A Stronger Secure Ciphertext Fingerprint-Based Commitment Scheme for Robuster Verifiable OD-CP-ABE in IMCC

Outsourced decryption attribute-based encryption (OD-ABE) is emerging as a promising cryptographic tool to provide efficient fine-grained access control for data accessing and sharing in cloud-assisted Intelligent Internet of Mobile Things (IIoMT). Decryption verification is an essential property of OD-ABE to enable the mobile user to verify the precision of the decryption data. Unfortunately, the most representative verification (commitment) algorithms have various security flaws. In this article, we first indicate that the two state-of-art key-based commitment schemes are vulnerable to “Commitment Extract(Decrypt)-then-Reuse Attack” and “Commitment Impersonation Attack” which demolish the unforgeability of the commitment. Then to cover all the existing attacks to commitment algorithms, we redefine a robuster verifiable security model for verifiable OD-ABE. Subsequently, we invent a ciphertext fingerprint (CTfp)-based commitment scheme and give rigorous proof to the proposed commitment scheme, including binding, hiding, unforgeability, and nonrepudiation (traceability) in the random oracle. Next, we apply our CTfp-based commitment to the widely used OD-ABE schemes to provide them robuster verifiability. Finally, the theoretical comparison and simulation experiments are presented to show our new type of commitment algorithm is more secure and practical.

I. Introduction

With the rapid advancements of the intelligent sensor technologies and new generation wireless networks [1], [2], the number of Intelligent Internet of Mobile Things (IIoMT) [3] is exponentially growing and being widely deployed in smart city. To provide big data storage and high-speed data processing capabilities to IIoMT, some researchers adopted the cloud computing [4] in IIoMT and then proposed a promising computing paradigm—cloud-assisted IIoMT, also known as the intelligent mobile cloud computing (IMCC) [5], [6]. The framework of IMCC is depicted as Fig. 1. In IMCC, popping up a myriad of mobile devices brings more challenges to data security, including transmission security and storage security. The secure channel protocols (TLS1.3 [7] /SSH [8], [9] /HTTPS [10]) only can ensure the data transmission security. Adopting an encryption scheme to the data before sharing it onto cloud will ensure both the storage security and transmission security. However, the traditional cryptographic primitives have no ability to provide fine-grained access control to encrypted data. Fig. 1.

Framework of IMCC.