys, but the access structure in their scheme [23] is using the less expressive “Strict AND-gate Policy.” These works [24, 25] use [23] as their base construction using the less expressive “Strict AND-gate Policy.”. The users in all the above outsourced CPABE schemes will expose their attribute sets to the proxy server for running the semidecryption, which will lead to the disclosure of the privacy

AND-gate Access Structures

Our Constant-Size CP-ABE Scheme with Privacy-Preserving Outsourced Decryption

Scheme Construction

Evaluation and Implementation

Conclusion