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The infection rate of COVID-19 and lack of an approved vaccine has forced governments and health authorities to adopt lockdowns, increased testing, and contact tracing to reduce the spread of the virus. Digital contact tracing has become a supplement to the traditional manual contact tracing process. However, although there have been a number of digital contact tracing apps proposed and deployed, these have not been widely adopted owing to apprehensions surrounding privacy and security. In this paper, we propose a blockchain-based privacy-preserving contact tracing protocol, "Did I Meet You" (DIMY), that provides full-lifecycle data privacy protection on the devices themselves as well as on the back-end servers, to address most of the privacy concerns associated with existing protocols. We have employed Bloom filters to provide efficient privacy-preserving storage, and have used the Diffie-Hellman key exchange for secret sharing among the participants. We show that DIMY provides resilience against many well known attacks while introducing negligible overheads. DIMY's footprint on the storage space of clients' devices and back-end servers is also significantly lower than other similar state of the art apps.

There have been several digital contact tracing apps proposed and deployed. However, these have not been widely adopted owing to apprehensions surrounding privacy and security. We propose a blockchain-based privacy-preserving contact tracing protocol, "Did I Meet You" (DIMY), that provides full-lifecycle data privacy protection on the devices themselves as well as on the back end, to address most of the privacy concerns associated with existing protocols. We have employed Bloom filters to provide efficient privacy-preserving storage and have used the Diffie-Hellman key exchange for secret sharing among the participants. DIMY’s footprint on the storage space of clients’ devices and blockchain-based back end is significantly lower than other similar state-of-the-art apps. We have implemented DIMY with the front-end application on an Android platform and have used Hyperledger Fabric for the back end.

Blockchain has emerged as a technology that can change the way people and systems interact, providing mechanisms that ensure integrity and ownership of the data produced without reliance on a trusted third-party. Appendable-block blockchain is a novel instantiation that suits for solutions that require a high transaction throughput. Appendable-block blockchains focus on data produced by nodes instead of a relation (transaction) between two entities. This new kind of blockchain can improve how data are stored and managed in distributed systems. This chapter introduces the notion of appendable-block blockchain and exemplifies its applicability in multiple practical domains. Additionally, the authors provide a discussion on the security aspects of this new blockchain. Finally, the chapter presents current issues and possible future directions for appendable-block blockchains.

In the last few years, different researchers presented proposals for using blockchain in the Internet of Things (IoT) environments. These proposals consider that IoT environments can be benefited from different blockchain characteristics, such as: resilience, distributed processing, integrity and non-repudiation of produced information. However, researchers faced some challenges to use blockchain in IoT, e.g., latency, hardware and energy constraints, and performance requirements. One of the prominent solutions is the appendable-block blockchain, which uses a hierarchical peer-to-peer (p2p) gateway-based architecture. Additionally, current proposals present simplified evaluation scenarios, usually performed in controlled environments, which do not include important network features, for example, latency. Consequently, a model to evaluate a geographically distributed environment, for example, in a situation in which health data have to be collected from different countries in a pandemic situation, can help to understand the behavior and possible flaws of blockchains. In order to evaluate appendable-block blockchains in a realistic scenario, this paper presents an analysis of different consensus algorithms in geographically distributed hosts, in which latency can impact the performance of main operations in a blockchain, such as block and transaction insertion.

Currently, blockchain proposals are being adopted to solve security issues, such as data integrity, resilience, and non-repudiation. To improve certain aspects, e.g., energy consumption and latency, of traditional blockchains, different architectures, algorithms, and data management methods have been recently proposed. For example, appendable-block blockchain uses a different data structure designed to reduce latency in block and transaction insertion. It is especially applicable in domains such as Internet of Things (IoT), where both latency and energy are key concerns. However, the lack of some features available to other blockchains, such as Smart Contracts, limits the application of this model. To solve this, in this work, we propose the use of Smart Contracts in appendable-block blockchain through a new model called context-based appendable-block blockchain. This model also allows the execution of multiple smart contracts in parallel, featuring high performance in parallel computing scenarios. Furthermore, we present an implementation for the context-based appendable-block blockchain using an Ethereum Virtual Machine (EVM). Finally, we execute this implementation in four different testbed. The results demonstrated a performance improvement for parallel processing of smart contracts when using the proposed model.

The video footage produced by the surveillance cameras is an important evidence to support criminal investigations. Video evidence can be sourced from public (trusted) as well as private (untrusted) surveillance systems. This raises the issue of establishing integrity and auditability for information provided by the untrusted video sources. In this paper, we focus on a airport ecosystem, where multiple entities with varying levels of trust are involved in producing and exchanging video surveillance information. We present a framework to ensure the data integrity of the stored videos, allowing authorities to validate whether video footage has not been tampered. Our proposal uses a lightweight blockchain technology to store the video metadata as blockchain transactions to support the validation of video integrity. The proposed framework also ensures video auditability and non-repudiation. Our evaluations show that the overhead introduced by employing the blockchain to create and query the transactions introduces a very minor latency of a few milliseconds.

The Internet of Things (IoT) is transforming our physical world into a complex and dynamic system of connected devices on an unprecedented scale. Connecting everyday physical objects is creating new business models, improving processes and reducing costs and risks. Recently, blockchain technology has received a lot of attention from the community as a possible solution to overcome security issues in IoT. However, traditional blockchains (such as the ones used in Bitcoin and Ethereum) are not well suited to the resource-constrained nature of IoT devices and also with the large volume of information that is expected to be generated from typical IoT deployments. To overcome these issues, several researchers have presented lightweight instances of blockchains tailored for IoT. For example, proposing novel data structures based on blocks with decoupled and appendable data. However, these researchers did not discuss how the consensus algorithm would impact their solutions, i.e., the decision of which consensus algorithm would be better suited was left as an open issue. In this paper, we improved an appendable-block blockchain framework to support different consensus algorithms through a modular design. We evaluated the performance of this improved version in different emulated scenarios and studied the impact of varying the number of devices and transactions and employing different consensus algorithms. Even adopting different consensus algorithms, results indicate that the latency to append a new block is less than 161ms (in the more demanding scenario) and the delay for processing a new transaction is less than 7ms, suggesting that our improved version of the appendable-block blockchain is efficient and scalable, and thus well suited for IoT scenarios.

The exponential increase in connected devices with built-in sensing, processing, and communication capabilities has fuelled the development of IoT applications, which creates new ecosystems for device-to-device interactions, supports smart environments, and leads to new business models. Empowered by these capabilities, IoT devices interact with each other and their environments to collect, process, and share data. Security, privacy, and reliability of data are major concerns that need to be addressed for the development of IoT applications. Recently, blockchain technology has attracted significant interest from researchers and industry leaders due to its potential for enhancing security, privacy, and reliability of the data. Blockchain offers distributed and immutable ledgers for IoT communications in the form of tamper-proof records, built-in cryptocurrency support for transactions between devices and other entities, and smart contracts to execute automated programs when certain conditions are met. Although there are potential benefits of the integration of blockchain technology to IoT, the integration introduces new challenges, such as scalability, in the design of blockchains suited for IoT applications. In this chapter, we explore key benefits and design challenges for blockchain technologies, and potential applications of blockchain technologies for IoT.

The ubiquity of connecting technologies in smart vehicles and the incremental automation of its functionalities promise significant benefits, including a significant decline in congestion and road fatalities. However, increasing automation and connectedness broadens the attack surface and heightens the likelihood of a malicious entity successfully executing an attack. In this paper, we propose a Blockchain based Framework for sEcuring smaRt vehicLes (B-FERL). B-FERL uses permissioned blockchain technology to tailor information access to restricted entities in the connected vehicle ecosystem. It also uses a challenge–response data exchange between the vehicles and roadside units to monitor the internal state of the vehicle to identify cases of in-vehicle network compromise. In order to enable authentic and valid communication in the vehicular network, only vehicles with a verifiable record in the blockchain can exchange messages. Through qualitative arguments, we show that B-FERL is resilient to identified attacks. Also, quantitative evaluations in an emulated scenario show that B-FERL ensures a suitable response time and required storage size compatible with realistic scenarios. Finally, we demonstrate how B-FERL achieves various important functions relevant to the automotive ecosystem such as trust management, vehicular forensics and secure vehicular networks.

In the last few years, novel approaches for using blockchain to solve Internet of Things (IoT) security and dependability issues have been proposed. Currently, different solutions were applied to Smart Homes, Smart Cities, Smart Grids, Supply Chains, Industry, and Vehicular Networks scenarios. Despite of that, the main advantages on the adoption of different architectures, models and algorithms proposed in the state of art of blockchain in IoT scenarios are not yet clear. This paper presents some discussion about the usage of blockchain technology in IoT environments and proposes a layer model of blockchains for IoT. In addition, we present an overview of the latest research regarding network architectures, consensus algorithms, data management, and applications. Finally, this paper presents open issues and future trends about blockchain in IoT.

There is increased interest in smart vehicles acting as both data consumers and producers in smart cities. Vehicles can use smart city data for decision-making, such as dynamic routing based on traffic conditions. Moreover, the multitude of embedded sensors in vehicles can collectively produce a rich data set of the urban landscape that can be used to provide a range of services. Key to the success of this vision is a scalable and private architecture for trusted data sharing. This paper proposes a framework called SpeedyChain, that leverages blockchain technology to allow smart vehicles to share their data while maintaining privacy, integrity, resilience and non-repudiation in a decentralized, and tamper-resistant manner. Differently from traditional blockchain usage (e.g., Bitcoin and Ethereum), the proposed framework uses a blockchain design that decouples the data stored in the transactions from the block header, thus allowing for fast addition of data to the blocks. Furthermore, an expiration time for each block to avoid large sized blocks is proposed. This paper also presents an evaluation of the proposed framework in a network emulator to demonstrate its benefits., 10 pages

Security has been one of the major concerns for the computer network community due to resource abuse and malicious flows intrusion. Before a network or a system is attacked, a port scan is typically performed to discover vulnerabilities, like open ports, which may be used to access and control them. Several studies have addressed Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS) methods for detecting malicious activities, based on received flows or packet data analysis. However, those methods lead to an increase in switching latency, due to the need to analyze flows or packets before routing them. This may also increase network overhead when flows or packets are duplicated to be parsed by an external IDS. On the one hand, an IDS/IPS may be a bottleneck on the network and may not be useful. On the other hand, the new paradigm called Software Defined Networking (SDN) and the OpenFlow protocol provide some statistical information about the network that may be used for detecting malicious activities. Hence, this work presents a new port scan IPS for SDN based on the OpenFlow switch counters data. A non-intrusive and lightweight method was developed and implemented, with low network overhead, and low memory and processing power consumption. The results showed that our method is effective on detecting and preventing port scan attacks.

Due to increased number of attacks on the Internet of Things (IoT) devices, the security of IoT networks became critical. Some recent researches proposed the adoption of blockchain in IoT networks without a thorough discussion on the impact of the solution on the devices performance. Furthermore, blockchain employment in the context of IoT can be challenging due to the devices hardware limitations. To fill this gap, this paper proposes an IoT ledger-based architecture to ensure access control on heterogeneous scenarios. This research applies conventional devices used on IoT networks, such as Arduino, Raspberry and Orange Pi boards. Finally, we perform performance evaluation focused on access control of IoT devices and on information propagation through peers on a private IoT network scenario.

One of the challenges in developing multi-robot systems is the design of appropriate coordination strategies in such a way that robots perform their operations efficiently. In particular, efficient coordination requires judicious task allocation. Without appropriate task allocation, the use of multi-robot systems in complex scenarios becomes limited or even unfeasible. Real-world scenarios usually require the use of heterogeneous robots and task fulfillment with different structures, constraints, and degrees of complexity. In such scenarios, decentralised solutions seem to be appropriate for task allocation, since centralised solutions represent a single point of failure for the system. During the allocation process, in decentralised approaches, there are often communication requirements, as participants need to share information. Maintaining data integrity, resilience, and security in data access are some of the important features for this type of solution. In that direction, we propose an architecture for dynamic and decentralised allocation of tasks built on the idea of having communication and coordination in a multi-agent system through a private blockchain.

Reliable network time measurement tools are important to ensure that monitoring network systems work properly, but their development do not consider security as a concern and, for example, delay attacks could compromise those tools effectiveness. Indeed, nowadays the network time measurement is not always reliable. Some researches do propose to increase network time measurement reliability using Openflow. Nonetheless, those researches do not consider the impact of altering some of the Openflow controller algorithms in their analysis. On one hand, this paper investigates how the provided POX Openflow Controller packet forwarding strategies could be applied to compromise network time measurement reliability. On the other hand, this paper also shows that the way those strategies are applied could prevent against new attacks that need to trust on network time measurement. Therefore, some experiments were performed to show the impact of the POX packet forwarding algorithms on network time measurement, either to compromise or to help in protecting the network.

Data traffic on the Internet is growing continuously due to the high number of connected devices and increased number of applications and transactions performed online. To ensure information security, integrity and confidentiality, cryptography is applied over transmitted or stored data. Hence, even if an attacker capture data packets, its reading is hampered or not even possible. However, an attacker can also use cryptography to mask an attack in order to avoid detection, for example, by an Intrusion Detection System (IDS). Recent studies in network technologies introduced a new paradigm called Software Defined Networking (SDN). By decoupling data and control plans, the SDN architecture allows centralizing the network management, intelligence and control into a single point, called Controller. The OpenFlow protocol, widely adopted in SDN, provides specific messages to get statistical information of an OpenFlow switch. A Controller can request this information, which enables the development of new IDS models to detect encrypted attacks. In this work, we intend to identify encrypted insider attacks in SDN by developing a new IDS approach that can detect encrypted attacks.

Authentication is a crucial solution to be considered for securing an application or user's personal data. It is a mechanism that plays a role to allow only the rightful user to access an application and the corresponding data, without allowing any kind of impersonation. To avoid this impersonation, biometric mechanisms have been used to read some biological characteristic from the user. However, the extra hardware needed for reading the biometric feature is usually a problem. Besides, in some scenarios, this will definitely avoid its adoption. Nonetheless, nowadays, this problem may be reduced since almost every adult person possesses a smartphone, which contains several sensors that can be used to read biometric information from a user. This work proposes a mechanism to allow a smartphone to act as a biometric reader for different levels of task/data available in a web application. In order to bind a smartphone to a web application, we use QR-Code sent from a web server to a web client, which will have to be read by a smartphone and then be sent back to the web server, so the web server knows that the actual user is close to the web client. This paper also provides a discussion on how to evaluate the usability of the proposed mechanism.

The major challenge for usability tests on mobile systems is to reproduce the context in which they are used. This paper points out some of the main difficulties encountered in the evaluation of such mobile systems, considering the real context of the user. Considering the need to assess such applications on the user's context, it was conducted a field study to evaluate an urban mobility system and, for this purpose, it was proposed a collection instrument, which can be used by the observer to take notes related to the evaluation, enabling various forms of content (observations, important points of the environment, user's verbal utterances, etc.). Through the field study, it was evaluated the benefits of using the proposed instrument, as well as identifying some of the difficulties faced in this type of study, i.e., evaluation of mobile systems on the move.