Cybersecurity is an crucial characteristic that should be addressed before the extensive deployment of smart city applications. Blockchain, a decentralized and tamper-resistant digital ledger, offers a transformative solution to address the evolving challenges associated with securing smart cities. In this research area we leverage the inherent characteristics of blockchain, such as decentralization and immutability, to contribute to the security of smart cities and to the prevention of unauthorized access, data tampering, and other cyber threats.
My First work on Blockchain deals with the security of Internet of Things (IoT). Then, Blockchain was used for the security of Healthcare applications (with my PhD student Bessem Zaaber), and for the security of Internet of Vehicles (collaborations with colleagues).
In what follow, I briefly describe these works.
The security and privacy of patient health data such as collected vital signs and electronic healthcare records (EHRs) remain a critical issue for both healthcare services consumers and providers. Breaching a healthcare system causes the disclosure of sensitive health data. This data is usually saved into centralized databases, which creates vulnerabilities and gives rise to cyber attacks. This research focuses on enhancing the security and privacy of patient health data by using Blockchain technology.
With my PhD student Bessem Zaaber (2018-2023), we have used Blockchain for the security of healthcare applications and we proposed a new architecture for a blockchain-based Remote Patient Monitoring (RPM) system. In the proposed solution, a patient’s medical data is collected from wearable healthcare devices through an IoT Fog gateway. The Wearable Health Devices (WHD) and the IoT Fog Gateway (GW) are considered assets for a permissioned Blockchain that is built on Hyperledger Fabric. To define and deploy the business model in Hyperledger Fabric, Hyperledger Composer has been used to generate a REST API consumed by a Mobile Web Application (RPMApp). All transactions and distributed ledger of a Blockchain network are stored in the cloud to provide faster service and scalability.
This work was published in:
[1] B. Zaabar, O. Cheikhrouhou, M. Ammi, A.I. Awad, M. Abid, (2021, October). Secure and Privacy-aware Blockchain-based Remote Patient Monitoring System for Internet of Healthcare Things. In IEEE 17th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob) (pp. 200-205). 2021.
10.1109/WiMob52687.2021.9606362 Class: B
· The second contribution consists in an extension to the first one where we considered both the security of Remote Patient Monitoring (RPM) system and Electronic Healthcare Records (EHR) sharing data. We have used two channels in the blockchain network to ensure data privacy. In fact, we have used a devices blockchain channel for saving the wearable healthcare devices and IoT Gateway, which provide data integrity. Besides, we have used a consultation blockchain channel to save hashes of stored data in a decentralized database (OrbitDB with IPFS) and to control access to the patient’s medical data. The use of decentralized storage enhances data availability as no single point of failure in the system. The access control policies are defined by the patient and executed by the smart contract, which ensure data confidentiality. Performance evaluation results issued from Hyperledger Caliper and comparative analysis have proved the robustness and superiority of the proposed system in terms of security and privacy requirements, key features of blockchain-based healthcare systems, and performance metrics including various throughput and latency.
This work was published in:
[2] B. Zaabar, O. Cheikhrouhou, F. Jamil, M. Ammi, & M. Abid, (2021). HealthBlock: A secure blockchain-based healthcare data management system. Computer Networks, 200, December 2021,108500.
https://doi.org/10.1016/j.comnet.2021.108500 Rank=Q1 IF=5.6
Moreover, to detect abnormal traffic in Internet of Medical Things (IoMT) network, we proposed to use an intrusion Detection system (IDS). Traditional signature-based IDS are incapable of detecting zero-day or unknown attacks. Anomaly-based IDS using classical machine learning algorithms share private training data with a central server. To preserve data privacy, a Federated Learning (FL)-based Intrusion Detection System (IDS) is used to train models independently and locally on IoT Gateway, rather than sharing data with a central server. However, the central server presents a single point of failure that could lead to system failure or breach. To address the security issues of the typical FL approach and to build an efficient IDS, we propose a blockchain-based Federated Learning for detecting abnormal traffic in the IoMT networks. The Blockchain network proposed is a channel regrouping the IoT Gateways as members. In essence, each IoT Gateway is not only a client of FL but also a peer of the learning channel. To begin with, an IoT Gateway obtains a generic model that trains it locally based on its local dataset. Then, each IoT Gateway sends the generated updated parameters as a transaction to the peers of the learning channel for endorsement, aggregation, and commitment (these functions belong to Hyperledger framework). After validation, the updates are aggregated and preserved in the learning channel’s ledger to provide a secure training process. Therefore, we have proposed a new architecture for IDS and resolved the security issues of a typical FL approach.
This work was published in:
[3] B. Zaabar, O. Cheikhrouhou, M. Abid, (2022, November). Intrusion Detection System for IoMT through Blockchain-based Federated Learning. In 2022 15th IEEE International Conference on Security of Information and Networks (SIN) (pp. 01-08).
10.1109/SIN56466.2022.9970536 Class: C
Internet of Vehicles (IoV) is an emerging communication architecture for intelligent transportation systems (ITS) in Smart Cities. It was introduced following a striking evolution of Vehicular Ad-Hoc Networks (VANET) with the aim of supporting a wide range of essential applications in smart cities, such as traffic and congestion information, road side services, accident reporting and prevention, navigation, traffic flow management, and entertainment, paving the way towards the betterment of people and contributing to road safety.
The motivations behind our work are: first, in order to avoid security problems in previous blockchain mechanisms that assume all RSUs can act as blockchain miners, we propose a blockchain consensus mechanism in which the blockchain miners are selected among the RSUs based on their accumulated trust. Second, in order to take into account that acting as a blockchain miner can be overwhelming for an RSU in terms of energy consumption, we propose that the task of generating the next block in the blockchain should be interchangeably assigned to a single trusted RSU. Finally, in order to avoid compromise attacks in which the attacker is able to compromise multiple vehicles and/or RSUs, we introduce a redundancy mechanism in which each participant in a transaction sends the latter to multiple RSUs, and each RSU sends the transaction to multiple trusted nodes. Hence, we proposed a new blockchain consensus protocol based on the Proof of Accumulated Trust (PoAT). Our model relies on dynamic selection of miners, based on the change in the trust level of the miner. Our model is the first that calculates the trusts of RSUs based on the legitimacy of exchanged transactions and selects the highest trusted RSUs to become blockchain miners. We conducted extensive experiments in which we compare our system to two recent blockchain-based security frameworks for the IoV. The simulation results illustrate the superiority of our system in terms of attack detection rate, blockchain generation time, and network overhead traffic.
The new proposed Blockchain consensus protocol was called “Proof of Accumulated Trust” and was published in:
[4] K. Mershad, O. Cheikhrouhou, L. Ismail (2021). Proof of Accumulated Trust: A new consensus protocol for the security of the IoV. Vehicular Communications, 32, December 2021, 100392.
https://doi.org/10.1016/j.vehcom.2021.100392 Rank=Q1 IF=6.7
Another work in collaboration with Faisal Jamil (from Jeju National University, Jejusi, Korea) deals with the use of smart contracts (a concept in Blockchain) to avoid problem of classical payment system of smart vehicles. In this work, we present a novel blockchain-based strategy for payment of fueling of smart cars without any human interaction while maintaining transparency, privacy, and trust. The proposed system provides a blockchain-based secure privacy-preserving strategy for payment of fueling among the fuel seller and buyer without human intervention based on the concept of smart contract. Furthermore, we have also analytically evaluated several experiments to determine the proposed blockchain platform’s usability and efficiency. This work was published in:
[5] F. Jamil, O. Cheikhrouhou, H. Jamil, A. Koubaa, A. Derhab, M.A. Ferrag, (2021). PetroBlock: a blockchain-based payment mechanism for fueling smart vehicles. Applied Sciences, 11(7), 3055.
https://doi.org/10.3390/app11073055 Rank=Q2 IF=2.7
The healthcare system, specifically RPM (Remote Patient Monitoring) systems, relies on small and constrained devices known as IoMT (Internet of Medical Things). Although blockchain has demonstrated its benefits for the healthcare system, including security, scalability, and the availability of data (as shown in Section 1) Blockchain for smart healthcare security), it cannot be directly applied to these constrained devices due to the resource-intensive requirements of the blockchain.
To overcome these challenges, we proposed a lightweight Blockchain solution adapted to RPM systems. Moreover, we have designed a three-layer RPM architecture by introducing a fog layer to reduce the latency of traditional RPM systems. In our proposed architecture, fog computing will not replace cloud computing but will cooperate via the lightweight blockchain to provide real-time and efficient service. More precisely, the fog computing layer will host a lightweight blockchain application with low latency requirements.
The proposed solution was published in:
[6] O. Cheikhrouhou, K. Mershad, F. Jamil, R. Mahmud, A. Koubaa, S. R. Moosavi, (2023). A lightweight blockchain and fog-enabled secure remote patient monitoring system. Internet of Things, 100691, 2023.
https://doi.org/10.1016/j.iot.2023.100691 Rank=Q1 IF=5.9
Based on this previous work, we observed that the lightweight Blockchain is a new paradigm that can be applied in different contexts and at different levels of the Blockchain ecosystem. For this reason, we decided to write a survey paper about this new emerging paradigm of lightweight Blockchain. In this paper, we presented a taxonomy of lightweight blockchain solutions proposed in the literature, and we discussed the various methods employed in each category, highlighting existing gaps and identifying areas for improvement.
The survey was published in:
[7] M. Khaleel, and O. Cheikhrouhou. Lightweight blockchain solutions: Taxonomy, research progress, and comprehensive review. Internet of Things 24 (2023): 100984.
https://doi.org/10.1016/j.iot.2023.100984 Rank=Q1 IF=5.9
The main collaboration in the Blockchain based security research area are:
Ø Khaleel Mershad from Lebanese American University (LAU), Beirut, Lebanon,
Ø Faisal Jamil from Norwegian University of Science and Technology,
Unmanned aerial Traffic Management system (UTM) refers to tracking, coordinating and managing the flights of different UAVs in a collaborative and automated way, that enables safe and efficient operations of UAVs into the airspace.
The ability to track UAVs within the UTM system was considered a critical service as this requires drone operators to share their intended flight paths, position data and drone flight data, with airspace authorities. These data are critical and integral to the correct and normal operations of unmanned traffic management. Therefore, the data must be protected from cyber threats, which can lead to serious damage and even casualties and prohibit of the UTM system to function effectively.
Motivated by these facts, in our work, we propose UTM-Chain, a lightweight blockchain solution for securing the UAV flight path, which fits the computational and storage resources limitations of UAVs. Moreover, UTM-Chain provides secure and unalterable traffic data between the UAVs and their ground control stations.
This work was published in:
[8] A. Allouch, O. Cheikhrouhou, A. Koubâa, K. Toumi, M. Khalgui, T.N. N Gia, (2021). UTM-chain: blockchain-based secure unmanned traffic management for internet of drones. Sensors, 21(9), 3049.
https://doi.org/10.3390/s21093049 Rank=Q2 IF=3.9
[9] Allouche, A., Koubaa, A., Khalgui, M., & Cheikhrouhou, O. (2021). Blockchain-based solution for internet of drones security and privacy, U.S. Patent Application No. 16/733,451.
https://patents.google.com/patent/US11488488B2/en
The Internet of Things (IoT) is a prominent component of smart cities. Moreover, several IoT applications are tightly dependent on the locations of the devices. However, localization algorithms can be easily compromised by injecting false locations. During this work, we proposed a Blockchain-based secure localization algorithm for the Internet of Things (IoT). The algorithm uses a public ledger (Blockchain) that contains nodes position and the list of their neighbor nodes. This ledger is shared among the IoT devices. Once an IoT device is localized its new position and the list of neighbor nodes are added to the Blockchain. This shared localization data will be used later by other IoT devices for their localization process. To avoid the attack where a malicious node sends a fake position, the correctness of the claimed position is verified before adding it to the Blockchain. Moreover, data exchanged between nodes (IoT devices) are signed to guarantee their authenticity and integrity. The integration of these security mechanisms into the localization process permits to exclude false data and therefore reduces the localization error. The simulation results show that adding the proposed security mechanism improves the localization accuracy of the algorithm when running in the presence of malicious nodes. The proposed idea was applied to the already proposed Hybrid DV-Hop localization algorithm and proves its efficiency.
This work was published in:
[10] O. Cheikhrouhou, A. Koubaa. "BlockLoc: Secure Localization in the Internet-of-Things using Blockchain." in the International Wireless Communications and Mobile Computing Conference (IWCMC) in Morocco, June 2019.
10.1109/IWCMC.2019.8766440 Class: B
Additionally, we have work about introducing the blockchain Technology to secure routing in WSNs in:
[11] W. Jerbi, O. Cheikhrouhou, A. Guermazi, H. Hamam, H. Trabelsi, (2021, June). A Blockchain based Authentication Scheme for Mobile Data Collector in IoT. In 2021 International Wireless Communications and Mobile Computing (IWCMC) (pp. 929-934). IEEE.
10.1109/IWCMC51323.2021.9498656 Class: B
[12] W. Jerbi, O. Cheikhrouhou, A. Guermazi, A. Boubaker, H. Trabelsi. (2021, June). A Novel Blockchain Secure to Routing Protocol in WSN. In 2021 IEEE 22nd International Conference on High Performance Switching and Routing (HPSR) (pp. 1-6). IEEE.
10.1109/HPSR52026.2021.9481805 Class: C
[13] W. Jerbi, O. Cheikhrouhou, A. Guermazi, M. Baz, H. Trabelsi, (2022). BSI: Blockchain to secure routing protocol in Internet of Things. Concurrency and Computation: Practice and Experience, 34(10), e6794.
https://doi.org/10.1002/cpe.6794 Rank=Q2 IF=2
[14] W. Jerbi, O. Cheikhrouhou, H. Hamam, H. Trabelsi, A. Guermazi, (2022, May). A blockchain-based storage intelligent. In 2022 IEEE International Wireless Communications and Mobile Computing (IWCMC) (pp. 635-640).
10.1109/IWCMC55113.2022.9824790 Class: B