The blockchain technology has revolutionized the digital currency space with the pioneering cryptocurrency platform named Bitcoin. From an abstract perspective, a blockchain is a distributed ledger capable of maintaining an immutable log of transactions happening in a network. In recent years, this technology has attracted significant scientific interest in research areas beyond the financial sector, one of them being the Internet of Things (IoT). In this context, the blockchain is seen as the missing link toward building a truly decentralized, trustless, and secure environment for the IoT and, in this survey, we aim to shape a coherent and comprehensive picture of the current state-of-the-art efforts in this direction. We start with fundamental working principles of blockchains and how blockchain-based systems achieve the characteristics of decentralization, security, and auditability. From there, we build our narrative on the challenges posed by the current centralized IoT models, followed by recent advances made both in industry and research to solve these challenges and effectively use blockchains to provide a decentralized, secure medium for the IoT.

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Applications of Blockchains in the Internet of Things: A Comprehensive Survey

Vehicular ad hoc networks (VANETs) are becoming the most promising research topic in intelligent transportation systems, because they provide information to deliver comfort and safety to both drivers and passengers. However, unique characteristics of VANETs make security, privacy, and trust management challenging issues in VANETs’ design. This survey article starts with the necessary background of VANETs, followed by a brief treatment of main security services, which have been well studied in other fields. We then focus on an in-depth review of anonymous authentication schemes implemented by five pseudonymity mechanisms. Because of the predictable dynamics of vehicles, anonymity is necessary but not sufficient to thwart tracking an attack that aims at the drivers’ location profiles. Thus, several location privacy protection mechanisms based on pseudonymity are elaborated to further protect the vehicles’ privacy and guarantee the quality of location-based services simultaneously. We also give a comprehensive analysis on various trust management models in VANETs. Finally, considering that current and near-future applications in VANETs are evaluated by simulation, we give a much-needed update on the latest mobility and network simulators as well as the integrated simulation platforms. In sum, this paper is carefully positioned to avoid overlap with existing surveys by filling the gaps and reporting the latest advances in VANETs while keeping it self-explained.

A Survey on Recent Advances in Vehicular Network Security, Trust, and Privacy

Modern cyber physical systems (CPSs) has widely being used in our daily lives because of development of information and communication technologies (ICT). With the provision of CPSs, the security and privacy threats associated to these systems are also increasing. Passive attacks are being used by intruders to get access to private information of CPSs. In order to make CPSs data more secure, certain privacy preservation strategies such as encryption, and k-anonymity have been presented in the past. However, with the advances in CPSs architecture, these techniques also need certain modifications. Meanwhile, differential privacy emerged as an efficient technique to protect CPSs data privacy. In this paper, we present a comprehensive survey of differential privacy techniques for CPSs. In particular, we survey the application and implementation of differential privacy in four major applications of CPSs named as energy systems, transportation systems, healthcare and medical systems, and industrial Internet of things (IIoT). Furthermore, we present open issues, challenges, and future research direction for differential privacy techniques for CPSs. This survey can serve as basis for the development of modern differential privacy techniques to address various problems and data privacy scenarios of CPSs.

Differential Privacy Techniques for Cyber Physical Systems: A Survey

The public key infrastructure-based authentication protocol provides basic security services for the vehicular ad hoc networks (VANETs). However, trust and privacy are still open issues due to the unique characteristics of VANETs. It is crucial to prevent internal vehicles from broadcasting forged messages while simultaneously preserving the privacy of vehicles against the tracking attacks. In this paper, we propose a blockchain-based anonymous reputation system (BARS) to establish a privacy-preserving trust model for VANETs. The certificate and revocation transparency is implemented efficiently with the proofs of presence and absence based on the extended blockchain technology. The public keys are used as pseudonyms in communications without any information about real identities for conditional anonymity. In order to prevent the distribution of forged messages, a reputation evaluation algorithm is presented relying on both direct historical interactions and indirect opinions about vehicles. A set of experiments is conducted to evaluate BARS in terms of security, validity, and performance, and the results show that BARS is able to establish a trust model with transparency, conditional anonymity, efficiency, and robustness for VANETs.

A Privacy-Preserving Trust Model Based on Blockchain for VANETs

Authentication and privacy schemes for vehicular ad hoc networks (VANETs): A survey

The initial phase of the deployment of vehicular ad-hoc networks (VANETs) has begun and many research challenges still need to be addressed. Location privacy continues to be in the top of these challenges. Indeed, both academia and industry agreed to apply the pseudonym changing approach as a solution to protect the location privacy of VANETs’ users. However, due to the pseudonyms linking attack, a simple changing of pseudonym shown to be inefficient to provide the required protection. For this reason, many pseudonym changing strategies have been suggested to provide an effective pseudonym changing. Unfortunately, the development of an effective pseudonym changing strategy for VANETs is still an open issue. In this paper, we present a comprehensive survey and classification of pseudonym changing strategies. We then discuss and compare them with respect to some relevant criteria. Finally, we highlight some current researches, and open issues and give some future directions.

A Survey on Pseudonym Changing Strategies for Vehicular Ad-Hoc Networks

The initial phase of the deployment of Vehicular Ad-Hoc Networks (VANETs) has begun and many research challenges still need to be addressed. Location privacy continues to be in the top of these challenges. Indeed, both of academia and industry agreed to apply the pseudonym changing approach as a solution to protect the location privacy of VANETs'users. However, due to the pseudonyms linking attack, a simple changing of pseudonym shown to be inefficient to provide the required protection. For this reason, many pseudonym changing strategies have been suggested to provide an effective pseudonym changing. Unfortunately, the development of an effective pseudonym changing strategy for VANETs is still an open issue. In this paper, we present a comprehensive survey and classification of pseudonym changing strategies. We then discuss and compare them with respect to some relevant criteria. Finally, we highlight some current researches, and open issues and give some future directions.

A survey on pseudonym changing strategies for Vehicular Ad-Hoc Networks

VLPZ: The Vehicular Location Privacy Zone☆

Location privacy remains an open issue in VANETs. Although, frequently pseudonym changing is commonly accepted as solution to protect privacy in VANETs, many studies have been shown its weakness to provide the required level of privacy protection. In this paper, we propose a practical pseudonym changing strategy, called Silence a Swap at Signalized Intersection (S2SI). S2SI consists of two protocols, one for creating of safe silent mix zones and another for exchanging pseudonyms between vehicles under the control of RSUs within these zones. We evaluate the provided privacy protection of our strategy by developing anonymity set analytic model and by performing a simulative study of the strategy using the entropy of vehicles' anonymity set as the primary metric.

S2SI: A Practical Pseudonym Changing Strategy for Location Privacy in VANETs

Location privacy is one of the main challenges in Vehicular Ad-hoc Networks (VANETs), since weak protection may hinder the public acceptance of this technology. Frequently changing pseudonyms are commonly accepted as a solution to protect the location privacy in VANETs. However, a simple pseudonym change is not enough to provide the required protection. Although many pseudonym changing strategies have been proposed to enhance the location privacy protection provided by this approach, the development of an effective strategy is not yet achieved. In this paper, we propose a new pseudonym changing strategy called Traffic-Aware Pseudonym Changing Strategy (TAPCS). The aim of this strategy is to provide an effective location privacy protection against the different types of pseudonyms linking attacks that can be performed by a strong passive adversary model. TAPCS is a distributed pseudonym changing strategy and is one of the strategies that use the radio silence technique. Unlike the existing distributed pseudonym changing strategies that use this technique, TAPCS aims to provide a high level of location privacy protection without impacting the safety in the VANETs. The analytical evaluation and simulation results demonstrate the effectiveness of the proposed strategy.

Abdelwahab Boualouache

Papers

A Survey on Pseudonym Changing Strategies for Vehicular Ad-Hoc Networks

A survey on pseudonym changing strategies for Vehicular Ad-Hoc Networks

VLPZ: The Vehicular Location Privacy Zone☆

S2SI: A Practical Pseudonym Changing Strategy for Location Privacy in VANETs

TAPCS: Traffic-aware pseudonym changing strategy for VANETs