Location Privacy in VANETs: Provably Secure Anonymous Key Exchange Protocol Based on Self-Blindable Signatures

open access articleSecurity and privacy in vehicular ad hoc networks (VANETs) are challenging in terms of Intelligent Transportation Systems (ITS) features. The distribution and decentralisation of vehicles could threaten location privacy and confidentiality in the absence of trusted third parties (TTP)s or if they are otherwise compromised. If the same digital signatures (or the same certificates) are used for different communications, then adversaries could easily apply linking attacks. Unfortunately, most of the existing schemes for VANETs in the literature do not satisfy the required levels of security, location privacy, and efficiency simultaneously. This paper presents a new and efficient end-to-end anonymous key exchange protocol based on Yang et al. 's self-blindable signatures. In our protocol, vehicles first privately blind their own private certificates for each communication outside the mix-zone and then compute an anonymous shared key based on zero-knowledge proof of knowledge (PoK). The efficiency comes from the fact that once the signatures are verified, the ephemeral values in PoK are also used to compute a shared key through an authenticated Diffie-Hellman key exchange protocol. Therefore, the protocol does not require any further external information to generate a shared key. Our protocol also does not require an interference with the Roadside Units or Certificate Authorities, and hence can be securely run outside the mixed-zones. We demonstrate the security of our protocol in an ideal/real simulation paradigm. Hence, our protocol achieves secure authentication, forward unlinkability, and accountability. Furthermore, the performance analysis shows that our protocol is more efficient in terms of computational and communication overheads compared to existing schemes

Improved Chaff-Based CMIX for Solving Location Privacy Issues in VANETs

open access articleSafety application systems in Vehicular Ad-hoc Networks (VANETs) require the dissemination of contextual information about the scale of neighbouring vehicles; therefore, ensuring security and privacy is of utmost importance. Vulnerabilities in the messages and the system’s infrastructure introduce the potential for attacks that lessen safety and weaken passengers’ privacy. The purpose of short-lived anonymous identities, called “pseudo-identities”, is to divide the trip into unlinkable short passages. Researchers have proposed changing pseudo-identities more frequently inside a pre-defined area, called a cryptographic mix-zone (CMIX) to ensure enhanced protection. According to ETSI ITS technical report recommendations, the researchers must consider the low-density scenarios to achieve unlinkability in CMIX. Recently, Christian et al. proposed a Chaff-based CMIX scheme that sends fake messages under the consideration of low-density conditions to enhance vehicles’ privacy and confuse attackers. To accomplish full unlinkability, in this paper, we first show the following security and privacy vulnerabilities in the Christian et al. scheme: Linkability attacks outside the CMIX may occur due to deterministic data sharing during the authentication phase (e.g., duplicate certificates for each communication). Adversaries may inject fake certificates, which breaks Cuckoo Filters’ (CFs) updates authenticity, and the injection may be deniable. CMIX symmetric key leakage outside the coverage may occur. We propose a VPKI-based protocol to mitigate these issues. First, we use a modified version of Wang et al.’s scheme to provide mutual authentication without revealing the real identity. To this end, the messages of a vehicle are signed with a different pseudo-identity “certificate”. Furthermore, the density is increased via the sending of fake messages in low traffic periods to provide unlinkability outside the mix-zone. Second, unlike Christian et al.’s scheme, we use the Adaptive Cuckoo Filter (ACF) instead of CF to overcome the false positives’ effect on the whole filter. Moreover, to prevent any alteration of the ACFs, only RUSs distribute the updates, and they sign the new fingerprints. Third, the mutual authentication prevents any leakage from the mix zones’ symmetric keys by generating a fresh one for each communication through a Diffie–Hellman key exchange

Efficient CO2/CH4 Separation Using Polysulfone/NH2-MIL-125(Ti) Mixed Matrix Membranes

This study investigates the fabrication and optimization of mixed matrix membranes (MMMs) composed of NH2-MIL-125(Ti), a metal–organic framework (MOF), dispersed within a polysulfone (PSf) polymer matrix, for efficient CO2/CH4 separation. The MMMs were prepared by using a solution casting method, and their morphology and gas separation performance were systematically characterized. The effect of MOF addition into the polymer matrix, gas permeability, and selectivity were evaluated using a gas permeation setup. Results indicate that incorporating NH2-MIL-125(Ti) nanoparticles enhances the selectivity of the membranes for CO2 over CH4 compared to pure polymer membranes while maintaining acceptable permeability. The membrane morphology demonstrates the uniform distribution of the filler in the polymer matrix. The PSf/NH2-MIL-125(Ti)-15% membrane showed exceptional CO2 permeability and selectivity performance. Specifically, it achieved a CO2 permeability of 19.17 Barrer. Additionally, it exhibited a CO2/CH4 selectivity of 31.95, indicating its ability to effectively differentiate between the CO2 and CH4 gases, which is critical for applications such as natural gas purification and carbon capture. Furthermore, the MMMs produced in this study showed outstanding resistance to CO2 plasticization. The PSf/NH2-MIL-125(Ti)-15% membrane demonstrated superior pressure resistance, withstanding up to 14 bar without significant performance degradation compared to the pristine PSf membrane, which succumbed to plasticization at 4 bar. The enhanced plasticization resistance is attributed to incorporation of NH2-MIL-125(Ti) into the PSf matrix. The combination of high CO2 permeability, excellent selectivity, and robust plasticization resistance positions the PSf/NH2-MIL-125(Ti)-15% membrane as a highly effective solution for CO2 separation applications. The results underscore the potential of these MMMs to achieve significantly better performance metrics than traditional PSf membranes, making them a promising option for industrial gas separation processes

A Transition Towards Localizing the Value Chain of Photovoltaic Energy in Saudi Arabia

Abstract The present paper draws attention to the importance of localizing the value chain of photovoltaic solar energy in Saudi Arabia based on the country’s vision for 2030 to meet the expected increase in energy demand. This paper describes various obstacles and enablers and shows the critical factors that restrain the development of the value chain of photovoltaic solar energy. In this paper, different phases of upstream and downstream activities of the photovoltaic industry value chain related to the current situation in Saudi Arabia were examined and analyzed. This paper further examines the capabilities of the local content of photovoltaic solar energy to determine the scenarios that can be adopted to enhance the photovoltaic solar energy industry. This paper analyzes the expected significant positive impact of localizing the value chain of the photovoltaic solar energy industry on the socioeconomic development, job creation, and technology transfer in Saudi Arabia. The paper concludes with recommendations to facilitate the expansion of the photovoltaic solar industry in Saudi Arabia.</jats:p